&EPA
United States
Environmental Protection
Agency
Office of Health and Ecological EPA-600/9-78-013
Effects June 1978
Washington DC 20460
Research and Development
Comprehensive Standards
The Power Generation
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/9-78-013
June, 1978
COMPREHENSIVE STANDARDS:
THE POWER GENERATION CASE
EPA No. 68-01-0561
FUEL CYCLES FOR ELECTRIC POWER GENERATION
by Thomas H. Pigford*, .Michael J. Keaton, Report No. EEED 101
Bruce J. Mann* and Peter M. Cukor and
Gladys L. Sessler
FUEL CYCLE FOR 1000-Mu URANIUM-PLUTONIUM FUELED WATER REACTOR
by Thomas H. Pigford*, Robert T. Cantrell*, Report No. EEED 104
and K. P. Ang*
FUEL CYCLE FOR 1000-f-fu) HIGH-TEMPERATURE GAS-COOLED REACTOR
by Thomas H. Pigford*, Robert T. Cantrell*. Report No. EEED 105
K. P. Ang* and Bruce J. Mann**
FUEL CYCLE FOR COtfBUSTION TURBINE-STEAM TURBINE COMBINED CYCLE POWER PLANT
by Peter M. Cukor Report No. EEED 106
* Department, of Nuclear Engineering, University of California, Berkeley, California
** U. S. Environmental Protection Agency, Office of Radiation Programs, Las Vegas, Nevada
Office of Research and Development
Environmental Protection Agency
Washington, D.C.
Project Officer: Paul H. Gerhardt
March, 1975
-------
DISCLAIMER
This report has been reviewed by the Office of Research and Development,
U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the
views and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement
or recommendation for use.
NOTICE
This publication is actually four reports under one cover. Each report
is printed in its entirety, with its own page numbers, table of contents,
etc, one following another.
-------
FUEL CYCLES FOR ELECTRIC POWER GENERATION
Thomas H. Pigford*
Michael John Keaton
Bruce J. Mann**
and
Peter M. Cukor
Gladys L. Sessler
Teknekron Report No. EEED 101
January, 1973
(Revised March, 1975)
* Department of Nuclear Engineering, University of California, Berkeley,
California.
** Now at U.S. Environmental Protection Agency, Office of Radiation
Programs, Las Vegas, Nevada.
-------
ABSTRACT
This study presents an illustrative data base of material quantities and
environmental effluents in the fuel cycles for alternative technologies of
thermally generated power. The entire fuel cycle for each of ten alterna-
tive technologies is outlined for a representative power plant generating
1000 Mw of electrical power. The required utilization of material resources
and the fuel-cycle material quantities are indicated on a flow sheet for
each technology. The technologies considered are:
i
1. Light-Water Nuclear Reactor
2. Coal: Appalachian Bituminous and Northwestern Sub-bituminous
3. Residual Fuel Oil
4. Natural Gas
5. High-Sulfur Coal, with Coal Gasification and Sulfur Removal
6. High-Sulfur Coal, with S02 Recovery by Wet-Limestone Scrubbing
7. Geothermal Steam
8. Breeder Fission Reactor
9. Solar Energy
10. Thermonuclear Fusion
-------
TABLE OF CONTENTS
1 . Introduction ------------------------------------------------------
2. Electrical Power from Uranium Fueled Light-Water Reactor ---------- 7
2.1 Reactor Characteristics ------------------------------------- 7
2.2 Mining ------------------------------------------------------ "
2.3 Milling and Concentration ----------------------------------- ]|
2.4 Conversion of UsOs to UFe -----------------------------------
2.5 Uranium Enrichment ----------- '• ------------------------------- 17
2.6 Fuel Conversion and Fabrication ----------------------------- 20
2.7 Nuclear Power Plant Operation ------------------------------- 22
2.8 Shipment of Irradiated Fuel and Solid Radioactive Wastes ---- 43
2.9 Fuel Reprocessing ------------------------------------------- 44
2.10 Management of High-Level Radioactive Wastes ----------------- 49
2.11 Accidental Environmental Releases --------------------------- 55
2.12 Effect of Plutonium Utilization ----------------------------- 59
References -------------------------------------------------------- 63
3. Electrical Power Generation from Coal:
Appalachian Bituminous and Northwestern Subbituminous ---------- 67
3.1 Introduction ------------------------------------------------ 67
3.2 Underground Mining in the Appalachian Region ---------------- 73
3.3 Surface Mining, Appalachian and Northwestern ---------------- 74
3.4 Cleaning and Preparation of Raw Coal ------------------------ 79
3.5 Transport to Power Plant ------------------------------------ 83
3.6 Coal Storage at Power Plant --------------------------------- 85
3.7 Power Plant Operation --------------------------------------- 86
3.8 Flue Gas Effluents ------------------------------------------ 87
3.9 Fly Ash Removal --------------------------------------------- 89
3.10 Ash Storage ------------------------------------------------- 90
3.11 Liquid Wastes ----------------------------------------------- 91
3.12 Condenser Cooling ------------------------------------------- 92
References -------------------------------------------------------- 94
4. Electrical Power from Residual Fuel Oil --------------------------- 97
4.1 Introduction ------------------------------------------------ 97
4.2 Crude Oil Production ---------------------------------------- 101
4.3 Transport from Wells to Refinery ---------------------------- 103
4.4 Oil Refining ------------------------------------------------ 103
4.5 Transport of Residual Fuel Oil ------------------------------ 110
4.6 Power Plant Operation --------------------------------------- 110
4.7 Flue Gas Effluents ------------------------------------------ 111
4.8 Fly Ash Storage --------------------------------------------- 112
4.9 Condenser Cooling ------------------------------------------- 113
References -------------------------------------------------------- 114
-------
5. Electrical Power from Natural Gas --------------------------------- 117
5. 1 Introduction ------------------------------------------------ Ul
5.2 Gas Production ...... ' ''
5.3 Transmission of Raw Gas to Processing Plant ------ ......
5.4 Raw Gas Processing ------------------------------------------
5.5 Transmission of Residual Gas to Power Plant ---- ...... ------- 126
5.6 Power Plant Operation --------------------------------------- 12°
5.7 Flue Gas Effluents ------------------- ............ ~ ...... — 12/
5.8 Condenser Cooling ------------------------------------------- '28
References
6. Waste Heat Rejection
6.1 Once-Through Cooling Water
6.2 Evaporative Cooling Towers and Spray Cooling ---------------- '34
6.3 Cooling Ponds ...... - ..... - ..... ---------- ...... ------------- 143
6.4 Dry Cooling— ................ ---- ...... ------ ..... ---------- 147
References -------------------------------------------------------- 155
7. Electrical Power from Low Btu Gas Made from High-Sulfur Coal ------ 157
References -------------------------------------------------------- 164
8. Electrical Power from High-Sulfur Coal, S0£ Removal by
Wet Limestone Scrubbing ---------------------------------------- 165
8.1 Process Description ----------------------------------------- 165
8.2 Basis for Flowsheet Quantities- ...... ---- ......... - ...... -— 169
References -------------------------------------------------------- 175
9. Electrical Power from Geothermal Steam ---------------------------- 177
9.1 Introduction ------------------------------------------------ 177
9.2 Geothermal Steam-Extraction Wells --------- ..... ------------- 182
9.3 Turbine-Generator Operation --------------------------------- 183
9.4 Air-Ejector Effluents ------ ..... - ...... — .............. ____ 183
9.5 Cooling System ---- ......... - ....... ---------- ....... _ ....... 184
9.6 Disposal of Condensate Blowdown-- ........................... 185
9.7 Power Plant Land Area ----- ..................... _ ........ ____ 187
References -------------------------------------------------------- 188
-------
10. Electrical Power from Uranium-Plutonium Fueled Breeder Reactoi 189
10.1 Reactor Characteristics and Fuel Requirements 189
10.2 Cooling Irradiated Fuel 193
10.3 Radiological Releases from Reactor 194
10.4 Mining, Milling and Fuel Fabrication 196
10.5 Shipment of Irradiated Fuel 197
10.6 Fuel Reprocessing 198
10.7 Management of High Level Radioactive Wastes 199
10.8 Accidental Environmental Releases 200
References 201
11. Electrical Power from Solar Energy 203
11.1 Introduction 203
11.2 Solar Energy Collection 203
11.3 Turbine Generator Operation 207
11.4 Cooling System 208
11.5 Electrical Energy Transmission 209
References 210
12. Electrical Power from Thermonuclear Fusion 211
12.1 Energy Producing Reactions 211
12.2 Power Conversion 211
12.3 Fuel Materials 215
12.4 Tritium Losses 216
12.5 Activated Structural Material 217
References 221
13. Electrical Power Transmission 223
References 224
VTL.
-------
LIST OF FIGURES
2.1
2.2
3.1
4.1
5.1
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
7-1
8.1
9.1
10.1
11.1
12.1
Light Water Reactor Nuclear Power Plant
Radioactivity Produced in One Year by a 1000 Mw(e)
Light Water Nuclear Power Plant
Coal Power Plant
Residual Fuel Oil Power Plant
Natural Gas Power Plant
Light-Water Nuclear Plant, Waste-Heat Rejection by
Once-Through Cooling
Coal-Fired Power Plant, Waste-Heat Rejection by
Once-Through Cool ing
Light-Water Nuclear Plant, Waste-Heat Rejection by
Evaporative Cooling
Coal -Fired Power Plant, Waste-Heat Rejection by
Evaporative Cool ing
Light-Water Nuclear Plant, Waste-Heat Rejection by
Cooling Pond
Coal -Fired Power Plant, Waste-Heat Rejection by
Cooling Pond
Light-Water Nuclear Plant, Waste-Heat Rejection by
Dry Cooling
Coal -Fired Power Plant, Waste Heat Rejection by
Dry Cooling
Fossil Fueled Power Plant Fueled with Clean Power Gas
Made from 3%-S Coal
Coal Fired Power Plant - S02 Removal by Wet Limestone
Scrubbing
Geothermal Steam Power Plant
Breeder Reactor Nuclear Power Plant
Solar Power Plant
Fusion Reactor Nuclear Plant
9
50
69
99
119
132
133
136
137
145
146
149
150
159
167
179
191
205
213
-------
LIST OF TABLES
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
Environmental Quantities for UgOg - UFg Conversion
Environmental Quantities for Uranium Enrichment
Environmental Quantities for Fuel Conversion and Fabrication-
Radioactivity in Reactor and Fuel Cycle for a 1000 Mw(e)
Water Reactor
Allowable Concentrations and Yearly Releases of Kr85 and I131
for Assumed Atmospheric Dilution
Radioiodine Releases for 1000 Mw(e) Plant Extrapolated
from 1971 Reported Releases
Tritium in Liquid Effluents for Pressurized-Water Nuclear
Power Plants, Extrapolated to 1000 Mw(e)
Tritium Release to Coolant of PWR Plant Equilibrium Fuel
Cycle
Concentrations of Radionuclides in Liquid Effluents for
Light-Water Nuclear Plant with Evaporative Cooling
Estimated Yearly Quantities of Radionuclides, Other than
16
19
21
23
29
31
35
36
38
Tritium, in Liquid Wastes Collected for Processing and
Conversion to Solids, 1000 Mw(e) PWR 40
2.11 Non-Tritium Radionuclides in Liquid Effluents for Light-
Water Nuclear Power Plants, Reported for 1971 42
2.12 Environmental Quantities for Fuel Reprocessing 47
2.13 Estimated Release Rates for an Embedded Salt High-Level
Waste Storage Facility. Full-Scale Operation 54
3.1 Characteristics of Coal Assumed in Flowsheet 72
3.2 Contour and Area Mining as a Percentage of Surface Mining
in the Appalachian Region 75
3.3 Water Usage in Coal-Cleaning Plants in Appalachian States 81
3.4 Thermal Energy Balance for Coal-Fired Power Plant - 1000 Mw(e)- 85
-------
3.5 Uncontrolled Emissions of Gases and Participates from Coal-
Fired Power Plant - 1000 Mw(e) 88
3.6 Radium and Thorium Radionuclides Released from Coal-Fired
Power Plant Stack - 1000 Mw(e) 90
3.7 Radium and Thorium Radionuclides in Stored Ash - 1000 Mw(e) 91
3.8 Boiler Blowdown Releases in Liquid Wastes - 1000 Mw(e) 92
3.9 Cooling Tower Quantities for Coal-Fired Power Plant -
1000 Mw(e) - — 93
4.1 Refinery Products 105
4.2 Oil Refinery Gaseous Effluents — 107
4.3 Oil Refinery Liquid Effluents - 109
4.4 Gaseous Effluents from Oil Fired Power Plant - 1000 Mw(e) 111
4.5 Radium and Thorium Radionuclides in Residual Fuel Oil Ash 112
5.1 Gaseous Effluents from Natural Gas Processing Plant 124
5.2 Gaseous Effluents from Natural-Gas-Fired Power Plant -
1000 Mw(e) - 127
6.1 Water Consumption for Evaporative Cooling Tower, Light-Water
Nuclear Plant - 139
6.2 Heat Rejection by Forced Draft Dry Cooling 1000 Mw(e) Net
Electrical Output 152
8.1 Materials Entering the Scrubbing System 171
8.2 Calcium and Sulfur Products Leaving the Scrubbing Stage 172
8.3 Water Used in the Scrubbing System 173
9.1 Typical Composition of Geothermal Steam 181
9.2 Yearly Quantities of Non-Condensable Gases Emitted
from Turbine Air Ejectors 184
9.3 Composition and Yearly Quantities in Condensate
Return Water
-------
11.1 Boiler Slowdown Releases 208
12.1 Neutron Reactions for Structural Activation in a Fusion
Reactor 219
12.2 Radioactivity in Fusion Reactor Blanket Structure 220
-------
1. INTRODUCTION
It is the purpose of this study to present an illustrative data base for
estimating environmental effluents from alternative technologies for ther-
mally generated electrical power. The data have been developed to illustrate
the characteristics and possible magnitude of effluents to various environ-
mental media and to illustrate the effect of choices of technology on the
media effluents. The entire fuel cycle for each alternate technology is
examined, representative sources of environmental effluents at each step in
the fuel cycle are identified, and material and environmental quantities are
indicated on a representative flow sheet.
The following methods of generating electric power are discussed:
1. Light-water nuclear reactor
2. Coal: Appalachian bituminous and Northwestern subbituminous
3. Residual fuel oil
4. Natural gas
5. High-sulfur coal, with coal gasification and sulfur removal
6. High-sulfur coal, with SO,, recovery by wet-limestone scrubbing
7. Geothermal steam
8. Breeder fission reactor
9. Solar energy
10. Thermonuclear fusion
The technologies include presently available means of electrical power
generation and some examples of alternative means that may be available in
-------
the near future and distant future. To provide an illustrative but specific
data base, within a study whose scope was constrained by resource availability
and time, it was necessary to select a limited number of examples from the very
large number of existing and future alternative technologies, and from the very
large number of technical and regional permutations thereof. Thus, only two
major categories of coal, only one of the many means of removing sulfur from
high-sulfur coal prior to combustion, and only one of the many processes for
removing SCL from combustion gases were examined. Similarly, a number of de-
velopments which may be significant now, or possibly in the future, for low-
effluent electrical power generation were not included, such as fuel cells,
magnetohydrodynamic energy conversion, and direct-conversion solar cells. This
study does not attempt to provide an encyclopedic and definitive analysis of
the environmental releases from all possible fuel cycles, or even of a given
fuel cycle. Nor does the study attempt to examine the range of values for
residual releases associated with current and advanced technologies for elec-
tricity production and pollution control. Rather, by means of the specific
materials shown in the flow sheets, it illustrates the type of analysis that is
essential to a meaningful cost-benefit assessment of alternative technologies
for electrical power-generation.
/
Of all the fuel cycles considered here, the greatest amount of specific and de-
tailed data was available for the light-water nuclear plants. This fact
is reflected by the relatively detailed analysis of the light-water nuclear
plant fuel cycle given in this report. Consequently, the section on the
light-water reactor fuel cycle illustrates the kind of technical data base
and analyses which should be developed for all the fuel cycles before com-
parable environmental impact assessments can be made, and it also illustrates
the additional data on material and environmental release quantities needed
-------
before a complete assessment of the environmental impact of this fuel cycle
can be made.*
Each flow sheet is normalized to an assumed rate of electrical power genera-
Q
tion of 1000 Mw(e) (10 watts). Material and environmental quantities are
given in metric tonnes (Te), resulting from operating continuously for one
year at full power, i.e., at 100% capacity factor. The quantities corresponding
to actual operation at less than 100% capacity factor can be obtained by multi-
plying the flowsheet quantities by the appropriate fractional capacity factor.
No attempt was made to assess environmental impacts resulting from the
indicated effluents, although consideration of possible impact influenced
and, in some instances, restricted the choices of effluents to be shown.
Each fuel cycle flow sheet shows waste heat rejection by evaporative cooling.
Alternative heat-rejection flow sheets for light-water nuclear plants and
fossil-fueled plants are shown separately in Chapter 6. The flow sheets
for these alternative heat-rejection schemes, as well as the two flow
sheets for reduction of SO^ releases from high-sulfur coal (Chapters 7 and
8) are presented in forms that may be combined, so that, for a fuel cycle
describing a combination of the alternative technologies, the effluents are
readily obtainable. For example, a light-water nuclear plant with dry-
cooling heat rejection operates at lower thermal efficiency and requires
more make-up fuel, as shown in Figure 6.7. The increased environmental
effluents in all other portions of the light-water nuclear fuel cycle are
* Determination of environmental impact also requires data and analyses
concerning the effects of releases. Environmental effects are not
specifically considered in this report.
-------
then found by multiplying the quantities shown in the light-water fuel cycle
flow sheet (Figure 2.1) by the ratio of fuel required for dry cooling to that
shown on the flow sheet.
Brief consideration of electrical losses and land use associated with elec-
trical power transmission is given in Chapter 13.
The overall fuel-cycle flow sheet format provides ready identification of
the interaction of technological choices on effluents. The choice of a
particular power generation technology involves environmental considerations
not only at the generating plant site but also throughout the entire fuel
cycle. Choice of a particular waste-heat rejection system for a given power
generating technology involves more than consideration of water-supply and
thermal discharge. It affects the ability to discharge liquid effluents by
dilution and dispersion, and it can result, in some instances, in increased
effluents to the air.
To the extent possible, environmental-release data from original sources
were examined for technical consistency, leading in many instances to
corrections based on material balances and thermodynamic calculations. A
\
few of the flow sheets include results of original calculations for this
study. However, most of the information on the flow sheets was adapted from
data in various written sources.
-------
Selection of data and the limited data evaluation possible for this study
reflect, in many instances, individual judgment by the authors. Therefore,
the authors accept full and sole responsibility for the judgment implied
herein and for errors of fact and interpretation which may be present.
-------
2. ELECTRICAL POWER FROM URANIUM FUELED LIGHT-WATER REACTOR
2.1 Reactor Characteristics
The fuel cycle flowsheets for the light-water nuclear power plant, shown in
Figure 2.1, is characteristic of the current generation of 1000 Mw(e) water
reactors now operating or under construction. There are small differences
oq c
in the fuel enrichment, i.e. the percentage of U in the fresh fuel, and
in the overall thermal efficiencies of pressurized water reactors (PWR) and
boiling water reactors (BWR). However, corrections for these small
differences would result in only small perturbations in the quantities shown
in the flowsheets. Where there are significant differences in environmental
releases from these two types of water reactors, such as releases of radio-
active tritium and radioactive gases at the power plant site, the character-
istic releases for each of the two reactor types are indicated.
The fuel cycle characteristics are calculated on the basis of the equilibrium
annual reload cycle whereby each fuel element operates for 1100 full-power
days prior to discharge, corresponding to an average thermal exposure of
33,000 Mw days/Te U and an average thermal specific power of 30 Mw/Te U.
The reactor core is refueled by a program of partial batch replacement, in
which one third of the reactor core is replaced with new fuel each year.
The make-up fuel is sintered uranium dioxide clad in zircaloy tubing, con-
23K
taining uranium enriched to 3.3% U .
-------
FLOW QUANTITIES ARE STAtED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
-------
Figure 2.1
Light Water Reactor Nuclear Power Plant 1000 Mwe
Material And Environmental Release Flowsheet
Electrica
Energy:
8.76 x 10
n~~
9 kwh
Transmission
f
Delivered Electrica! Energy: 7.984 x I09 kwh
Transmission Losses: 0.776 x 103 kwh
Gaseous
56.7 Ci Rn222
0.0226 Ci Ra228
0.0226 Ci Th230
0.0334 Ci U
15.0 Te NOX
Gaseous
9.43 Te NOX
O.I Te fluorides
27.4 Te S02
0.012 Ci U
Gaseous
12.21 Te NOX
0.69 Te fluorides
22.4 Te SOy
0.002 Ci U
A
Surface Water
l^R^
5.03 Te Na +
0.23 Te Cl~
0.415 Te S0|
0.176 Te N0§
, Gaseous _
1 3.73 xlO5 Ci Kr85
20,580 Ci H3
0.06 Ci I129. I?
0.918 Ci other F.P.
0.0037 Ci transuranics
7.4 Te NOX
Pressurized
Water
Reactor
Input
85,700 Te ore
2.54 x I06 Te overburden
FLOW QUANTITIES ARE
UNLESS OTHERWISE 1
100 % CAPACITY FACTOR
.— .,,_ , :
OlCATEO
-»• ELECTRICAL ENERGY
-*• AIRBORNE RELEASE
=$• LIQUID EFFLUENT
^ SOLID EFFLUENT
T» -
CI
M*(«)
METRIC TONNES
CURIES
KILOWATT -HOURS
M A xttTuM Tp E RL ^s s A BL*E"
CONCENTRATION
-------
The discharge fuel is stored at the reactor site for 150 days to allow time
pOT
for decay of radioiodine and U . The discharge fuel is then shipped to
a reprocessing facility where the fuel is separated into uranium, plutonium,
and mixed fission products. The recovered uranium, containing about 0.80%
235
U , is returned as an input to the isotope-separation plant for re-
enrichment. The quantities of transuranic and fission-product nuclides in
the irradiated fuel at discharge and at various cooling times after dis-
(1 2}
charge were calculated using the Origen codev ' '. For the purpose of the
present study it is assumed that the 0.296 tonnes of plutonium recovered
yearly from the discharge fuel is stored.
The issue of plutonium utilization and its relevance to the analysis of
material quantities and environmental impact of light-water nuclear power
plants now being constructed is discussed in Section 2.12.
2.2 Mining
Uranium is assumed to be obtained from carnotite ore, nominally containing
0.2% uraniunr . Open-pit mining is assumed^ ', with a yield of 5400 Te
ore*- ' and 160,000 Te overburden^- ' per acre of land disturbed. Mine
drainage water discharged to the ground is calculated on the basis of
1350 gal/yr per Te of ore extracted^ . The yearly quantity of 171.4 Te
of uranium to be contained in the ore is based upon the yearly make-up to
the reactor of 34.53 Te and a material balance on the isotope separation
11
-------
plant with the indicated enrichments in the feed, the tails, the product,
and the recycle uranium. No losses of uranium in the processing operations
were considered in calculating this material balance.
The estimate for the required land is based upon the final environmental
statement for a large uranium milling facility, which includes projections
fo\
for both mining and milling operationsv '. It is expected that for a
recovery of 1210 tonnes/yr of uranium concentrates, 3200 acres will be
temporarily committed over a period of 12 years. Additionally, mining-
related activities will require the commitment of 830 acres. Of these 830
acres, 100 acres will be permanently committed. Scaling to the present
flow sheet yields an annual land requirement of 46 acres, only 1.2 acres
of which are permanently committed.
2.3 Milling and Concentration
A model milling plant with a capacity of 960 Te per year of ILOg is eSti-
^a}
mated to occupy 15.4 acresv '. Of this total land usage, approximately
12.7 acres are devoted to a pond for the permanent disposal of mill tailings,
This scales to 3.3 acres attributable to the milling of 171.4 Te per year
of uranium for the light water reactor flowsheet. Of the 3.3 acres, approxi-
mately 2.7 are required for storage of solid tailings.
The process water requirement is 62 million gallons for the current modeP9',
Waste liquors from milling are estimated at 1560 Te per Te of uranium pro-
cessed^- ', containing the following concentrations of radionuclides'6'10^:
12
-------
Ra226 1.9 x 10"7 yc/ml
port _K
Th"u 1.2 x 10 ° uc/ml
These concentrations multiplied by the yearly volume of liquid effluent,
2.67 x 1011 ml, result in the yearly releases of 0.051 curies of Ra226 and
pon
3.2 curies of Th as shown in the flowsheet. The annual radioactive air
(9)
releases of uranium and daughters are estimated to be 1.9 curiesv . The
waste liquor is stored in a retention basin to prevent discharge into the
surface water and to minimize percolation into the ground.
Airborne radionuclide releases from the milling process include gaseous
238
radon-222, a radioactive decay daughter in the U decay chain, and parti-
culates of uranium and the uranium-decay daughters. Natural uranium con-
238
tains 99.29% U , with a half life of 4.51 billion years, corresponding
238
to 0.3308 curies of U per tonne of uranium. Even though the half life
235
of U is 0.71 billion years, its relatively small concentration results
235
in only 0.01513 curies of U per tonne of natural uranium. Therefore,
238
the radioactivity in the milling wastes will be dominated by the U decay
daughters. The yearly throughput of 171.4 Te of uranium corresponds to
238
56.7 curies of U , accompanied by an equal number of curies of each of
ooo
the U decay daughters which are formed without chain branching. There-
pop
fore the total amount of Rn is 56.7 curies. It is assumed that all radon
is released as gaseous effluent. The estimates of the releases of airborne
particulates of Ra , Th , and uranium are based on data in references
(6) and (10).
13
-------
The greatest amount of radioactivity separated from natural uranium in
milling appears in the solid tailings. Here it is assumed that all the
radioactive daughters originally present in the uranium ore and not
accounted for in the gaseous and liquid releases appear in the tailings.
ope
The most important species to be considered is 1622-year Ra , which is
indicated on the flowsheet. The possible leaching of the chemical com-
ope
pounds containing Ra into the ground waters and surface waters near the
milling storage site is an important environmental consideration.
2.4 Conversion of UsOs to UF6
The conversion operations involve removal of chemical contaminants and
impurities from the uranium and conversion to the volatile hexafluoride as
feed to the isotope separation plant. Conversion to the hexafluoride
involves reduction to U02, hydrofluori nation to UF. with anhydrous hydrogen
fluoride, and fluorination to UFg with gaseous fluorine. In the hydro-
fluor process purification is then accomplished by fractional distillation
of the UFg. The principal environmental releases from this process are
gases and solids. In the alternative solvent-extraction purification pro-
cess, the 1)303 is first converted to uranyl nitrate in aqueous solution,
which is then contacted with an immiscible organic liquid phase containing
a complexing agent to extract the uranium preferentially from the impurities.
The purified uranium is then converted to UFg. Purification by solvent
extraction involves larger quantities of liquid wastes but smaller quantities
14
-------
of gaseous and solid wastes than the hydrofluor process. Both processes
are used industrially, and the flowsheet quantities in this study are based
upon a model plant analyzed by the AEC, in which each of the two processes
contributes to half the production capacity. The environmental quantities
for the AEC model plant, translated to amounts per ton of uranium processed,
are tabulated in Table 2.1.
15
-------
Table 2.1
Environmental Quantities for
- UFC Conversion*
b
Natural Resource Use
(ID
Land, acres per 1 Te U/yr production capacity
Temporarily committed -
Undisturbed area
Disturbed area
Permanently committed
Water,_ga1/Te U
Discharged to air
Discharged to surface water
Fossil Fuel
Electrical energy, kwh/Te U
Natural gas, cu.ft./Te U
Effluents
01)
Chemicals, Te/Te U
Combustion gases
S0
hydrocarbons
CO
Other gases
F"
Solids
Radiological , Ci/Te U
Gases
uranium
Liquids
Raoon
Th230
uranium
Solids
Other than high-level
Thermal , kwh/Te U
,0138
.0126
.0011
.00011
2.04 x 104.
22.4 x 104
1.16 x 104
1.7 x 105
0.16
0.055
0.0035
0.0011
0.0006
0.22
0.00007
0.000148
0.00148
0.000148
0.00154
4.83 x ]
*Environmental release quantities shown on the flowsheet are
obtained by multiplying the above data by the uranium throughput,
16
-------
2.5 Uranium Enrichment
The feed streams to the isotopic separation plant consist of natural hexa-
fluoride, containing 0.715% U in uranium, and uranium recycled from fuel
reprocessing. In this flowsheet the recycled uranium is calculated to con-
poc
tain 0.7983% of U . Material balances on total uranium and on the con-
tained U yield the uranium quantities shown on the flowsheet.
The total annual separative work to perform the indicated isotopic separa-
tion is obtained by summing the products of the uranium output quantities
and the separative potential functions and subtracting the similar products
(o\
involving the uranium input quantities^ . The electrical input to the
gaseous diffusion plant to perform this isotopic separation is calculated
from data in Reference (12), using a ratio of 2435 kwh of electrical energy
per kgm of separative work (SW) , for a plant of total plant capacity of
8750 Te SW per year. The resulting annual electrical requirement of
4.20 x 10^ kwh represents over 98% of the total energy input for the entire
(A)
fuel cycle . It represents 4.8% of the net electrical output from the
1000,Mw(e) nuclear power plant. For a net thermal efficiency of 32% for
the light-water nuclear power plant itself, the electrical consumption for
isotopic separation reduces the overall fuel cycle thermal efficiency to
30.5%. Essentially all of the electrical energy input to isotope separa-
tion appears eventually as waste heat, to be dissipated via surface water
coolant or as humidified air from an evaporative cooling tower.
17
-------
Additional environmental releases are scaled according to separative work,
using the above data in electrical energy input and data from an AEC
summary of the total environmental releases for the present diffusion-plant
complex with a total capacity of 10,500 Te/yr of separative work'^'. The
172 Te/yr of separative work required for the light-water nuclear power plant
amounts to 1.64% of the capacity of the total complex. The environmental
release, expressed as quantities per unit of separative work (SW), are
listed in Table 2.2. Effluents arising directly from the generation of
electrical power to operate the diffusion plant are not shown.
18
-------
Table 2.2
Environmental Quantities for Uranium Enrichment
Natural Resource Use
Land(4), acres per Te SW/yr
Temporarily committed 0.007
Undisturbed area 0.005
Disturbed area 0.002
Water(4), gal/Te SU
Discharged to air (diffusion t-
plant cooling) 7.1 x 10
Discharged to surface water at 7
electrical generating plant 8.6 x 10
Electrical energy^12), kwh/Te SW 2.435 x 106
Effluents
(4)
Chemical, Te/Te SW
Gases from coal-fired electrical power generation
SOX 34
NOX 8.8
hydrocarbons 0.08
CO 0.22
particulates 8.8
Gases from chemical processing
SOX 0.13
NOX 0.071
fluorides 0.004
Liquids
Ca2+ 0.046
Cl- 0.071
Na+ 0.071
$04 0.046
Fe 0.003
N0§ 0.023
Radiological, Ci/Te SW
Gases
uranium 0.000017
Liquids
uranium 0.00017
Thermal, kwh/Te SW
at diffusion plant 2.435 x 106
at electrical generating plant 3.972 x 10^
(38% thermal efficiency) 6
6.407 x 10
total
*Environmental release quantities shown on the flowsheet are
obtained from the above data, scaling according to the total separative
work.
19
-------
2.6 Fuel Conversion and Fabrication
The slightly enriched uranium hexafluoride shipped from the isotope-
separation facility is hydrolyzed to uranyl fluoride, converted to ammonium
diuranate, and calcined to the dioxide. The dioxide powder is pelletized,
sintered, and loaded into stainless or zircaloy tubing which is then capped
and welded. The fuel rods, each about 12 feet long and slightly less than
1/2 in. in diameter, are assembled in arrays to be handled as fuel elements.
Scrap material from fuel fabrication is dissolved in nitric acid, purified
by solvent extraction, calcined and reduced to the dioxide.
The most significant chemical effluents are fluorine, fluorine compounds,
and nitrogen compounds. The bulk of the fluorine released from the UFg
appears ultimately as solid CaF2 resulting from lime neutralization. The
environmental effluents from a representative model fuel fabrication plant,
with a capacity of 3 Te U/day, have been defined by the AEC^. These data,
translated to environmental quantities per tonne of uranium fabricated, are
listed in Table 2.3.
20
-------
Table 2.3
Environmental Quantities for Fuel Conversion and Fabrication*
Natural Resource Use
(4)
Land, acres per Te U/yr
Temporarily committed 0.0057
Undisturbed area 0.0045
Disturbed area 0.0011
Permanently committed 0
Mater, gal/Te U 1.48xl05
Electrical energy, kwh/Te U- 4.83 x 10
Natural gas, cu.ft./Te U 1.02 x 105
Effluents
(4)
Chemical, Te/Te U
Gases from coal-fired electrical power generation
SO 0.65
NOx 0.17
hydrocarbons 0.002
CO 0.004
Process gases
F" 0.00014
Liquids
N as NH3 0.24
N as NOo 0.15
F- J o.on
Solids (calculated as stoichiometrically equivalent
to UF6 feed)
CaF2 0.98
Radiological, Ci/Te U
Gases
uranium 0.000006
Liquids
uranium 0.0006
Solids (buried)
uranium 0.0017
Thermal, kwh/Te U 7.5 x 104
*Environmental release quantities shown on the flowsheet are
obtained by multiplying the above data by the uranium throughput.
21
-------
2.7 Nuclear Power Plant Operation
Environmental releases of concern at nuclear power stations are radiologi-
cal, chemical, and thermal. The nature of the thermal releases and the
alternative technologies to control these releases are discussed in the
section on waste-heat rejection systems. The chemical releases are those
characteristic of water treatment systems for steam power plant operation
and are shown in the heat-rejection flowsheets. The radiological releases
considered in these flowsheets are those resulting from normal operation.
The rate of formation and inventory of the radionuclides important in con-
sidering environmental radiological releases are shown in Table 2.4,
calculated for a typical 1000 Mw(e) light-water reactor by means of the
H 2}
Origen code^ ' . The radionuclide inventories are calculated on the basis
of all fuel elements in the reactor being at the discharge composition.
This is a good assumption for those radionuclides whose half lives are
short compared with the fuel exposure life of three years. For longer half
life radionuclides, the actual inventory in the reactor will be less than
the amount listed, depending upon the fuel management program. For example,
for a partial batch replacement of one third of the core every year, the
inventory of 12.26-year tritium will be about two thirds of the inventory
listed in the table. The yearly quantities in the discharge fuel are
essentially independent of the fuel management program.
22
-------
Table 2.4
Radioactivity in Reactor and Fuel Cycle for a 1000 Mwe Water Reactor
(a)
Radionuclides
Tritium(d), H3
Krypton 83m
85m
85
87
88
89
90
Total (e)
Strontium 89
90
Total(e)
Iodine 129
131
132
133
134
135
336
Total (e)
Xenon 131m
133m
133
135m
135
137
138
139
Total (e)
Cesium 134
137
Total (e)
Zr, Nb, Mo, Tc,
Ru, Rh, Pd, Ag,
Cd, In, Sn, Sb
Rare Earths:
La, Ce, Pr, Nd,
Pm, Sra, Eu, Gd,
Tb, Dy, Ho
Total Fission
Products
Half-Life
12.26 yr.
1.R6 hr.
4.4 hr.
10.76 yr.
76 min.
2.8 hr.
3.18 mi n .
33 sec.
52.7 days
27.7 yr.
1.7xl07 yr.
8.05 days
2.26 hr.
20.3 fir.
52.2 min.
6.68 hr.
83 sec.
11.8 days
2.26 days
5.27 days
15.6 min.
9.14 hr.
3.9 min.
17.5 mi n .
43 sec.
2.046 yr.
30.0 yr.
Rciact.or „
Inventory ;
10 ' curies;
.0723
5.71
17-. 2
1.16
34.0
49.0
61.8
58.5
325
71.6
7. 80
526
3.03xlO"6
71.9
103
137
156
123
54.0
1017
0.582
3.29
137
36.8
25.7
132
128
107
680
19.0
9.92
595
1880
4140
11,970
In di so Kirgr fuel ,
10 ' curiea/yr.
at
discharge
] 50-cJay
decay
10-yr.
decay
Elemental
Boili ng
Te mp c r a t u r e
Health
Considerations
FISSION PRODUCTS
.0241
1.90
5.70
0.383
11.3
16.5
20.3
22.7
107.7
23.8
2.58
174
l.OOxlO"6
23.9
34.2
45.6
51.8
40.7
17.9
337
0.193
1.09
45.6
12.2
8.52
43.8
42.5
35.6
225
6.32
3.29
198
625
1374
3970
1.067 Te/yr)
.0239
0
0
0.373
0
0
0
0
0.373
3.22
2.56
5.78
1.02x10"^
6.01x10
0
0
0
0
0
e.iixio"5
9.05xlO~5
0
0
0
0
0
0
0
g.osxio"5
5.49
3.26
8.75
54.1
48.8
330
.0139
0
0
0.201
0
0
0
0
0.201
0
2.02
2.02
1.03x!0"6
0
0
0
0
0
0
1.03xlO~6
0
0
0
0
0
0
0
0
0
0.215
2.61
2.83
0.0450
0.416
9.98
212°F
(as 1ITO)
-2
-------
Radionuclides
Uranium 237
239
Total
Plutonium 238
239
240
241
242
243
Total
-------
In addition to the radioactive tritium resulting from fission, as listed
in Table 2.4, tritium is also produced by fast-neutron reactions in boron
used for reactor control, as well as by neutron reactions in lithium con-
taminants. This tritium probably remains in the matrix of the solid
metal-clad boron control absorbers. Also, the absence of a phase change
in the primary coolant of pressurized water reactors makes it possible to
use soluble boron dissolved in the coolant, for reactivity control. Tri-
tium produced from this dissolved boron contributes to the increased tri-
tium environmental releases from pressurized water reactors.
The fission-product radioactivity involved in environmental releases in
normal operation first reaches the reactor coolant through defects in clad-
ding, except for tritium which also reaches the coolant by diffusing through
the cladding. The principal fission products which reach the coolant in
this way are radioiodine and the noble gases, krypton and xenon, which
diffuse from the fuel matrix. Smaller quantities of non-volatile fission
products recoil from the fuel matrix and escape through defective cladding.
Fission products are also formed on the outer surface of the cladding due
to uranium contaminants. Additional radionuclides formed in the coolant
include activated corrosion products, tritium formed due to neutron reac-
tions with dissolved boron and lithium, N formed by (n,p) reactions with
oxygen, 9.99-min. N formed by (p,a) reactions with oxygen and (a,n)
reactions with B , and 110-min. F formed by (p,n) reactions with oxygen.
25
-------
The primary source of gaseous radioactive effluents arises from the extrac-
tion of non-condensable gases from the primary circuit. Secondary sources
of gaseous effluents are gases evolved from primary coolant leaking from the
reactor circuit, gases evolved from primary coolant handled in low-pressure
coolant purification operations, gases evolved from primary coolant during
refueling operations, gases evolved from the PWR steam (secondary) system
containing radionuclides leaked from the primary system, gases evolved in
the air-sparging of process equipment such as ion-exchange resin storage
tanks, and gases evolved in the liquid waste handling system. Radionuclides
released as gaseous effluents are krypton, iodine, tritium, and particulates,
and tritium as tritiated water vapor.
Radioactive Noble Gases
In a pressurized water reactor power plant the primary gaseous source is of
relatively small volume, because there is no pressure gradient for leakage
of noncondensable gases into the primary coolant system and because the
volume of noncondensable hydrogen and oxygen from radiolytic decomposition
is suppressed by hydrogen pressurization. The noncondensable gas from pri-
mary sources is held up for 30 days, sufficient for all the noble-gas radio-
nuclides other than 10.76-yr. Kr85 to be reduced to negligible levels by '
radioactive decay. It then flows through particulate filters and a charcoal
filter for iodine removal and discharges to the atmosphere at the roof vent.
Typically, the released krypton dilutes rapidly to a concentration far below
the allowable level by the time it reaches the site boundary.
26
-------
Radioactive noble-gas effluents are of greater magnitude in boiling water
reactors because of the much higher volume of noncondensables to be extracted
from the reactor coolant system. Without the benefits of hydrogen pressuri-
zation of the PWR, the BWR generates about 160 cu.ft./min of hydrogen and
oxygen by radiolytic decomposition. Also, because the reactor coolant is
the working fluid and expands in the turbine to pressures below atmospheric,
about 18 to 40 cu.ft./min of air leaks into the primary coolant and inter-
feres with condensation. The air and other noncondensables must be contin-
uously removed by a steam ejector. A gas hold-up tank to provide significant
radioactive decay time would be exorbitantly large. The practice in many
large boiling water reactors already licensed and operating is to hold the
gas up for 30 minutes, pass it through a particulate filter, and discharge
it from a tall stack to enhance atmospheric dilution. The released gas thus
contains a relatively high activity of the short-lived krypton and xenon
radionuclides. The yearly release rate is typically about 3 million Ci/yr.
Newer BWR power plant installations employ additional technology to reduce
noble-gas radioactive emissions. The air ejector gas passes through a
recombiner to remove the explosion hazard from the hydrogen and oxygen
formed by radiolytic decomposition of reactor water. The gas then passes
through a charcoal bed where the continued absorption, diffusion, and
desorption of krypton and xenon provide an effective delay time of about
16 to 24 hours for krypton and 10 to 15 days for xenon(^). jhe gas js
then filtered and released at the roof vent. Boiling water reactor
27
-------
plants employing this technique for reducing noble-gas radionuclide
effluents are expected to have noble-gas releases in the neighborhood of
30,000 to 50,000
If further reduction in the release of noble-gas radionuclides were desir-
able and justified, the small volume of gas evolved as the primary gaseous
effluent in pressurized water reactors could be stored in compressed-gas
tanks. Krypton and xenon can be removed from the steam-ejector gas in
boiling water plants by cryogenic adsorption or condensation or by absorp-
tion in a chilled organic.
Gaseous Radioiodine
The secondary sources can, however, account for significant quantities of
radioactive iodine in the gaseous effluents. Because iodine is selectively
taken up by the thyroid gland when ingested, and because it can be trans-
ported to the more critical infant recipients via the milk-food chain, a
small number of curies of radioiodine can be far more significant biologic-
ally than the relatively large releases of noble-gas radionuclides. For a
more specific comparison, the maximum permissible concentrations of Kr^5
and I131 in the present 10 CFR 20 regulations^5) and the design-objective
concentrations proposed in 10 CFR 50, Appendix I^16), are listed below.
Also listed are the yearly release rates which would result in a yearly
average concentration 'complying with the quoted regulation, calculated on
the basis of a typical site-boundary dilution factor of 2 x 10"12 sec/ml
for building-vent release'^'.
28
-------
Table 2.5
on
Allowable Concentrations and Yearly Releases of Kr and
1 31
I for Assumed Atmospheric Dilution
Kr85
maximum permissible concentration
for unrestricted exposure of 500
mrem/yr, 10 CFR:20, microcuries -,
per mi Hi liter 3 x 10
calculated^ ' allowable fi
yearly release, curies/yr 4.73 x 10
design-objective concentrations,
proposed Appendix I, 10 CFR 50, -g(r)
microcuries per milliliter 6 x 10 ^ '
j!31
1 x I0"10^a^
1580(a)
1 x ID'15
calculated^ ' allowable .
yearly release, curies/yr 9.5 x 10 0.0158
^a'When allowance^ is made for the milk food chain the allowable
iodine concentration and yearly release is lower by a factor of 700.
* Calculated by dividing the allowable specified concentration
by the assumed yearly average dilution factor of 2 x 10~12 sec/ml for
releases from top of reactor building. The dilution factor is the con-
centration at the site boundary divided by the emission rate at the
reactor.
^'Calculated from the dose specification of 10 mrem/yr in
Appendix I.
29
-------
The primary noncondensable gas streams in PWR and BWR plants are passed
through charcoal, which is expected to remove about 99% of the contained
iodine^7)*. In the BWR plants, radioiodine is associated with the
secondary gaseous effluents, such as the steam leaking through the turbine
gland seal, direct leakages of reactor coolant into the reactor and turbine
building, liquid radiological waste system vents, and air sparging of pro-
cess equipment for handling ion exchange resins^
The secondary sources are expected to contribute a greater source of
gaseous iodine release for pressurized water reactors, even though only
minor quantities of iodine are discharged via the primary gas treatment
systenr '. Reactor coolant water containing dissolved radioiodine leaks
into the steam system, and a portion of this iodine is evolved with non-
condensables through the steam ejector system. An even larger source of
gaseous radioiodine appears in the ventilation system for the auxiliary
building where the reactor coolant is processed. Another source of gaseous
radioiodine effluent results from the monthly purge of air within the
reactor contaminant building^17).
The reported yearly releases of gaseous radioiodine from existing BWR and
PWR power plants for the year 1971 have been published by the AEC^18^, and
are summarized in Table 2.6.
The efficiency for removing iodine by charcoal depends upon the moisture
content and upon the fraction of the iodine in the form of methyl iodide.
Methyl iodide does not absorb readily on charcoal.
30
-------
Table 2.6
Radioiodine Releases for 1000 Mw(e) Plant
Extrapolated from 1971 Reported Releases
thermal
power'9'
Mw(e)
BWR 700
to
2 x 2527
PWR 600
to
2200
^a^USAEC, Report
for 1971, Directorate of
thermal
energy / »
producedv '
Mw-days
reported
radioiodine
release^9'
curies/yr
99,200 0.49
to to
513,000 8.11
209,000 < 0.0001
to to
327,000 0.17
on Releases of Radioactivity in Effluents
Regulatory Operations,
December, 1972.
radioiodine release
extrapolated to
1.141 x 105 Mw days
thermal energy (b)
curies/yr
5.63
to
18.0
0.0001
to
1.61
from Nuclear Power Plants
^ 'Corresponding to 1000 Mw(e), 32% thermal efficiency, 100% load factor, one-year
operation.
-------
Releases of radioiodine from BWR plants of thermal capacity varying from
700 Mw(e) to 2527 Mw(e) varied from about 0.5 to 4 Ci. Normalizing these
data according to the reported thermal energy produced by each of these
reactors during the year 1971 and scaling to the energy produced by a
1000 Mw(e) nuclear power plant operating at 32% thermal efficiency for a
year at 100% load factor, releases varying from 0.30 to 18 Ci/yr of gaseous
radioiodine are predicted. Similarly reported data for PWR plants with
capacities from 600 Mw(e) to 2200 Mw(e), scaled to the 1000 Mw(e) plant at
100% load factor, are in the range of 0.0001 to 1.6 Ci of radioiodine.
These reported releases are based upon primary sources of effluents. It
is difficult to monitor radioiodine in the concentrations of significance
in many of the secondary sources and reported operating experience does not
yet verify the iodine releases associated with these sources.
For the purpose of the present flowsheet the gaseous radioiodine release is
that which would comply with the proposed Appendix I guidelines, assuming
the dilution factor given in Table 2.5.
Tritium in Gaseous Effluents
Tritium appears in the gaseous releases as tritiated water vapor carried in
the air streams. The releases here are based upon Rodger's^17) estimates
of 100 Ci/yr of tritium released to the BWR coolant, and 500 Ci/yr to the
PWR reactor coolant and his estimate that 10% of the tritium released to
32
-------
the coolant will appear in the gaseous releases as tritiated water vapor,
the remaining 90% appearing in the liqui:d effluents. If additional technol-
ogy were employed to decrease tritium in the liquid effluents, some increase
in the release of gaseous tritium would be expected.
Radioactive Particulates in Gaseous Effluents
The AEC report of radioactive effluent releases for 1971 lists airborne
radioactive particulate releases for BWR and PWR plants'18'. Scaling these
to the yearly energy production assumed for the present study, as was done
previously for radioiodine, particulate releases varying from about 0.06
to 2 Ci/yr are estimated for BWR plants and 0 to 0.037 Ci/yr for PWR plants.
Direct and Skyshine Radiation
Although the radionuclides N , and N , and F'° appear in the effluent
gases, their contribution is small compared to the other gaseous radionu-
clides. However, in boiling water reactors N is a source of off-site
radiation which may have environmental significance. The N'^ in the reactor
coolant follows the steam through the external steam separator, piping,
turbine, and condenser, and forms a distributed source of 6.28-Mev gammas
throughout this circuit. In some plants no biological shielding is pro-
vided around the turbine and steam piping; in some plants only peripheral
shadow shielding is provided. Consequently, the N decay gammas can pene-
trate through weakly attenuating structures to the site boundary. Upwardly
33
-------
directed N16 decay gammas undergo Compton scattering with air, resulting
in lower-energy scattered gammas reaching the site boundary(35). In some BWR
installations this direct and "skyshine" radiation could be a principal
contributor to off-site radiation exposures at the site boundary, once the
exposures from radionuclide effluents are reduced to the levels proposed
in 10 CFR 50 Appendix I.
Tritium in Liquid Effluents
Reported releases^18) of tritium in BWR liquid effluents for 1971, scaled
according to the energy production of a model 1000 Mw(e) plant, agree well
with the present'^) estimates of 90 Ci/yr for a BWR plant. However, for
the PWR plants there are wide variations in the reported tritium in liquid
effluents. The 1971 data for PWR plants and their extrapolation to a
model 1000 Mw(e) plant at 100% load factor, are listed on Table 2.7.
34
-------
Table 2.7
on
Tritium in Liquid Effluents for Pressuri zed-Water
Nuclear Power Plants, Extrapolated to 1000
thermal power ^a'
Mw(e)
600
615
1,300
1,825
2,200
1,518
1,347
^^USAEC, Report
for 1971, Directorate of
Mw(e)
reported tritium tritium release
thermal energy release in liquid extrapolated to ,,\
produced^) effluents^) 1 .141 x 105 Mw-daysl ;
Mw-days
209,000
120,000
352,000
559,000
327,000
418,000
418,000
on Releases
Regulatory
curies/yr
1,680
725
154
5,830
118
266
4,570
of Radioactivity in Effluents
Operations, December, 1972.
curies/yr
9,168
6,041
499
11,900
411
726
12,470
from Nuclear Power Plants
^Corresponding to 1000 Mw(e), 32% thermal efficiency, 100% load factor, 1-yr.
operation.
-------
These variations in tritium in liquid effluents may result in part
from variations in the extent to which neutrons are absorbed in soluble
boron controls, as well as in solid boron. For ex.mple, a detailed esti-
(18}
matev ' of the rate of release of tritium to reactor coolant for a 1000
Mw(e) PWR nuclear plant operating with an equilibrium fuel cycle if given
in Table 2.8
Table 2.8
(18)
Tritium Release to Coolant of PWR Plant Equilibrium Fuel Cycle
expected release of
tritium to coolant,
curies/yr
ternary fission 110.
burnable poison rods 10
control rods 410
soluble poison boron in
reactor coolant 560
Li reaction 11
Li reaction 6
deuterium reaction 1
1108
The startup cycles require more control poison and may result in a rate
of tritium production in the coolant greater than that listed above^19\
Variations in tritium release may also be attributable to the metal used
for fuel cladding. Older PWR plants, which have stainless steel fuel
36
-------
cladding instead of zircaloy, would be expected to have greater releases of
tritium to the coolant and to the environment.
A liquid release of 450 Ci/yr of tritium, as is assumed here for the PWFr ',
may be a problem in some installations, depending upon the type of waste
heat rejection system which is used. The liquid radioactive wastes are norm-
ally discharged into the cooling water returned from the power plant to the
environment, so the concentration of tritium in the exit liquid effluent is
the tritium production rate divided by the coolant flow rate. For once-
through cooling, with a temperature rise of 15°F, the coolant stream leaves
a light-water nuclear plant at a flow rate of 966,000 gal/min, so that the
450 Ci/yr of released tritium dilutes to an average concentration of
2.3 x 10"' microcuries/ml. This is considerably lower than the maximum per-
o
missible concentration of 3 x 10~° microcuries/ml for tritium in water from
10 CFR 20, and it is lower than the tritium design objective of 5 x 10~°
microcuries/ml proposed in Appendix I of 10 CFR 50.
With evaporative cooling the rate of discharge of blowdown water to the sur-
roundings is typically about one hundred times lower, e.g., 7210 gal/min,
resulting in a diluted tritium concentration of 3.1 x 10"^ microcuries/ml,
as shown in Table 2.9. If the waste tritium is injected directly into the
cooling water which circulates between the cooling tower and condenser, much
of it will appear as tritiated water vapor in the humidified air leaving the
cooling tower. For a water make-up rate of 19,230 gal/min, as shown on the
flowsheet, the concentration of tritium in the water blowdown leaving the
37
-------
Table 2.9
CO
CO
Concentrations
Light-Water
of Radionuclides in Liquid Effluents for
Nuclear Plant with Evaporative Cooling
Yearly average concentrations in
water blowdown from plant site(a'
Tritium
BWR
PWR
Radionuclides
other than H^
yearly
release
in liquid
ef f 1 uents
Ci/yr
90<17)
450(17>
liquid wastes
liquid wastes discharged
discharged into condenser
into blowdown circulating
water(b) water(c'
yd'/cc uCi/cc
6.3 x 10"6 2.4 x 10"6
31 x 10"6 12 x 10"6
3.5 x 10"7 3.5 x 10"7
design-objective
concentrations
proposed in
Appendix If .
10 CFR 5Q('6'
yCi/cc
5 x 10"6
5 x 10"6
A "?
r to dilution in natural bodies of water into which the blowdown water is
discharged.
^ ^Based upon 7210 gal/min of water blowdown.
(c)
^ 'Based upon 19230 gal/min of make-up water.
(d)yCT = 10'6 Ci.
-------
plant would then be reduced to 1.2 x 10"5 microcuries/ml, still a factor of
2.4 above the proposed design objectives. Using the atmospheric dilution
parameters assumed for Table 2.5, the off-site concentration of tritiated
water vapor will be far below the 10 CFR 20 maximum permissible concentra-
tion, even without taking into account the further dilution resulting from
the mixing of tritiated water vapor with the cooling tower air.
Technology is available to reduce the tritium effluents below the levels
indicated in the flowsheet. Reactor coolant water withdrawn for auxiliary
processing can be returned to the reactor coolant system, although some
increase in tritium concentration in the reactor coolant and in the gaseous
effluents will result^''. Although expensive, isotope separation^) can
remove tritium before the process water from the liquid waste management
system is discharged as liquid effluent.
Other Radionuclides in Liquid Effluents
(19)
A representative estimatev ' of the yearly quantities of radionuclides
other than tritium which appear in the liquid wastes to be treated by the
radioactive liquid waste management system for a 1000 Mw(e) pressurized
water reactor is given in Table 2.10. The function of the waste management
system is principally that of concentrating these non-volatile radionuclides
so that they can be encapsulated or cast into'solids and shipped for perma-
nent storage. Evaporator condensates still contain finite carryover of
radionuclides, but the radionuclide content of the distillate can be further
reduced by ion exchange.
39
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Table 2.10
Estimated Yearly Quantities of Radionuclides, Other than Tritium,
in Liquid Wastes Collected for Processing and Conversion to Solids
Cr51
Mn54
Mn56
CO
Fesy
RR
r< ~ ^O
Co
60
Co°U
OQ
Sroy
Qn
Sryu
Sr91
Y90
Y91
Y92
Zr95
Zr97
1000 Mw(e) PW,
Ci/yr
0.31
1.02
27.8
1.65
31.0
3.66
9.57
6.06
2.62
1.12
22.2
5.40
1.78
1.14
( ~\ Q ^
D » /
Ci/yr
Nb95 1.76
QQ
Moyy 13,200
Te132 735
i "31
IIJI 6,960
1 ^9
IU^ 295
1 3"3
V66 5,400
1 _ ,,
1 * 22.7
1 ^c;
IMb 2,740
Cs134 914
Cs136 88.0
Cs137 4,820
Ba140 2.40
La140 2.47
Ce144 8.23
Total Activity 35,300 Ci/vr
40
-------
According to the proposed Appendix I, 10 CFR 50, design objectives,
the radioactive liquid waste management system should be capable of reduc-
ing the yearly release of non-tritium radionuclides to 5 Ci/yr or less,
and this appears attainable with evaporation and ion exchange. Appendix I
further proposes a design-objective concentration of non-tritium radio-
nuclides in the liquid effluents from the plant, prior to dilution of these
Q
effluents in natural bodies of water, of 2 x 10 microcuries/ml. This
is easily attainable with once-through cooling, where dilution of 5 Ci/yr
in discharge water flowing at 966,000 gal/min (cf. Section 6.1) results
-9
in a discharge concentration of 2.6 x 10 microcuries/ml. However, as
in the case of tritium, operating with evaporative cooling results in less
discharge water for dilution of the liquid effluents. For the water blow-
down rate of 7210 gal/min for the evaporative cooling tower shown on the
flowsheet (cf. Section 6.2), the discharge of 5 Ci/yr would result in a
discharge concentration of 3.5 x 10~ microcuries/ml, as shown in Table
2.9. Further treatment of the process waste to reduce the non-tritium
liquid radionuclide discharge to about 0.3 Ci/yr would be required in this
example for evaporative cooling.
The reported non-tritium liquid radionuclide releases for 1971"°' are
listed in Table 2.11.
-------
Table 2.11
Non-Tritium Radionuclides in Liquid Effluents for
Light-Water Nuclear Power Plants Reported for 1971
reported
thermal non-tritium
thermal. energy , . liquid ,
power(a> produced^3' release^0'
Mw(t) Mw-days curies/yr
BWR
700 99,200 6.2
1670 181,000 0.014
1850 381,000 32.2
1930 486,000 12.1
2011 475,000 19.7
2 x 2527 513,000 23.2
PWR
600 209,000 0.012
615 120,000 81.1
1300 352,000 0.96
1825 559,000 5.88
2200 327,000 0.74
1518 418,000 0.15
1347 418,000 1.54
^ ^USAEC, Report on Releases of Radioactivity in Effluents from
Nuclear Power Plants for 1971, Directorate of Regulatory Operations,
December, 1972.
42
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Non-Radiological Chemical Releases
Chemical releases are characteristic of those involved in the boiler
water treatment system of a steam power plant (cf. Chapter 3). There
are additional chemical releases involved in the water treatment systems
for plant cooling water (cf. Section 6.2). Thermal releases to surface
water and the release of large quantities of humidified air, airborne
liquid drift, the concentration of dissolved solids by evaporative cool-
ing systems, and environmental and land-use quantities associated with
other possible heat-rejection systems appropriate to light-water nuclear
power plants are discussed in Chapter 6.
2.8 Shipment of Irradiated Fuel and Solid Radioactive Hastes
Prior to shipment, the irradiated nuclear fuel removed yearly from
the core of a light-water reactor is stored at the nuclear power plant
site for about 150 days to allow time for decay of 8.05-day I and to
237
allow for decay of 6.75-day U so that its radioactivity level in the
uranium recovered from fuel reprocessing will be comparable to the radio-
1-3}
activity of natural uraniumv '. Shipment of the shielded irradiated
fuel to the reprocessing plant involves, in normal accident-free opera-
tion, only very small exposures from gamma radiation penetrating through
the shield of the shipping container. No other environmental effects
from shipping, in normal operations, are identified in typical environ-
mental impact reports *• '. Although possible releases of radionuclides
from some classes of postulated shipping accidents are considered in
43
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typical environmental impact reports, consideration of these accidents
and other accidental environmental releases throughout the nuclear fuel
cycle is beyond the scope of the present study (cf. Section 2.12).
2.9 Fuel Reprocessing
Irradiated fuel is reprocessed for the purpose of recovering the con-
tained plutonium and uranium, which have significant monetary value as
fuel. If recovery of the plutonium and uranium were not economically
essential, the solid irradiated fuel and its contained fission products
could be stored as high-level wastes. Metal-clad U02 fuel -rods are, in
fact, an excellent physical form for long and safe storage of the high-
level, long-lived radioactive fission products, plutonium, and other
/
transuranic elements present^'n irradiated fuel.
Fuel reprocessing technology involves chopping the fuel rods into
pieces, separating the radioactive cladding hulls from the U0? fuel, dis-
solving the U02 in acid, and performing chemical separation by liquid-
liquid extraction and ion exchange to yield an aqueous stream of purified
uranyl nitrate (U02(N03)2), an aqueous stream of purified plutonium ni-
trate (Pu(N03)4), and an aqueous stream of dissolved and suspended
fission-product salts. In some processes part of the purification is
accomplished by fluoride distillation.
44
-------
In the present flowsheet the uranium product is then converted to
uranium hexafluoride for recycle to the isotope separation plant. The
Plutonium product is stored (cf. Section 2.13). The high-level fission
product aqueous stream is either stored in large tanks for up to 5 years,
or it is converted immediately into a dry chemical form and cast into an
inert solid matrix. Within ten years after separation the high-level
radioactive wastes are to be shipped, in converted solid form, to a fed-
eral repository for long-term storage^ '.
The yearly rates at which radioactivity in the irradiated fuel from a
1000 Mw(e) light-water nuclear plant appears at the reprocessing plant,
after 150 days cooling, are listed in the fifth column of Table 2.4.
When the fuel is dissolved all of the noble-gas fission products, con-
taining 373,000 Ci/yr of 10.76-yr Kr^, are discharged to the atmosphere
through a stack tall enough to obtain adequate atmospheric dispersion
before the discharge gas reaches the site boundary.
The tritium in the irradiated fuel forms tritiated water upon fuel dis-
solution. About 86% of this is evolved as tritiated water vapor, and
the remaining 14% is ultimately discharged with the liquid effluents
into the surface water leaving the plant site^ '. The ultimate disposi-
tion of the additional tritium formed in solid boron control absorbers,
and the possible release of portions thereof when the control absorbers
are removed from the reactor and stored or processed, is not shown on
this flowsheet.
45
-------
The indicated iodine release is based upon data in Reference (2), using
an iodine decontamination factor of 1000 for the iodine scrubber system.
The release of 3.7 Ci/yr of Ru106 in the liquid wastes, 0.9 Ci/yr of
other airborne fission products, and 0.0037 Ci/yr of transuranics in
gaseous effluents are derived from data in Reference (4), scaled to the
uranium throughput shown on the flowsheet. Additional environmental
quantities, expressed as quantities per tonne of uranium throughput, are
listed in Table 2.12, derived from data on a model plant with a capacity
of 2.5 tonnes/day(4).
The volumes of high level wastes, intermediate level liquid wastes, low
level liquid wastes, and solid wastes shown on the flowsheet are derived
from data in Reference (2). Plutonium remaining with the high level
wastes is 0.5% of the total plutonium processed^2'.
Solid wastes of lower activity result from off-gas cleanup, solvent
washes, spent ion exchange resin, and other cleanup and decontamination
operations. These wastes, principally in the form of nitrate and nitrite
solutions, are concentrated and crystallized as salt and stored in metal
containers inside a concrete vault. Typically, these wastes contain
about 8 grams of plutonium, 0.2 kilograms uranium, and less than 0.01%
of the total fission products per tonne of uranium processes^23'. Using
data on this flowsheet, the yearly quantities for the 1000 Mw(e) nuclear
plant are 3600 Ci of plutonium, less than 13,000 Ci of fission products,
and 0.002 Ci of uranium.
46
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Table 2.12
Environmental Quantities for Fuel Reprocessing*
Natural Resource Use'' '
Land, acres per 1 Te U/yr capacity
Temporarily committed 0.11
Undisturbed area 0.10
Disturbed area 0.01
Permanently committed 0.001
Hater, gal/Te_LT ' c
Discharged to air 1.1 x 10
Discharged to water 1.7 x 10^
Total 2.8 x 10b
Electrical Energy^, kwh/Te U 1.28xl04
Effluents
Chemical^;, Te/Te U
Combustion Gases
sox c
NOX G.^u> -, .
hydrocarbons 0.0006^a|
CO O.OOll'"
F" 0.0014
Liquids
Na+ 0.15
cr o.ooe
S04 0.01
NO^ 0.006
Radiological, Ci/Te U
Gases (including entrained matter)
|/y,85 1
Vri
f\ * * 3 t.-/ \J f »
H3 596(c^ v
1 on O-7
-------
Lower-level dry chemical wastes resulting from fluorination operations
are stored as dry fluorides of aluminum, sodium, and magnesium in a steel
lined vault. These wastes contain about 3 grams of plutonium, 1.75 kilo-
grams of uranium, and less than 0.01% of the fission products per tonne
of uranium processed^23). This corresponds to yearly quantities for the
1000 Mw(e) nuclear plant of 1370 Ci of plutonium, 0.02 Ci of uranium,
and less than 13,000 Ci of fission products.
It should be recognized that the indicated releases and process quanti-
ties in fuel reprocessing indicated on the flowsheet are those resulting
only from the fuel from the reference 1000 Mw(e) light water nuclear
plant. Commercial fuel reprocessing plants are now designed to handle
uranium throughputs from 1 to 4 tonnes per day^ ', and even larger through-
puts are calculated for the most economical operations. Therefore, the
total releases from the fuel reprocessing plant will be greater than the
quantities indicated on the flowsheet. For example, a reprocessing plant
with a capacity of 4 Te U/day could process the fuel from 42 light water
nuclear plants operating as shown in the flowsheet, all operations at
100% load factor.
There are several technologies which could be applied to reduce the
radionuclide effluents in fuel reprocessing, if such reduction were found
to be necessary or desirable.* For example, tritium can be removed as
a gas, rather than being incorporated in aqueous dissolver solutions, by
* The AEC has published proposed numerical guides specifying radionuclide
releases from light water nuclear power plants which meet the provision
of the 10 CFR 20 regulations that radiation exposures shall be "as low
as practicable." No such guides have been issued for other operations
in the nuclear fuel cycle.
48
-------
heating sheared fuel in air or oxygen prior to dissolution. Krypton can
be removed by cryogenic distillation or by selective absorption in
chilled organic, followed by storage in gas cylinders. Iodine can be
further removed by scrubbing the dissolver off-gases with concentrated
nitric acid, oxidizing the iodine to solid loO,-, followed by further
treatment of the off-gases with a charcoal scrubber or with a bed of
silver-deposited zeolite. These operations concentrate on recovery of
radionuclides from the primary sources of gaseous and liquid effluents.
It would be expected that secondary sources of iodine, such as process
cell ventilation air, building ventilation air, etc., could also contri-
bute to iodine releases (see discussion of gaseous radioiodine releases
in Section 2.7).
2.10 Management of High-Level Radioactive Hastes
The radioactivity associated with the fission products produced by the
1000 Mw(e) light-water nuclear power plant in one year of operation as
a function of elapsed time since the irradiated fuel was discharged from
the reactor, is shown in Figure 2.2. Data for this figure were calculated
on the assumption that 0.5% of the plutonium in the discharge fuel
remains with the high-level fission-product wastes^. It is apparent
that significant quantities of radioactivity remain after hundreds of
years of storage, so the waste-management program must provide for iso-
lation of these wastes from the environment.
49
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Figure 2.2
Radioactivity Produced in One Year by a 1000 Mw(e)
Light Water Nuclear Power Plant
DECAY TIME, years
10'
10
10
RE = rare earths: La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Dy, Ho
Zr-Sb = Zr, Nb, Mo, Tc, Ru, Rh
Pd, Ag, Cd, In, Sn, Sb
Pu is 0.5% of total Pu present in
spent fuel
Based on: 30 Mw/tonne
33,000 Mw days/tonne
3125 Mw (thermal)
100% load factor
Zr93
Nb93m
Tc"
note change of scale
10"
I03
DECAY TIME, days
50
-------
The solidified and encapsulated high level wastes are to be shipped
to a federal repository for interim or perpetual storage within 10 years
after they are separated in the chemical reprocessing plant. Typically,
the wastes would be cast in a solid matrix in the form of steel-clad
cylinders 6 in. in diameter and 8 to 10 ft. long'2' . One cubic foot
of the solid matrix is allotted to the fission products resulting from
to]
10,000 Mw-days of thermal energy production in the reactorv ', resulting
in 114 cu.ft./yr. of solid high-level matrix containing the high-level
fission products from the 1000 Mw(e) light water nuclear power plant.
This is equivalent to 58 waste containers per year. Each waste con-
tainer, containing 10-year old fission products, generates about 5000
watts of thermal power.
Two approaches to long-term isolation are considered^ '. One
involves disposal of the wastes in some form and location such that the
long term integrity of each waste container, and continual surveillance
thereof, would be unnecessary. Continual isolation from the environment
would be obtained by the favorable retention properties of the surround-
ing natural media. Such disposal would involve no plans or intent to re-
cover the emplaced high-level wastes. Disposal in bedded salt deposits
is an example of this apporach. Another approach involves retrievable
storage, whereby the long-term integrity of the storage container is to
be preserved and is to be verified by periodic monitoring, with provisions
for retrieving and, if necessary, reconstituting the wastes if monitoring
51
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indicates the possible deterioration of an individual container or of any
of the several other additional isolation barriers that are provided.
This is characteristic of the storage of fission-product waste canisters
in water-filled canals in a Federal repository, which would be designed
and constructed for this purpose. The present AEC plans for waste manage-
ment appear to allow for both approaches, with individual surveillance
storage as a possible interim method until uncertainties associated with
non-surveillance disposal are resolved.
Perpetual storage in bedded salt would require about 1.6 acres per year
for the amount of fission-product high-level wastes produced in the
1000 Mw(e) light-water nuclear power plant ^ '. If canal storage is used,
data in ORNL-4451^2^ lead to the calculation that about 50 sq.ft./yr. of
canal storage would be required for the solidified wastes from the
1000 Mw(e) nuclear plant.
The AEC now contemplates^ ' a storage facility located in some remote
area, constructed for a service life of 100 years. The massive struc-
ture would provide radiation shielding, and the structure could be kept
serviceable beyond its design lifetime. The overall site would occupy
about 1000 acres, of which about 30 acres would be devoted to an initial
module capable of storing the annual high-level wastes from 250
1000 Mw(e) light-water nuclear power plants.
52
-------
Storage of high-level wastes in bedded salt is expected to result in
only small releases of radionuclides to the environment. The projected
radiological and chemical releases include gaseous Kr , H , and He that
pop ??n
result from radioactive decay; Rn and Rn emitted by radioactive
sources occurring naturally in the underground salt formation; 1^ and
HC1 resulting from salt decomposition, corrosion, electrolysis, and
radiolysis; diesel exhaust fumes; and salt particles^24'.
Average annual release rates'^' projected for an embedded-salt storage
facility are tabulated in Table 2.13.
The embedded salt facility was designed to handle a yearly input of
21,300 containers of high-level solidified waste by the year 2000, with
a total accumulated inventory of 200,000 containers. It would appear,
therefore, that the projections in Table 2.13 for the effluents for the
entire facility at full-scale operation would be attributable to the accu-
mulated output of several hundred 1000 Mw(e) nuclear power plants or to
the yearly output of several thousand plants. Therefore, the effluents
resulting from storage of high level wastes from the reference 1000 Mw(e)
nuclear plant would be several orders of magnitude lower than those listed
in Table 2.13.
53
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Table 2.13
Estimated Release Rates for an Embedded Salt High-Level
Waste Storage Facility. Full-Scale Operation
(24)
Radiological, Ci/yr.
high-level waste particles
alpha waste particles
on
Kr (from spontaneous fission)
2
H (from spontaneous fission)
222
Rn (natural sources)
220
Rn (natural sources)
Chemical, s.cu.ft./min.
Hp (corrosion, radiolysis, electrolysis)
He (alpha decay)
HC1 (brine decomposition)
(XL (diesel exhaust)
CO (diesel exhaust)
N02 (diesel exhaust)
S09 (diesel exhaust)
Other
CH20 (diesel exhaust)
Soot (diesel exhaust)
Salt particles
0.007
0.04
0.014
0.0009
0.9
0.04
37
0.001
0.07
50
0.05
0.05
0.03
0.0007
2 Ib/yr.
5 Ib/yr.
54
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2.11 Accidental Environmental Releases
Additional environmental impact and risk can result from radiologi-
cal and chemical releases from various possible accidents through the fuel
cycle. Accidents of environmental significance range over a broad spec-
trum, from small accidental releases of almost routine occurrence to
accidents of low probability but serious consequence. The environmental
consequence alone is determined by the magnitude of a given accidental
release and by its biological and ecological effect. However, for a given
accident, the environmental significance and environmental risk are not
determinable unless the accident consequence and accident probability are
both known.
It is apparent that there will be some accidents near the low-consequence
end of the accident spectrum which are of low enough consequence to
involve negligible risk, even if the accident were assumed to occur with
certainty, i.e., with a probability of unity. This is characteristic of
the accidental-release estimates that can be obtained from present
environmental impact statements. These estimates are useful in identify-
ing the sources and magnitude of some of the accidental releases that
might be more likely to occur. Elsewhere there are also estimates of
* ;
releases from other accidents, including accidents of high consequence
and undoubtedly low probability. However, these release estimates for
high-consequence accidents are not accompanied by estimates of accident
* Examples are the loss-of-coolant design basis accident, and its asso-
ciated radiological releases, as well as the many other accidents and
associated releases, considered in the safety analysis of nuclear-
power plants. Accidents with greater releases are also possible^) _
There are similar examples throughout much of the nuclear fuel cycle(25)
55
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probabilities that can be reasonably associated with these releases.
Therefore, accidental release estimates now available in the public litera-
ture do not yet provide a data base for the object.ve and comprehensive
analysis of the environmental significance of accidental environmental
releases. High-consequence release estimates without associated probabil-
ities, and low-consequence estimates alone, are insufficient and mislead-
ing for comprehensive determination of environmental impact. The diffi-
culties of estimating accident probability and accidental risks, and the
questionable and invalid assumptions and conclusions that can arise as a
result of this lack of information, are considered in the following
paragraphs.
Various estimates of probabilities of nuclear reactor accidents have
(27 28 29 30)
appeared in the literaturev ' ' ' ' but are of questionable validity
because of the lack of meaningful and reliable input data on failure
mechanisms and failure rates, because of the very limited extent to which
real and possible failure mechanisms have been considered, and because
of idealized and optimistic assumptions of uncorrelated failure modes
made in calculating probabilities of multi-event accidents.
Correlated failure modes result, for example, when the operation of a
particular component or system is adversely affected by failure of
nearby or surrounding equipment or by failure of other equipment and
systems to which it is attached. For example, an otherwise reliable
56
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plumbing system may be damaged and become inoperative if the surrounding
building structure fails. To idealize each component and system as fail-
ing only by the statistical occurrence of that item alone, as in fault-
tree analysis incorporating the assumption of independent random pro-
bability of failure of each component, results in simple mathematical
techniques but in idealistically low probabilities of multi-event acci-
dents. Techniques are available to take correlated failures into account,
and these should be applied. However, because of the lack of sufficiently
reliable input data, accurate and definitive probability and risk analy-
sis will still not be possible for low-probability high-risk accidents.
Therefore, one must also know the bounds of the probability estimates
before meaningful conclusions as to risks can be made.
Present estimates of accident probabilities that have appeared in
the literature do not, therefore, define an upper bound or even a lower
bound to probabilities and risks. The bounds of the estimates are un-
known, the input data are of doubtful reliability for analysis of these
low-probability events, and the flaws and assumptions in analytical tech-
niques lead to probability estimates which can be over-optimistically
low.
Although estimating meaningful accident probabilities is extremely
difficult, it is less difficult to estimate the consequences of a postu-
lated accident and then to determine how low the accident probability must
be for the risk to be reasonable. By "reasonable" we mean that the risk
57
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be of the same order of magnitude as other calculable risks to which
society is frequently exposed, such as driving automobiles. Such analysis
shows that for some high-consequence accidents the accident probability
must be less than one such accident in several hundred thousand years of
reactor operation. Unfortunately, the excellent record of operating
experience for nuclear power plants and for other facilities in the nu-
clear fuel cycle is statistically insignificant for the purpose of con-
firming the expected low probabilities of high-consequence accidents.
These probabilities and their associated risks are unknowable by experi-
ence. Therefore, risk analysis for the low-probability accidents must
rest upon prediction, but the prediction must result from a far more
detailed and careful analysis and with more reliable and meaningful input
data than has occurred at present.
Before any conclusion can be reached that the probabilities of releases
from high-consequence accidents are so low as to be meaningless for the
purpose of analyzing impact, quantitative estimates of accident prob-
abilities and quantitative estimates of risks are needed. In the
absence of such- probability and risk estimates* a conclusion as to which
accidents have environmental significance is meaningless. It has been
shown*1 ' that some accident probabilities suggested as being so low as
to be insignificant can actually involve risks and environmental impacts
significantly greater than from normal operation. Quantification of acci-
Although the idealized estimates of accident probabilities which have
recently appeared in the literature^27'28'29) are quoted in some
environmental impact statements as background information, they have
not been used as the basis for assessing risk limits of high-consequence
accidents for the purpose of environmental impact assessment^1).
58
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dental releases and associated accident probabilities, and quantifica-
tion of risks, are necessary before meaningful conclusions can be drawn
concerning the environmental significance of the broad spectrum of
possible accidents. The necessary data are not yet available.
2.12 Effect of Plutonium Utilization
For the purpose of the present study it is assumed that the plutonium
recovered from the discharge fuel is stored. This is characteristic of
the present mode of operation of light water reactors, but it is an
unrealistic assumption for even the present reactors over their operat-
ing life of 30 to 40 years. The 0.296 Te of plutonium recovered yearly
from the discharge fuel contains 0.208 Te of fissile plutonium.
This recovered plutonium could be recycled as makeup fuel for this same
reactor by blending it with uranium, thereby decreasing the required
poc
enrichment of U in the makeup uranium. Alternatively, the plutonium
recovered from the discharge fuel of several water reactors operating
without plutonium recycle could be blended with natural uranium to form
the makeup fuel for other water reactors. On the basis of these schemes
the fuel value of plutonium has been estimated to be about $10 per gram
of fissile plutonium' '. Thus, the plutonium recovered yearly from the
discharge fuel in the present flowsheet is worth about $2 million/yr. in
a water-reactor nuclear power economy. This compares with $61 million/yr.
59
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as the value of the total electrical energy produced, assuming a generat- -
ing cost of 8 mills per kwh(e) and a load factor of 100%. In fact, it is
the fuel value of the recovered plutonium which is the principal justifi-
cation for reprocessing discharge fuel. There is indeed economic gain
235
from the recovered uranium. However, at an enrichment of 0.798% U ,
the discharge uranium is worth about $30/kg. in the form of UFg. The
value of the uranium recovered from fuel reprocessing for the 1000 Mw(e)
nuclear plant is about $920,000/yr. as compared with the plutonium value
of about $2 million/yr. Clearly, utilization of the recovered plutonium
is significant to the economy of these water reactors. The plutonium
must be used, and its use will involve new environmental considerations.
There are several alternative ways of utilizing the plutonium
recovered from water-reactor fuel. Fissile plutonium is more valuable
as a fuel for fast breeder reactors because of its more favorable neu-
tronic properties in a fast reactor spectrum. Although a fast-breeder
reactor can be fueled solely on natural uranium makeup when it has reached
its equilibrium fuel cycle, a significant inventory of plutonium is needed
to provide the initial fuel loading and startup reloads for such reactors.
This should provide the most beneficial use of plutonium from water re-
actors once economical fast-breeder power reactors are available for new
construction to meet the expanding power demands. However, the time sche-
dule for development of economical fast-breeder power reactors cannot re-
sult in a significant demand for water-reactor plutonium as fast-breeder
60
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startup fuel until the latter part of this century. Assuming introduction
of the first commercial fast breeder reactors in the mid-1980's, plutonium
inventories aimed at this use will not become a significant factor in the
1-3')}
plutonium market before the early 1990'sv '. Storage of plutonium for
such a long period and consequent deferral of income from plutonium values
would be extremely expensive. In the continued absence of any military
market for plutonium recovered from water-reactor fuel, it is clear that
there is an enormous financial incentive to utilize this plutonium as
water reactor fuel. Recyle of plutonium in light-water reactors is an
(33)
economic necessityv , and the environmental consequences of plutonium
recycle are a necessary part of a complete analysis of the light-water
reactor fuel cycle.
Plutonium utilization would entail its shipment to a fuel refabrication
plant, where it would be chemically converted to the oxide and mixed with
uranium oxide. The uranium releases associated with fabrication (cf.
Table 2.3) correspond to a total release of 0.8% of the uranium processed.
If the 0.296 Te of recovered plutonium, with a total radioactivity level
of 4.09 x 10^ Ci , were fabricated into a U02- Pu02 fuel with the same
losses, the plutonium effluents would amount to about 33,000 Ci/yr.
Because of the biological hazard of plutonium, it is apparent that fabri-
cation operations involving plutonium fuel must be carried out with pro-
cess losses several orders of magnitude below those now characteristic of
This includes radioactivity from decay of Pu236, Pu238, Pu239, Pu240,
Pu241, and Pu242 (cf. Table 2.4). Additional radioactivity is asso-
ciated with radioactive-decay daughters of Pu23" and Pu24', which grow
in after fuel reprocessing.
61
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uranium fuel fabrication. At equilibrium, the plutonium concentration
in the uranium fuel and the yearly amounts of plutonium handled in the
fuel cycle would be several times greater than the amounts shown in the
non-recycle flow sheetv32).
Because of the extreme toxicity and radioactivity of plutonium, considera-
tion of the effects of plutonium recycle or of equivalent means of utiliz-
ing plutonium as a reactor fuel is an important element in a comprehensive
environmental analysis of technologies of electrical power generation.
Although such an analysis is an intrinsic part of the comprehensive
environmental impact study for the light-water reactor fuel cycle, limi-
tations of time precluded further consideration of the effects of pluto-
nium utilization in water reactors in the present study.
62
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REFERENCES
1. Arnold, E. D., Phoebe-A Code for Calculating Beta and Gamma Activity
and Spectra for~^5|j Fission Products. ORNL-3931, USAEC (July, 1966).
2. Siting of Fuel Reprocessing and Waste Management Facilities, ORNL-4451
(July, 1970), U.S. AEC, Clearinghouse for Federal Scientific and Tech-
nical Information, Springfield, Virginia, 22151.
3. Benedict, M. and T. H. Pigford, Nuclear Chemical Engineering, McGraw
Hill, New York (1958).
4. United States Atomic Energy Commission, Environmental Survey of the
Nuclear Fjje1 Cycle, Fuels and Materials Directorate of Licensing,
U.S. Atomic Energy Commission, November, 1972.
5. United States Atomic Energy Commission, Draft Detailed Statement on
the Environmental Considerations by USAEC, DML, Relating to the Proposed
Issuance_of an Operating License to Humble Oil and Refining Company for
the Highland Uranium Mill, USAEC Docket No. 40-8102 (April 15. 1972).
6. Humble Oil and Refining Company, Environmental Report, Highland Uranium
Mill. Converse County. Wyoming, Docket No. 40-8102 (July, 1971).
7. Utah International, Inc., Draft Detailed Statement for Highland Uranium
Mill, Supplemental Environmental Information Requested by the AEC in
letter dated February 11, 1972, Docket No. 40-6622, June 23, 1972.
8. Highland Uranium Mill. Final Environmental Statement; Directorate of
Licensing; AEC; Washington, D.C. (March, 1973).
9. Environmental Survey of the Uranium Fuel Cycle, U.S. Atomic Energy
Commission, Fuels and Materials Directorate of Licensing, WASH-1248
(April, 1974).
10. Humble Oil and Refining Co., Response to Agency Comments on Draft State-
ment, Highland Uranium Mill. USAEC Docket 40-8102 (August, 1972).
11. Kerr-McGee Corporation, Uranium Hexafluoride Plant, Supplemental Appli-
cant's Environmental Report, USAEC Docket No. 40-8027 (June, 1972).
63
-------
12. United States Atomic Energy Commission, AEC Data on New Gaseous
Diffusion Plants, ORO-685 (April, 1972).
13. Denton, H. R., Statement on the Sources of Radioactive Material
Effluents from Light-Water Cooled Nuclear Power Reactors and State
of Technology of Waste Treatment Equipment to Minimize Releases,
U. S. AEC, Docket RM-50-2 (January 10, 1972).
14. Detroit Edison Company, Enrico Fermi Atomic Power Plant, Unit 2,
U. S. AEC Docket No. 50-341.
15. U. S. Atomic Energy Commission, 10 CFR 20.
16. U. S. Atomic Energy Commission, Proposed As Low As Practicable
Amendment to 10 CFR 50 Licensing of Production and Utilization Facil-
ities, Federal Register, Vol. 36, No. Ill, June 9, 1971.
17. Rodger, W. A., Testimony on Behalf of the Consolidated Utility Group,
presented at the AEC Rule-Making Hearing on the Proposed Appendix I
to 10 CFR 50, Docket RM-50-2 (April, 1972).
18. Report on Releases of Radioactivity in Effluents from Nuclear Power
Plants for 1971, Directorate of Regulatory Operations, U. S. Atomic
Energy Commission (December, 1972).
19. Pacific Gas and Electric Company, Preliminary Safety Analysis Report
for the Diablo Canyon Nuclear Power Plant, Unit 2, U. S. AEC,
Docket No. 50-323.
20. U. S. Atomic Energy Commission, Final Environmental Statement Related
to Operation of Monticello Nuclear Generating Plant, Northern States
Power Co., Docket No. 50-263 (November, 1972).
21. 10 CFR 50, Appendix F.
22. U. S. Atomic Energy Commission, Management of Commercial High Level
Hastes. SECY-2371 (March, 1972).
23. U. S. Atomic Energy Commission, Final Environmental Statement Related
to Operation of the Midwest Fuel Recovery Plant by the General Electric
Co., Docket No. 50-268 (December, 1972).
24. U. S. Atomic Energy Commission, Environmental Statement Radioactive
Waste Repository. Lyons, Kansas (June, 1971).
25. Pigford, T. H., "Study of Behavior of Clouds and Contaminants in the
Lower Atmosphere Over the K-25 Area," M.I.T. EPS, Report K-904
(April, 1952). (Declassified)
64
-------
26. Seattle, J. R. and P. M. Bryant, "Radiological Dose Computation,"
Nuclear Safety, 11, (6) 490-491 (November-December, 1970).
27. Otway, H. J. and R. C. Erdmann, "Reactor Siting from a Risk Viewpoint,"
Nuclear Engineering and Design, 1_3 (1970), 365-376. North-Holland
Publishing Co.
28. Starr, C., M. A. Greenfield, and D. F. Hausknecht, "Public Health
Risks of Thermal Power Plants," Nuclear News, 15, No. 10, 37-45
(October, 1972).
29. Otway, H. J. and R. C. Erdmann, "Risk Estimate for an Urban-Sited
Reactor," Nuclear Technology, 12, 173-184 (October, 1971).
30. Pigford, T. H., "Protection of the Public from Radioactivity from
Nuclear Power Plants," Proceedings of the 1971 Symposium on Nuclear
Science, I.E.E.E. (February, 1972).
31. U. S. Atomic Energy Commission Regulatory Staff, Testimony, U. S.
AEC Docket No. 50-341.
32. U. S. Atomic Energy Commission, Potential Nuclear Power Growth
Patterns, Division of Reactor Development and Technology, WASH 1098
(December, 1970).
33. Dawson, F. G., W. C. Astley, J. Haley, J. R. Tomonto, T. Trocki,
"Plutonium Utilization in Light-Water Reactors," Proc. U. N. Interna-
tional Conference on the Peaceful Uses of Atomic Energy, Vol. 9,
131-147 (September, 1971).
34. Rubin, J. H., "Evolving U. S. Policies in Radioactive Waste Management,"
AIF/ANS International Conference, Washington, D. C. (November, 1972).
35. Ward, J. T.A Jr., and T. H. Pigford, "A Dose Rate Kernel for Air-
Scattered 16N Decay Gamma Rays," Trans. ANS, 1_9, 446-447 (1974).
65
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3. ELECTRICAL POWER GENERATION FROM COAL:
APPALACHIAN BITUMINOUS AND NORTHWESTERN SUBBITUMINOUS
3.1 Introduction
In this chapter the use of coal as a fuel for electrical generation is
examined. Environmental releases are quantitatively presented at each stage
of the fuel cycle, from the mining of coal through the generation of elec-
tricity at a 1000 Mw(e) power plant operating at 100% of capacity. Two
types of coal are considered: Appalachian, for which both surface-mining
and underground mining are examined; and Northwestern, for which only sur-
face mining is meaningful. The corresponding illustrative flowsheet is
shown in Figure 3.1.
Characteristic physical and chemical properties are assigned to the coal
from each region being studied. Deviations from these values are, however,
significant. Within any region or mine, or even a particular seam, the
composition of the solid organic materials, designated as coal, may vary.
For example, in the state of Utah sulfur content can vary from less than
.5% to 8%; in Montana, the recorded calorific values range between 6000 and
13000 Btu/lb. Thus, although the generalizations used here will not apply
to a particular coal bed, they can be used as a basis for significant com-
parisons between different types of coal and between coal and other fuels.
* (24)
The Appalachian region contributed 70%v ' of the total U.S. coal production
in 1970, virtually all of it bituminous. Recoverable resources in Appalachia
* The Northern Appalachian region is comprised of central and western
Pennsylvania, the northern part of West Virginia and Ohio. The central
Appalachian region includes Virginia, the eastern portion of Kentucky,
and the southern portion of West Virginia. Alabama, Maryland, Tennessee
are also included, with smaller contributions.
67
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FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
— AIRBORNE RELEASE
C> LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
When values for Northwestern
coal differ from those of
Appalachian coalt they are
stated in brackets, [ ] .
68
-------
EASTERN
bituminous
Input
4xl06 Te coal
2xl07 Te overburden
Surface
Mining
80% extraction
efficiency
1 1
I.Ox IO7 Te overburden waste
80OO acres disrupted land
water
Te dissolved
solids
2.2 x!05Te suspended'
Dramo<
1.4 x IO1
Input
6.UI06 Te coal
.5xl05 Te water
6.6
Deep
Mining
57% extraction
efficiency
x !04Te acid
1.3 xlO5 Te solid waste
2 acres
150 acres land
subsidence
11—> 5x)05 Te acid
in drainage water
makeup water
3.5xl06 Te cool
circulating water
.9
3.99xl06Te
r x IO6 Te *
1
76 xlO6 Te coa
*
Cleaning
Waste
Storage
8 acres
at
30ft. depth
I
Liquid
1.6x10
3.1 xlO
3 x 10
COAL
•- 73°
200-4
i (3xl02Te)
Evopcrated water COAL POWER PLANT
| 3.8x10= Te Material and Environrr
i
i
CLEANING
/<. YIELD
1.28 XlO6 Te
1 *
1 Liquid wastes
1 I.59xl0s Te black water
± 7.1 xlO4 Te solids
Solid wastes
4.1 x IO5 Te solids
Irainage
' Te disso ved solids
3 Te suspended solids
Teacid 1.76 x
IO6 Te coal
Transportation
~ 70% Roil
3.0 x IO6 Te coal
for rail
30% Waterways
0.1% losses
^».
/
Figure 3.1
1000 Mwe
\Q\ Release Flowsheet
j When values for Northwestern
' coal differ from those of
Transrr
ission
Delivered
Electrical
Energy
7.984 x I09 kwh
Electrical Energy
8.76xl09kwh
iTransm
Losses
ismission
0.776 XlO9 kwh
Flue Gas
i 2.3 xlO9 kwh waste heat
1 II xl04[5.2x!04]Te S02
2.7xl04[3.8xl04]Te NOX
2 x I03 Te CO
400 [600] Te hydrocarbons
7[ll]Te Aldehydes
2.9 x I04 [2.3 x IO4] Te particulates
46[-]mCi Th23°,Ra226
78 [30] mCi Th232* Ro228*Th228
iAirborne Particulates
NORTHWESTERN
Subituminous
Input
2xl06 Te cool
Surface
Mining
80% extraction
efficiency
1
A 5.8 xlO6
.1 Drainage
V 2.6xl03
4-OxlO3
Te overburden
4.2 xlO6 Te coal
water
Te dissolved solids
Te suspended solids
waste
Transportation
Rait
9000 acres
for rail
Slurry pipelines
0.1% losses
stated in brae
Coal Storage
at Generating
Plant
13 acres at
40ft. depth
Ms, 1 J
coal
3.0xl06 Te
[4.2xl06Te]
Internal Thermal Losses
0.923 xlO9 kwh
Coal
Steam - Electric Generating
Plant
1000 Mwe
38% Thermal Efficiency
Fuel: 2%S, 12,000 Btu/lb.
[0.65 %S, 8500 Btu/lb.]
Plant Area: 900-l200acres
23xl09
JL
kwh/yr
V
Liquid Waste
497 Te suspended solids
66.2 Te organics
2.4 Te BOD
82.5 Te H2S04
26.3 Te CI2
41.7 Te phosphates
331 Te boron
2.4 Te chromates
2.9xl05[2.3xl05]Te
particulates
Drift
1
1
Fly Ash
90% Recovery
_iquid
Bottom <
7. 5 XlO4
j, 287 gal./min. "20L J
286 Te dissolved solids 200 [74
Evapo
Coo
^ T0¥(
Circulating Water
574,000 gal./min. 6 ac
r
Recovered Fly Ash
2.6xl05[2.lxl05] Te
420 [-] mCi Th230i Ra226
7IO[270]mCi Th232tRa228f
[5.7xl04]Te
nCi Th230*Ra226
]mCi Th232*Ra228 tTh228
,- Humidified Air
ative l.37x!07Te H20 evaporated
ln' II.O7xl09 kwh waste heat
er
es V
Slowdown Water
4?QO nal./min.
^ Bottom Ash
and
Fly Ash Storage
25ft. depth
~i \ 4
'acres "Liq
UNLESS OTHERW SE
EVAPORATIVE COOLING
»
c* * cu
Mw(e) : ME
MPC = MA
Liquid Drainage
AIRBORNE RELEASE
LIQUID EFFLUEHT
SOLID EFFLUENT
Makeup Water
11,430 gal./min.
4270 Te dissolved solids
69
-------
*
are estimated to be 35% of total coal reserves in the U.S. For this
study Appalachian coal is characterized by a heating value of 12000 Btu/lb.,
ash content of 12% and density of 85 lb/ft3. 8% of the low-sulfur, U.S.
coal (less than 0.6 Ib. of sulfur/10 Btu.) is found in this region' ' or,
alternatively stated, 20% of Appalachian coal is low-sulfur. The average
(36)
sulfur content in the Appalachian region, by states,is between 1 and 3%v
For this study, a sulfur content of 2% is assumed. Of the 400 million
tonnes of coal produced in 1970 in the Appalachian region, 35% was surface-
mined^ . The ratio of the depth of overburden to the thickness of seam
(27}
(the stripping ratio), for the strippable mines is 15:1v . 30% of these
mines are on slopes exceeding 20°, while 40% are on slopes between 15° and
20°(26).
Of the total U.S. known coal reserves, 70% are located west of the Mississippi
(28)
riverv '. However, on the basis of calorific values, the percentage is
(27}
only 45%. The Western coals comprise 67%v ' of the low-sulfur coal in the U.S.
Approximately 60% of these coals are located in the states of Montana and
Wyoming, which are the states to which this report will refer as Northwestern.
Northwestern coals are characterized here by a heating value of 8500 Btu/lb.,
an ash content of 6.8%, a density of 81 lb/ft3, and a sulfur content of 0.65
Essentially all of the 10 million^ ' tonnes of subbituminous coal (2% of the
total U.S. production) produced annually in these states is surface-mined
* Measured reserves calculated from p.116, Reference (23). They are for
beds 28 and more inches thick and overburdens less than 1000 feet thick.
71
-------
on inclinations of less than 15°, with an estimated stripping ratio of 7:1.
Contrasted with Eastern coal, for which the moisture content is negligible,
(26}
the moisture content of Northwestern coals can be ,s high as 30%v .
The flow chart for coal-fired electrical generation shows the confluence
of two alternative routes at the 1000 Mw(e) power plant. One route originates
with Northwestern coal, while the other route originates with Appalachian
coal. The branch for Appalachian coal is subdivided prior to the coal-
cleaning phase, .according to the two major modes of mining operations. Al-
though on an average regional basis 35% of the raw Appalachian coal origin-
ates in underground mines and 65% in strip mines, the present flowsheet
traces the cases for which the Appalachian coal is either exclusively deep-
mined or exclusively surface mined.
The assumed characteristics used here are tabulated in Table 3.1.
TABLE 3.1
Characteristics of Coal Assumed in Flowsheet
Appalachian Northwestern
Density 85 lb/ft3 81 lb/ft3
Heat value* 12000 Btu/lb 8500 Btu/lb
Ash content 12% 6.8%
Sulfur content* 2% 0.65%
% surface mined 35 100
Stripping ratio 15:1 7:1
* Values apply to coal entering the power plant.
72
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3.2 Underground Mining in the Appalachian Region
Back-calculating from the quantity of coal consumed in power generation
yields a total annual production requirement for raw coal of 3.5 x 10 Te.
Based on an extraction efficiency of 57v ' the required in-ground coal
resource is 6.1 x 10 Te.
Water is used in underground mining at the rate of 10 gallons per ton of
/o\ c
coal minedv '. This scales to 1.5 x 10 Te/yr of water for the present
flowsheet.
The value of 57% for the extraction efficiency is applicable to the tradi-
tional room-and-pillar method which is employed almost exclusively in the
U.S. This method requires that supporting columns of coal be left behind
in the mines. It is an inherently low-efficiency method and one which
(25)
results in the subsidence of about one-third^ ' of the undermined land
over a period of 30-50 years ^ . Since 0.0001 acres of land have been
( 25)
undermined v ' in the U.S. for each ton of coal extracted from underground
mines, the area caused to subside annually in our model, in which 3.5 x 10
Te/yr are extracted by deep-mining, is 150 acres.
Solid wastes from underground coal mining are generated at the rate of 36
5
tons per 1000 tons of raw coal producedv ', which scales to 1.3 x 10 Te/yr -
Assuming that these solid wastes are stored in piles 40 feet deep and that
•3
the coal density is 85 Ib/ft , the land requirement is 2 acres per year.
Equivalently, there are approximately 50,000 tonnes of solid waste occupying
an acre.
73
-------
Increasing the practice of backfilling underground mines will, besides de-
creasing the subsidence of land surfaces, also lower the amount of solid
wastes and the associated acidic drainage, assuming that proper sealants
are used.
An estimated 4 x 106 tons of acid drain annually from underground coal mines
in the U.S.^10^. The annual coal requirement for the reference 1000 Mw(e)
power plant, 3.5 x 106 Te, represents 1.39% of the underground-mined coal
production in the U.S. This fraction of the total annual drainage is 5.5
x 10 Te of acid. Assuming that the drainage from a mine occurs over a
period of 10 years, 5.5 x 10 Te of acid are attributable to the yearly
supply of deep-mined Appalachian coal to a 1000 Mw(e) power plant. With
currently feasible techniques, as much as 90% of the acid could be neutral-*
ized<25>.
3.3 Surface Mining, Appalachian and Northwestern
There has been a steady increase in the percentage of U.S. coal production
which is surface-mined. In 1920 surface mining accounted for just 2% of
total production^25'. In 1973 the figure was more than 50%^27'. Principal
environmental considerations involve the reclamation of land. In this regard
* In 1970, the total Appalachian underground production was 2.52 x 108
tonnes(24).
74
-------
the problems in the East with hilly terrain, and the difficulties of re-
vegetation in those areas of the West which may receive fewer than 10 inches
of annual rain, are of particular concern. The wastes from contour-mining
on the steeper slopes in the East were, in previous years, piled on resulting
land benches or dumped downhill. The area-mining technique used on the
more horizontal surfaces in the East, and almost exclusively in the West,
is one in which the excavated area is back-filled, with the exception of
the most recently mined strip. The resulting furrowed surfaces have not,
generally, been in a usable state, either for agriculture or wildlife.
Table 3.2 shows the percentage of contour and area mining in the Appalachian
states.
TABLE 3.2
Contour and Area Mining As a Percentage of Surface Mining
(23)
in the Appalachian Regionv ''
State Contour (percent) Area (percent)
Kentucky 20 80
West Virginia 90 10
Virginia 90 10
Tennessee 100 0
Ohio 0 100
Pennsylvania 25 75
75
-------
Ideally, the overburden from surface mines is excavated and replaced in
properly ordered layers. Besides allowing reutilization of mined areas and
decreasing land requirements for waste storage, reclamation prevents other
damaging impacts. For example, it is reported that increases by a factor
of 500 are common in the erosion and sedimentation rates from surface mines
over that of neighboring lands. Exposure of material in unfilled mining
areas and in waste piles results in oxidation of these materials by air and
water. The surfur-bearing layers are often directly above and below the
coal deposits. As a result these layers are particularly susceptible to
oxidation, causing the formation of sulfuric acid and ferrous and ferric
sulfate which may affect the quality of groundwater and surface water. In
the Northwest, where inorganic sulfur compounds are not generally present,
alkaline compounds may be present in large enough quantities to increase
the salinity in aquifers.
In the accompanying flowsheet the two alternative coal inputs to the coal-
cleaning plant are from the Appalachian and the Northwestern regions. In
the text, values for Northwestern coal follow [in brackets] the stated values
for .Appalachian coal.
The efficiency of extraction for both the Appalachian"' and the Northwestern^ '
surface-mined coal is 80%. Back-calculating from the raw coal requirement,
fi fi
which is'3.5 x 10 Te [4.2 x 10 Te] and dividing by .80 yields an annual
requirement of 4.4 x 10 Te [5.2 x 10 Te] of in-ground coal.
76
-------
Using the value of 15 tons [7 tons] overburden removed per ton of coal
mined^ ', open pit mining of the required 3.5 x 10 Te [4.2 x 10 Te] of
raw coal requires the removal of 5.2 x 10 Te [2.9 x 10 Te] of overburden.
A large portion of the overburden is returned to the pit. For example,
*
between 1930 and 1971 an average of 80% of the area used for disposal of
overburden and other wastes from surface mining in the U.S. was reclaimed.
The yearly, nationwide average has been increasing, and in recent years has
included reclamation from previously mined waste piles.
If it is assumed that 20% of the extracted overburden remains in waste
piles, 1.0 x 10 Te [5.8 x 10 Te] of solid wastes are produced each year.
To determine the land area consumed by surface mining, a value of 700 acres
/- "Jr^c*
[36 acres] of land per 10 tons mined was used . Approximately three
(24)
times the mined surface^ ' including 10% for the construction of access
and haulage roads^ ' is disturbed by mining. The total affected area,
scaled to the present model, is 8.0 x 10 acres [520 acres].
Additional damage to the land is caused by erosion from runoff as well as
by ancillary processing units, such as acid-neutralization plants.
(5)
According to measurements at a Kentucky strip minev , surface-water run-
off carries 1900 tons of suspended solids per year per square mile of
3
disturbed area. Using the above value of 8.0 x 10 acres, and assuming
* Calculated from data on page 16 of Reference (34).
** Calculated from data on the number of mined tons/disrupted square miles
in Reference (24), pp. 885, 1006-1012. A national average of 335
acres/106 tons mined was calculated from (24), p. 194. These values
pertain only to the mine site.
77
-------
that drainage and erosion continue at the same rate for 10 years, the
yearly quantity of solids in the drainage water from surface mining is
2.2 x 105 tonnes. Similarly, for dissolved solids the same study reports
an annual value of 1250 tons per square mile of distrubed area, which
yields 1.4 x 105 Te/yr of dissolved solids attributable to the surface
mining of Appalachian coal. Corresponding data for Northwestern coal
mining are not available. However, a rough estimate can be made by assuming
that the rate of flow per surface area of dissolved solids and suspended
solids, in a given region, is directly proportional to the annual precipi-
tation in that region. Since the annual precipitation in Montana and
*
Wyoming is about 27% that of the Appalachian region , the estimated yearly
quantities of suspended solids and dissolved solids in the effluents from
Northwestern coal mines are, respectively, 0.27 x [1.4 x 10 Te) or
4 x 103 Te, and 0.27 x [9.2 x 103 Te] or 2.6 x 103 Te.
The leaching and drainage of acid from waste piles associated with
^
Appalachian surface mines has been reported as 198 Ib. per acre per
Using this value and the previously calculated value for waste storage of
50,000 Te/acre, yields an annual drainage of 6.6 x 10 Te acid per Te of
solid waste. Using the previously estimated figure of 1.0 x 10 Te per
year of solid wastes, the annual acidic drainage from the mining of
Appalachian coal is 6.6 x 10 Te, assuming a 10-year drainage period. The
value of 10 years is conservative. There are many significant sources of
* Calculated from data in "The 1972 World Almanac and Book of Facts,"
Newspaper Enterprises Association, New York, N. Y., p. 252.
78
-------
pollution from old, abandoned mines, and it has been suggested that an
effective period of acid drainage from untreated mines could be as long as
(27)
800-3000 years'1 '.
The coal in the Northwest does not generally contain much pyritic (inorganic)
sulfur, which, upon exposure to water and oxidants reacts to form sulfuric
acid. Drainage water from these mines, however, may have a high alkaline
content. The water-monitoring measurements near a Western mine show a
(27}
sodium concentration 16 times the normalv .
3.4 Cleaning and Preparation of Raw Coal
In 1972, 46.3% of the coal produced in the U.S. and 50% of the coal produced
in Appalachia was mechanically cleaned^ '. Cleaning processes are utilized
principally on coals containing inorganic sulfur and involve techniques for
physically separating the constituents of coal in order to remove inorganic
impurities. The impurities removed include shale, clay, ash, rock and
pyritic sulfur. The removal of sulfur can be fairly effective so that, for
example, medium-sulfur, Eastern coal (1% - 2% sulfur) can be reduced to
(2(5)
1% sulfur*1 . The processed coal will weigh less and, therefore, will have
a higher heating content. The disadvantages of the method include the loss
of some usable coal; emissions of fine particulates, NOX and SOX from ther-
mal dryers; and the resulting waste piles which consume land and affect
water quality in a manner similar to that described for mining. New tech-
niques are currently being developed for the utilization, in the manufacture
Computed from data on page 375, Reference (11).
79
-------
of construction materials^29), of sulfur and ash pellets produced from the
.waste piles. Research is also being pursued in the technology of chemical
desulfurization, in which organic as well as pyritic sulfur is removed.
A description of a modern mine-site, mechanical, coal-cleaning facility
which prepares coal for shipment to an electric utility, is given by
Manwaring^2'. In the accompanying flowsheet 5Q% of the Appalachian coal
is processed in a mine-site mechanical cleaning plant having an efficiency
of 73%*. Of the 3.5 x 106 Te of Appalachian coal mined, 1.76 x 10 Te is
processed in the facility, yielding 1.28 x 10 Te of cleaned coal. The sum
of the cleaned coal, 1.28 x 10 Te and the non-cleaned coal, 1.76 x 10 Te
is 3.04 x 10 Te per year. This amount of coal is transported to the power
plant. It is assumed that there are no wastes due to the sizing and
crushing operations performed on the coal which bypasses the mechanical -
cleaning stage.
The water required by the coal-cleaning facility is 1500 gallons - 2500
(38}
gallons per ton of coal processedv '. This requirement is met by recircu-
lating water and by makeup water. The makeup water supplies the losses
which result from the discharge of "black water," and the evaporation of
water from the thermal dryers.
The percentage of required water which is recirculated, and the percentage
of makeup water which is discharged in the mechanical cleaning of coal
from major Appalachian coal-producing states are given in Table 3.3.
* Calculated from data presented in Reference (11), p. 202. For the more
important coal-producing Appalachian states, the average efficiencies
range from 69 to 76 percent.
80
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TABLE 3.3
WaterJJsafle^in Coal-Cleaning Plants in
*
Appalachian States
Discharged Water
Required Hater Recirculated Water (Black water)
125,109 x 106 gal 102,594 x 106 gal 18,265 x 106 gal
82% of required water 14.5% of required water
The value of 1500 gallons (or 5.66 Te) of water per ton of processed coal
is used in the present model. Since 1.76 x 10 Te of coal are processed
yearly in the present model, 10.96 x 10 Te of water are required per year
in the cleaning plant. According to Table 7.3, 82.0% of this value, or
8.99 x 10 Te of water per year are recirculated, and 18%, or 1.97 x 10 Te
of water per year must be supplied as makeup water. The black water com-
prises 14.5% of the required water or 1.59 x 10 Te/yr.
(9)
The black water contains 4 to 5% coal solidsv '. Using the value of 4.5%
4
and scaling to the present model yields 7.1 x 10 Te of solids in the
annual flow of water discharged from the cleaning plant.
5
The quantity of wastes resulting from the cleaning process, 4.8 x 10 Te,
is simply the difference between the weight of the processed raw coal,
1.76 x 106 Te and the weight of the cleaned coal, 1.28 x 106 Te. The
* Calculated from data in reference (39), for the following states:
Alabama, Kentucky, Ohio, Pennsylvania, Virginia, West Virginia.
81
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weight of the solid wastes, 4.1 x 105 Te, is calculated as the difference
between that of the total wastes and the weight of the solids contained in
the black water. In the case of strip-mined coal, these wastes may be
returned to the mining site. Cleaning wastes from deep-mined coal are
generally stored in surface piles. Assuming that all wastes are stored in
surface piles, 8 acres of land per year are required. This value is based
upon a surface density of 50,000 Te/acre.
The concentration of suspended solids in mine-spoil bank runoff has been
reported as 27,000 tons per square mile per year^ '. Assuming that the
mine spoils are similar to coal cleaning refuse, and that the drainage
occurs for 10 years, 3060 Te/yr of suspended solids are attributable to
coal cleaning waste drainage associated with the coal for the reference
1000 Mw(e) power plant. Spoilbank runoff carries a dissolved solids load
(5\
of 14,000 tons per square mile per yearv , which leads to an estimate of
1590 Te/yr of dissolved solids in runoff from coal cleaning wastes
(assuming a 10 year drainage period).
On the basis of 198 Ib. acid per acre per day for acid drainage from
refuse piles at coal mine-sites^ ' the 8-acre refuse pile yields
3
3 x 10 Te/yr of acid for an assumed 10-year drainage period.
Airborne particulates, of unknown quantity, result from the combustion of
coal in thermal drying, from wind suspension of mine-site waste piles, and
from occasional spontaneous combustion of the piles themselves.
82
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Uncontrolled airborne emissions of participates from thermal dryers used
(13)
in cleaning are listed as 20 Ib/ton of processed coalv '. In 1972 21% of
the mechanically cleaned coal in the Appalachian region was subject to
thermal drying . Applying the emission factor to this percentage of the
o
cleaned coal in the model, 3.0 x 10 Te of particulates are released.
Assuming a representative —not an ultimate —collection efficiency of 90%
from a scrubber system, 300 Te per year of airborne particulates are
released in the coal cleaning process.
In general, Northwestern coal is not processed at mechanical coal-cleaning
plants, largely because it contains organic sulfur (rather than inorganic
sulfur) which is not susceptible of removal by physical methods. It is
assumed here that wastes and effluents from breaking and sizing operations
are negligible.
3.5 Transport to Power Plant
Approximately 70% of the U.S. coal produced in 1970 was moved by rail. The
remainder was moved on waterways, particularly rivers and canals. These
percentages are stated on the flowsheet for Appalachian coal. Of the coal
(23)
hauled as rail freight, about 18% was moved jointly on water carriers'1 '.
Movements of Northwestern coal were almost entirely by rail.
The land requirement for coal-hauling railroads in the Appalachian [Montana'
Wyoming] region was computed by calculating the land needed by railroads in
4
the ICC Eastern district [west of the Mississippi]. There are 5.4 x 10
* Calculated from data in reference (11), p. 375.
83
-------
miles [1.19 x 105 miles]^31' of rails. In 1971, coal accounted for 43%
[9%]^32^ of the rail freight, by weight. Assuming that the right of way is
100 ft. wide, the transportation by rail requires 2.8 x 10 acres in the
Eastern district [1.3 x 105 acres west of the Mississippi]. Since annual
coal production in Appalachia of 4.24 x 108 Te represents 85% of production
in the ICC Eastern district [10 x 106 Te in Montana-Wyoming represents 24%
of western production^33'] and 0.7% [30%] of this production is utilized
in the present model, the land requirement is .007 x .85 x (28 x 10 acres)
1700 acres for the Appalachia region, and .3 x .24 x (13 x 10 acres) =
9000 acres in the Northwest.
An estimated .1% of the total tonnage shipped by rail is lost by spillage
fn\
in loading, unloading and transitv . The same percentage is assumed for
water carriers. The material loss due to transportation is, therefore,
3000 Te/yr [4000 Te/yr] of coal.
The emissions to the air from diesel engines, water carriers, handling, and
shipment are not quantified here.
The character of the transportation of coal in the Northwest is still
evolving. Railroad transportation has been the dominant mode. A small
percentage of coal mined in the Northwest is transported by truck.
Coal-slurry pipelining is an important alternative to rail shipments for
the future development of coal reserves in the Northwest. In slurry pipe-
lining a finely ground mixture of approximately equal parts of coal and
84
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water is pumped through a large-diameter underground pipe. The processing
at the mining site involves the preparation of the slurry. Pumping sta-
tions are located as required along the pipeline route. Although the con-
struction of several slurry pipeline systems is now being considered, only
one such system is now operating in the U.S. The pipeline is 280 miles
long and carries coal from the Black Mesa strip mine in southern Arizona
to a large power plant near Bullhead City, Nevada. For the Black Mesa coal
slurry pipeline, the water requirement is 15% of that for the power plant.
A portion of the slurry water is utilized as makeup water for the cooling
system of the power plant.
EHV —extra high voltage transmission —also promises to be used more
extensively in the future replacing long distance rail hauls in the West.
It is feasible only when location of a generating plant near the mine site
is practical. Like the slurry pipeline, its economic advantage increases
as the tonnage increases. Current research on superconducting lines is
aimed at decreasing transmission losses.
3.6 Coal Storage at Power Plant
An on-site coal storage capacity for 90 days of power plant operation is
assumed, corresponding to about 40 acres piled to a depth of 40 feet for
a 3000 Mw(e) power plant or 13 acres for a 1000 Mw(e) plant^15'. The
aqueous runoff from the storage piles contains dissolved and suspended
coal particles. An unknown quantity of coal fines will become airborne
85
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due to wind. In cold climates, the spraying of coal with oil and saline
solution to prevent freezing during transportation adds to the liquid
wastes from storage pile drainage.
3.7 Power PI ant Operation
The present discussion is based upon a 1000 Mw(e) pulverized fuel coal
boiler operating at 100% capacity factor. For a heating value of 12000
Btu/lb, typical of Appalachian coal, the annual coal consumption is
3.0 x 106 Te. For a heating value of 8500 Btu/lb, typical of Northwestern
coal, the required coal supply is 4.2 x 10 Te. The input energy is
2.3 x 10 kwhr. Table 3.4 shows the thermal balance for a typical
1000 Mw(e) coal burning power plant.
TABLE 3.4
Thermal Energy Balance for Coal-Fired Power Plant - 1000 Mw(e)
Net electrical output
Heat rejected to condenser
Sensible heat in flue gas
Internal thermal losses and
plant consumption
Percent . .
of thermal input^'8'
38
48
10
Energy/yr at
100% capacity
factor, kwh/yr
8.76 x 10"
11.07 x 10
2.30 x
9
0.92 x 10'
86
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3.8 Flue Gas Effluents
The gaseous effluents are listed in Table 3.5, along with the emission of
particulates. It is assumed that 80% of the ash appears as suspended
particles of fly ash in the flue gas leaving the boiler, and the remaining
2Q% appears as furnace-bottom asfr '.
The values for SOX emissions could be reduced in the future either by new
combustion techniques or by stack-gas cleanup methods. It is estimated
that by 1975 5% of coal-fired electric generating capacity will be equipped
with flue gas desulfurization processes having removal efficiencies
*
between 75 and 90 percent . The majority of these processes will be
scrubber systems with throw-away products. Use of such air pollution con-
trol systems will create additional solid wastes. This environmental
problem is further discussed in Chapter 8.
* Based upon a letter of January, 1973 from S. M. Greenfield, then EPA
Assistant Administrator for Research and Development, published in
page 162 of reference (26).
87
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TABLE 3.5
Uncontrolled Emissions of Gases and Particulates from Coal-Fired
Power Plant - 1000 Mw(e)
Emission factor
1b/ton coal burned
Effluents. Te/yr
Appalachian Northwest
Sulfur oxides
CO
Nitrogen oxides
Hydrocarbons
Aldehydes
38 * S
1
18
0.3
.005
11 x 1
1.5 x 1
2.7 x 1
400
7
5.2 x 10"
2 x 103
3.8 x 104
600
11
Particulates
16 * A
2.9 x
2.3 x
t Values from page 1.1-3, reference (13) for a large pulverized-fuel furnace
(greater than 108 Btu/hr). Values listed are for bituminous coal. They are
assumed to be applicable to N.W. subbituminous coal. S = % of weight of
sulfur (2% East, .65% N.W.). A = % ash (12% East, 6.8% N.W.).
88
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3.9 Fly Ash Removal
Using the emission factors in Table 3.5, the annual uncontrolled release
of particulates from the boiler would be 2.9 x 105 Te [2.3 x 105 Te]. The
same figures are obtained if one assumes that 80% of the ash content of the
*
coal becomes fly ash. Ten percent of the entering particles, or
2.9 x 10 Te/yr [2.3 x 10 Te/yr] are emitted from the stack, leaving a resi-
due of fly ash weighing 2.6 x 10 Te/yr [2.1 x 10 Te/yr]. Fly ash removal
systems generally remove precipitated particulates in liquid slurries but
ultimately the residue ends up in solid form as indicated in the flowsheet.
An undetermined quantity of fine particles are emitted due to the inadequacy
of current control technology.
Data on radioactivity in coal ash are shown in Table 3.6, along with the
radioactive emissions for our current model in which 2.9 x 10 Te [2.3 x
10 Te] of ash are emitted from the stack. The thorium-decay daughters
228 2?8 232
Ra and Th are assumed to be in secular equilibrium with Th in the
230
ash, and secular equilibrium of the uranium-decay daughters Th and.
22fi
Ra is assumed. It is assumed that these radionuclides form stable oxides
upon combustion and are carried by the ash, i.e., the radioactivity per
unit of ash remains constant.
* While technology exists for 99.5% removal-by-weight of particulates
from flue gases, and is currently employed in some instances(37), the
typical efficiencies today are actually much
89
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TABLE 3.6
230
Th
232
Th
Radium and Thorium Radionuclides Released
from Coal-Fired Power Plant Stack - 1000 Mw(e)
226
Ra
228
Ra
Content in Coal Ash
pico curies/gm ash*
228
Th
1.6
2.7
1.3
Quantities released
with discharged fly ash
Curies/yr
Appalachian Wyoming Appalachian
.046
.078
Wyoming
.030
3.10 Ash Storage
A total of 3.3 x 105 [2.7 x 105] Te of ash is added to on-site storage each
year. A 3000 Mw(t) power plant operating for 35 years at 50% average capacity
factor requires 300 to 400 acres for ash storage if piled to an average
depth of 25 feet^15^. Scaling to a 1000 Mw(e) plant at 100% capacity
factor yields a land requirement for ash storage of 17 to 23 acres per year.
An unknown quantity of liquid wastes are produced from surface runoff, and
an unknown quantity of ash dust is produced from the ash storage piles.
Based on the ash analysis presented in Table 3.6, the annual quantities of
radioactive radium and thorium in the stored ash are shown in Table 3.7.
* Data is from page 777, reference (21).
from Widow's Creek, TVA One picocurie
The Appalachian sampling is
10~12 curies.
90
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TABLE 3.7
Radium and Thorium Radionuclides in Stored Ash - 1000 Mw(e)
+ 226Ra 232Th + 228Ra
curies/yr _ curies/yr _
Appalachian Appalachian Wyoming
Bottom Ash .12 .20 .074
Precipitated Fly Ash .42 .71 .27
Total in Stored Ash .53 .90 .34
(35)
In 1972, 7%v ' of the subbituminous fly ash collected was utilized, mainly
as partial replacement of cement in concrete and as a stabilizer for sur-
faces such as road beds. None of the bottom ash has been utilized.
3.11 Liquid Hastes
Liquid wastes from a power plant are primarily due to boiler blowdown which
contains chemicals added for corrosion and organic growth control. The
emission rates for the various pollutants in liquid wastes and the calculated
releases for a 1000 Mw(e) power plant are listed in Table 3.8.
91
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TABLE 3.8
Boiler Slowdown Releases in Liquid Wastes - 1000 Mw(e)
Component
Suspended solids
Non-degradable organics
BOD
Acids
Alkalinity
Chlorine
Phosphates
Boron
Chromates
3.12 Condenser Cooling
It is assumed that the condenser cooling for the 1000 Mw(e) coal fired
power plant is .provided entirely by evaporative cooling towers. The
characteristics of the towers, summarized in Table 3.9, are scaled on the
basis of the amount of heat rejected by the condenser from the parameters
presented in Section 15.2. Additional environmental effluents associated
with cooling tower operation are discussed in Section 15.2.
Releases^' '
Ib/day
3,000
400
15
500
63
160
250
2,000
15
Releases
Te/yr
497
66.2
2.4
82.5
10.4
26.3
41.7
331
2.4
92
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TABLE 3.9
Cooling Tower Quantities for Coal-Fired Power Plant - 1000 Mw(e)
Thermal load
Circulating coolant
Slowdown discharge rate
Dissolved solids released
in blowdown
Make-up water rate
Drift rate
Dissolved solids released
in drift
Evaporated water
11.07 x 10 kwh/yr
574,000 gal/min
4290 gal/min
4270 Te/yr
11,430 gal/min
287 gal/min
286 Te/yr
1.37 x 107 Te/yr
The land area required is scaled from data presented by Parker and
(22\
Krenkelv ' for natural draft towers and is about 6 acres.
93
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REFERENCES
1. Averett, Paul, "Stripping Coal Resources in tha U.S. - January 1, 1970,"
U.S. Geological Survey Bulletin 1322, Washington, D.C. [1970), pp. 7-8.
2. "Environmental Effects of Underground Mining and Processing," U.S. Depart-
ment of Interior, an unpublished report.
3. Siehl, G. C., "Issues Related to Surface Mining," A report of the Senate
Committee on Interior and Insular Affairs, Washington, D.C. (1971).
4. "Surface Mining and Our Environment," U.S. Department of Interior,
Washington, D.C. (1971), p. 52.
5. "Influences of Strip Mining on the Hydrologic Environment of Parts of
Beaver Creek Basin, Kentucky, 1955-66," U.S. Department of Interior,
Geological Survey Paper 427-C (1970), p. C-2.
6. "Control of Mine Drainage from Coal Mine Mineral Wastes," U.S. Environ-
mental Protection Agency, 14010 DDH (August, 1971).
7. Averettj Paul, "Coal Resources of the U.S., January, 1967," U.S.
Geological Survey Bulletin No. 1275, Washington, D.C. (1969), p. 29.
8. Kaufman, Alvin, Nadler, "Water Use in the Mineral Industry," U.S.
Department of Interior, Bureau of Mines Information Circular 8285 (1966),
p. 36.
9. Delson, J. K. and R. J. Frankel, "Residuals Management in the Coal-Energy
Industry," Resources for the Future, Inc., Washington, D.C. (1974).
10. Fortune, M., "Environmental Consequences of Extracting Coal-Underground
Mining," Electric Power and Human Welfare, AAAS/CEA group preliminary
report (August 1972), pp. 1-50.
11. "Minerals Yearbook - 1972," Vol. I, U.S. Department of Interior (1972).
12. Manwaring, L. G., "Coarse Coal Cleaning at Monterey No. 1 Preparation
Plant," Mining Congress Journal, 58:3 (March, 1972), pp. 43-48.
13. "Compilation of Air Pollutant Emission Factors," U.S. Environmental Pro-
tection Agency (April, 1973).
14. "Bituminous Coal Facts - 1970," National Coal Association, Washington,
D.C. (1970).
94
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15. "Considerations Affecting Steam Power Plant Site Selection," Energy
Policy Staff, Office of Science and Technology (December, 1968).
16. Cuffe, S. T. and R. W. Gerstle, "Emissions from Coal-Fired Power Plants:
A Comprehensive Summary," U.S. Department of Health, Education and
Welfare, PHS Pub. No. 999-AP-35 (.1967).
17. "Fly Ash/Sulfur Removal Systems are Slated for Two Plants," Electrical
World, 176, 33 (September 1, 1971).
18. Eliassen, R., "Power Generation and the Environment," Bulletin of Atomic
Scientists, 27:7 (September, 1971).
19. Aynsley, E. and M. R. Jackson, "Industrial Waste Studies: Steam
Generating Plants," Environmental Protection Agency, Water Quality
Office (1971).
20. Esso Research and Engineering Co., "Systems Study of NO Control Methods
for Stationary Sources, Final Report," Vol. II, Report GR-2-NOS-69.
21. Martin, J. E., E. D. Harwood, D. T. Oakley, "Comparison of Radioactivity
from Fossil Fuel and Nuclear Power Plants," in Environmental Effects of
Producing Electric Power, JCAE hearings, 91st Congress, Part I (1969),
p. 777.
22. Parker, F. L. and P. A. Krenkel, "Engineering Aspects of Thermal Pollu-
tion," Vanderbilt University Press, 265 (1969).
23. National Petroleum Council, "U.S. Energy Outlook, Coal Availability"
(1973).
24. "Surface Mining," Hearings of the Committee on Interior and Insular
Affairs, U.S. Senate, Serial No. 92-13 (November, December, 1971).
25. Perry, H. and H. Berkson, "Must Fossil Fuels Pollute?", Technology
Review (December, 1971).
26. "Coal Policy Issues," Hearings of the Committee on Interior and Insular
Affairs, U.S. Senate, Serial No. 93-12 (92-47) (June, 1973).
27. "Environmental Crosscut Task Force for Project Independence Blueprint,"
ERCO for EPA (July 31, 1974).
28. "Mineral Facts and Problems," Bureau of Mines, Bulletin 650, U.S. Depart-
ment of Interior (1970).
29. Black, "Sulfur Recovery from Coal Refuse," Water Pollution Control
Research Series, for U.S. Environmental Protection Agency, 14010 FYY
(September, 1971).
95
-------
30. "Power Generation and Environmental Change," Symposium of Committee on
Environmental Alteration of MAS at Mil [December, 1969).
31. "Railroads, Transportation Statistics in the U.S., 1971," Bureau of
Accounts, Interstate Commerce Commission (1972).
32. "Freight Commodity Statistics, Class I Railroads, Year Ended December 31,
1971," Interstate Commerce Commission, Bureau of Accounts.
33. "Mineral Industry Surveys, Coal - Bituminous and Lignite in 1971,"
U.S. Department of Interior, Bureau of Mines (September 1972).
34. Paone, James, "Land Utilization in the Mining Industry, 1930-1971,"
U.S. Department of Interior, Bureau of Mines, Information Circular 8442
(1974).
35. Manz, Oscar E., "Utilization of Lignite and Subbituminous Ash," 1973
Lignite Symposium, University of North Dakota, Grand Forks, N.D.
(May, 1973).
36. "Steam-Electric Plant Air and Water Quality Control Data for Year Ended
December 31, 1970," based on Federal Power Commission Form No. 67
(July, 1973).
37. Berkowitz, Squires, A.M., "Power Generation and Environmental Change,"
Symposium on Environmental Alternatives AAAS, MIT (1971).
38. Perry's Chemical. Engineer's Handbook, 4th Edition, Perry, R. H., Chilton,
C. H., Kirkpatrick, S. D., editors, McGraw-Hill, New York (1963).
39. Leonard, J. W., Mitchell, D. R., "Coal Production," 3rd Edition, AIME,
New York (1968).
96
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4. ELECTRICAL POWER FROM RESIDUAL FUEL OIL
4.1 Introduction
The fuel cycle for a 1000 Mw(e) power plant fueled with residual oil
derived from domestic crude is shown in Figure 4.1. The maximum domestic
environmental effects are associated with oil produced, processed and con-
sumed within the United States; therefore other fuel sources for power
plants, such as imported residual fuel oil, will not be considered here.
The flowsheet quantities for fuel cycle operations prior to the power plant
are developed primarily on the basis of industry-wide data, scaled to the
oil flow associated with the annual fuel supply for a 1000 Mw(e) power
plant.
Residual fuel oil is a by-product of the domestic petroleum industry. The
flowsheet illustrates the operations of crude production, transport, and
the refining of crude into typical refinery products and crude by-products.
Alternate production of domestic crude oil from continental oil fields and
from off-shore fields is illustrated.
The material and environmental quantities are those resulting from the
production of the required amount of residual fuel oil to fuel an oil-fired
1000 Mw(e) power plant for one year at 100% capacity factor. The environ-
mental effluents associated with production, transportation, and refining
are, therefore, only partly attributable to producing power-plant fuel.
97
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FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
98
-------
Gas (vented and flared)
A
1
Off -Shore
Crude Oil
Extraction
40% extraction
efficiency
11
Brine „
5.28xl08bbl
"-Input
4.56 x IO8 bbl oil Oil 1
1.0 x IO7 bbl water spill
Crude oil extracted
1.82 x IO8 bbl
Crude Oil
Transport
To Refinery
(via pipe Ine}
0.04% losses
1!
1 *
Oil spills, losses
>st by blowouts, 73,000 bbl
sat wells, 4x10* bbl 11,000 Te
Figure 4.1
Residual Fuel Oil Power Plant 1000 Mwe
Material And Environmental Release Flowsheet
Gaseous
Refinery Products
Delivered
Electrical
Energy
7.984 x 10 kwh
Transmission
Losses Q
0.776 x 10s kwh
Flue Gas
A 8.81 x IO'1 cu.ft.
1 2.30 x 10 kwh waste heat
I 37,000 Te SO,
I 24.800 Te NO,
I 7l6 Te CO
. 470 Te hydrocarbons
! 24OTe aldehydes
1,500 Te porticulotes
Airborne
Porticulotes
Brit<
L input 5'2£
6.08 i IO8 bbl oil
1-0 x IO7 bbl water
305 (vented and flared)
»
Continental Crude
Oil Extraction
3O% extraction
efficiency
7,400 acres for
wells
Crude oil extracted
1.82 x IO8 bbl
11 1
i
( x IO8 bbl 0
Oil lost by blowouts.
spills at wells, 2.0xl04 bbl
Crude Oil
Transport
To Refinery
(via pipe line)
0.04% losses
42 ,OOO acres
tor pipelines
I
Oil spills, losses
73,000 bbl
1,000 Te
23,000 Te organics 1.49 x IO7 bbl jet fuel distillate
IR oon TP wo 3.95 x 10, bbl fuel oil
„ ™ -, rr, * L28 x '°7 bbl °°ses
4,300 Te CO U5 „ |o7 bbl coke-asphalt
2,230 Te ammonia 4.56x10° bbl petrochemicals
1 3.46 x 10? bbl lubricants - wax
* 1.64 x 10° bbl naptha-ethane
2,800 Te porticulates 1
* !
500°00R0 bbTJdoy «««•»' 0»
. ^ eou.valent capacity* ^ P P°p J?
Crude oil to refinery 6.8% residual yield Residual oil Ivia^tanke"/ Residual oil
1.82 x IO8 bbl 4,000 acres 1.24 x IO7 bbl 0.03% losses 1.24 x IO7 bbl
I
* II *
Solids, sludges II Oil spills ,
1.4 xlO9 Te waste water containing s^Te'''"
3 Te Phenol
24,000 Te Chlorides .iqui
ery fuel 7 Te Chromium 2 4
x IO9 cu.ft. natural gos 3 Te Lead 82.5
.lectncal ;""-"
Inergy Losse
3.76 x I03 kwh i
Residual Fuel Oil
Steam-Electric
Generating Plant
1000 Mwe
s 0.923 x 10 kwh
38% Thermal Efficiency
Fuel: 1% 5,0.5% ash
200- 350 acres
23.05 x IO9 kwh/yr
1
Te suspended solids
Te BOD
Te H-SO,,
Te Cl,
1
Drift
287 gal
286 Te
Fly Ash
Removal
84% recovery
A AH
/min. * T i.
dissolved II
solids | |
Circulating Water
574,000 gol./min.
Evaporative
Cooling Tower
0.27 mCi Th"U RaZ2b
0.25 md Th228.232
Ra228
Fly
„ Sto
Recovered Fly Ash 25 ft.
7800 Te ,,,, ,,-,
1.40 mCi Th230 Ra226
,.33mCiTh||.232
Ash
age
depth
0.5 acre
jmidified Air
37 x IQ7 Te H.O evaporated
07 x 10s kwh waste heat
il Slowdown Water
fy 4290gal./min.
4270 Te dissolved solids
FLOW OU
100% C
EVAPORA
r=t
Liquid Drainage
FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE
IEAT REJtCTION
I.24xl06bbl
natural gas
liquids for blending
total water input
3.3 x I09bbl
5.4 x I08 Te
6 Te Copper
600 Te Grease
600 Te Ammonio Nitrogen
3 Te Phosphate
1,000 Te BOD
6,000 Te COD
2,000 Te suspended solids
100,000 Te dissolved solids
41.7 Te phosphates
331 Te boron
2.4 Te chromates
66.2 Te organics
METRIC TONNE3
CURIES
KILOWATT- HOURS
MEGAWATTS ELECTRICAL
CONCENTRATION
Makeup Water
I 1,430 gal./min.
99
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As a result of the increasing needs for low-sulfur fuel to generate elec-
tricity, the U.S. demand for residual fuel oil increased from 27 million
(15)
bbl/yr to 555 million bbl/yr between 1966 and 1971 v , with a corresponding
massive decline in utility use of coal. While domestic crude oil is
generally low in sulfur content, averaging .6% by weight for offshore crude,
(19)
and .8% for continental crude v ', only approximately 7% of domestic U.S.
refinery output has been residual fuel oil^ . At the same time there has
been a virtual standstill in the growth of domestic refinery capacity (a 2%
(18)
increase in 1973)^ . The coupling of increased demand and negligible
growth in refining capacity has resulted in a large dependence upon imports
of residual fuel. In 1972, U.S. production of residual fuel amounted to
293 x 106 bbl while imports amounted to 592 x 106 bbr, mostly from
Caribbean refineries. In the future a greater fraction of the crude oil
used in the U.S. refineries will be from foreign sources. The sulfur con-
tent of these crudes is between 1 and 4% by weight. Hence further deploy-
ment of developing desulfurization techniques will be effected in order to
produce fuels which meet sulfur-emission standards.
4.2 Crude Oil Production
Q
A yearly production of 1.82 x 10 barrels of crude oil at the well is
required to produce sufficient residual fuel oil for the 1000 Mw(e) power
plant. Production of this amount from off-shore wells would result in a yearly
o
consumption of oil-pool resources of 4.56 x 10 bbl, based on an extraction
101
-------
efficiency of 40%^). The estimated oil extraction efficiency for on-shore
or continental oil wells is 30%^), which results in a yearly consumption
of 6.08 x 108 bbl of continental resources.
On the basis of data presented by Buttermore(2), approximately 1 x 107 bbl/yr
of water is required for the indicated yearly production of crude oil. Brine,
or saline water, is present in underground oil pools and must be separated
from the crude oil at the well site. The residue, containing small amounts of
oil, must be disposed of as liquid waste. Based on 2.9 bbl of brine produced
per barrel of extracted crude oil^ ', 5.28 x 108 bbl/yr of brine is produced.
An estimate of the number of wells required to produce the crude oil is
obtained as follows. The average yearly production per well in the U.S. for
the year 1969 was 6168 bbl*, which scales to 29,600 such average wells
required to produce 1.82 x 108 bbl/yr of crude oil. Assuming one quarter
acre of land per continental well , 7390 acres are required for the annual
production shown in this flowsheet.
i
Roughly 0.02% of the oil produced from off-shore wells is lost at the well
site by spills and blowouts^4'. This results in 4 x 104 bbl/yr of oil waste
at the off-shore well sites. On the basis of 0.011% losses by spills, blow-
outs and incomplete separation from waste water for continental production^4',
an estimated 2.0 x 104 bbl per year of oil wastes are produced at the wells
associated with the production quantities shown in the flowsheet. An unknown
quantity of natural gas associated with oil bearing formations is vented and
flared at the wells.
* Calculated from data presented in Reference (3), pp. 824-25.
** An estimate for the purposes of this report, including land used for
oil field water separators and oil gathering mains, etc.
102
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4.3 Transport from Hells to Refinery
The material quantities for on-shore oil transport are identical with those
developed for off-shore wells, with the exception of the land area required
for oil pipeline right-of-way. On an industry wide basis, an estimated
0.04% of oil transported from wells to refineries via pipeline is lost due
(4)
to leaks and spills^ , this results in a loss of approximately 73,200 bbl/yr
for the transported quantities shown on the flowsheet.
In 1969 there were 46,000 miles of oil-gathering pipelines v . The crude
oil production associated with a one year supply of residual fuel oil for
the 1000 Mw(e) power plant represents 6.58% of the domestic crude oil pro-
*
duction for 1969 . This share of the total U.S. oil-gathering pipeline
mileage and an assumed 14 acres of land required per mile of pipeline, yield
a land requirement of 42,000 acres. Other environmental effects associated
with pipeline construction are not included in this report.
4.4 Oil Refining
(3}
As calculated from data reported for 1969 in the Minerals Yearbook , the
residual fuel oil output of domestic oil refineries was 6.8% of the crude
oil input. Based upon this product yield, refinery capacity of 500,000
bbl/day is required to supply the annual requirement of residual fuel oil to
a 1000 Mw(e) power plant.
* Calculated from data represented in Reference (3), p. 830.
103
-------
The hypothetical refinery discussed in this report is based on industry-
wide data, representing contributions from the mix of existing refinery
operations in the U.S. It does not represent the most modern available
technology and does not necessarily represent the operation of any parti-
cular refinery. However, some of the effluent data are based on data
from individual facilities when these are the only source available.
The land requirement, stated on the flowsheet, of 4000 acres, is based
(21 )
upon the estimate of 1500 acres for a typical refinery of 200,000 bbl/dayv ' ,
It includes expansion potential as well as a visual greenbelt.
The model refinery shown here requires the input of additional quantities
of crude oil and natural gas for refinery fuel. In 1969, for the industry
as a whole, 0.0397% of the refinery crude oil input was used as refinery
(3) 4
fuelv '. Scaling to the flowsheet refinery input yields 7.04 x 10 bbl/yr
of crude oil for refinery fuel. A similar procedure using natural-gas
Q
consumption datav ' results in the estimate of 4.70 x 10 cu.ft./yr of
natural gas as fuel for the model refinery. U.S. refineries used
o
2.65 x 10 bbl of natural gas liquids for blending and as feed stock in
I 0\
various manufacturing processes in 1969V '. On a pro-rata basis, the
500,000 bbl /day refinery would utilize 1.24 x 106 bbl/yr of natural gas
liquids.
Besides the input of fuels and blending stocks, significant volumes of water
are required. The values used here were taken from a report on a particular
refinery of 190,000 bbl/day capacity^. It is expected that, with a shift
104
-------
toward closed water systems, remarkable decreases in water requirements will
result. By 1985, it is expected that the water consumption of the 500,000
bbl/day refinery in the flow chart will decrease from 3.3 x 10 bbl water/year
to 1.8 x 108 bbl water/year^21 \
The yields of important refinery products other than residual fuel are shown
in Table 4.1.
Item
Gasoline
Jet fuel
Distillate fuel oil
Gases
Naphtha-ethane
Petrochemicals
Lubricants-wax
Coke, asphalt, road oil
Residual fuel oil
Table 4.1
Refinery Products
Yield in percent
of crude input(3)
44.7
8.2
21.7
7.0
0.9
2.5
1.9
6.3
6.8
Annual yields for 500,000
bbl/day refinery
bbl/yr
8.16 x 107
1.49 x 107
3.95 x 107
1.28 x 107
1.64 x 106
4.56 x 106
3.46 x 106
1.15 x 107
1.24 x 107
100.0%
105
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Table 4.2 lists the average 1972 rate of gaseous effluents emitted from the
six major oil refineries in the San Francisco Bay Area^ . Taken together,
these refineries process 595,000 bbl/day, of crude oil. Corresponding numbers
for the flow chart are also shown.
Due to inadequate sampling techniques, the estimate in Table 4.2 for organics,
(which include hydrocarbons, organic acids, and oxygenates such as aldehydes)
is subject to the most uncertainty. These compounds are highly sensitive to
photochemical reactions and, therefore, are associated with smog.
An increase in the fraction of high sulfur foreign crudes which is processed
in domestic refineries, coupled with a decrease in the use of natural gas as
refinery fuel will tend to increase SO emissions. On the other hand, the
X
greater use of advanced desulfurization techniques, which can attain a 99.8%
efficiency^ , will tend to decrease the SO emissions. The latter effect
X
is expected to outweigh the result of processing higher-sulfur crude and
replacing natural gas with higher-sulfur fuel oil, so that SO emissions per
X
barrel of crude oil processed will not tend to exceed their current values.
Besides a greater sulfur content, the foreign crudes, especially Venezuelan,
contain a higher concentration of metals. The vanadium and nickel, which are
present, tend to impede catalytic sulfur-removal processes by rendering the
catalysts inactive.
106
-------
The burning of carbon deposits for the purpose of regenerating catalysts is
subject to stringent controls. CO boilers are generally used to control
CO emissions. The heat generated in these CO boilers is profitably utilized
in the operation of the refinery.
The emission of ammonia shown in the flow chart is based upon the estimate
that 50% of refinery input goes through fluidized bed catalytic crackers,
which emit ammonia at an average rate of .054 Ib of ammonia per barrel of
feed. Correspondingly, 2230 Te/yr of ammonia are emitted from the model
refinery.
Table 4.2
Oil Refinery Gaseous Effluents
Effluent
Particulates
Organics
N0x
S0x
CO
1972 emissions from
6 refineries with
crude input of /9nx
595,000 bbl/day^u;
tons/day
Emissions from a
500,000 bbl/day refinery
Te/yr
10.2
81.5
63.5
74
15.5
2840
22,700
17,700
21,000
4310
107
-------
Liquid effluents from oil refineries vary considerably with each refinery.
I 00\
Final EPA guidelines'1 ' which will take effect July 1, 1977, are expected
to be significantly more stringent than present'regulations.
In this study the 1973 monitors of liquid effluents as reported by 6 re-
(22)
fineries in the San Francisco Bay Areav ' were used as the basis for the
values on the flowsheet. Each refinery reported only a particular subset
of the list of types of liquid effluents, according to current requirements.
Therefore, while the total capacity of the six refineries is 595,000 bbl/day,
the capacity represented for each type of effluent is usually smaller.
The values from each refinery are normalized in Te/yr, for a model refinery
of 500,000 bbl/day capacity. For each type of effluent these normalized
values are then averaged over the number of reporting refineries. These
averages, along with ranges of reported values, are listed in Table 4.3.
108
-------
Table 4.3
Oil Refinery Liquid Effluents
Item
Waste water
Phenol
Chlorides
Chromium
Lead
Zinc
Grease
Copper
Ammonia Nitrogen
Phosphate
BOD
COD
Suspended solids
Dissolved solids
Refinery
capacity
represented
bbl/day
487,000
419,000
100,000
487,000
487,000
487,000
514,000
400,000
324,000
114,000
419,000
324,000
297,000
100,000
Range of 1973
effluents ad-
justed for a
500,000 bbl/day
refinery
Te/yr
0.1 x 108 - 4.0 x 108
0.8 - 1.3
—
2.2 - 14
1.4 - 10.0
0.8 - 14.0
33 - 2100
0.1 9.0
20 - 850
1.3 5.0
140 - 1900
650 - 12,600
500 - 2900
—
Average 1973
effluents ad-
justed for a
500,000 bbl/day
refinery
Te/yr
1.4 x 108
3
24,000
7
3
6
600
6
600
3
1000
6500
2000
110,000
109
-------
4.5 Transport of Residual Fuel Oil
Due to its high viscosity at ambient temperatures nearly all residual fuel
oil from U.S. refineries is shipped by tanker or oil barge to power plants.
For the purposes of this report, other modes of transport will not be con-
sidered. An estimated 0.03% of the oil shipped via tankers from refineries
is lost by spills in loading and transport^ , corresponding to an annual
spillage loss of 550 Te (3700 bbl) for the present flowshpet. Fuel oil
consumption as tanker fuel is not considered.
4.6 Power Plant Operation
The 1000 Mw(e) power plant is assumed to have an overall thermal efficiency
of 38% and a 100% capacity factor. The overall energy budget is assumed to be
the same as for the coal-fired plant (cf. Table 3.1). The thermal energy
available from combustion of residual fuel oil used as the basis for calcu-
lations in this report is 6.36 x 106 Btu/bbr8'. Low-sulfur residual fuel
oil containing 1% sulfur^ ' is assumed, with an ash content of Q.5%'1 .
An estimated 200-350 acres of land are required for a 1000 Mw(e) oil fired
(13)
power pi ant ; this is considerably less than that required for a coal-
fired plant because of the smaller area required for ash and fuel storage.
Liquid wastes associated with boiler feedwater treatment and blowdown are
also assumed to be identical to those shown in Table 3.7 for the coal-fired
power plant.
110
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4.7 Flue Gas Effluents
On the basis of 215 cu. ft. of flue gas per pound of residual fuel oil
burned^ , the annual quantity of flue gas produced by the 1000 Mw(e)
power plant is 8.81 x 10 cu. ft. Assuming that all of the ash appears
as fly ash upon combustion, 9300 Te of fly ash is released annually to
the flue gas system. A fly-ash removal efficiency of 84% for an oil-
(12)
fired power plant is assumed^ ', resulting in an annual particulate re-
lease to the environment of 1500 Te.
The yearly quantities of gaseous effluents are given in Table 4.5.
Table 4.4
Gaseous Effluents from Oil Fired Power Plant - 1000 Mw(e)
Pollutant
S0x
CO
Hydrocarbons
N0x
Aldehydes
Emission factors
lb/103 gal oil consumed^
157 (for r/o sulfur oil)
3
2
105
1
Yearly emissions
Te/yr
37,000
705
472
24,800
236
Radium and thorium radionuclides exist in residual fuel oil ash in measurable
(12)
quantities^ '. Concentrations reported for these radionuclides in oil ash,
230
corrected by the assumption that Ra is in secular equilibrium with Th
23?
and that Th, Ra and Th are also in secular equilibrium, are listed
in Table 4.6.
Ill
-------
Table 4.5
Radium and Thorium Radionuclides in Residual Fuel Oil Ash
230
Th
226
Ra
232Th + 228Ra + 228Th
Concentration in
oil ash(12)
Total amount in
annual fuel supply
for 1000 Mw(e)
power plant
Annual releases
from power plant
stack
Annual quantity
collected in fly
ash precipitate
0.18 picocuries*/gm dry ash 0.17 picocuries*/gm dry ash
1.67 millicuries/yr
0.27 millicuries/yr
1.40 millicuries/yr
1.58 millicuries/yr
0.25 millicuries/yr
1.33 millicuries/yr
-1 ?
* Picocurie =10 curies
4.8 Fly Ash Storage
Of the 9300 Te of fly ash produced annually in the power plant, approximately
7800 Te is recovered in the gas cleaning system and must be stored at the
power plant site or disposed of in some other fashion. An estimated annual
land area requirement for dry surface pile storage can be made by scaling from
the approximately 23 acres/yr required for the storage of the 3.3 x 105 Te per
year of ash recovered from the coal-fired power plant. This results in an
annual land requirement of about 0.5 acres. If landfill methods of storage
112
-------
and disposal were used, considerably more land area would be necessary, but
alternate use of the land would be possible after the filling operations
were completed. If uncovered surface storage is used, an undetermined quan-
tity of airborne particulates will be produced by wind action. Liquid
wastes are produced by the use of water slurries to transport fly ash from
stack cleaning to storage sites. Additional, but unknown quantities are
produced by drainage from stored piles and land fill sites.
4.9 Condenser Cooling
Condenser cooling for the 1000 Hw(e) residual-oil-fired power plant is
assumed to be provided entirely by evaporative cooling towers. The cooling
tower quantities are calculated by scaling from the parameters developed in
Section 6.2 on the basis of heat rejected by the condenser. The quantities
are identical to those for the 1000 Mw(e) bituminous coal power plant sum-
marized in Section 6.2.
113
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REFERENCES
1. "An Initial Appraisal by the Oil Supply Task Group 1971-1985," National
Petroleum Council, Washington, D.C., p. 45 (U72).
2. Buttermore, P. M., "Water Use in the Petroleum and Natural Gas Indus-
tries," Washington, D.C., p. 32 (1966).
3. "Minerals Yearbook - 1969," Vols. I-II, United States Department of
Interior.
4. "Draft Environmental Statement for Proposed Outer Continental Shelf Oil
and Gas General Lease Sale - Off-Shore Eastern Louisiana," United States
Department of Interior, Washington, D.C. (1972).
5. "American Almanac for 1972," p. 550.
6. "Air Pollution in the San Francisco Bay Area," Stanford Air Pollution
Workshop, Final Report, p. 73 (1970).
7. Nernerow, N. L., "Liquid Waste of Industry; Theories, Practices and
Treatment," Addison-Wesley, p. 436 (1971).
8. Compilation of Air Pollutant Emission Factors, United States Environ-
mental Protection Agency, pp. 1.3-1, 1.3-2 (April, 1972).
9. "San Francisco Bay Area Water Conservation District Limits," reported for
a 190,000 bbl/day refinery in San Francisco Chronicle, September 27, 1972.
10. 1967 Domestic Refinery Effluent Profile, American Petroleum Institute,
Committee for Air and Water Conservation; Washington, D.C. (September, 1968)
11. Smith, W. S., "Atmospheric Emissions from Fuel Oil Combustion,"
U.S. Public Health Service, Environmental Health Series, Air Pollution
No. 999-AP-2, p. 5 (1966).
12. Martin, J. E., E. D. Harward, D. T. Oakley, "Comparison of Radioactivity
from Fossil Fuel and Nuclear Power Plants," Department of Health, Educa-
tion and Welfare, p. 3 (November, 1969).
13. "Considerations Affecting Steam Power Plant Site Selection," Office of
Science and Technology, Energy Policy Staff, p. 11 (December, 1968).
14. Williams, R. H., Private Communication (The Energy Policy Project)
(January, 1973).
15. Hearings before Committee on Interior and Insular Affairs, U.S. Senate,
Serial No. 93-12(92-47), p. 79 (June, 1973).
114
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16. Oil and Gas Journal , Vol. 72, No. 13, p. 73 (April 1, 1974).
17. Environmental Science and Technology, p. 494 (June, 1973).
18. Worldwide Directory 1973-1974. Oil and Gas Journal, Tulsa, Oklahoma.
19. Oil and Gas Journal , Vol. 70, No. 4, Petroleum Publishing Co.,
Tulsa, Oklahoma (January 24, 1972).
20. "Source Inventory of Emissions in the San Francisco Bay Area," Say Area
Air Pollution Control District, San Francisco, California (1972).
21. Draft Environmental Impact Statement on Refinery Development, for
Federal Energy Administration (September 17, 1974).
22. Monitoring reports for 1973, collected by the State of California
Regional Water Quality Control Board, San Francisco Bay Region.
23. Federal Register, p. 16560 ff. (Hay 9, 1974).
115
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5. ELECTRICAL POWER FROM NATURAL GAS
5.1 Introduction
The fuel cycle flowsheet shown in Figure 5.1 for a 1000 Mw(e) power plant
is based upon processed natural gas produced from continental domestic wells.
Other supply schemes such as gas from offshore areas or gas from oil-producing
wells are also used by various electrical generating plants but are not
considered here. The flowsheet quantities for production, processing, and
transport of natural gas fuel are developed primarily on the basis of
industry-wide data, scaled to the gas volume required for a 1000 Mw(e) power
plant.
5.2 Gas Production
A yearly production of 8.71 x 10 cu. ft. of natural gas is required to
furnish the annual fuel supply for the 1000 Mw(e) power plant. However,
based on industry-wide data, the actual volume of natural gas extracted is
about 10 percent greater. The excess volume is returned to the gas bearing
formation to stimulate flow and enhance production. Assuming an 80% extrac-
*
tion efficiency for gas wells , the net annual consumption of gas-field re-
source is 10.9 x 1010 cu. ft.
In 1969, there were about 114,500 gas wells in production in the U.S. pro-
1 O Q
ducing some 20.7 x 10 cu. ft. of gas, for an average of 1.81 x 10 cu. ft.
**
of gas produced per well . On this basis, the annual production of about
480 "average" wells is required to supply the 1000 Mw(e) power plant. Based
* General industry-wide estimate based on private communications with
industry source.
** Calculated from data presented in the 1969 Minerals Yearbook' '.
117
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
118
-------
Figure 5.1
Natural Gas Power Plant 1000 Mwe
Material And Environmental Release Flowsheet
Gas (vented and flared)
540 Te NOX
Flue Gas and
Gas Vented and Flared
2.1 xlO8 cu.ft.
900 Te S02
267 Te NOX
20 Te CO
3 Te hydrocarbons
3 Te aldehydes
8 Te organics
21 Te participates
Liquid Petroleum Products
2.96 x I06 bbl
_ Residual Natural Gos
Liquids
Input
10.9xlO10 cu.ft. natural gas
Returned to Underground Gas Formations
6.9 x I09 cu.ft.
7,67 xlO10 cu.ft.
Fuel Gas
1.8xlO9 cu.ft
Natural Gas
7.49 x I010 cutt
Delivered Electrical Energy: 7.984 x I09 kwh
Transmission Losses: 0.776 x Kr kwh
Electrical
Energy: Q
8.76x I09 kwh
Internal Thermal Losses
0.923 x I09 kwh
Steam-Electric Generating Plant
1000 Mwe
38% thermal efficiency
Natural Gas: 1050 BTU/cu.ft.
Plant Area: 100-200 acres
23.05 xlO9 kwh/yr.
, Flue Gas
* 8.53xlO11 cu.ft.
I 2.30xlO9 kwh waste heat
I 20.4 Te S02
1 2.0 x I04 Te NOX
134 Te hydrocarbons
102 Te aldehydes
I 136 Te organic*
1 510 Te participates
Circulating Water
574,000 gal./min.
Makeup Water
11,430 gal./min.
•»• Humidified Air
1.37 x IO?Te H20 evaporated
11.07 x I09 kwh waste heal
Drift
287 gal./min.
286 Te dissolved solids
Slowdown Water
4290 gal./min.
4270 Te dissolved solid*
Liquid Waste
497 Te suspended solids
66.2 Te organics
2.4 Te BOO
82.5 Te HgSQ*
26.3 Te CI2
41.7 Te phosphates
331 Te boron
2.4 Te chromatB*
METRIC TONNES
CURIES
KILOWATT . HOURS
119
-------
on one quarter acre of land per well*, 125 acres are required, assuming that
the wells produce continually during the power plant operating life and
neglecting additional requirements for exploration and drilling activities
associated with this amount of production.
Quantities of salt water and condensed hydrocarbons are separated from the
gas at the well head of high-pressure gas wells; however, no quantitative
estimates are available.
In the processes of drilling and proving gas wells, gas is lost at the well
head by venting and flaring, and by leaks and accidents. The practice of
venting is being curtailed by the industry. Quantitative estimates of efflu-
ents are presently not available.
Unknown quantities of pollutants are emitted by power equipment used to drive
pumps at gas wells.
5.3 Transmission of Raw Gas to Processing Plant
An estimate of the land area required for field-gathering mains and trans-
mission pipe is obtained as follows. The 1969 Minerals Yearbook reported
the total mileage of gas-field-gathering mains as 64,400 miles^ '. The
calculated share of the marketed gas production represented by the fuel
supply for the 1000 Mw(e) power plant is 0.39%. Scaling the total field-
gathering pipeline mileage to this fraction yields 250 miles of pipeline
* An assumption for the purposes of this paper which includes land for well
structures and associated equipment.
121
-------
required for the gas for the present flowsheet. On the assumption that
the land required for gas transmission pipelines is 14 acres per mile
and that a 10-acre pumping station is required for every 75 miles .of pipe-
(2)
linev , 3,500 acres are required for transmission. Pipeline right of
way is generally available for other limited beneficial uses after con-
struction.
In the transmission of natural gas a certain fraction of the gas is con-
sumed in fueling compression stations, both in the transmission to the
processing plant (gathering) and at the later stage of transmission between
the processing and power plants. Of the 7.49 x 10 cu. ft. of natural gas
delivered annually to the power plant, 3% is consumed as fuel in the two
(3\
stages of transmissionv '; hence the total natural gas used as fuel is 2.3
x 109 cu. ft. Of this total fuel gas, 21% is used in the first stage,
o
so that 4.7 x 10 cu. ft. per year is consumed in transmission to the pro-
cessing plant. This value represents 0.5% of the raw natural gas leaving
the well-head.
The annual quantity of NO emitted during transmission to the processing
A
Q
plant, 540 Te, is the product of the fuel gas used, 4.7 x 10 cu. ft., and
the emission factor for gaseous-fueled stationary internal combustion engines,
6 *
2500 lb/10 cu. ft. Turbine-driven compression units, which are used to a
limited extent for gas transmission, have lower NO emission rates.
A
* This emission factor is based upon a unit of 5000 h.p. ', operating at
.0375 x 10° cu. ft. per hour(5), and read from the graph of nitrogen oxides
emissions from stationary internal combustion engines, on page 3.3.2-2 of
Reference (6).
122
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5.4 Raw Gas Processing
Of the raw gas leaving the well-head, 99.5% or 8.67 x 10 cu. ft./yr arrives
at the processing plant. On an industry-wide basis in 1972, the efficiency
of raw natural gas processing was 88.5% , leaving 7.67 x 10 cu. ft./yr of
fuel transmitted to the power plant in the present flowsheet.
The land requirement for a modern gas processing plant is approximately
30 acres' '.
Water requirements for natural gas processing in 1962 were 8.425 x 10 gal.
of water' ' to process 11.089 x 10 cu. ft. of raw natural gas^ '. The
processing of 8.67 x 10 cu. ft./yr of raw gas would then require 2.6 x 10
Te/yr of water, a large portion of which is reusable.
On an industry-wide basis in 1972, 2.95% of the raw gas input to gas process-
*
ing plants was used to fuel the processing operations . Based on this figure,
Q
2.6 x 10 cu. ft. of gas fuel is required for processing the annual amount
of 8.67 x 10 cu. ft. of raw gas. It is assumed that this requisite quantity
of gas fuel is used to run industrial process boilers, for which the emission
factors and corresponding emissions are shown in Table 5.1. If gaseous-fueled
engines were to be used in place of process boilers then the emission factors
would be greater.
(15)
* Calculated from data presented in the 1972 Minerals Yearbook
123
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TABLE 5.1
Gaseous Effluents from Natural Gas Processing Plant
Pollutant
S0x
Particulates
CO
Hydrocarbons
NOX
Aldehydes
Organics
Emission factors
1b/106 cu. ft.
18
17
230
(6)
(6)
s(6)
(6)
,(11)
-(11)
Annual quantities associated
with process boiler consuming
2.56 x 109 cu. ft. of gas
Te/yr
900
21
20
3
267
3
8
(10)
124
-------
A major function of the processing stage is the conversion of the hydrogen
sulfide in the natural gas to elemental sulfur. Although techniques now
under development have F^S removal efficiencies as high as 99.8%, current
natural gas processing plants typically utilize a two-stage or three-stage
Claus process, for which the conversion efficiency is 95%'^'. The uncoverted
H2S is burned so that the releases are in the form of SC^- Using data on
the S02 released from natural gas processing in selected areas of the
U.S.''0), and assuming a sulfur-removal efficiency of 95%, the emission rate
of S02 is 2.5 x 10 Ib per million Btu of processed gas. Scaled to the
model plant, where 8.67 x 10^ cu. ft./yr of natural gas is processed, the
release of S02 is 900 Te/yr.
Natural-gas processing produces by-product natural gas liquids at the rate
of 32.8 bbl. per million cu. ft. of gas processed*, corresponding to 3.0 x 10^
bbl. of liquid petroleum products for the present flowsheet.
Of the raw gas entering processing plants, 0.24% is flared or vented to the
atmosphere*; this corresponds to the venting and flaring of 2.1 x 10^ cu.
ft./yr for the present flowsheet.
* Calculated from data presented in the 1969 Minerals Yearbook^), p. 740.
125
-------
5.5 Transmission of Residual Gas to Power Plant
Residual natural gas leaves the processing plant ct th° ^nual rate of
7.7 x 10 cu. ft. The efficiency, 98%, of the ti ansmission system bet-
ween the processing and power plants is deterrnineu uj the ratio of the
rate of residual natural gas usage for fueling the compressors at this
stage, 1.8 x 109 cu. ft., to the input of 7.7 x 10 cu. ft.
g
The quantity of fuel gas used here, 1.8 x 10 cu. ft. per year, is based
upon the discussion in Section 5.3. It is 795P ^ ' of the fuel gas used
g
annually in both stages of transmission, 2.3 x 10 cu. ft. The yearly
output of NO at this stage, based upon the emission factor of 2500 Ibs.
^» i
NOV per 106 cu. ft. of fuel gas consumed (5^6^, is 2.0 x 103 Te.
X
In 1968, there were 233,940 miles of gas transmission lines in the U.S. .
Scaling the total transmission pipeline mileage, the industry fraction of
0.39% associated with this flowsheet (cf. Section 5.3) yields 910 miles
of pipeline for transmitting fuel from the processing plant to the 1000 Mw(e)
power plant. Based on data presented in Section 5.3, transmission requires
12,800 acres of land.
5.6 Power Plant Operation
The 1000 Mw(e) power plant is assumed to operate at a 100% capacity factor
and have an overall thermal efficiency of 38%. The resulting thermal energy
budget is the same as that given in Table 3.1. For a natural-gas heating value
of 1050 Btu/cu.ft/11', the annual fuel supply is 7.49 x 1010 cu. ft.
126
-------
An estimated TOO to 200 acres is required for the power plantv , which is
less than that for coal -fired power plants because of the absence of fuel
and ash storage facilities.
Liquid wastes associated with boiler feedwater treatment and blowdown are
assumed to be identical to those for the coal -fired power plant, summarized
in Table 3.5.
5.7 Flue Gas Effluents
Combustion of the natural-gas fuel results in 8.53 x 10 cu.ft./yr of flue
*
gas . A typical particulate emission rate for natural -gas-fired power
plants is 15 Ib. per 10 cu. ft. of gas consumed, resulting in 510 Te/yr
emitted from the stack. No fly ash removal is required.
Quantities of gaseous effluents emitted from the power plant stack are summarized
in Table 5.2, based upon the input of 7.49 x 10 cu. ft. of natural gas.
Table 5.2
Gaseous Effluents from Natural -Gas-Fired Power Plant - 1000 Mw(e)
Emission factors Yearly effluents
Ib. per IP6 cu. ft. _ Te/yr
SO 0.6^ 20.4
A
Hydrocarbons 1 34
NO 600^ 2.0 x 104
X
Aldehydes 3(11) 102
Organics 4(1) 136
* Calculated from data presented in Reference (13).
127
-------
5.8 Condenser Cooling
It is assumed that condenser cooling is provided by evaporative cooling
towers. The quantities are identical to those for the 1000 Mw(e) coal-
fired power plant discussed in Section 6.2.
128
-------
REFERENCES
1. U.S. Department of the Interior, "Minerals Yearbook - 1969," vols. I-II
(1971).
2. U.S. Federal Power Commission, Opinion No. 162: Arkansas Louisiana Gas
Company, Docket No. CP 70-267, p. 5 (February, 1972).
3. National Petroleum Council, "U.S. Energy Outlook. An Initial Approach,"
Vol. 2, (July, 1971).
4. Oil and Gas Journal, "Oil Refineries," Volume 72, No. 13, p. 73 (April,
1974).
5. Private communication, George W. Rowe, Sr. Gas Engineer, Pacific Gas
and Electric Company, San Francisco, California.
6. U.S. Environmental Protection Agency, "Compilation of Air Pollutant Emission
Factors," (April, 1973).
7. U.S. Federal Power Commission, Docket No. CP72-8, "Environmental Impact
of Columbia ING Corporation Gas Processing Plant," p. 4 (November, 1971).
8. U.S. Department of the Interior, "Water Use in Mineral Industry," Bureau
of Mines Information Circular 8285, p. 28 (1966).
9. U.S. Department of the Interior, "Minerals Yearbook - 1092," vol. II,
p. 340 (1963).
10. Processes Research, Inc., Sulfur Dioxide from Natural Gas Fields, Task
Order No. 20, Contract No. CPA 70-1, prepared for Office of Air Programs,
Environmental Protection Agency (July 21, 1972).
11. U.S. Environmental Protection Agency, "Compilation of Air Pollutant Emission
Factors," (February, 1972).
12. Energy Policy Staff, Office of Science and Technology, "Considerations
Affecting Steam Power Plant Site Selection," p. 11 (December, 1968).
13. Esso Research and Engineering Co., "Systems Study of Nitrogen Oxide Control
Methods for Stationary Sources," Final Report Vol. II, p. 1-18 (November,
1969).
14. Gas Facts, 1971 Data, American Gas Association, Arlington, Virginia, 1972.
15. U.S. Department of the Interior, "Minerals Yearbook-1972," Vol. I.
129
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6. WASTE HEAT REJECTION
6.1 Once-Through. Cooling Water
Once-through cooling involves withdrawing large quantities of surface water
from a river, large lake, estuary, or ocean and returning that surface water
after it has passed through the steam condenser. The required quantity of
cooling water is proportional to the heat rejection rate divided by the
temperature rise. Temperature increases of 10 to 20°F are typical. A tem-
perature rise of 15°F has been assumed in the present analysis, resulting
in a water requirement of 966,000 gal/min for the light-water power reactor
and 574,000 gal/min for the coal-fired power plant, as shown on the flow-
sheets Figures 6.1 and 6.2.
Because of the enormous quantities of water circulated, the heated water
must be discharged at a point well removed from the intake location to
avoid recirculation of the heated water. The intake structure is usually
submerged and extends far from the shoreline. The intake must be designed
with screens and low-velocity diffusers to minimize the loss of fish by
physical impact. In some installations submerged outfalls for discharge
water are necessary to minimize locally heated areas.
Besides being the most economical cooling technology when sufficient
quantities of surface water are available, once-through cooling has the
advantage that it offers large quantities of discharge water for the
dilution of liquid effluents. For example, the indicated yearly releases
of tritium and non-tritium radioactivity from the light-water nuclear
131
-------
Figure 6.1
Light-Water Nuclear Plant, Waste-Heat
Rejection by Once-Through Cooling
Electrical
Energy
8.76 x I09 kwh
Gaseous
Kr+Xe
BWR
10
0.3
50,000
PWR
50
0.8
7000
Ci
Ci
Ci
Nuclear
Steam-Electric
Generating Plant
1000 Mwe
32% thermal efficiency
2.738 xlO10 kwh heat
T
Intake Water
966,000 gal./min.
385,000 Te dissolved
solids, 200 ppm
Discharge Water
966,000 gal./min.
I5°F temperature rise
1.862x10'° kwh waste heat
385,000 Te dissolved
solids, 200 ppm
Radioactive
Solids
35,300 Ci
34.53 Te U
Liquid waste and radioactive discharge
BWR PWR
H3 90 450 Ci
Other 5 5 Ci
590 Te dissolved solids
78.6 Te organics
2.8 Te BOD
98.0 Te acids
31.2 Te chlorine
49.5 Te phosphates
393 Te boron
2.8 Te chromates
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
IOO % CAPACITY FACTOR
EVAPORATIVE COOLINO
REJECTION
TOWER FOR WASTE HEAT
ELECTRICAL. ENEROY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
CI
kwh
Mw(*>
MPC
METRIC TONNES
CURIES
KILOWATT-HOURS
MEOAWATTS ELECTRICAL
MAXIMUM PCRMIS3ABLE
CONCENTRATION
132
-------
Figure 6.2
Coal-Fired Power Plant, Waste-Heat
Rejection by Once-Through Cooling
Electrical
Energy
8.76 x!0y kwh
Internal Thermal
Losses
9.23 xlO8 kwh
Flue Gas
i 2.30 x I09 kwh waste heat
9.69 xlO11 cu.ft.
I.I xlO5 Te S02
2.7xlO4,Te NOX
1.5 x!03Te CO
400 Te hydrocarbons
2.9 x I04 Te fly ash
Coal-Fired
Steam-Electric
Generating Plant
Appalachian Coal-'
2 % sulfur
12 % ash
12,000 BTU/lb
38% thermal efficiency
2.304 x I010 kwh heat
Intake Water
574,000 gal./min.
228,000 Te dissolved
solids, 200 ppm
Discharge Water
574,000 gal./min.
I5°F temperature rise
1.107x1010 kwh waste heat
228,000 Te dissolved
solids, 200 ppm
Bottom Ash and
Recovered Fly Ash
2.6 xlO5 Te
3.03 x I06 Te coal
Liquid Wastes
497 Te suspended solids
66.2 Te organics
2.4 Te BOD
82.5 Te acids
26.3 Te Cl
41.7 Te phosphates
331 Te boron
2.4 Te chromate
V
FLOW QUANTITIES ARE 3TATED IN
UNLE33 OTHERWISE INDICATED
METRIC TONNES/YEAR
ICO °/a CAPACITY FACTOR
EVAPORATIVE COOLINO TOWER FOR WASTE HEAT
REJECTION
ELECTRICAL ENEROY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
T»
Cl
kwh
Mw(«>
MPC
METRIC TONNES
CURIES
KILOWATT-HOURS
MEGAWATTS ELECTRICAL
MAXIMUM PCRMIS3ABLC
CONCENTRATION
133
-------
plant, when diluted tn the discharge water, result in concentrations well
below the proposed Appendix I, 10 CFR 50, design-objective concentrations
6 -8
of 5 x 10 microcuries/cc for tritium and 2 x 10~ microcuries/cc for
non-tritium radionuclides in liquid effluents. Also, the concentration of
dissolved salts in the liquid discharge is the same as that in the intake;
there is no salt concentration by evaporation that occurs in evaporative
cooling towers and cooling ponds. There are no plumes of humidified air,
as from evaporative cooling, which can contribute to icing and fogging.
The visual profile is the least obtrusive of all the cooling technologies.
Some environmental benefits are claimed as a result of the rapid growth of
certain fish species in the vicinity of the heated outfall, but these
species appear to be sensitive to the loss of heated discharge water during
plant shutdown.
The discharge of large quantities of hot water does change the ecology of
the water in the vicinity of the discharge; the oxygen content is lowered,
metabolic rates are altered, and the growth of undesirable bacteria is
enhanced. Also various forms of aquatic life, such as fish larvae, flow
through the intake screens and through the condenser tubes, resulting in
high mortality rates of these species.
6.2 Evaporative Cooling Towers and Spray Cooling
Equipment for evaporative cooling may consist of a mechanical draft cooling
tower, a natural draft cooling tower, or a spray cooling pond or canal.
For the purpose of this report, the rate of circulation of water between
134
-------
the steam condenser and the evaporative cooler is calculated on the basis
of an assumed 15°F temperature rise in the water as it flows through the
condenser. Consequently, the circulation rate is numerically equal to the
flow rate for once-through cooling, which was calculated on the basis of
the same temperature rise.
To calculate the water evaporation rate it was assumed that air enters the
evaporative cooler at a temperature of 85°F and a relative humidity of 40%,
corresponding to a wet bulb temperature of 68.4°F. Using thermodynamic
^ '
for air at various temperatures and water content, the dissipative
heat load can be translated into a volumetric flow rate of air and a rate
of evaporation of water. The results are shown on the flow sheets,
Figures 6.3 and 6.4.
Since the water make-up to the cooling system contains dissolved solids
which are not removed in the evaporation process, it is necessary that
there be a water discharge, or blowdown, to keep the dissolved solids from
building up to a high concentration in the water circulation system. The
blowdown rate depends upon the salt concentration in the make-up water and
the tolerable salt concentration in the circulating system and the blow-
down. Typical blowdown rates are of the order of 1% of the circulation
rate.
Drift, or airborne entrained water containing dissolved solids, can be an
important environmental pollutant from evaporative cooling towers. The
amount of drift varies with tower design and local wind conditions.
135
-------
Figure 6.3
Light-Water Nuclear Plant, Waste-Heat
Rejection by Evaporative Cooling
Electrical Gaseous
Energy 1
8.76 xlO9 kwh
PWR
H3 10 50 Ci
0.8 Ci
Kr + Xe 50,000 7000 Ci
Nuclear
Steam-Electric
Generating Plant
1000 Mwe
32% thermal efficiency
2.738 x I010 kwh heat
T
Drift
483 gal./min.
481 Te dissolved solids
24.1 Te chromates
4.8 Te zinc
O.I Te chlorine
Humidified Air-^ 1 I
2.30xl07 Te H20 evaporated I I
1.862xlO10 kwh waste heat I I
3.81 xlO13 cu.ft. air
Circulating Water
966,000 gal./min.
Evaporative
Cooling
Tower
6-8 acres
or
Spray
Pond
Radioactive
Solids
35,300 Ci
34.53 Te U
Liquid waste and radioactive discharge
BWR PWR
H3 90 450 Ci
Other 5 5 Ci
590 Te dissolved solids
78.6 Te orgonics
2.8 Te BOD
98.0 Te acids
31.2 Te chlorine
49.5 Te phosphates
393 Te boron
2.8 Te chromotM
Makeup Water
19,230 gal./min.
7670 Te dissolved
solids, 200 ppm
V
Water Slowdown
7210 gal./min.
7185 Te dissolved solids, 500 ppm
360 Te chromates
72 Te zinc
1.4 Te chlorine
FLOW QUANTITIES
UNLBS9
IN
ATCD
too •/» CAMCITV
CVAPORATrVB
MBJECTKMI
COOklMft
METRIC TONNES/VC AH
WASTE HEAT
•kKCTRICAL KNEROY
AMftOflNB RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
T«
CI
kwh
METRIC TONNE9
CURIES
KILOWAT T - HCXJRS
MEOAWATT9 ELECTRICAL
MAXIMUM PCRMI9SABLC
CONCENTRATION
136
-------
Figure 6.4
Coal-Fired Power Plant, Waste-Heat
Rejection by Evaporative Cooling
Electrical
Energy
8.76 xlO9 kwh
Internal Thermal
Losses
9.23 xlO8 kwh
Flue Gas
i2.30x!09 kwh waste heat
T 9.69x1011 cu./ft.
57,600 Te SO?
27,300 Te NOX
1516 Te CO
2910 Te fly ash
Drift
287 gal./min.
286 Te dissolved solids
14.3 Te chromates
2.8 Te zinc
0.06 Te chlorine
Coal-Fired
Steam-Electric
Generating Plant
Coal: 1% sulfur
12.3% ash
11,770 BTU/lb
38% thermal efficiency
2.304 x I0'° kw heat
Bottom Ash and
Recovered Fly Ash
3.61 x I05 Te
Humidified Air
l.37x!07Te H20 evaporated
U07xl010 kwh waste heat
2.26 x I013 cu.f t. air
L_
Circulating Water
574,000 gal./min.
Evaporative
Cooling Tower
4-5 acres
or
Spray Pond
3.03 x I06 Te coal
Liquid Wastes
497 Te suspended solids
66.2 Te organics
2.4 Te BOD
82.5 Te acids
26.3 Te CI2
41.7 Te phosphates
331 Te boron
2.4 Te chromates
V
Makeup Water
11,430 gal./min.
4560 Te dissolved
solids, 200 ppm
Water Slowdown
4290 gal./min.
4270 Te dissolved
solids, 500 ppm
214 Te chromates
43 Te zinc
0.8 Te chlorine
FLOW QUANTITIES ARE
UNLESS OTHERWISE
3TATED IN
INDICATED
METRIC TONNE8/YEAR
ICO l/o CAPACITY FACTOR
EVAPORATIVE
REJECTION
COOLINO
TOWER FOR WASTE HEAT
ELECTRICAL ENEROY
•— AIRBORNE RELEASE
l[> LIQUID EFFLUENT
•^ 8OLID EFFLUENT
T»
Cl
kwh
Mw(«)
MPC
METRIC TONNES
CURIES
KILOWATT- HOURS
MEGAWATTS ELECTRICAL
MAXIMUM PERMIS3ABLE
CONCENTRATION
137
-------
Because of their taller stacks and lower air velocities, the natural draft
towers operate with less drift than do mechanical draft towers. Drift
losses are probably greatest for spray ponds and spray canals^ '. Drift
loss rates are usually expressed as a percentage of the circulating water
flow. For evaporative cooling towers drift percentages as high as 0.2%
and as low as 0.002% are quoted^- ''^. The current drift warranty on
(?) (3)
large natural-draft cooling towers is 0.1%v '. A nominalv ' drift loss
from mechanical-draft towers of 0.05% of the recirculating flow is used in
the present analysis. For the reference light-water nuclear power plant
this corresponds to a drift loss of 483 gallons per minute.
The concentration of dissolved solids in the circulating system and in the
blowdown water and drift depend upon the rate of water evaporation, the
drift rate, the blowdown rate, and the concentration of solids in the water
make-up. In the flowsheets shown here the make-up water is assumed to
contain a nominal concentration of 200 parts per million (ppm) of dissolved
solids. It is assumed that the concentration in the blowdown water is
limited to 500 ppm, resulting in a typical concentration ratio of 2.5 for
the salt concentration in blowdown and drift relative to the concentration
in water make-up.
Higher salt concentrations than tfce 200 ppm concentration considered in
this reference design are found in many inland waters. For example, the
Colorado River, which supplies Urge quantities of water to the south-
western United States, contains an average salinity of 600 ppm as it flows
138
-------
through Arizona, increasing to 850 ppm at the Imperial Dam. These salt
contents are expected to increase to 800 ppm and 1340 ppm by the year 2000
unless measures are taken to control the river's salinity^ '.
Drift becomes a more serious environmental contaminant when salt water is
used as make-up. Typical sea water contains 19,000 ppm chloride,
400 ppm calcium, 1350 ppm magnesium, and 25 to 40 ppm total carbon'22^.
Distribution of even several hundred gallons per minute of sea water over
adjacent terrain as drift presents ecological problems, and these are
amplified by the concentrating effect of evaporation (2.5 times in the
present example).
The following quantities in Table 6.1 are calculated for the evaporative
cooling system for the reference light-water nuclear power plant.
Table 6.1
Water Consumption for Evaporative Cooling
Tower, Light-Water Nuclear Plant
Waste heat dissipated: 1.86 x 1010 kwh/yr
Water evaporation rate: 11,540 gal/min
Make-up water
Drift
Slowdown water
flow rate
gal/min
19,230
483
7,210
dissolved solids
Te/yr
7660
480
7180
139
-------
The salt concentrated by evaporation appears as the increased concentration
of dissolved solids in the blowdown and drift. The amount concentrated is
the product of the quantity of water evaporated and the concentration of
dissolved solid in the make-up water. For the light-water reactor reference
design this corresponds to 4600 Te/yr. The above data are scaled according
to the amount of waste heat dissipated to obtain the evaporative cooling
quantities shown in the flowsheets.
In addition to the concentrated dissolved solids, the drift and blowdown
water from evaporative cooling systems will contain chemicals added to the
circulating water to prevent scale, to control corrosion, and to prevent
microbiological growth. Sulfuric acid is usually added to lower the pH,
reducing the deposition of dissolved solids as scale on the condenser heat
transfer surfaces. Corrosion inhibitors generally are a combination of
cathodic and anodic inhibitors. The chromate-based inhibitors have been
(9)
the most widely accepted^ . Where it has been necessary to discontinue
the use of environmentally hazardous chromates, blends of zinc sulfate and
lignosulfonates are used. Other chemical combinations for inhibiting
corrosion are chromates-zinc, chromates-hexametaphosphates, chromates-
organics, chromates-hexametaphosphates-zinc, chromate-zinc-organic,
organic-zinc, nitrites, sodium silicates, and sodium silicated with dis-
persives and anti-nucleating agents. The increased use of zinc-containing
-chemicals may result in requirements for ion-exchange treatment of the
water blowdown to reduce the likely toxicity to fish. These chemicals
140
-------
appear in the drift losses. For example, at a chromate concentration of
25 ppm and zinc concentration of 5 ppm in the circulating water, the calcu-
lated drift for the reference light-water nuclear power plant carries
24.1 Te/yr of chromates and 4.8 Te/yr of zinc.
Biocides used to kill microorganisms in the cooling tower and circulating
system have, in some instances, consisted of copper compounds, tributyl tin,
and chlorophenates^ . These substances have proved dangerous to the
microorganisms in the surface waters to which the blowdown water is dis-
charged and have been supplanted by shorter-lived biocides, such as chlorine,
bromine, and acrolein, or by other biocides which are less harmful after
dilution of the blowdown water. Free-chlorine residuals in the circulating
water may be in the concentration range of 0.1 to 1.0 ppnr ' '.On the
basis of 0.1 ppm, the free-chlorine residuals discharged in the reference
light-water nuclear plant amount to 0.1 Te/yr in the drift and 1.4 Te/yr
in the water blowdown.
Additional chemical contaminants are introduced when wood packing is used
in the cooling tower to obtain increased surface area for mass transfer and
heat transfer. To reduce deterioration the wood can be impregnated with
copper and arsenic salts, but some copper aresinide can be expected to
leach into the circulating water. Creosote impregnation has also been
usecP . In modern cooling tower construction non-wood packing materials
such as transite, ceramics, and plastic-laminates are utilized.
Increased oxygen content of the evaporative cooling blowdown water, resulting
from multipass contacting of the circulating water with air, is an environ-
mental benefit.
141
-------
The mixing of the large quantities of highly humidified air from the
evaporative cooling system can, under some conditions, result in water pre-
cipitation, in the form of fog, rain, or ice. It may also result in local
air recirculation. The local effects may be less for natural draft cooling
towers because of the great height at which the humidified air is released.
Even in this case, however, humidity increases in the surrounding air can
(A)
be detected several miles down-wind of the cooling tower^ . Even under
those atmospheric conditions when there may be no visible plumes from
cooling towers, the general humidity level may be raised when conditions of
poor atmospheric mixing prevail. Subsequent nocturnal cooling may produce
extensive fog in areas not necessarily contiguous with the towers themselves.
Also, on days when cumulus clouds form naturally, there can be a tendency
for clouds to initiate in the large plumes of humidified air discharged
from the evaporative cooling towers and to propagate down-wind as cloud
(12)
streets, with the possibility of increased precipitationv '.
For fossil-fueled power plants with elevated discharges of combustion gases,
the plumes of combustion gas will tend to merge with the plume of humidified
air from the cooling tower. The increased humidity can affect gaseous air
pollutants in the flue gas. For example, sulfur dioxide in the discharged
flue gas can slowly oxidize to sulfur trioxide as it progagates downwind.
The sulfur trioxide will react with water vapor to precipitate water droplets
containing sulfuric acid, giving rise to "acid rain"'21).
142
-------
The relatively small volume of discharge water from evaporative cooling
systems creates some problem in the dilution-dispersal of liquid wastes.
This is illustrated in the case of tritium and non-tritium radio-nuclides
in liquid effluents in light-water nuclear power plants, discussed in
Section 2.7 of this report.
Land area for spray cooling ponds or spray canals is calculated on the
basis of a nominal water loading of 500 Ib/hr per square foot of pond or
canal area^ . This results in a land area requirement comparable to that
for forced draft and natural draft evaporative cooling towers. The rela-
tively large height, 400 to 600 ft., of the natural-draft cooling tower
has become a visual impact consideration in some instances.
6.3 Cooling Ponds
The evaporative loss for cooling ponds is calculated on the basis of data
quoted by Oleson and Boyle^ ' and by Jaske and Drew^ ' for evaporation
rates for cooling towers and cooling ponds. Their data, translated to
gallons evaporated per unit of waste heat to be disposed of, are as follows:
cooling pond area specific evaporation
acres per megawatt gallons per kwh of
of waste heat waste heat
0.47 0.4
0.94 0.5
1.12 (Benton Cty., Wash.) 0.4
2.08 (Lake Arlington, Texas) 0.58^13'
143
-------
By comparison, for the evaporative cooling tower we have calculated a spe-
cific evaporation rate of 0.325 gallons per kwh of waste heat. The total
evaporation rate from cooling ponds is greater than that for cooling towers
because of the additional surface water exposed to the sun. The pond sur-
face is also exposed to rainfall, and for very large ponds in regions of
high rainfall this may reduce the quantity of make-up water. For example,
for the pond area of 1.2 acres per megawatt of waste heat, the evaporation
of 0.43 gallons per kwh corresponds to a total loss rate of 122 inches of
water per year.
Flowsheets for waste-heat rejection by cooling ponds are shown in Figures
6.5 and 6.6. In calculating the quantities of the flowsheets we have used
a pond area of 0.94 acres per megawatt and an evaporation rate of 0.50
gallons per kwh of waste heat. The rates of water make-up and blowdown are
calculated on the assumption that the concentration of dissolved solids in
the make-up and discharge water are the same as those calculated for the
evaporative cooling towers.
144
-------
Figure 6.5
Light-Water Nuclear Plant, Waste-Heat
Rejection by Cooling Pond
Electrical
Energy
8.76 xlO9 kwh
Gaseous
BWR PWR
. H° 10 50 Ci
1 I131 0.3 0.8 Ci
1 Kr + Xe 50,000 7000 Ci
I
Evaporated Water
3.53xl07 Te
1.862x10'° kwh waste heat
A
Nuclear
Steam- Electric
Generating Plant
1000 Mwe
32% thermal efficiency
2.738xl010kwh heat
Circulating Water
966,000 gal./min.
Cooling
Pond
2000 acres
Radioactive
Solids
35,300 Ci
34.53 Te U
Liquid waste and radioactive discharge
BWR PWR
H3 90 450 Ci
Other 5 5 Ci
590 Te dissolved solids
78.6 Te organics
2.8 Te BOD
98.0 Te acids
31.2 Te chlorine
49.5 Te phosphates
393 Te boron
2.8 Te chromates
Makeup Water
29,500 gal./min.
11,770 Te dissolved
solids, 200 ppm
V
Water Slowdown
11,810 gal./min.
11,760 Te dissolved solids, 500 ppm
588 Te chromates
118 Te zinc
2.3 Te chlorine
METRIC TONNES/YEAR
FLOW QUANTITIES ARE STATED IN
UNLESS OTHERWISE INDICATED
IOO % CAPACITY FACTOR
EVAPORATIVE COOLINO TOWER FOR WASTE HEAT
REJECTION
ELECTRICAL ENEROY
AIRBORNE RELEA8K
LIQUID EFFLUENT
SOLID EFFLUENT
T«
CI
kwh
Mw(«>
MPC
METRIC TONNES
CURIES
KILOWATT-HOURS
MEGAWATTS ELECTRICAL
MAXIMUM PCRMISSABLE
CONCENTRATION
145
-------
Figure 6.6
Coal-Fired Power Plant, Waste-Heat
Rejection by Cooling Pond
Electrical
Energy
8.76 xlO9 kwh
Internal Thermal
Losses
9.23xlO8 kwh
I
Flue Gas
i 2.30 x lOr; kwh waste heat
9.69 x I011 cu.ft.
57,600 Te S02
27,300 Te NOX
1516 Te CO
2910 Te fly ash
Evaporated Water
2.10 x lOTTe
I.l07xl0lokwh waste heat
i
Coal-Fired
Steam-Electric
Generating Plant
Coal: 1% sulfur
12.3% ash
11,770 BTU/lb
38% thermal efficiency
2.304 x I010 kwh heat
T
Circulating Water
574,000 gal./min.
Cooling Pond
1190 acres
Bottom Ash and
Recovered Fly Ash
3.61x105 Te
3.03 x I06 Te coal
Liquid Wastes
497 Te suspended solids
66.2 Te organics
2.4 Te BOD
82.5 Te acids
26.3 Te CI2
41.7 Te phosphates
331 Te boron
2.4 Te chrorrtate
Makeup Water
17,540 gal./min.
7000 Te dissolved
solids, 200 ppm
V
Water Slowdown
7021 gal./min.
6990 Te dissolved
solids, 500 ppm
350 Te chromates
70.1 Te zinc
1.4 Te chlorine
FLOW QUANTITIES ARE STATED IN
UNLESS OTHERWISE INDICATED
METRIC TONNES/YEAR
IOO % CAPACITY FACTOR
EVAPORATIVE COOLINO
REJECTION
TOWER FOR WASTE HEAT
ELECTRICAL. ENEROY
AIRBORNE RELEASE
LIQUID EC FLUENT
SOLID EFFLUENT
T»
Cl
kwh
Mw(*>
MFC
METRIC TONNES
CURIES
KILOWATT - HOURS
MEGAWATTS ELECTRICAL
MAXIMUM
CONCENTRATION
146
-------
6.4 Dry Cooling
In dry cooling, the waste heat from the power plant is rejected by heating
a stream of ambient air circulated through a large heat exchanger. The
heat is transported from the condenser to the heat exchanger by a separate
circulating water system. This circulating water may be a closed loop,
physically separated from the condensing stream by the condenser heat
exchange surfaces. Alternatively, a direct contact spray condenser may be
used, wherein a portion of the condensate flows to the boiler, while the
remainder is pumped through the dry cooling tower and returns as spray to
the condenser. In some designs the low pressure steam from the turbine is
condensed directly on the air-cooled heat exchange surfaces, but this is
probably not feasible for large power plants because of the enormous volumes
of heat exchanger and piping associated with the low pressure steam.
Air is circulated through the dry cooling tower either by electrically
driven blowers or by natural circulation through a large hyperbolic tower
similar in design but much larger than the hyperbolic towers used in
natural draft evaporative cooling towers.
Because it operates on the dry-bulb ambient air temperature, dry cooling is
less efficient in energy utilization than evaporative cooling, which
operates on the much lower wet-bulb temperature of the air. Consequently,
the average temperature at which steam is condensed is higher for dry
cooling, the steam condenses at a higher pressure, and less total work is
147
-------
obtained in expanding the steam through the turbine. Mechanical draft dry
coolers also require substantial inputs of electrical power for the blowers.
Consequently, dry cooling decreases the net thermal efficiency of the power
plant and, for the same electrical output, results in larger quantities of
make-up fuel, chemical and radiological effluents, and thermal discharges.
Dry cooling towers are also more expensive in capital cost than evaporative
cooling towers. Recent cost estimates in the range of $15/kw(e)^ ' to
$26/kw(e)^ ' have been quoted.
Balanced against these disadvantages is the very small water consumption for
a dry cooled electrical power plant.
In a recent design^- ' of a 350 Mw(e) power plant with dry cooling the
total plant water requirement is specified as 50 gal/min for boiler feed
make-up, bearing cooling, and fire protection. This is scaled here accord-
ing to the total thermal power to yield estimated water make-up rates of
193 gal/min for a light-water nuclear pl-ant and 151- gal/min for a coal-
fired plant, each with dry cooling, as shown in the dry-cooling flowsheets
Figures 6.7 and 6.8. This water make-up rate is, however, much smaller
than that quoted by Reti^ ' 7', where 30 gal/min per megawatt of electri-
cal power was estimated. This must reflect differences in estimated water
consumption for plant auxiliary services and leakage, since the actual
blowdown water from the steam system of a 1000 Mw(e) nuclear plant is only
about 10
148
-------
Figure 6.7
Light-Water Nuclear Plant, Waste-Heat
Rejection by Dry Cooling
trical Gaseous 1
rgy j^ BWR PWR
5 xlO9 kwh 1 H3 100 500 Ci
1 1 I131 0.3 0.8 Ci
f 1 Kr + Xe 50,000 7000 Ci
Nuclear
Sleam- Electric
Generating Plant
1000 Mwe
29.2% thermal efficiency
8.3 in. Hg condenser pressure
3.00 x I010 kwh heat
I 11
Circulating Water
1,092,000 gal./min.
Blower Electrical
Power: 17.6 Mw
Makeup Water
193 gal./min.
^ated Air at 120°1
.855xlOl4cu.ft.
2.104 x I010 kwh
waste heat
A
Dry Cooling
Tower
16 acres
'
Radioactive
Solids
35,300 Ci
37.64 Te U
Liquid Waste
193 gal./min.
647 Te dissolved solids
86.2 Te organics
3.1 Te BOD
107.4 Te acids
34.2 Te CI2
54.3 Te phosphates
431 Te boron
3.1 Te chromates
Air at 100° F
1.855 xlO14 cu.ft
6.81 xlO9 Te
FLOW QUANTITIES ARE
UNLESS OTHERWISE
STATED IN
INDICATED
METRIC TONNES/YEAR
IOO '/, CAPACITY FACTOR
• VAPORATIVE
REJECTION
COOLINO
TOWKI* FOR WA»TE HEAT
ELBCTRtCAL KMKROV
AIR«OAf«B RE4.BA8C
LIQUID CrrUUBNT
SOLID EFFLUENT
T»
CI
kwh
Mw(«)
MPC
METRIC TONNE3
CURIES
KILOV/ ATT -HOURS
MEGAWATTS ELECTRICAL
MAXIMUM PERMIS9A0LC
CONCENTRATION
149
-------
Figure 6.8
Coal-Fired Power Plant, Waste-Heat
Rejection by Dry Cooling
Electrical
Energy ...
8.76 x I09
kwh
Internal Thermal
Losses
9.6 xIOB kwh
i
Flue Gas
i 1.009x10" cu.ft.
2.40 x I09 kwh waste heat
60,000 Te S02
28,400 Te NOX
1579 Te CO
3031 Te fly ash
Heated Air at I20°F
1.184 xKTj cu.ft.
1.189xlO10 kwh waste heat
Coal-Fired
Steam-Electric
Generating Plant
Coal: 1% sulfur
12.3% ash
11,770 BTU/lb
36.5% net thermal efficiency
8.3" Hg condenser pressure
2.401 x I010 kwh
I
Circulating Water
612,000 gal./min.
Blower Electrical
Power: 9.9 Mw
Dry Cooling
Tower
9 acres
Makeup Water
154 gal./min.
Bottom Ash and
Recovered Fly Ash
3.76xlO5 Te
3.15 xlO6 Te coal
Liquid Wastes
154 gal./min.
517 Te suspended solids
68.9 Te organics
2.5 Te BOD
85.9 Te acids
27.4 Te CI2
43.4 Te phosphates
345 Te boron
2.5 Te chromates
Air at 100°F
1.084 x I014 cu.ft.
3.98xlO9 Te
FLOW QUANTITIES ARE STATED IN
UNLESS OTHERWISE INDICATED
METRIC TONNES/YEAR
IOO "/a CAPACITY FACTOR
EVAPORATIVE COOL I NO
REJECTION
TOWER FOR WASTE HEAT
ELECTRICAL. KNEROY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
T»
Cl
kwh
Mw(«)
MPC
METRIC TONNES
CURIES
KILO WATT- HOURS
MEGAWATTS KLECTRICAL
MAXIMUM PCRMIS3ABLE
CONCENTRATION
150
-------
Representative performance characteristics for mechanical-draft dry cooling
towers for a light-water nuclear plant and for a fossil plant are presented
in Table 6.2, calculated from data presented by Chave' ' on heat-transfer,
blower power, and cost. For this analysis it is assumed that the tempera-
ture rise of the circulating coolant is 15°F and the temperature rise of the
air is 20°F. Inlet air temperatures of 60, 80, and 100°F are considered.
Listed in Table 6.1 are the blower power and the total heat generation rate
to furnish the blower power, other plant energy loads, and a net electrical
product of 1000 MwCe). The increase in thermal power with increasing inlet
air temperature is a result of the increasing condenser pressure. Because
of the relatively low pressure of turbine-inlet steam in the light-water
nuclear plant and because of the greater importance of expansion work in
the low-pressure portion of the steam cycle, the nuclear plant is relatively
sensitive to condenser pressure. As compared with once-through cooling or
evaporative cooling with a low wet-bulb temperature, dry cooling with an
inlet air temperature of 100°F results in a reduction of the net thermal
efficiency from 32% to 29.2% and a 9% increase in make-up fuel requirement.
Similarly, for the fossil plant, dry cooling with 100°F air reduces the net
thermal efficiency from 38% to 36.5% and increases the fuel make-up require-
ment by 4%.
As a result of the very small amount of water discharged from a dry-cooled
nuclear plant there is no medium to dilute the liquid radioactive discharges
The radioactive waste management system must then be capable of reducing
151
-------
Table 6.2
Heat Rejection by Forced Draft Dry Cooling
1000 Mw Net Electrical Output
en
ro
Condenser back pressure, in. Hg
Total heat generation rate, Mw(t)
Condenser heat reject rate, Mw(t)
Blower power, Mw(t)
Condenser cooling water,
15°F temperature rise, gal/min.
Air circulation rate, 20°F
temperature rise, cu.ft./min.
Capital cost of cooler, $10
Land for coolers, acres
Fuel requirement relative to
wet cooling at 1.5 in. Hg
back pressure
Nuclear (Water Reactors)
Ambient
60
2.75
3198
2182
16.0
992,000
3. 20x1 O8
31
15.0
1.02
Air Temper
80
5.0
3315
2299
16.8
1,045,000
3. 37x1 O8
33
15.8
1.06
"ature, °F
100
8.3
3423
2408
17.6
1,095,000
3. 53x1 O8
34
16.5
1.09
Fossil
Ambient /
60
2.75
2662
1280
9.4
582,000
1.88xl08
18.8
8.8
1.01
\ir Temper
80
5
2696
1309
9.6
595,000
1.92xl08
19.2
9.0
1.02
-ature, °F
100
8.3
2741
1347
9.9
6.12,000
1.97xl08
19.7
9.2
1.04
-------
the non-tritium radioactive liquid discharges to about 0.006 Ci/yr and the
tritium liquid discharges to about 1.5 Ci/yr to meet the proposed Appendix
o
I design-objective concentrations of 2 x 10~ microcuries/cc for non-tritium
radionuclides and 5 x 10" microcuries/cc for tritium in liquid effluents.
There is technology available to accomplish these reductions. If the tri-
tium is controlled by returning all tritiated water to the reactor coolant
system, the tritium released yearly to the reactor coolant will eventually
n s}
appear as gaseous tritium release1 ;, as is indicated on the flowsheet.
There is a compensating advantage resulting from the large volume of air
passing through the cooling tower. If all the primary and secondary air
sources containing gaseous radionuclides are discharged into the air stream
leaving the cooling tower, the rapid mechanical dilution followed by
atmospheric dispersion will result in far lower concentrations of airborne
radionuclides at and beyond the site boundary. This may provide an alter-
native means of reducing the offsite concentration of gaseous radioiodine
to the design-objective levels proposed in Appendix I of the 10 CFR 50
regulations, i.e., 10 microcuries/cc when milk-food chains are considered.
(The possible problem of gaseous radioiodine effluents is discussed in
Section 2.8).
The large volume of exhaust air from dry cooling towers may also be useful
in aiding the dilution of flue gas effluents in fossil-fueled plants. The
volume of dry-cooling tower air is about 1000 times greater than the volume
of flue gas from a coal plant. Discharging the flue gas into the dry-cooling
153
-------
air would result in a thousand-fold dilution at the point of release, with
further atmospheric dilution occurring as the mixed discharge air disperses
through the environment. (The total mass emission of thfcje emission of
these effluents is, of course, not reduced by di^'Hon.) Because the dry-
cooling air is not humidified in the process of receiving the waste heat,
the acid-rain problems discussed earlier for evaporative cooling, which can
result from the oxidation and interaction of sulfur oxides with water vapor,
would be expected to occur to a far less extent with dry-cooling air. In
fact, because of the relatively high temperature of the mixed flue-gas air
stream and the consequently higher vapor pressure of sulfuric and sulfurous
acids, acid rain could conceivably be less of a problem with dry cooling
than when the flue gas is discharged into the ambient air environment.
154
-------
REFERENCES
1. Perry, J. H., Ed., Chemical Engineers' Handbook, 3rd ed., 766, McGraw
Hill (1950).
2. Detroit Edison Co., Final Environmental Impact Statement for the
Fermi II Nuclear Power Plant.
3. Shofner, F. M. and C. 0. Thomas, "Drift Measurements in Cooling Towers,"
Cooling Towers. Chemical Engineering Progress Technical Manual, A.I.Ch.E.
(1972).
4. Macaluso, C. A., "Ecological Aspects of Cooling Systems," Cooling Towers,
Chemical Engineering Progress Technical Manual, A.I.Ch.E. (1972).
5. Holburt, M. B. and B. J. Gindler, "Legal Aspects of Salinity Caused by
Cooling Towers," Cooling Towers, Chemical Engineering Progress Technical
Manual, 54-58 A.I.Ch.E. (1972).
6. Nester, D. M., "Salt Water Cooling Tower," Cooling Towers. Chemical
Engineering Progress Technical Manual, 115-117 A.I.Ch.E. (1972).
7. Oleson, K.A. and R. R. Boyle, "How to Cool Steam-Electric Power Plants,"
Chemical Engineering Progress Technical Manual, 94-100 A.I.Ch.E. (1972).
8. Kerst, H., "Evaluation of Cooling Tower Water Treatments," Cooling
Towers, Chemical Engineering Progress Technical Manual, 70-75 A.I.Ch.E.
(1972).
9. Griffin, R. W., "Corrosion Control of Cooling Towers," Cooling Towers,
Chemical Engineering Progress Technical Manual, 65-69 A.I.Ch.E. (1972).
10. Brooke, M., "Development of Cooling Water Treatment," Cooling Towers,
Chemical Engineering Progress Technical Manual, 76-77 A.I.Ch.E. (1972).
11. Comeaux, R. V., "Supply, Use, and Disposal Problems," Cooling Towers.
Chemical Engineering Progress Technical Manual, 78-82 A.I.Ch.E. (1972).
12. Hosier, C. L., "Wet Cooling Tower Plume Behavior," Cooling Towers,
Chemical Engineering Progress Technical Manual, 27-32 A.I.Ch.E. (1972).
13. Jaske, R. T. and H. R. Drew, "Simulation of Evaporation from a Cooling
Lake with a Comparison to a Real Case and the Alternative Use of Cooling
Towers," Cooling Towers. Chemical Engineering Progress Technical Manual,
131-137 A.I.Ch.E. (1972).
155
-------
14. Johnson, V.T., "A Conceptual Design for a Power Plant Dry-Cooling
System Using a Hyperbolic Tower," Cooling Towers, Chemical Engineering
Progress Technical Manual, A.I.Ch.E.' (1972).
15. Rossie, J.P., "Dry-Type Cooling Systems," Cooling Towers, Chemical
Engineering Progress Technical Manual, A.I.Ch.E. (1972).
16. Dynatech R/D Company, "A Survey of Alternate Methods for Cooling Con-
denser Discharge Water, Large Scale Heat Rejection Equipment," 16130
DHS, (July, 1969).
17. Reti, 6.R., "Dry Cooling Towers," Proc. American Power Conference, 1963,
18. Rodger, W.A., Testimony on Behalf of Consolidated Utility Group,
U.S.A.E. United States Atomic Energy Commission Hearings on Proposed
"As Low As Practicable" Amendment to 10 CFR 50 "Licensing of Production
and Utilization Facilities," DOCKET RM 50-2 (April, 1972).
19. Chave, C.T., "Applicability of Air Cooling to Siting Problems in the
Pacific Coast Area," Pacific Coast Electrical Association, Engineering
and Operating Conference, San Francisco (March, 1970).
20. Parker, F.L. and P.A. Krenkel, "Thermal Pollution: Status of the
Art," Report No. 3, Department of Env. and Water Resources Engineering,
Vanderbilt University, Nashville, Tennessee (December, 1969).
21. Likens, G.E., F.H. Bormann, N.M. Johnson, "Acid Rain," Environment,
1_4, 33-40 (March, 1972).
22. Home, R.A., Marine Chemistry: The Structure of Water and the
Chemistry of the Hydrosphere, John Wiley and Sons, Inc., New York,
568 p, (1969).
156
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7. ELECTRICAL POWER FROM LOW Btu GAS MADE FROM HIGH-SULFUR COAL
One of the several alternate processes for reducing sulfur dioxide effluents
from the combustion of high sulfur coal involves the production of fuel gas
from the coal and the chemical separation of sulfur before this gas is burned
as fuel in an electrical generating plant. A representative fuel cycle for
this process, beginning with coal shipped to the gasification process, is
shown in Figure 7-1. The process considered here is based upon the design
(1 2)
by Squiresx ' ', whereby pulverized coal is gasified in a high-temperature
ash-agglomerating fluidized bed fed with air and steam, producing a low-Btu
(i.e. low heating value) fuel gas according to the overall water-gas reaction.
C + H20 + CO + H2
Heat for the endothermic reaction is supplied by oxidation of carbon by air
in the lower part of the bed, locally forming C02 which then shifts to combusti
ble CO by contact with carbon in the higher-temperature zones of the gasifier.
Volatiles from the coal form hydrogen, methane, and higher hydrocarbons. Much
of the coal ash agglomerates and is removed from the bottom of the gasifier
for storage. Volatile sulfur compounds in the gasified product are H2S and,
f->\
to a lesser extent, COSV . It is assumed that 0.01% of the gasifier product
leaks to the atmosphere and that .01% of the ash is emitted at this stage.
*
The crude power gas from the gasifier is cooled to about 1400°F and flows
into a gas desulfurization system, consisting of a panel bed filter charged
* The heat extracted can be used to generate high-pressure steam for power
conversion.
157
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
158
-------
Porticulotes (cool fines)
Tronsported Cool—
3.64 x 10s Te (3%
12,000 BTU/lb.
Liquid Drainage
3.64 x I06 Te cool (3% S)
233,000 Te steom
1.144 x I07 Te oir
20-28 ocres/yr.
Figure 7.1
Fossil Fueled Power Plant 1000 Mwe
Fueled With Clean Power Gas Made From 3%-S Coal
Material And Environmental Release Flowsheet
Gosifier Leakage, (0.01%)
4.9 x I07 cu.ft.
Dust
4840 Te MgO • CaCO,
1 MgO-CaS 3
Crude Power Gos
4.92 x 10" cu.ft.
0.55% H-S
Clean Power Gas
157 BTU/cu.ft.
5.01 xlO" cu.ft.
0.5% CH4
31.2% CO
15.2% H2
1.1% CO?
1.1% HoO
50.1 N2
0.0016% H2S
»-!573 Te S02
' Recovered Sulfur
l.lxlO5 Te
——- »• Delivered Electrical Energy: 7.984 x I09 kwh
Electrical
Energy:
8.76 x I09 kwh
Transmission Losses: 0.776 x I09 kwh
Internal Thermal Losses Flue Gas
0.923 xlO9 kwh A 3.20 x 10f eufl
2.30 x I09 kwh waste heat
655 Te S02
1.32xlO4 Te NOX
1000 Mwe Steam - Electric
Generating Plant
38% thermal efficiency
Clean Power Gas: 157 BTU/cu.ft.
200-300 acres
2.305 x I010 kwh/yr.
Circulating Water
574,000 gol./min. ^
Makeup Water
11,400 gal./min.
Liquid Drainage
Liquid Waste
497 Te suspended solids
66.2 Te orgonics
2.4 Te BOD
82.5 Te H2SQ4
26.3 Te ClJ
41.7 Te phosphates
331 Te boron
2.4 Te chromotes
'00 % CAPACITY FACTOR
EVAPORATIVE COOLING T(
SOLID EFFLUENT
Humidified Air
1.37 x I07 Te H20 evaporated
1.107 x I010 kwh waste heat
Drift
287 gal./min.
286 Te dissolved solids
Slowdown Water .
4290 gal./min.
4270 Te dissolved solids
METRIC TONNES
CURIES
KILOWATT - HOUftS
CONCevTRATlOW
159
-------
with half calcined dolomite^2'4^, CaC03'MgO. Gaseous H2$ reacts with the
CaC03-MgO to form a sulfurized solid on the filter, with an assumed sulfur
*
removal efficiency of 99.7% and an assumed 0.5% loss of dolomite.
Sulfurized solid from the panel bed filter is then reacted with steam and
C02 at 1100°F to release gaseous H2S and to regenerate the half-calcined
(?}
dolomite for recycle to the panel bedv '. The heat evolved in regeneration
and in the subsequent cooling of the H2S-rich by-product gas can be used to
generate additional high-pressure steam for power conservation. The C02
required for regeneration can be obtained from limestone calcination or can
be recovered from the power-plant flue gas.
The gas, rich in H2$ from sulfur desorption, is converted to elemental sulfur
for safe storage and for sale as a marketable by-product. The H2S-rich gas
is contacted at high pressure with aqueous FLSO,, yielding elemental sulfur
according to the exothermic reaction
The H2S03 solution is obtained by burning a portion of the sulfur product in
(2)
air at high pressure and absorbing the resulting S02 gas in water ^ '. It is
estimated that about 0.7% of the sulfur is lost to the atmosphere as S02 leak-
. The separated liquid sulfur is cooled and solidified, and the remaining
gaseous C02 and water vapor are recycled to the previous operation where the
H2S-rich gas was generated.
* Laboratory experiments^ indicate sulfur removal of better than 99%, and
dust removal of better than 99.9%.
161
-------
The clean power gas consists mainly of combustible CO and H2 and inert N,,.
(2)
The heating value is estimated to be 157 Btu/cu.ft. (STPr • (By comparison,
the heating value of natural gas is 1050 Btu/cu.ft.).
For the present flowsheet, illustrating the material and environmental
quantities resulting from application of the coal gasification technology
to the basic steam-cycle for power conversion, the clean product gas is
assumed to flow directly to a gas-fired boiler.
Based upon one of the more advanced and efficient concepts for coal gasifi-
cation and gas cleaning, and assuming the same composition of Eastern bitu-
minous coal as that used in Chapter 3, about 20% more make-up coal is required
for the fuel cycle described here. Whereas 3.04 x 10 Te/yr are consumed in
the coal-burning generator of Chapter 3, the quantity «of coal required for
the gasifier in the present flowsheet is 3.64 x 10 Te/yr. Consequently,
assuming the same coal-treatment operations prior to gasification, the en-
vironmental and material quantities for the fuel-cycle operations prior to
gasification would be 20% greater than those listed in Figure 3.1.
Using 3% sulfur coal, there are 1.092 x 105 Te of sulfur in the 3.64 x 106
Te of make-up coal. The crude gas contains .55% sulfur, by volume. 99.7%
of the sulfur is recovered by the desulfurization technique, or .997 x 1,092
x 105 Te = 1.089 Te. Since 0.3% of the sulfur in the crude gas is left in
the clean product gas, and the crude gas contains .55% sulfur, the clean gas
contains .0016% sulfur mainly in the form of H2S. It is estimated that the
cost of removing sulfur from the crude gas is about 30% of the cost of re-
moving sulfur from the stack gases of a coal-fired boiler'10'.
162
-------
If the coal gasification and the gas cleaning process are located at the
site of the electrical generating plant, an increase in the thermal efficiency
of power generation can be obtained by taking advantage of the high tempera-
ture and high pressure, e.g. 1200°F and 14 atm., of the product fuel gas.
This is accomplished by burning the fuel gas with air and expanding the
high-pressure combustion gases through a gas turbine. The hot turbine
(2 5)
exhaust gases are then passed through a conventional steam boi1erv ' ;.
The gas turbine drives a compressor to furnish compressed air for combustion
for the gasifier and for the sulfur burner. It also drives an electrical
generator. Details of combined-cycle power plant operation and associated
material and environmental releases are presented in Part II of this report^ '
The efficiency of energy conservation from this type of combined cycle is
(2\
expected to be 46%v , so that the make-up coal requirement would be about
20% less than that shown in Figure 3.1.
163
-------
REFERENCES
1. Squires, A.M., "Clean Power Gas from Dirty Fuels," Scientific American.
227, No. 4, 26-35 (October, 1972).
2. Dobner, S., M.J. Gluckman and A.M. Squires, Production of Low-BTU Gas
from Coal in Combination with Advanced Power Cycles. Paper No. 68b.,
A.I.Ch.E. Annual Meeting (November 26-30, 1972).
3. Hottel, H.C. and J.B. Howard, New Energy Technology, Some Facts and
Assessments, 144-161, M.I.T. Press (1971).
4. Ruth, L.A., A.M. Squires, R.A. Graff, "Desulfurization of Fuels with
Half-Calcined Dolomite: First Kinetic Data," Environmental Science and
Technology, 6., 1009 (1972).
5. Robson, F.L., A.J. Giramonti, G.P. Lewis and G. Gruber, "Technological
and Economic Feasibility of Advanced Power Cycles and Methods for Pro-
ducing Nonpolluting Fuels for Utility Power Systems," United Aircraft
Research Laboratories Report for National Air Pollution Control Admin-
istration, U.S. Department of Health, Education and Welfare (December,
1970).
6. Squires, A.M., "Clean Power from Coal," Science 169. No. 3948, pp. 821-
828.
7. Squires, A.M., The Coal pi ex: Gas, Gasoline, and Clean Electricity from
Coal, Paper No. 653, A.I.Ch.E. Annual Meeting (November 26-30, 1972).
8. Grossman, P.R. and R.W. Curtis, "Pulverized-Coal-Fired Gasifier for
Production of Carbon Monoxide and Hydrogen," Trans - ASME, 76, 689-695
(1954).
9. Chopey, N.P., "Coal Gasification: Can It Stage a Comeback?", Chemical
Engineering, 44-46 (April 3, 1972).
10. Hammond, A., W. Netz, T. Maugh, "Energy and the Future," AAAS, Washington,
D.C. (1973).
11. Cukor, P. M., "Electrical Power from Combustion Turbine -Steam Turbine
Combined Cyple Power Plant," Fuel Cycles - Part II, Teknekron Report
No. EEED 106,(December, 1974}~
164
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8. ELECTRICAL POWER FROM HIGH-SULFUR COAL, S02 REMOVAL
BY WET LIMESTONE SCRUBBING
8.1 Process Description
The wet-limestone scrubbing process is designed to remove 90% of the sulfur
which would otherwise appear in the stack-gas effluent when burning high-
sulfur coal. A representative fuel cycle for this process, beginning with
coal shipped to the electrical generating plant, is shown in Figure 8.1.
Finely ground limestone (CaCOo) or dolomite (CaMg(C03)? is injected into
the furnace, or into the hot flue gas, of a power plant fueled with high-
sulfur coal. Thermal energy is consumed in decomposing the limestone,
according to the reaction
CaC03 •* CaO + C02
About 20%^ ' ' of the sulfur dioxide formed in coal combustion reacts with
the solid CaO according to, the reaction
CaO + S02 + 1/2 02 -> CaS04
and is removed from the flue gas. The remaining S02 and the suspended
calcined solids flow with the flue gas and fly ash into a scrubbing tower,
where the gases are contacted counter-currently with a recirculating
liquid solution and slurry of hydrated calcium oxide and calcium sulfate.
165
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FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
> LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
166
-------
Figure 8.1
Coal Fired Power Plant - S02 Removal By
Wet Limestone Scrubbing - 1000 Mwe
Material And Environmental Release Flowsheet
Transported Cool: 3.27 x 10 Te
3.27 x I06 Te cool
3%S 9.81x10* Te S
Electrical Energy
8.76 x I09 kwh
Transmission Losses
0.776 x I09 kwh
Internal Thermal Losses
0.923 x I09 kwh
1000 Mwe Steam-Electric
Generating Plant
35.2% thermal efficiency
Coal: 3% S
!2,OOOBTU/lb
12.3% ash
1100-1400 acres total
2.488 x I010 kwh
Liquid Waste
536 Te suspended solids
71.5 Te organics
2.6 Te BOD
88.9 Te H-SO.
28.4 Te Cl|
45.0Te phosphates
357 Te boron
2.6 Te chromates
Delivered
Electrical
Energy Q
7.98 x 10 kwh
2.7x10* Te NOX
1.4x10* Te S02
I.I xlO* Te CaSCVt
l.4xlO*Te CaO
2.88x10° Te fly ash
4.14 x 10^ kwn waste r>ect
Flue Gas
1 2.47 x 10 cu.ft.
i 2.0xlO*Te SO,
2.7x10* Te NO,
2880 Te fly osh
0.0046 Ci Ro226, Th«°
0.0078 Ci Ra228, Th228'232
6.13 xlO Te HZ0
7.0 xlO5 Te dissolved
and suspended solids
• Limestone
37x10* Te dry CoCOj
Recirculation Water
1956 gal./min.
3.93 x 10s Te
Makeup Water
1590 gal./mm.
3.19 x 10s Te
Circulating Water
574,000 gal./mm.
Makeup Water
11,400 gal./mm
Bottom Ash
1.14x10* Te
0.18 Ci Ro2z$, Th230
0.31 Ci Ra226,TJ,22e'230
• Drift
287 gal
286 Te
Evaporated Water
2.21 x 106 Te
./min.
dissolved solids
Recovered Solids
3.7 x 10? Te CaS04
4.5xlO*Te Ca(OH)2
2.8 x 10* Te fly ash
0.46 Ci Ra226, Th2
0.77 Ci Ra228, Th228- 232
6 acres/yr
Liquid Drainage
*- Humidified Air
1.37 x loJ-Te H,0
1.107 x 10'° kwh waste heat
Slowdown Water
4290 gal./mm.
4270 Te dissolved solids
FLOW QUANTITIES ABE STATED I
100% CAPAC'Tr FACTOR
[ METRIC TONNES/YEAf)
ELECTRICAL ENERG
-fr. AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
AXIMUM PERMISSIBLE
CONCENTRATION
167
-------
Sulfur dioxide in the gas absorbs and reacts with hydroxyl and bicarbonate
ions to form HS03 and S03 ions. These ultimately oxidize to the more stable
SO^ ions and precipitate as CaSO^. The scrubber is also expected to remove
fly ash from the flue gas, eliminating the need for an electrostatic precip-
itator.
A purge stream of slurry from the scrubbing circuit flows to a settling pond
where the solid CaS04, Ca(OH)2, CaC03, and fly ash are removed and stored.
Settling pond overflow is recycled and make-up process water is added to the
system to compensate for the evaporation loss in the settling pond and in
the scrubbing tower.
8.2 Basis for Flowsheet Quantities
The coal fuel described in this chapter is similar to the Appalachian coal
described in Chapter 3. The heating value is 12,000 Btu/lb, and the ash
content is 12.3%. The sulfur content, however, has been increased from 2%
to 3%. The quantity of transported coal includes 3.03 x 10 Te/yr for the
basic coal plant of 38% thermal efficiency plus 240,000 Te/yr to calcine
the CaC03 injected into the boiler^1), for a total of 3.27 x 106 Te/yr.
The net overall thermal efficiency is then 35.5%. Environmental releases
in coal mining, coal cleaning and processing are those indicated on the
basic coal-plant flowsheet (Figure 3.1), multiplied by 1.14 to allow for
the increased coal consumption due to limestone injection.
169
-------
The flowsheet quantities for this chapter are based upon the model described
in Reference (1), which has been demonstrated in two commercial plants of
125 and 140 Mw(e) capacity. The amount of dry limestone injected is 110%
of that which is stoichiometrically needed to react with all the sulfur in
the coal: The wet limestone (91.8% CaCOg) is actually 8.2% heavier. On-site
storage of make-up limestone should be sufficient for at least a one-week
supply. On-site wet-grinding and pulverizing is required and handling the
limestone contributes to a dusting problem. It is assumed that all of the
raw limestone is calcined to CaO in the boiler and 25% of the CaO is con-
verted to CaSO, in the boiler. All of the sulfur originally present in the
coal is assumed to evolve in the flue gas, either as suspended CaSO* or as
sor
The quantity of sulfur entering the power plant (3% by weight of the input
coal) is .03 x 3.27 x 10 Te, equivalent to 3066 tonne-moles. Based upon
this number of tonne-moles and the reactions described above, the quantities
entering the scrubber are calculated. They are shown on the flowsheet and
are listed in Table 8.1.
Sulfur recovery in the model is 90%. It may be limited by the partial
pressure of S02 above the locally acidic, scrubbing liquid containing
dissolved HgSOg. The gas entering the scrubber is cooled to 177°F. The
gas leaving the scrubber is reheated to 250°F to minimize acidic condensa-
tion and corrosion in the exhaust system"'. The quantities of sulfur and
calcium products leaving the scrubbing stage are listed in Table 8.2.
170
-------
TABLE 8.1
Materials Entering the Scrubbing System
Item
Tonne-moles/yr
Te/yr
Calcium carbonate
(CaC03)
Calcium sulfate
(CaS04)
Calcium oxide
(CaO)
Sulfur dioxide
(so2)
3372
(110% of # moles
of sulfur in coal)
843
(25% of CaC03)
2529
(75% of CaC03)
2223
(# moles of sulfur in
coal minus # moles of
CaS04)
3.67 x 1CT
1.13 x
1.42 x
1.42 x
171
-------
TABLE 8.2
Calcium and Sulfur Products Leaving the Scrubbing Stage
Item
Tonne-moles/yr
Je/j
Gas emitted to atmosphere
SO,
306
(10% of sulfur enter-
ing furnace)
2.0 x 10*
Solids in slurry
CaSO,
Ca(OH),
2759
(90% of sulfur enter-
ing furnace)
613
(difference between, #
moles of injected CaC03
and CaSO. in slurry)
3.7 x
4.5 x 10"
172
-------
The ash content of the coal supplied to the furnace is 12.3% by weight or
4.02 x 105 Te/yr. In the model of this chapter 28.4%, or 1.14 x 10 Te/yr
become bottom ash, while 71.6%, or 2.88 x 105 Te/yr becomes fly ash. A 99%
•3
removal of ash is assumed here, so that 2.9 x 10 Te/yr of ash is emitted to
the atmosphere; the remainder, 2.59 x 10 Te/yr, becomes part of the
solids in the slurry leaving the scrubbing system. The quantities of water
which are used in the present model are indicated in Table 8.3.
Item
Make-up water
Recycled water
TABLE 8.3
Hater Used in the Scrubbing System
Value in Kellog model^ '
based upon 2.85 x 10 Te/yr
of dry coal input to power
plant
1794 gal/min
Evaporated water
(from settling pond)
2206 gal/min
6.2 x 10° Ib/hr
Value of 1000 Mw(e)
power plant, with 3.27 x
10^ Te/yr of dry coal
input
3.19 x 10° Te/yr
3.93 x 10° Te/yr
2.11 x 10° Te/yr
173
-------
5
The total quantity of solid wastes indicated on the flowsheet is 7 x 10
Te/yr. These wastes consist of 285,000 Te of recovered fly ash, and
415,000 Te of CaS04 and Ca(OH)2 from the limestone scrubber. The 415,000
Te/yr of solid wastes generated due to SO removal represent an increase
A
of 160 percent over the quantity of solid wastes calculated in Chapter 3
for coal combustion without flue gas desulfurization.
The settling pond may serve as the storage area for the large amounts of
solid wastes in the liquor extract leaving the scrubber. The slurry must
be discharged to new settling areas as the ponds fill, or the settled
solids can be recovered and piled for separate storage. The required
settling-storage volume is about 182 acre-feet per year, equivalent to 18
acres for a 10-foot depth. Groundwater contamination by acidic leach water
can be a problem with the settling pond and storage of separated solids.
If the limestone used for injection into the boiler is dolomite, the con-
tained magnesium will follow the calcium in the process and will appear in
the recovered solids. Since MgSO, is more soluble than CaSO., it will more
readily enter the goundwater and surface-leach water. Settling ponds and
storage areas may require impermeable materials to avoid environmental
contamination.
Environmental releases involved in waste heat rejection and liquid releases
for plant operation are identical to those identified for the basic coal-
plant flowsheet (Figure 3.1).
174
-------
REFERENCES
1. M.W. Kellogg Co., Evaluation of S00 - Control Processes, last No. 6,
Final Report, PB204711, EPA Contract No. CPA 70-63 (October, 1971).
2. M.W. Kellogg Co., Detailed Cost Breakdown for Selected Sulfur Oxide
Control Processes. last No. 7, Final Report, RED-72-1268, EPA Contract
NO. CPA 70-68 (March, 1972).
3. Tennessee Valley Authority, Sulfur Oxide Removal from Power Plant Stack
Gas-Use of Limestone in Wet Scrubbing Process, TVA Conceptual Design
Study (1969) Final Report, Contract No. TV-29233A.
4. Pollock, W.A., J.P. Tomany, and 6. Frieling, Mech. Ang. 89_ (8), 21 (1967),
5. Radian Corp., A Theoretical Description of the Limestone Inspection Met
Scrubbing Process, Final Report on Contract No. CPA 22-69-138, Vol.1
(June, 1970).
6. Battelle Memorial Institute, Investigation of the Limestone - SO^ Wet
Scrubbing Process, Final Report, Contract No. PH86-68-84, Task
Order No. 17 (November, 1969).
7. Tennessee Valley Authority, Sulfur Oxide Removal from Power Plant Stack
Gas Sorption by Limestone for Lime-Dry Process, Conceptual Design Study
(1968).
175
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9. ELECTRICAL POWER FROM GEOTHERMAL STEAM
9.1 Introduction
The fuel cycle flowsheet for the generation of 1000 Mw(e) from geothermal
steam energy sources, shown in Figure 9.1, is based upon the technology
used at the Geysers Geothermal Project of the Pacific Gas and Electric
Company in Sonoma County, California. Low pressure steam, typically at
114 psig, 1200 Btu/lb and 355°F, is extracted and piped from several nearby
geothermal wells and flows into a low-pressure turbine for power generation.
The expanded steam is condensed by direct contact with water from an evapora-
tive cooling tower. About 84% of the condensed steam serves as make-up water
for the evaporative cooling system, and the remaining 16% of the condensate
is returned as blowdown water to separate injection wells in the geothermal
field. Evidently there is sufficient underground water supply to meet the
water requirements for steam production.
The electrical capacity of each generating unit and its associated steam-
supply wells is limited by the physical arrangement of steam piping. The
present conceptual design of the 1000 Mw(e) facility consists of ten generating
units, each with a capability of 100 Mw(e). Operating data on 55 Mw(e) units
are available from the Geysers fielcP1'. A new unit in the range of 100 Mw(e)
was installed in 1974, bringing the total plant capacity up to about 500 Mw(e).
On the basis of these data, the overall plant efficiency of the 100 Mw(e)
conceptual design is 15.7%, requiring 7.25 x 107 Te/yr of geothermal steam
to deliver 8.76 x 109 kwh of electrical product at 100% capacity factor.
177
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
— AIRBORNE RELEASE
C> LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
178
-------
Pai
ticulates, rocks, dust
J
I
Atmospheric Venting
of New Steom Wells
Prior to Operation
i tnot yearly quantities)
* 12.09 x I06 Te steam
1 9.55 x I04 Te C02
I 8.46 x I03 Te NH,
I 6.04 i I03 Te CH4
I 6.04 x I03 Te H2S
I 3.63 x I03 Te N2, A
L2IUI03 Te H2
Figure 9.1
Geothermol Steam Power Plant 1000 Mwe
Material And Environmental Release Flowsheet
Turbine steam
7.254 x 10' Te steam
0.79% CO,
0.07% NH,
0.05% CH.
0.05% H,S
0.03% N2, A
0.01% H.
6.80 x I07 Te
Auxiliary steam
0.453 x 10' Te
r™
ElectricolJ
Energy: }
_.jrgy:
8.76 x I09 kwh
Delivered Electrical Energy; 7.984 x I09 kwh
Transmission Losses: 0.776 x I09 kwh
Gases from Turb ne A,r Ejector
4.87 x I05 Te COj
7.25 x I03 Te H2
3.63 x I04 Te CH4
2.IB x I04 Te M2. A
1.21 x I04 Te H2s
4.39 x 10" Te NH3
I
Geothermol Steom
Turbine - Generator
Ten 100 Mwe units
15.7% Thermal Efficiency
Dry Steom: 1200 BTU/lb
114 ps,g, 355°F
Condensing at 4in. Hg bock pressure
Plant Area: 100 ocres
55.67 x I09 kwh/yr
Power for Coolant Pumps
and Other Internal Use
0.327 x I09 kwh
Circulating cool'ng water
910,000 gal./mm.
Condensate and cooling water
Condensote return: 5940 gal. /mm.
5O70Te alkalinity as HCOj
I75O Te NH3
1549 Te sulfate
202 Te B
2190 Te total solids
2440 Te orqonics and volatile solids
Drift
455 gal./min.
165.7 Te solids
. Humidified Air
T 5.99 x I07 Te H20
| 44.9 x I09 kwh waste heat
I 5.08xlO5 T« NH3
I 8.60xlO4 Te C02
1 2.35 x I04 Te H2S
IOO % CAPAO'V rACTtM
fV»f>Of*T(Vt COOt 1*6 TO«Eft FOB **STt. H(»T RLJECHOH
LIQUID E'
SOI 10 £"
CTRIC TONNES
units
iLOWATT-HOUHS
CONCENTRATION
179
-------
The geothermal steam from the wells carries with it several pollutants,
including C02, NH3, CH^, H2$, and boron compounds, along with Np, A, Hp,
dust, and gravel. A typical steam analysis is shown in Table 9.1. The
solids and particulates are separated before the steam enters the turbine.
The more volatile species are emitted with the steam-ejector air vented
from the condenser, others are emitted to the air flowing through the
evaporative cooling tower, and the less volatile species are returned, to
the geothermal field via the injection wells.
Table 9.1
Typical Composition of Geothermal Steanr '
weight
percent
C02 0.79
NH3 0.07
CH4 0.05
H2S 0.05
N2, A 0.03
H2 0.01
Geothermal energy-conversion fuel cycles can be expected to differ
significantly at different locations. For example, in some areas of the
country with geothermal potential, such as Southern California, the
geothermal wells produce hot brine instead of steam. Energy conversion
181
-------
would involve flashing the brine to steam or transferring the heat from
the brine to a working fluid such as a low-boiling organic, which
volatilizes and expands through a turbine and is then condensed and re-
cycled. The material and environmental fuel cycle parameters would, in
these cases, be quite different from those shown in the present flowsheet.
Further, since deposits from the hot brine are highly corrosive, frequent
replacement of existing types of heat exchangers would be required.
9.2 Geothermal Steam-Extraction Hells
The wells supplying a single turbine-generator unit are generally located
in the land area surrounding each generating unit. The entire Geysers
development is comprised of a number of such adjacent areas in the geothermal
field.
There is considerable variation in the steam production capability of each
well. A typical rate of 200,000 Ib/hr from the newer wells is reported^ '.
To furnish the annual steam requirement of 7.25 x 10 Te/yr for the 1000 Mw(e)
conceptual design, about 91 such wells would be required. However, in the
existing field, about 6 to 8 wells of earlier vintage supply steam for the
55 Mw(e) unit, and this scales to about 150 wells for the present flowsheet.
The land area associated with the wells fueling the 55 Mw(e) unit at Geysers
averages about 58 acres per well. This scales to about 5000 to 9000 acres for
the 90 to 150 steam-producing wells estimated for the 1000 Mw(e) installation.
When a new well is to be brought into production it is first proved by venting
to the atmosphere for a few weeks. Assuming venting for 2 months at the full
182
-------
production rate expected for power generation and with a steam composition
given in Table 9.1, the atmospheric discharges are calculated and listed
in Figure 9.1. These are not yearly quantities, and are to be considered
to occur once in the generating-plant lifetime, assuming that a producing
well has a production life as long or longer than the life of the generating
plant. Some audible sound would be expected to accompany the venting operations.
9.3 Turbine-Generator Operation
Of the 7.25 x 10 Te/yr pf geothermal steam required for the 1000 Mw(e) con-
ceptual plant, 6.2% is required for auxiliary purposes, primarily to operate
the ejectors which remove noncondensable gases from the condenser^ . The
remainder of the steam expands through a low-pressure turbine and condenses
at a pressure of 4 inches of Hg (abs.). About 3.6% of the electrical power
generated is used to operate coolant pumps, cooling tower blowers, and other
plant equipment^ .
9.4 Air-Ejector Effluents
The noncondensable gases removed continuously by the steam ejector are released
to the atmosphere. All the methane, argon, and hydrogen in the geothermal
steam are released at this point, as are 85% of the C02, 87% of the NH3, and
33% of the H2S. These release fractions, and the calculated yearly releases,
are given in Table 9.2.
183
-------
Table 9.2
Yearly Quantities of Non-Condensgjle Gases
Emitted from Turbine Air Ejectors
Gas geothermal steam to power pi ant ' Te/yr
co2
NH3
CH4
H2S
N2, A
H,
85%
87%
100%
33%
100%
100%
487,000
43,900
36,300
12,100
21 ,800
7,250
9.5 Cooling System
The steam condensed in the contact condenser and the steam ejector condensate
join the cooling water circulating between the condenser and the evaporative
cooling tower. The circulating coolant increases 38°F in temperature as it
passes through the condensers, requiring a total circulating flow for the
1000 Mw(e) conceptual plant of 910,000 gal/min. The total evaporation rate
in the cooling tower is estimated to be 30,200 gal/min. A drift carryover
of 0.05% of the circulating flow is assumed (cf. Section 4.2). The remainder
of the steam condensate flows at a rate of 5940 gal/min into injection wells
in the geothermal field, thereby serving as blowdown water to control the
accumulation of non-volatiles in the circulating coolant.
184
-------
About 15% of the C02 and 10% of the NH3 in the geothermal steam follow the
steam condensate and are volatilized in the cooling tower. About two thirds
of the H2S in the geothermal steam follows the condensate, and most of this
is volatilized in the cooling tower. The remainder is reduced to sulfur
and non-volatile sulfur compounds, which are returned with the blowdown
condensate to the geothermal field. The quantity of H^S volatilized in the
cooling tower in the present flowsheet is calculated from a material balance
on sulfur in the geothermal steam.
9.6 Disposal of Condensate Blowdown
The typical composition of the condensate returned to the geothermal field,
and the calculated yearly quantities for the 1000 Mw(e) conceptual plant,
are given in Table 9.3.
185
-------
Table 9.3
Composition and Yearly Quantities in Condensate Return Water
Concentration in /~\ Yearly quantity for
condensate return^ ' 1000 Mw(e) plant
Item mg/liter Te/yr
total alkalinity
as HCO~
ammonia
sulfide
sulfate
free sulfur
nitrate
chloride
calcium
magnesium
silica
boron
total solids by evaporation
organics and volatile solids
429
148.3
2.0
131.2
8.35
0.1
3.5
5.3
1.0
3.75
17.1
n 185.2
ds 206.3
5070
1750
23.6
1549
98.6
1.18
41.3
62.6
11.8
44.2
202
2190
2440
186
-------
On the basis of an estimated capacity of 1 million gallons per day for a
(5)
single large injection wellv ' , the 1000 Mw(e) conceptual design would
require about ten such wells for disposal of the condensate return.
9.7 Power Plant Land Area
The land requirement for the 1000 Mw(e) power plant, not including the land
estimated previously for the geothermal wells, is about 100 acres, scaled
from 2.5 acres for a 27 Mw(e) unit at Geysers^.
187
-------
REFERENCES
1. Finney, J.P., F.'J. Miller, and D.B. Mills, "Geothermal Power Project
of Pacific Gas and Electric Company at the Geysers, California," pre-
sented at the IEEE Power Engineering Society Summer Meeting (July 1,
1972).
2. McClure, H.K., Pacific Gas and Electric Company, Private Communication
(October 12, 1972).
3. Ham, W.C., "Materials and Corrosion, Geysers Geothermal Power Plant,"
presented at National Association of Corrosion Engineers Conference,
San Francisco, California (October 1, 1972).
4. Bruce, A.W. and D.B. Barton, Pacific Gas and Electric Company Mechanical
Engineering Department, "Natural Steam Power Doubled by Unit 3 at the
Geysers in California," (September, 1967).
5. Goldsmith, M., "Geothermal Resources in California; Potentials and
Problems," California Institute of Technology, Environmental Quality
Laboratory Report No.5, p.29 (December, 1971).
188
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10. ELECTRICAL POWER FROM URANIUM-PLUTONIUM FUELED BREEDER REACTOR
10.1 Reactor Characteristics and Fuel Requirements
The fuel cycle flowsheet for a representative breeder reactor is shown in
Figure 10.1. The flowsheet quantities are representative of a 1000 Mw(e)
plant operating on a near-equilibrium fuel cycle, such that uranium and
Plutonium recovered from the discharge fuel are recycled and blended with
natural or depleted make-up uranium and fabricated into fresh fuel. The
equilibrium fuel cycle is attained only after several years of operation.
During the first few years the entire uranium and plutonium in the fresh
fuel must be obtained from outside sources, i.e., about 25 tonnes per year
of natural or depleted uranium are required, and about 2.1 tonnes per year
of plutonium must be obtained from the discharge fuel of water reactors or
from the net plutonium product from other fast breeders which have reached
their equilibrium fuel cycle.
The overall thermal efficiency of 41% is based upon data on the expected
(3)
performance of a 1000 Mw(e) liquid-metal fast-breeder reactorv ' (LMFBR).
The reactor core is composed of stainless-clad Pu02 - UO^ fuel containing
12.6 tonnes of plutonium and uranium. The core fuel operates at an average
specific power of 174 Mw(t) per tonne of uranium-plutonium mixture. Core
fuel is discharged after an average thermal exposure of 80,000 Mw days per
tonne, corresponding to core-fuel operating life of 460 full-power days.
About 10 tonnes of core fuel are discharged yearly for reprocessing (at
100% load factor).
189
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
190
-------
Figure 10.1
Breeder Reactor Nuclear Power Plant 1000 Mwe
Material and Environmental Release Flowsheet
Gaseous ... Gaseous
1 0.41 Ci Rn222 0.00014 Ci
T 0.00016 Ci Th230 .
I 0.00016 Ci Ra226 t
1 1
Conversion
and
Mimr,, Milling Fabrication
0 , / ' Concentration " <«"»<«
°-2 '" °" 1.25 Te Pu wastes
0.025 acres ( not shown
1 I D I '
18 500 Te Solid Tailings: Liquid: Solid
overburden 624 Te I960 Te 0.017 Ci U
0.39 Ci Th230 0.0137 Ci U
0.41 Ci Ro226 0.00018 CI Ra226
"p"' 0.0018 Ci Th"°
25 Te ore
1,500 Te overburden
.33 acres/year
Elec
Ene
8.7
U
Fabricated
Fuel
24.86 Tell
2.14 TePu
Liquid
0.014 CiU
Makeup Water:
13,000 goL/mia
'
Transmission — ~ — •»• Delivered Electrical Energy: 7.984 x 10' kwh
'^ 9 *
5X10 k"h Transmission Losses: 0.776 xlO' kwh Gaseou-
2.17 x 1C
Gaseous n v» r
7,000 Ci Kr*Xe 14,780
1 5.8 Te
1 .
Nuclear
Steam - Electric
Generating Plant
lOOO Mwe
41% Thermal Efficiency
Plant Area: 160 ocres
21.365x10' kwh/yr.
1
Circulating Water
i 654,000 gol./min.
Cooling
Tower
I
i_
*
Surface Water
O5 Ci Kr 2396 Ci H3
,8 ri „. 2.64 Ci Ru'°*
' T U X' 3.61 Te Na*
n Hs o.ie Te cr
NO A 0-30 Te so<
N0* If O.I 3 Te NO,4
Storage of Shipment of interim «
Irradiated Irradiated ,« . > High-level shioment High-level Perpetual
Fuel Fuel High-level Wastes J^- year) SoMd Wastes snipmem So|jd Wostes storage of
,„ _. 23.73 TeU 5.42x10° Ci F.P. High Level 2.43xl07 Ci F.P. Federal 2.43xl07 Ci F.R uj,«,.«
30 days 2.32 TePu ^^ 0.0116 Te Pu Wastes 73xlO*CiPu Repos tory 7.3xlO*CiPu
I.67XI07 Ci Pu 8.3x10* Ci Pu 89 cu.ft. ??fV-'"'i n
5.42x10* CiF.P. 1
6.75xl06 Ci cladding Process Water: 14 gal./min.
Liquid 3.86x10* Ci I Recovered Fuel
Radioactive 23.61 Te
Discharge u 4,860 Te dissolved solids p6 6/x °p 9.L,
15.6x10* Te H20 evaporated
1.26x10'° kwh waste heat
»• Drift: 327 gal./min., 326 Te dissolved solids
H, yOU gal It liquid ^.uuui.lO, hulls: WHJUUMIU nu"*. 1
89 cu.ft. if solid 1.3x10*0 1.3 x 10s Ci T
Clodding hulls: 235 cu.ft. 235 cu.ft. 235 cu.ft. '
Storage Area:
O.I to 1.3 acrex
> Intermediate Level (10* to 10* xMPC)
Liquid wastes to storage: 5,400 gal.
U=C>LowLeveHIOtol04 MKUI Fu», „,„„„„.« S,.,EO ,. «T,,C TO,«,/,E« T. , .ET..C ,„„»,
Liquid wastes: 270,000 gal. UNLESS OTHERWISE INDICATED c , CUHIES
100% C.P.CITV FACTOR >w> , «1LOW,TT . BOU.S
_k Buried Solid Wastes: 5.400 cu.ft.. O.IO acres EVA"""T™E C°°L""! "*"" F°" "5TE "E" ""ECT">" "<•' ' ««»"» ^"^
^_^^, -~ ELECTRICAL ENERGY COMCEMTHATIOK
R.rvM. 9-VKITnll ? 14 Tn Pu I.S4 » IO7 Ci Pu ' ' ' 1
191
-------
Surrounding the core is a blanket containing about 29 tonnes of uranium,
a small fraction of which will have been converted to plutonium by
absorbing neutrons which diffuse into the blanket from the core.
The total radioactivity in the yearly amount of fuel discharge, at the time
of discharge, is greater for the fast breeder reactor than for the light-
water plant because of the more frequent replacement core fuel in the
*
breeder .
Heat and fission products are generated in the blanket by fast-fission in
238
U and by fission of plutonium that has been formed. Periodically,
blanket elements are discharged to recover the plutonium, to be recycled
as core fuel .
The total discharge rate of core and blanket fuel is 27 tonnes per year,
containing 2.32 Te/yr of plutonium, with plutonium radioactivity of 28
million curies, at the time of discharge.
10.2 Cool ing Irradiated Fuel
It is plannedv ' that fast-breeder fuel will be stored for 30 days at the
reactor before it is shipped for reprocessing. This is shorter than the
150-day storage period planned for light-water nuclear plants because of
the economic incentive to minimize plutonium inventories in the fast-
breeder fuel cycle. The yearly amounts of plutonium in the fast-breeder
fuel cycle are about eight-fold greater than in the light-water nuclear
* These flowsheets are based on an estimated average core fuel life of
460 full-power days for the breeder and 3 years for the light-water
reactor.
193
-------
plant, when the latter is fueled with slightly enriched uranium without
Plutonium recycle. The greater the fuel cycle inventory, the longer the
fast-breeder must operate on purchased plutonium make-up fuel before it
can reach its equilibrium fuel cycle. Therefore, there is considerable
incentive to reduce holdup time in all the fast-breeder fuel-cycle opera-
tions. This introduces new problems in fuel reprocessing because of the
large amount, 3.86 million curies/yr, of radioactive iodine fission pro-
ducts remaining after 30 days.
Shorter cooling also results in about a four-fold greater amount of
radioactivity in the shipped fast breeder fuel. This increases the
shielding requirement for shipping containers and the rate of heat-genera-
tion in the fuel due to radioactive decay. Even for the same cooling time,
the heat generation rate in shipped fast-breeder core fuel, per unit mass
of fuel, is about six times greater than in light-water fuel, because of
the higher average specific power at which the breeder core fuel operates.
Shipping short-cooled breeder core fuel will impose more stringent require-
ments for shipping-container design than for water-reactor fuel.
10.3 Radiological Releases from Reactor
The radiological releases for the liquid-metal fast breeder are difficult
to predict at this time. According to the environmental statement'3' for
the proposed 360 Mw(e) LMFBR demonstration plant, noble-gas radionuclides
released into the sodium cover gas system will be separated by a process
* The cover gas'may also contain 1.83-hr A41 resulting from neutron
activation of argon.
194
-------
such as cryogenic distillation, bottling, and storage. However, for the
present flowsheet a noble gas release of 7000 Ci/yr is assumed, which will
(3)
meet the expectation of a release resulting in a site-boundary dose of
less than one percent of natural background.
It is likely that radioiodine releases might be quite small because iodine
fission products escaping from fuel rods will react with sodium coolant to
form Nal.
The total rate of tritium production is somewhat greater in a fast-breeder
*
reactor than in a light-water reactor , and more tritium is expected to
escape from fuel into the coolant because of the use of stainless steel fuel
cladding and the higher cladding temperatures. However, once in the coolant,
the tritium reacts with sodium to form sodium tritide, most of which will be
removed in the cold-trap filter system for purification. No environmental
releases of tritium at the reactor plant are projected in the LMFBR Demon-
stration Plant environmental statement^ . However, a liquid release of
**
16 Ci/yr of tritium is estimated for the 400 Mw(t) FFTF reactor now under
construction. This scales to about 100 Ci/yr of tritium from the 1000 Mw(e)
fast breeder in the present flowsheet. No non-tritium radioactive liquid
effluents are indicated in the Demonstration Plant environmental statement^ ,
The described process of evaporation and ion exchange is effective in con-
centrating wastes for solidification and storage as solids. For the purpose
* It is estimated that 25,000 Ci/yr of tritium is produced from fission in
the 1000 Mw(e) fast breeder.
** Fast Flux Test Facility, a sodium-cooled fast-spectrum reactor designed
to test fast-breeder fuel.
195
-------
of the present flowsheet, 5 Ci/yr is assumed, typical of radioactive efflu-
ents from light-water plants with similar liquid-waste management systems.
Neutron absorption in the sodium coolant results in about 70 million curies
of 14.96-hr Na24 and 600 curies of 2.62-yr Na . Sodium leaks and spills
are of some concern, and if the spilled sodium contacts air it can oxidize
to an aerosol containing activated sodium, fission products, and other
radionuclides which may be present in the sodium. Extensive precautions
are taken to prevent spills and to minimize the chances of anything but
chemically inert gas coming into contact with sodium. No releases of radio-
active sodium are projected for the LMFBR Demonstration Plant^ ' or for
normal operation of the FFTP ', and no sodium releases are indicated on
the present flowsheet.
The 1000 Mw(e) fast breeder reactor will contain about 1.8 to 2.8 tonnes of
(?] *
plutoniunr ' corresponding to 2.2 to 3.5 million curies of plutonium. No
environmental releases of plutonium are projected for the LMFBR Demonstra-
tion Plant^ ' or for normal operation of the FFTF^ , and none are indicated
in Figure TO.l.
10.4 Mining^, Milling and Fuel Fabrication^
Environmental quantities associated with mining and milling natural uranium
make-up fuel for the equilibrium breeder fuel cycle are based upon data
presented in Section 2.2 and 2.3, scaled according to uranium throughput.
940
* Including radioactivity of 4.98-hr Pu ,
196
-------
Mining and milling would be eliminated if the make-up uranium were obtained
from the presently stored depleted UFg tails from isotope separation plants.
Alternatively, the make-up uranium could be obtained from the depleted tails
produced in a system generating electrical power from reactors operating on
enriched uranium make-up fuel as well as from breeder reactors.
Environmental effluents associated with UFg conversion and isotope separa-
tion and the associated electrical energy consumption are not present in
the equilibrium breeder flowsheet.
Fabrication effluents are based upon data on UOp fabrication in Section 2.6,
scaled according to uranium throughput. Limestone neutralization of fluo-
rides is not present here because of the elimination of processes requiring
UFg. No plutonium effluents are indicated for the fabrication operation
because of lack of data on plutonium losses. As explained in Section 2.12,
the fractional losses of plutonium must be kept extremely small, and this
problem is even more acute in fabricating breeder fuel because of the larger
quantities of plutonium involved.
10.5 Shipment of Irradiated Fuel
The short 30-day cooling period (cf. Section 5.2) for irradiated fuel
introduces special considerations in the design of shipping containers.
Otherwise, the environmental considerations of .shipping appear to be similar
to those discussed in Section 2.8.
197
-------
10.6 Fuel Reprocessing
The technology contemplated for reprocessing breeder core and blanket fuel
is basically the same as that involved in processing water reactor fuel.
One new consideration does result from the considerably higher fissile con-
tent of fuel discharged from the breeder core, requiring more stringent
precautions to avoid criticality during dissolution and during the early
stages of chemical separation. Another consideration arises from the rela-
tively large amount (3.86 million curies/yr) of radioiodine fission products
remaining after 30 days of cooling . An overall iodine decontamination
factor of only 1000, as was assumed for light-water reactor fuel reproces-
sing, would be completely inadequate here. Additional iodine recovery
**
technology, such as that discussed in Section 2.9, must be installed ,
and it is planned to incorporate such technology when LMFBR demonstration
fuel is reprocessed^ . It is projected'- ' that with this additional tech-
nology an overall iodine decontamination factor of about 10 can be
achieved, resulting in an estimated iodine release of 0.386 Ci/yr.
In Section 2.9 several new chemical processes which could be applied, if
needed, to reduce effluents of noble gas radionuclides and tritium at fuel
reprocessing plants are discussed. The environmental statement^ ' for the
LMFBR Demonstration Plant indicates that these new chemical processes will
be applied to reprocessing demonstration-plant breeder fuel as well as to
* Water-reactor fuel cooled 150 days contains 61 curies/yr of radio-
iodine, as shown in Table 2.1.
** One alternate to incorporating additional iodine recovery technology
is to cool the discharge fuel for a longer period.
198
-------
the later reprocessing of fuel from 1000 Mw(e) breeders, resulting in the
reduction in concentration by a factor of 100 for noble-gas radionuclides
and 10 for tritium.
However, it is not apparent why, in reprocessing breeder fuel, there should
be any incentive to reduce noble-gas radionuclide releases and tritium
releases below the levels now acceptable for light-water reactor fuels.
There is, in fact, somewhat less Kr85 produced in the breeder fuel
(275,000 Ci/yr) than in the water-reactor fuel (373,000 Ci/yr) and the tri-
tium production is only slightly greater in the breeder. If there is incen-
tive to reduce releases of Kr and H3 at fuel reprocessing plants, it
would apply equally well to water reactors and breeder reactors, and the
technology would be essentially the same . Therefore, the present f lOW-
or q
sheets show all Kr and H released to the environment at the fuel repro-
cessing plant for both the breeder reactor and the light-water reactor.
The remaining environmental effluents for breeder fuel reprocessing are
calculated according to data in Section 2.9 scaled according to fuel through-
put.
10.7 Manage_ment_ of_Hi_gh Level Radioactive Wastes
The technology and environmental quantities associated with the management
of high-level wastes from fast-breeder fuel reprocessing are very much the
same as those described in Section 2.10. The fission-product quantities
————_»___—
* Recognizing some differences in H recovery by voloxidation because
of differences in fuel cladding and fuel composition.
199
-------
(1 2)
are calculated specifically for the fast breeder plantv ' . The volumes
(2)
of wastes are scaled on the basis of total fission product massv ' .
Assuming that 0.5% of the plutonium processes remains with the high-level
wastes^ ', the breeder high-level wastes will contain about eight times
more plutonium than the high-level wastes from the light-water plant.
As in the case of water reactors, plutonium is one of the main contributors
to radioactivity in high-level waste after a few hundred years of storage
•I oy
(cf. Figure 2.4). For shorter storage periods, e.g., 100 years, Cs and
90
Sr are the most significant contributors to total radioactivity. As
compared with the light water nuclear plant, the fast breeder is calculated
137 90
to produce 20 percent less Cs and over 5Q% less Sr .
10.8 Accidental Environmental^Releases
Estimates of accidental environmental releases are not included because of
lack of meaningful data and analyses (cf. Section 2.11).
200
-------
REFERENCES
1. Arnold, E.D., Phoebe-A Code for Calculating Beta and Gamma Activity and
Spectra for 235y Fission Products, ORNL-3931, USAEC (July, 1966).
2. Siting of Fuel Reprocessing and Waste Management Facilities, ORNL-4451
(USAEC) (July, 1970).
3. U.S. Atomic Energy Commission, Environmental Statement for Liquid Metal
Fast Breeder Reactor Demonstration Plant, HASH-1509' (April, 1972).
4. U.S. Atomic Energy Commission, Environmental Statement, Fast Flux Test
facility, Richland, Washington, WASH-1510 (May, 1972).
201
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11. ELECTRICAL POWER FROM SOLAR ENERGY"
11.1 Introduction
The fuel cycle flowsheet shown in Figure 11.1 illustrates one of the pro-
posed means of converting solar energy to electrical energy. Based upon
a concept proposed by MeineV , solar energy incident upon flat plate
energy collectors heats liquid sodium-potassium alloy (NaK) to about 200°C.
The circulating hot liquid metal transports the collected solar heat to
a boiler where low-pressure steam is generated. The steam expands through
a low-pressure turbine and is condensed by water coolant circulating from
the condenser to an evaporative cooling tower. The quantity of sodium-
potassium alloy which is used provides sufficient energy storage for con-
tinous power generation.
The net electrical output from the power plant is 4.7% of the solar energy
incident upon the collectors, requiring an annual incident solar energy
of 1.865 x 10 kwh(t) for a 1000 Mw(e) conceptual power plant operating
at 100% load factor.
11.2 Solar Energy Collection
The solar energy collectors are designed to maximize the transmission
of incident solar energy to the NaK coolant and to minimize the energy loss
due to radiation from the heated coolant. The high absorptivity collec-
tor plates are housed in evacuated containers of glass or other trans-
parent material. The plates are assumed to have an absorptivity of
* Chapter 11, Solar Energy, describes a particular distributed-collector thermal conversion system. Since 1973, when
Chapter 11 was written, studies have indicated that a central-tower conversion system is expected to be more advantageous
than the distributive system which is described here. Teknekron, Inc. has presented quantitative information on the
environmental releases from a 100 MUe intermediate-load central-tower thermal conversion system in a later report. See
"Pollutant Releases, Resource Requirements, Costs and Efficiencies of Selected New Energy Technologies", for the
Brookhaven National Laboratory, December 1975.
203
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
204
-------
Figure 11.1
Solar Power Plant 1000 Mwe
Material And Environmental Release Flowsheet —
i
Energy:
8.76 x I09 kwh
Average Solar Input
1.865 x
0" kwh(-t)
Radiation Loss
71.2 xlO9 kwh(t)
•
Solar Energy Collectors
Energy Storage and
Heat Transport System
Flat Plate
Collectors
61.8% heat collection
efficiency
41,000
acres
Circulating NoK 200° C
^ < • 50° C
Tronsmissioni
1
f
,^, - m Prlnrrrrrl Flrrtnrnl Frpri]y 7 Qft4 * in kulh
o
Transmission Losses: 0.776 x 10' kwh
Steam Generator and
Electric Turbine Generator
1000 Mwe
7.6% Thermal Efficiency
1200 BTU/lb steam
Condensing at 4in Hg
Il5.3xl09kwh(t)
200 acres
Drift
2760 gal./min.
2750 T"e dissolved solid
k
\
Circulating cooling water
5,550,000 gal./min.
|| Makeud
Evaporative
Cooling Tower
58 acres
J
Water v Blowd
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWE
___—_*
».
=O
1
TED
R FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFPLUENT
SOLID EFFLUENT
Cl - CURItS
CONCENTRflT'ON
Liquid Waste
2490 Te suspended solids
331 Te organics
12 Te BOD
413 Te H2S04
132 Te Cb
209 Te phosphates
1656 Te boron
12. Te chromates
Humidified Air
13.15 x I08 Te H20
106.5 x I09 kwh waste heal
110,000 gal./min.
41,200 gal./min.
41,000 Te dissolved solids
205
-------
0.93 for the incident solar spectrum, a low-temperature emissivity of
0.10, and a back-side emissivity of 0.08^. Analyses by Hottel and
(2)
Howardv , taking into account radiant energy absorption and re-emission
and the time-dependence of the angle of solar incidence, predict an over-
all heat collection efficiency of 61.8%. The incident energy not collected
is re-radiated.
For the average daily solar energy input at a location such as El Paso,
Texrfs, the average rate of collection of thermal energy is estimated to
be 0.155 thermal kilowatts per square meter of collector surface. For
the 1000 Mw(e) conceptual power plant this corresponds to a collector
area of 32.7 square miles. Assuming the actual land area required for the
(2\
collectors and primary heat transfer system is twice the collector areav ,
a total land area of about 65 square miles or 41,000 acres is required
for energy collection and transport.
11.3 Turbine Generator Operation
Assuming, optimistically, that saturated steam is generated at the NaK
temperature of 200°C and expands through a turbine to a condenser pres-
sure of 4 in. Hg (abs.), about 7.6% of the collected thermal energy is
converted to electrical energy. It is assumed that all of the generated
electrical energy appears as the electrical product.
The only significant chemical wastes expected are those associated with
boiler blowdown. An estimate is obtained by scaling the yearly quanti-
ties reported (cf. Section 3.8) for the fossil fuel power plants on the
basis of the power plant thermal input. The results are shown in Table 11.1
207
-------
Table 11.1
Boiler Slowdown Releases
Annual quantity released by
1000 Mw(e) solar power plant
Te/yr
suspended solids 2490
organics 331
BOD 12
H2 S04 413
C12 132
phosphates 209
boron 1656
chromates 12
Environmental releases may be associated with the NaK system, but no esti-
mates are currently available.
A land area of 100 to 200 acres is assumed to be required for the generating
equipment^ .
11.4 Cooling System
Q
A total of 106.5 x 10 per year of thermal energy is rejected from the
condenser to an evaporative cooling system. Scaled from the data in
Section 6.2, about 5,500,000 gal/min of circulating water and 110,000
208
-------
gal/min of make-up water are required, with about 58 acres allotted for the
cooling system.
11.5 Electrical Energy Transmission
There would be a considerable premium on locating solar energy power plants
in areas where high average solar input could be relied upon. This might
then require more extensive transmission systems than for other types of
power plants.
209
-------
REFERENCES
1. Meinel, A. B. and M. P. Meinel, "Is It Time fo a New Look at Solar
Energy," Bulletin of the Atomic Scientists 27:3, pp. 32-37 (October, 1971),
2. Hottel, H. C. and J. B. Howard, "New Energy Technology, Some Facts and
Assessments," MIT Press (1971).
3. "Considerations Affecting Steam Power Plant Site Selection," Energy
Policy Staff, Office of Science and Technology, Washington, D.C.
(December, 1968).
210
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12. ELECTRICAL POWER FROM THERMONUCLEAR FUSION
12.1 Energy Producing Reactions
The flowsheet shown in Figure 12.1 is based upon the conceptual design of
a fusion power plant described by Steiner and Fraas , extrapolated to a
electrical power production of 1000 Mw(e). The fusion reactions assumed
H2 + H3 = He4 + n1 1.92 x 1011 n/sec per watt thermal
H2 + H2 = He3 + n1 2.95 x 1010 n/sec per watt thermal
The reacting core is surrounded by a lithium blanket, where make-up tritium
for the core is produced according to the reactions
Li6 + n1 = H3 + He4
Li7 + n1 = H3 + He4 + n1
The tritium production rate quoted by Steiner^2) is equivalent to a pro-
duction rate of 2.16 x 1011 atoms of tritium per watt thermal.
12.2 Power Conversion
The Steiner-Fraas^1) design contemplates heat extraction from the blanket
by boiling potassium. The potassium vapor expands through a turbine and
211
-------
FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
C> LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
212
-------
Figure 12.1
Fusion Reactor Nuclear Plant 1000 Mwe
Material And Environmental Release Flowsheet
Electrical
Energy
8.76 x I09 kwh
Delivered Electrical Energy: 7.984 x I09 kwh
2800 Ci H3
I
18.95 Te Pegmotite Ore
contoining 1.895 Te LiAISi206
Mok.up Water: 9050 Te H,0
HVH = 0.00014
Open-Pit
Mining
Overburden
HgS Leakage
A
1
Isotope
Separation
H£S-H20 Dual
Temperature
1 '
H|O Product
0.254 Te
H2/H = 0.99 +
Milting
and
Extraction
Shipment
0.254 Te H|0
Shipment
Lithium Fuel
0.1516 Te Li
Duterium Fuel
0.0511 Te H2
Conversion
1
1000 Mw Electric
Generating Plant
Fusion Reactor with
Lithium Blanket
binary- vapor cycle
51.8% thermal efficiency
16.91 x I09 kwh
1!
!
Liquid Waste
1460 Ci H3
t
[_
Lithium
Blanket
Processing
and
Tritium
Recovery
0.0585 Te H3
5.55 x I08 Ci H3
Circulating water
423,000 gal. /min.
Evaporative
Cooling
Tower
Dr
»- 21
211
i »- Hu
1.0
8.1
il Blc
V 311
Depleted Water
9050 Te H20
H2/H = 0.000115
1.76 Te BOD
60.5 Te H2S04
19.3 Te 02
30.6 Te phosphates
243 Te boron
1.76 Te chromates
48.6 Te organics
Activated Blanket Structure
Nb structure V structure
1.70 x I07 Ci 1.70 x 10* Ci
5600 Ci
»-21 gal./min.
5.60 Ci
Nb
Makeup Water
8420 gal./min.
Te dissolved solids
Hulnidified Air
1.037 xlO7 Te H20 evaporated
8.15 x I09 kwh woste heat
Slowdown Water
~"— gal./mm.
Te dissolved solids
100 % CM»ClTt FACTO*
213
-------
is condensed by boiling water. The high-pressure steam expands through a
conventional turbine. The calculated overall thermal efficiency of this
dual cycle is 51.8%.
The steam condenser is cooled with water from the model evaporative cooling
system, scaled to the heat rejection load for this cycle.
12.3 Fuel Materials
The quantities of deuterium and lithium consumed per year are calculated
from the reaction rates quoted above. The deuterium fuel can be obtained
from electrolytic decomposition of heavy water with an isotopic composition
2
of over 99% H . The heavy water shipped to the power plant is obtained
from a deuterium isotope-separation plant, which is assumed to operate on
the dual-temperature process involving the isotopic exchange reaction
between gaseous hydrogen sulfide and liquid water^ . The water fed to the
isotope-separation plant is assumed to contain the natural isotopic abun-
(3)
dance of 0.014 percent deuterium in hydrogen. A typical recoveryv ' of 18%
of the deuterium in the feed is assumed.
It is assumed that the blanket is designed so that the ratio of lithium
isotopes in the blanket is the same as for natural lithium (7.52% Li ) and
that the reaction rates are such that the relative concentrations of Li6
and Li7 remain the same as in natural lithium. Otherwise lithium isotopic
separation and/or withdrawal of depleted lithium from the blanket may be
required, resulting in a larger net requirement for natural lithium. With
these assumptions, the make-up lithium is calculated as the molar equivalent
to the tritium production rate.
215
-------
Lithium ore requirements are calculated on the basis of mining pegmatite
ore with an assumed concentration of 10 percent spodumene '
The pegmatite ore containing spodumene is typically mined from 20-foot
benches in a large open pit. The spodumene is recovered by crushing,
screening, milling, and flotation. Extraction of lithium from spodumene
involves either acid treatment or alkali treatment. Acid treatment
involves calcining followed by sulfuric acid addition. The lithium sulfate
is leached, neutralized with limestone, and filtered. It is then brought
into water solution, precipated with soda ash, converted to the chloride
by reacting with hydrochloric acid, and electrolyzed to metallic lithium.
Alkali extraction involves calcination of spodumene with limestone and
hydrolyzing the calcined product with steam to produce lithium hydroxide.
This is converted to the chloride and electrolyzed to metallic lithium.
Techniques of lithium isotope separation are described in Reference (3).
12.4 Tritium Losses
Steiner and Fraas^ ' estimate a total tritium inventory of 6 kg. in their
conceptual design of a 1000 Mw(t) fusion power plant, including 0.4 kg. of
tritium in the lithium and potassium systems. They estimate that leakage
of gaseous tritium from the lithium and potassium systems can be kept as
C
low as 10" of the contained tritium per day, corresponding to a leakage
8
fraction of 7 x 10~ /day based on the total tritium inventory.- The
216
-------
estimated leakage of tritium from the potassium system into the steam
cycle, and ultimately into the plant cooling water, is 3 curies per day,
which corresponds to a leakage fraction of 5 x 10"8/day of the total tritium
inventory.
Scaling these estimates to the present 1000 Mw(e) plant design, the total
tritium inventory is 11.6 kg, or 1.1 x 108 curies. The tritium leakage to
the environment is 2820 curies per year of gaseous tritium and 2110 curies
per year of tritium in liquid wastes.
These tritium releases are lower than the corresponding leakage fractions
of tritium in water reactors. The total curie inventory of fission-product
tritium in a water reactor is about 20,000 curies (cf. Section 2.7). The
quoted leakage rate of about 100 curies per year for a boiling water reactor
corresponds to a daily leakage fraction of 10" /day. The high operational
temperatures contemplated for lithium blanket systems in fusion power plants
and the finite permeability of structural materials to hydrogen at high
temperature may make tritium containment difficult. For example, Fraas
suggests tungsten coatings on some structural components to control tritium
loss.
12.5 Activated Structural Material
Steiner and Fraas^' have calculated the radioactive inventories in the
structural system of their conceptual fusion reactor. Both niobium and,
alternatively, vanadium blanket structures are considered. The principal
217
-------
neutron activation chains are shown in Table 12.1. The calculated radio-
active inventories and the production rate of long-lived species are listed
in Table 12.2.
The actual rate of replacement of blanket structure is not yet specified.
However, the blanket structure is expected to have a finite useful life-
time in the fusion power plant because of radiation damage. If the rate of
blanket-structure replacement is less than the mean life of the long-lived
species, the average rate at which these radionuclides are withdrawn from
the reactor and sent to processing or disposal is equal to their production
rate in the reactor. It is on this basis that the average yearly withdrawal
rates of long-lived activated species in the blanket are calculated, and
the results of these calculations are shown in the flow diagram.
218
-------
Table 12.1
Neutron Reactions for Structural Activation in a Fusion Reactor
(1)
Niobium Activation
41
, n Nh 93m y
> Nb >
93
< yr
41
Nb
T > Nb
94m
, Nb
n.
-> Nb
,
6.3 min
Tc
94
n, y
-> Nb
95m
90 hr
95
2x1O4 yr 42
,Mo
94
35 day 42
Mo
95
Vanadium Activation
23
51 n, a , cr 48
C
2r 1.83 day 22
Ti
,48
23V
,51 n, a . ,,52
3.8 min 24
EC
27.8 day 24
Cr
Cr
52
n, 2n
51
23
P .
•
5.8 min
24
23V
n. a .
-
Ji
,49
r
21 C 3.43 day 22
Ti
.47
219
-------
Table 12.2
Radioactivity in Fusion Reactor Blanket Structure
curies per
thermal /,\
kilowatt11'
curies in
1000 Mw(e)
fusion plant
Niobium Blanket
Structure
Mu95
total niobium structure
155
714
2.99 x 10
1.38 x 10"
8
Vanadium Blanket
Structure
o-48
total vanadium structure
4.20
55.1
8.11 x 10C
1.06 x 10
8
nuclide
Niobium Blanket
Structure
Nb
93m
94
rate of generation of
long-lived radionuclides
half curies per year
life per Mw(t)
Nb
Vanadium Blanket
Structure (assume
1000 ppm Nb)
13.6 yr
2.0 x 104 yr
Nb
Nb
93m
94
13.6 yr
2.0 x 104 yr
8,800
0)
2.9
(1)
8.8
0.0029
curies per year in
1000 Mw(e) power plant
1.70 x 10'
5,600
17,000
5.6
220
-------
REFERENCES
1. Steiner, D. and A. P. Fraas, "Preliminary Observations on the Radio-
logical Implications of Fission Power," Nuclear Safety l_3_-5, 353
(September, October, 1972).
2. Steiner, D., "A Review of ORNL Fusion Feasibility Studies," 5th Inter-
society Energy Conversion Engineering Conference, Energy 70, Las Vegas,
Nevada (September, 1970).
3. Benedict, M. and T. H. Pigford, "Nuclear Chemical Engineering,"
McGraw Hill (1958).
4. "Mineral Facts and Problems," Bulletin 630, 1965 ed., U.S. Bureau of
Mines.
221
-------
13. ELECTRICAL POWER TRANSMISSION
Two of the many environmental considerations associated with the transmis-
sion of electrical power are transmission losses and land required for
transmission systems. According to the 1971 annual report of the Federal
Power Commission^ ', the 1971 production of electrical energy in the
United States was 1.53 x 1012 kwh, and the 1971 sale of electrical power
was 1.395 x 10'2 kwh. This corresponds to an average of 8.8% of the gener-
ated power lost or consumed in delivery, resulting in the average yearly
loss of 0.776 x 109 kwh for a 1000 Mw(e) power plant (100% load factor) as
shown on the flowsheets.
The Federal Power Commission reported that in 1968 there were over 300,000
miles of transmission lines, of 69 kilovolts or greater, in the United
States' '. The right of way occupied by this transmission system was esti-
mated at 4 million acres. On an industry-wide basis, the average land
requirement was 13.3 acres per mile of right of way. The total generating
capacity in 1968 was 290,000 Mw(e)(2), which corresponds to an average
transmission line distance of 1034 miles per 1000 Mw(e) of generating capa-
bility. The above data then led to the estimate of 14,700 acres of land
for transmission associated with each 1000 Mw(e) power plant.
Other environmental effects associated with electrical transmission include
visual impact, effects resulting from line and tower construction, and ozone
production by corona discharge
223
-------
REFERENCES
1. United States Federal Power Commission, "Annual Report - 1971," 11-13.
2. "Environmental Effects of Producing Electric Power," Hearings'Before
the Joint Committee on Atomic Energy, United States Congress (1971).
3. United States Department of the Interior, Bureau of Land Management,
"Final Environmental Statement for the Jim Bridger Thermal-Electric
Generation Project" (April, 1972).
224
-------
FUEL CYCLE FOR 1000-Mw URANIUM-PLUTONIUM FUELED WATER REACTOR
Thomas H. Pigford*
Robert T. Cantrell*
and
K. P. Ang*
Teknekron Report No. EEED 104
March, 1975
Department of Nuclear Engineering, University of California, Berkeley,
California.
-------
ABSTRACT
This study presents an illustrative data base of material quantities and
environmental effluents in the fuel cycle for a light-water nuclear reactor
fueled entirely with plutonium and natural uranium. Data were calculated
for a 1000 Mw nuclear power plant operating on an equilibrium fuel cycle.
Results are shown in tables and on a fuel-cycle flowsheet.
^^^
-------
TABLE OF CONTENTS
1. Introduction 1
2. Reactor Characteristics 2
3. Mining, Milling, and Concentration 20
4. Fuel Conversion and Fabrication 28
5. Nuclear Power Plant Operation 27
6. Shipping- 27
7. Fuel Reprocessing 28
8. High-level Waste Management 29
9. Low-Level Actinide Solid Wastes 35
References 37
-------
LIST OF FIGURES
1. Light Water Reactor with Uranium and Recycled Plutonium
1000 Mw(e) Material and Environmental Release Flowsheet 5
2. Actinide Chains in Uranium-Plutonium Fuel 8
3. Fuel Actinide Flowsheet for 1000-Mw U-Pu Fueled Water Reactor
Yearly Quantities, 80% Load Factoi 11
4. Americium Activity in High-Level Wastes 1000-Mw U-Pu Fueled
Water Reactor 31
5. Curium Activity in High-Level Wastes 1000-Mw U-Pu Fueled
Water Reactor 32
6. Plutonium Activity in High-Level Wastes 1000-Mw U-Pu Fueled
Water Reactor 33
7. Actinides in High-Level Wastes for U Fueled and U-Pu Fueled
Water Reactors 34
y^^
-------
LIST OF TABLES
1. Isotopic Composition of Plutonium in Equilibrium Fuel Cycle for
1000-Mw Uranium-Plutonium Fueled Water Reactoi
2. Radioactivity in Reactor and Fuel Cycle for a 1000-Mw Water
Reactor Fueled with Natural Uranium and Recycled Plutonium
3. Comparison of Neptunium, Plutonium, Americium and Curium
Reprocessed Yearly from Uranium Fueling and Uranium-Plutonium
Fueling in 1000-Mw Water Reactors, 150-day Cooling
4. Gaseous Effluents from Milling and Concentration of 2000 ton/day
of Uranium ----------------------------------------------------------- ^~^
5. Environmental Emissions for a Mixed-Oxide Fuel Fabrication Plant
(300 Mg/yr of Uranium and Plutonium) --------------- - ----------------- 2°
-------
FUEL CYCLE FOR 1000-Mw WATER REACTOR FUELED WITH
PLUTONIUM AND NATURAL URANIUM
1. Introduction
This study presents estimates of environmental effluents from a uranium-
plutonium fueled pressurized-water reactor and from the associated fuel
cycle operations. The study is based upon an adaption of current designs
of uranium-fueled pressurized water reactors.
A number of thermal-electrical power generating technologies were examined
in an earlier study for the EPA^ . The approach followed herein is similar
A flowsheet has been developed for a 1000-Mw nuclear generating plant and
its associated fuel-cycle facilities. Representative quantities for
material throughput and environmental release are estimated for the opera-
tion of the nuclear plant for one year at 80% load factor*. Many of the
quantities are the results of original calculations performed for this
study. Others are derived from various references and are scaled to the
current flowsheet. Variations from the quantities indicated herein may be
expected for particular installations.
The flowsheet shows waste-heat rejection at the nuclear power plant by
evaporative cooling. Water requirements for the cooling system are deve-
loped in Chapter 6 of "Fuel Cycles for Electric Power Generation"^ '.
* Most of the non-radiological quantities are given in metric tons (Mg)
Radiological quantities are given in curies (Ci).
-------
2. Reactor Characteristics
This fuel cycle is calculated for a 1000 Mw pressurized water reactor fueled
entirely with a mixture of plutonium and natural uranium. The reactor struc-
ture and fuel-coolant lattice is similar to that of the pressurized-water
reactor fueled with slightly enriched uranium, as described in Chapter 2
of "Fuel Cycles for Electric Power Generation^ . The make-up plutonium to
fuel the reactor considered in the present study is that recovered from the
fuel discharged from uranium-fueled water reactors. This concept of a
"dedicated plant", in which the entire reactor is fueled with a mixture of
plutonium and natural uranium, is one of the ways in which plutonium recovered
from uranium-fueled reactors can be utilized as fuel. This concept has the
advantage that all fuel within the reactor consists of the mixture of natural
uranium and plutonium. The reactor control absorbers can be designed speci-
fically to match the high neutron absorption cross section of plutonium. It
is possible that with fuel fabricated from a single fissile-fertile combi-
nation the reactor may be better optimized for power output and in-core fuel
management.
An alternate approach towards utilizing plutonium recovered from uranium
fuel is to recycle that plutonium in the same reactor, thereby replacing some
of the elements of slightly enriched uranium fuel with fuel composed of
recycled plutonium and natural uranium. This concept of recycle of "self-
generated" plutonium is likely to be a practicable means of beginning the
utilization of recycled plutonium in water reactors. It may be possible
-------
to design a fuel assembly consisting of an ensemble of slightly enriched
uranium fuel' rods and plutonium-uranium fuel rods so that the neutron
spectrum and the control absorber worth are not significantly altered by
the presence of plutonium. Alternatively, the reactor core may be loaded
with some assemblies of slightly-enriched uranium fuel and other assemblies
of plutonium-uranium fuel, by some combination of scatter and zone loading
of these different assemblies throughout the reactor core. In any of these
approaches the large differences in the thermal neutron cross sections of
fissile uranium and plutonium may result in difficult problems of controlling
the spatial distributions of power density and of minimizing the power peaking
It is possible that the early recycle of self-generated plutonium in water
reactors may later shift to the use of plutonium in dedicated plants, when
the amount of plutonium to be utilized becomes large enough to justify the
dedication of entire reactors for this purpose. Since the fuel cycle for
the dedicated plant most clearly illustrates the new environmental issues
associated with plutonium utilization in water reactors, it is the concept
considered in this report.
The equilibrium fuel cycle for a 1000-Mw water reactor dedicated for plu-
tonium utilization is shown in Figure 1. Fresh fuel is fabricated from a
mixture of natural uranium, make-up plutonium recovered from the fuel dis-
charged yearly from two (approximately) 1000-Mw uranium-fueled water reac-
tors, and plutonium recovered from the fuel discharged from this reactor.
The material quantities are calculated for a pressurized-water reactor
-------
FLOW QUANTITIES ARE STATED IN METRIC TONS/YEAR
UNLESS OTHERWISE INDICATED
80% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
J> LIQUID EFFLUENT
SOLID EFFLUENT
Mg = METRIC TONS
Ci = CURIES
kwh = KILOWATT-HOURS
Mw = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
-------
Figure I.
Light Woter Reactor With Uranium And Recycled Plutonium 1000 Mwe
Material And Environmental Release Flowsheet
T
4.37«l03Mg
overburden
Input
2.7 acres
14,769 Mg ore
437«l05Mg overburden
Gaseous
f9.77l Ci222Rn
.
0003 CiU
0 001 Ci "
Goseous
t cjpu
lQ.126 MgNOx
|3.5xlCr3MgNH3
Gaseous
t2.70«IO~4CiPu
I l.7»IO~5MgF-
0-126 MgNOx
l3.5xO"3MgNH3
Electrical
Energy
7.0UI09kwh
Delivered Electrical Energy: 6.387 x|Q9kwh
Transmission Losses: O.62I x|Q9kwh
I 0.001 Ci 230Th
I 0 004 Mg S02
|0.353MgNOz
!0.035MgNH3
I
Liquid
>4.05xlO-4C,Pu
0.117 MgNO3
5.6xlO'3 MgPO",,
Stored Liquid
•Vll,6OOgol.
405«IO-4CiPu
Buried Solid Wastes
BWR PWR|
I3.20O Cuft. 7700'cu.ft,
6O05 Ci . 1565 Ci
1
Gaseous BWR PWR
3H 10 to 52 Ci
I3CI 0.016 CI 0.016 Ci
Kr»Xe 44,500Ci 6200 Ci
Surface Water
3360 Ci'H
3.09 Ci IQ6Ru
4.224 Mg No'
0.168 MgCT
0.281 MgSOi
0 563 Mg NOj
Gaseous
*7.6I x
!2.06«l04CiJH
I !.80«l05CiB5Kr
' 0.062 Ci129'3'!
0.788 Ci other FP.
O.003 Ci transuronics
5.06 Mg SOX
5.63 Mg NOx
0.016 Mg hydrocarbons
25.8 MgU
0.71
1.36 MgPu
2.28>l07CiPu
0030 Mg CO
Liquid
0.311 CiU
0008 Ci 226Ra
0.535 Ci23°Th
Solid Tailings
14,741 Mg
0.174 CiU
9.761 Ci226Ro
9.234Ci23°Th
Stored Solid
l.24»!05CiPu
0.10 CiU
Pu Make-up
from u-fueied
Water Reactor
0.504 MgPu
6.02«l06Ci
Stored Solids
530 cu.ft.
7.2 Kg. Pu
l.2l«!05Ci
O.I36 MgU
O09CI
Make-up Woter —
15,150 gal./min.
Drift: 380gol./min.
379 Mg dissolved solids
Pu02-U02 Fuel Scrap
Humidified Air:
I8.I»I06 Mg HjO evaporated
l.46«IOlokwh waste neat
Slowdown Water: 5680 gol/min.
5660 Mg dissolved solids
BWR PWR
3H 93 467 Ci
Other 5.0 5.0 Ci
I 93 MgU + O.IO2 MgPu
1.71 *I06 Ci
Recycle PulN03)4
0.981 MgPu
l.88«l07Ci
JO.O39 MgF"
High-level Wastes
l.24x!08CiFR
0.0099 Mg Pu
l.89»D5CiPu
9000 gal. if liquid
90cu.ft.il solid
Cladding hulls:
532xl05Ci
72cufl
High-level Wastes
I 58«I07 Ci FR
90 cu.ft.
Cladding hulls:
8.l7«l04Ci
72cu.ft.
Storage ArK
0.17 to 1.4 acrts
. intermediate Level (I04to I06*MPC)
Liquid wastes to storage: 5880 gal
>LowLevel (iota lO
Liquid wastes: 2.89»l05gol.
» Buried Solid Wastes: 5880 cu ft , Olocrrt
-^Depleted U (as U02(NOj)2)
250MgU
408 Ci
-------
operating at an average specific power of 30 Mw(t) per metric ton of
actinides* initially in the fresh fuel and an average irradiation exposure
of discharge fuel of 33,000 Mw(t) days per metric ton of initial actinides.
The material quantities shown are the yearly amounts of the equilibrium
fuel cycle for a 1000 Mw** plant operating at 80% load factor. The radio-
nuclide compositions and amounts were calculated from the ORIGEN code for
a neutron spectrum characteristic of a dedicated reactor with mixed-oxide**
fuel. The principal nuclear reactions leading to the radionuclides of
neptunium, plutonium, americium, and curium are shown in Figure Z^3). The
flowsheet for the fuel actinides in the equilibrium fuel cycle is shown in
Figure 3.
* A metric ton consists of 106 grams and is denoted on the flowsheet by
"Mg". Actinides in the fresh fuel are uranium and plutonium. In this
report Mw refers to electrical output, and Mw(t) refers to thermal
output.
** "Mixed-oxide" fuel refers to fuel prepared from a mixture of uranium
oxide and plutonium oxide.
-------
Am*44
Figure 2
Actinide Chains in
rani urn-Plutonium Fuel
lO.lh
„ Cm"4
I7.6y
to PU24°
4.98 h
Am
,243
"•y
/I
Cm243
3.79 «I05y
tou238
/I
7950y/ 32y
toNPM9/n'r toPu239
Pu'.£_E^/_Am242.T, Cm242
16% / // 84% /
I52y / IS.Oh /a
./ 7 /163d
n-y Am242"/"''' /238
y / 10 Pu238
».y\/
Pu241 ^ > Am241
P
•A
0.0023%
»OU«7
13.2 y
". y
/458y
to Np2
/
6580y
loU2is
Pu240
"•y
n23?
_
23.5m
"2.35 d
-Pu
,239
•/
24.400y
to U»5
4.5UI09y
loth04
n, 2n
2.Id
-PuZM
6'
n.Y .
7 2.l4«l06y
toPu
233'
U»«
n, 2n
2.37 «I0ry
to
,jZM
T. K Pigford
8/73
T.lilO'y
10 Th"1
-------
FLOW QUANTITIES ARE STATED IN METRIC TONS/YEAR
UNLESS OTHERWISE INDICATED
80% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
•- AIRBORNE RELEASE
=> LIQUID EFFLUENT
SOLID EFFLUENT
Mg = METRIC TONS
Ci = CURIES
kwh = KILO WATT-HOURS
Mw = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
-------
Figure 3 Fuel Actimde Flowsheet .for 1000-Mw U-Ru Fueled Water Reactor
Yearly Quantities, 80 % Load Factor
Ci = curies
Plutonium Make-up
From U Fueled Water Reactor
% kg Ci
236Pu I02xl0"4 5.2xlO'4 2. 74 xlO2
238Pu 24325 12 28 2.07x|05
239Pu 584058 29493 I.SIxlO4
^Pu 240039 I2'l.2l 2.67x|Q4
^'Pu II 2387 56.75 5.77x|06
242Pu 39191 19.79 772x10'
Total Pu 100 504.96 252 xlO5 a
5 77xl06 0
Natural Uranium Make-up
% kg Ci *"
234U 0005 150 9.28
235U 071 19924 043
238U 99285 27861.51 928
Total U 100 28062.25 1899
0 5 % Loss
Pu 725kg
5.09x1 03 aCi
1 I6xl05^ Ci
U 136.80kg
0093 Ci
Fa bricotion
i
Conv
t
Pu 1449.69 kg
l.02»!06aCi
2.32«l07£Ci
U 27 360.7 kg
18.51 Ci
irsiun "
o
Pu02-U02
0.5% Loss
Pu 7.43kg
5.22 xlO3 a Ci
U9xl05/3Ci
U 140.3kg '
0.10 Ci
kg Ci
2341 1 1 ^8 " ^5 , „ . _, -
"SU '8358 0 3Q Light Water Reactor kg Ci
238U 2567094 855 1000 M we u 25245 428xl08
„ Shioment 25855.90 l7 ^ ^ A..c.agc Burnup - 33 000 Mwd/Mg NP 6°6 424xlCT
Pu 1366 a. 9.59xl05 Fuel Exposure Time =1100 days P" 8888 a 698 xlO5
2^ » 2|9"07 Capacity Factor =0.80 /3 1 1 1 x I08
5% Recycle Thermal Efficiency = 0.325 Am l4j * ^|°7
Pu 7248kg Cm 56 4 a (58,|07
^F-'in^r'i fp 9498 3.71 xlO9
,,- Clod 7385 265xl06
U 1368 kg
093 C' „ Shipment Pu02-
2% Recycle Pu 102.2
Pu 29 74 kg 7I8M
2.09x|Q4aCi |64x
U "SKI kg
0.38 Ci
Storage
of
Irradiated Fuel
ISOdays
U 25245 4.34 xlO2
Np 433 1.19x10^ Sh,c
Pu 889.6 a. 725x|05
B l.69x|Q7
0 2.I3«I03
Cm 53.9 a 1.01 xlO7
FP 949.8 I.24«l08
Clad 7385 532x|05
U02 Fuel Scrap
kg l> 1929 kg
04aCi 1.31 Ci
O6 0 Ci
Shipment ^ Plutonium Recycle
%
236Pu 4.12 xlO'5
238Pu 419
239Pu 38.68
24°Pu 27.53
24lPu 18.08
242Pu 11.53
Total Pu 100
Repro
| Vo
kg Ci n
4.0xlO"4 2.15
xlO2 U or
41 1 2 6.94x10 =
37980 2.33 x|Q4
270.27 5. 96x10"
177.54 1 .81 x)07
113. 18 441 x|Q2
981.91 778x|05a
1.81 xlO7^
1
ment
Radioactive wastes
kg Ci
U 2181.73 5 65
Np 4 33 119 xlO4
Pu . 9 92 a 7 86' I03
*" - 0 1 82«I05
Am 778- a 6 58xl04
- 0 2 I3.I03
Cm 53 9 a 1 OHIO7
FP 949 8 1 24xl08
Clad 7385 5 32«IO5
:essmg
Depleted Uranium
Loss " % kg Ci
HO 234U 00066 167 1021
d Pu „
236U 00791 19 77 1 25
237U I.9xl0~8 475x10 "6 38795
238U 99.59 2. 49 xlO4 829
Total U 100 24992 40788
11
-------
The problems of control-absorber worth may limit the extent to which a
water reactor designed originally for slightly enriched uranium can accommo-
date the recycle of plutonium, and this may vary significantly with the
type of reactor to which the plutonium is to be recycled. Use of soluble
boron in the reactor coolant in pressurized water reactors requires less
total reactivity in movable and fixed control absorbers in these reactors,
and it should be possible to increase the concentration of dissolved boron
with plutonium fueling and still maintain a negative coolant temperature
coefficient of reactivity. For pressurized water reactors using the rod-
cluster-control (RCC) configuration, whereby in some fuel assemblies some
of the fuel rods are replaced by ganged control rods, the increased control
necessary for plutonium recycle may be obtained by adding more of these RCC
assemblies to the reactor core.
However, in the boiling-water reactors the control absorbers are the cruci-
form elements located at the intersection of four adjacent fuel assemblies,
and it may be more difficult to increase the control rod worth in this
arrangement. It is estimated that a boiling-water reactor may be limited
to recycle fueling of no more than 110% to 130% of the self-generated plu-
(2)
tonium without substantial modification in the control absorber systenr '.
Without such modification, the boiling water reactor may be limited in the
extent to which it can be applied as a reactor dedicated for complete fuel-
ing with recycle plutonium.
13
-------
An important benefit from plutonium utilization is the reduction in the
amount of uranium ore consumed and the reduction in the amount of uranium
isotopic enrichment. There are many alternative ways in which these benefits
can be realized. Plutonium can be mixed with uranium of some intermediate
enrichment between that of natural uranium and the enrichment used for
uranium fueling, plutonium can be mixed with depleted uranium presently
stockpiled from isotope separation, or plutonium can be mixed with natural
uranium. It is the latter concept which is assumed for the present flow-
sheet. For the assumed irradiation exposure of 33,000 Mw(t) days per
*
metric ton, the calculated yearly requirement of natural uranium for fuel
fabrication on this flowsheet is 26.1 Mg. Even though the uranium in the
?QC 9TC
discharged fuel contains 0.33% U, which is greater than the U content
in depleted uranium from isotope separation, recycle of this recovered uranium
for isotopic enrichment is probably not economically justified because
of the costs of conversion to UFg for isotopic separation and subsequent
conversion of the product UFg to UOp. A feature of the fuel cycle shown
here is that the hexafluoride conversion steps are avoided.
An important consequence of plutonium utilization is that the amount of
plutonium in the fuel cycle continues to build up with each subsequent recycle
of the recovered plutonium until the equilibrium fuel cycle is reached,
usually after a period of about 8 years. At equilibrium the amount of plu-
tonium recovered yearly from reprocessing the discharge fuel and scrap
14
-------
recycle in this cycle is 0.982 Mg/yr, as compared with 0.207 Mg/yr* recovered
from the discharge fuel from the uranium-fueled water reactor^ . This
recycled plutonium is added to 0.505 Mg/yr of make-up plutonium, so that the
yearly input to mixed-oxide fuel conversion and fabrication is 1.486 Mg of
plutonium, with radioactivity of 9.59 x 105 alpha curies and 2.19 x 107 beta
curies. Extremely careful process control is required to maintain plutonium
effluents at the very low levels required to meet the plutonium radiological
standards.
At equilibrium the fuel charged to the reactor contains 5% plutonium in the
plutonium-uranium mixture. The calculated isotopic composition of the make-
up plutonium from the uranium-fueled water reactors, the recycled plutonium,
and the mixed plutonium in the fabricated fuel charge are shown in Table 1.
The calculated yearly quantities of radioactivity of these radionuclides in
the discharge fuel are shown in Table 2. The greatest amount of plutonium
238 240
alpha radioactivity results from Pu, with lesser amounts from Pu and
239 ?41
Pu. The beta activity from Pu, after 150 days of preprocessing cooling
is 23 times greater than the total plutonium alpha activity.
Because of the high concentration of the higher-mass plutonium isotopes in
the equilibrium cycle and because these isotopes are present during the
entire irradiation period of fuel in the reactor, relatively large quantities
* Corrected to 80% load factor.
15
-------
TABLE 1
Isotopic Composition of Plutonium in Equilibrium Fuel
Cycle for 1000 Mw Uranium-Plutonium Fueled Water Reactor
236
Pu
238
Pu
239
Pu
240
Pu
241
Pu
242
Pu
Make-up plutonium
recovered from dis-
charge fuel from Li-
fueled water reactor
Plutonium recovered
from discharge fuel
from this reactor
and recycled
100
100
Plutonium fabri-
cated into fresh
fuel for this
reactor
1 x 10'4
2.43
58.40
24.00
11.24
3.92
3.9 x 10"5
4.25
37.95
27.65
18.35
11.80
6J x 10"5
3.65
45.04
26.44
15.74
9.14
100
16
-------
Table 2
Radioactivity in Rcdctor and Fuel Cycle for a 1000 Mw Water Reactor
Fueled with Natural Uranium and Recycled Plutonium
Radionuclides
Half-Life
Reactor / ,
Inventory
106 Curies
In. Discharge Fuel
10b curies/yr.
At Discharge
150-day Decay
10-yr. Decay
Fission Products
Tritium(b) 3H
Krypton 83m
85m
85
87
88
89
90
TOTAL(c)
Strontium 89
90
TOTAL 'c'
Iodine 129
131
132
133
134
135
136
TOTAL 'c'
Xenon 131m
133m
133
135m
TOTAL 'c'
Cesium 134
137
TOTAL (c)
Zr, Nb, Mo, Tc, Ru, Rh,
Pd, Ag, Cd, In, Sn, Sb
Rare Earths: La,Ce,Pr,
Nd,Pm,Sm,Eu,Gd,Tb,Dy,
Ho
TOTAL FISSION PRODUCTS
12.26 yr.
1.86 hr.
4.4 hr.
10.76 yr.
76 m.
2.8 hr.
3.18 m.
33 sec.
52.7 d.
27.7 yr.
1.7 x 107 yr.
8.05 d.
2.26 hr.
20.3 hr.
52.2 m.
6.68 hr.
83 sec.
11.8 d.
2.26 d.
5.27 d.
15.6 m.
2.046 yr.
30.0 yr.
0.076
2.62
11.54
0.56
21.38
32.02
38.50
44.76
221 .42
40.98
3.74
395.68
3.90 x 10'6
73.50
102.96
129.12
143.98
112.72
40.84
938.58
0.52
3.12
129.20
34.08
671.60
17.44
9.08
548.20
4486.14
1626.72
11,166.18
(2.86 Mg)
0.025
0.87
3.83
0.19
7.09
10.60
12.78
14.80
73.49
13.61
1.24
131.33
1.29 x 10"6
24.40
34.17
42.86
47.78
37.41
13.55
311.51
0.17
1.03
42.88
11.31
222.90
5.78
3.01
181.95
1488.92
539.90
3706.00
(0.94 Mg/yr.)
0.024
0
0
0.18
0
0
0
0
0.18
1.84
1.23
3.07
1.30 x 10~6
6.18 x 10"5
4.35 x 10"13
0
0
0
0
6.32 x 10"5
8.98 x 10"5
0
1.42 x 10"7
0
9.00 x 10"5
5.04
2.98
8.03
63.39
40.86
123.56
0.014
0
0
0.10
0
0
0
0
0.10
0
0.97
0.97
1.30 x 10"6
0
0
0
0
0
0
1.30 x 10'6
0
0
0
0
0
0.19
2.39
2.59
0.08
0.44
7.44
17
-------
(Table 2 continued)
Rddionucl ides
Half-Life
Reactor
Inventory
106 Curies
In Discharge Fuel
106 curies/yr. ^
At Discharge
150-day Decay
10-yr. Decay
Actinides
Uranium 234
235
236
237
238
239
TOTAL
Neptunium 236
237
238
239
TOTAL
Plutonium 236
238
239
240
241
242
243
TOTAL
2.47 x 106 yr.
7.1 x 108 yr.
2.4 x 107 yr.
6.75 days
4.5 x 109 yr.
23.5 min.
5.0 x 103 yr.
2.1 x 106 yr.
2.12 days
2.35 days
2.85 yr.
87.4 yr.
24390 yr.
6600 yr.
14.3 yr.
, 3.87 x 105 yr.
4.96 hr.
2.90 x 10"5
(4. 69' Kg)
8.59 x 10"7
(401.03 Kg)
1.92 x 10'6
(30.05 Kg)
20.62
(0.24 Kg)
2.55 x 10~5
(76.54 Mg)
1268.40
(0.02 Kg)
1289.37
(77.11 Mg)
4.15 x 10"5
4.50 x 10"6
7.42
1266.74
1275.38 ,
(4.50 x 10 •"«)
(1275.38 B)
9.60 x 10"4
(1.80 gm.)
2.20
(130.81 Kg)
0.08
(1.42 Mg)
0.20
(915.28 Kg)
58.90
(579.55 Kg)
1.36 x 10'3
(351.06 Kg)
283.12
(0.10 Kg)
2.48 =
342.02 B
(3.39 Mg)
9.67 x 10"6
1.77 x 10"7
1.26 x 10"6
6.84
8.37 x 10~6
420.9
428.0
(25.24 Mg)
2.75 x 10"5
2.98 x 10"6
2.46
420.4
423.7 ,
(2.98 x 10 ""«)
(423.7 3)
1.94 x 10~4
0.62
0.02
0.05
17.2
4.19 x 10"4
94
0.69 -
111 B
(0.88 Mg)
1.04 x 10"5
1.77 x 10~7
1.26 x 10"6
4.06 x 10~4
8.37 x 10"6
0
K
4.33 x 10 *
0
3.05 x 10~6
0
0.01
0.01
1.76 x 10"4
0.65
0.02
0.05
16.8
4.19 x 10"4
7.95 x TO"10
0.72 -
16.8 B
(0.89 Mq)
2.8 x 10'5
1.7 x 10"7
1.2 x 10'6
2.5 x 10'4
8.3 x 10'6
0
A
2.9 x 10"*
0
0
0
0.01
0.01
1.7 x 10"5
0.63
0.02
0.05
10.6
4.19 x 10"4
7.95 x 10*10
0.71 «
10.6 B
(0.84 Mg)
18
-------
(Table 2 continued)
Radionuclides
Half-Life
Reactor
Inventory
106 Curies
In Discharge Fuel
10^ curies/yr.
At Discharge
150-day Decay
10-yr. Decay
Actinides
Amen ci urn 241
242m
242
243
244
TOTAL
Curium (242-248)
and Berkelium (249,250)
TOTAL ACTINIDES
(Th, Pa, U, Np, Pu,
Am, Cm, Bk)
433 yr.
152 yr.
16.0 hr.
7370 yr.
10.1 hr.
0.08
3.20 x 10~3
49.16
1.79 x 10'2
234.48
283.72
(0.13 =)
(283.64 0)
47.60
( « )
3240.32
(80.82 Mg)
0.04
2.12 x 10"3
16.32
1.18 x 10"2
77.82
94.21
(0.05 =)
(94.1 6)
15.79
( « )
1057.77
(26.27 Mg)
0.05
2.12 x 10"3
2.12 x 10~3
1.18 x 10~2
0
0.07
10.11
27.78
0.01
2.0 x 10"3
2.0 x 10"3
1.1 x 10~2
0
0.27
2.59
14.28
Cladding
ACTIVATED CLADDING
AND STRUCTURAL
MATERIAL
7.96
(22.25 Mg)
2.64
(7.38 Mg)
0.53
0.03
Total Fuel and Cladding
FISSION PRODUCTS
ACTINIDES
AND CLADDING
14,414.46
(105.93 Mg)
4766.41
(34.59 Mg)
151.87
21.75
(a) Inventories of fission products and activated cladding in the reactor are calculated on the basis that all fuel has
the composition of discharge fuel. For non-saturable species, whose half lives are large compared with the fuel
life of 3 years, the inventory within the reactor will be about one-half to two thirds of the value listed, depending
upon the fuel-management scheme. For long-lived actinides at linear change from charge to discharge is assumed to
calculate the reactor in calculating the reactor inventory.
(b) Quantities listed are fission-product tritium only and do not include tritium formed by neutron-activation reactions
in boron controls and contaminants.
(c) Totals include all iostopes of the element, including short-lived species not listed in the Table.
(d) Calculated for the equilibrium fuel cycle, average thermal exposure of discharge fuel: 33,000 Mw days per Mg of
actinides charged, average thermal specific power: 30 Mw per Mg of actinides charged.
19
-------
of americium and curium are produced in this fuel cycle*. The quantities
of plutonium, americium, and curium in fuel reprocessing for this uranium-
pi utonium fueled reactor are compared with equivalent quantities for the
uranium fueled reactor in Table 3. For the U-Pu fueled reactor the curium
alpha activity is 13.9 times greater than the plutonium alpha activity.
Not only is curium an important potential source of alpha effluents in
fuel reprocessing, but both curium and americium are the important actinides
in determining the ultimate long-term radioactivity in high-level wastes
from fuel reprocessing, as discussed in Section 7. The amounts of
americium and curium going into these high-level wastes is 30 times greater
for the U-Pu fueled reactor than for the U fueled reactor.
In summary, the resource and economic benefits of plutonium utilization in
water reactors are realized at the cost of increased amounts of plutonium
processed in the fuel cycle, increased inventory of plutonium in the reactor
and fuel cycle, and increased inventory of long-lived actinide emitters in
the high-level wastes. Estimates of the principal environmental effluents
of this fuel cycle are given in the following sections.
3. Mining. Milling, and Concentration
Environmental effluents from mining uranium ore are calculated from the
data presented in "Fuel Cycles for Electric Power Generation"^ , scaled
according to uranium throughput. Solid and liquid effluents from
milling and concentration are also based upon that data, but the
* Relatively small quantities of berkelium and californium are also
produced.
20
-------
Table 3
Comparison of Neptunium, Plutonium, Americium and Curium
Reprocessed Yearly from Uranium Fueling and Uranium-Plutonium
Fueling in 1000 Mw Water Reactors, 150-day Cooling
Neptunium
237
239
Total
Plutonium
236
238
239
240
241
242
Total
Americium
241
242m
242
243
Total
Curium
242
243
244
245
Total
Half Life
2.14 x 106 yr
2.35 day
Water Reactor Fueled with
Slightly Enriched Uranium
Water Reactor Fueled
with Natural Uranium
and Recycled Plutonium
2.85 yr
87.4 yr
24,390 yr
6,600 yr
14.3 yr
3.87 x 105 yr
433 yr
152 yr
16.0 hr
7370 yr
163 day
32 yr
17.6 yr
9300 yr
Kg/yr
20.8
20.8
2.4 x 10"4
5.98
143.7
59.0
27.6
9.64
246
1.32
0.011
2.48
3.81
0.133
0.002
0.911
0.055
1.101
Ci/yr
14.6
474
- 14.6
3 474
1.34 x 102
1.01 x 105
8.82 x 103
1.30 x 104
2.81 x 106
3.76 x 101
- 1.23 x 105
3 2.81 x 106
4.53 x 103
1.16 x 102
1.16 x 102
4.77 x 102
- 5.01 x 103
3 1.16 x 102
4.40 x 105
9.03 x 101
7.38 x 104
9.79 x 104
5.15 x 105
Kg/yr
4.33
4.33
3.31 x 10'4
38.5
331
247
166
108
890
15.73
0.218
2.62 x 10'6
61.8
77.8
1.92
0.0224
46.2
5.22
53.9
Ci/yr
3.05
1.19 x 1 O4
3.05
3 1.19 x 104
1.76 x 102
6.50 x 105
2.03 x 104
5.44 x 104
1.69 x 107
4.20 x 102
- 7.25 x 105
3 1.69 x 107
5.39 x 104
2.12 x 103
2.12 x 103
1.19 x 1 O4
« 6.58 x 104
3 2.12 x 103
6.36 x 106
1.03 x 103
3.74 x 106
9.21 x 102
1.01 x 107
21
-------
gaseous effluents are derived in part from the data for a plant operating
at a capacity of 2000 tons/day (1814 Mg/dayr . with the If oil owing esti-
mated gaseous releases:
Table 4
Gaseous Effluents from Milling and Concentration
of 2000 ton/day of Uranium
Uranium 439 Ci/day
226Ra 185 Ci/day
230Jh 185 Ci/day
S02 460 Ib/yr
N02 3.5 x 104 Ib/yr
NH, 3.5 x 103 Ib/yr
The effluents on the present flowsheet are then scaled from the data in
Table 4 according to uranium throughput. A 5% loss in uranium milling and
concentration is assumed^ .
22
-------
4. Fuel Conversion and Fabrication
The finished product from the conversion-fabrication operation consists of
Zircaloy-clad fuel rods containing pellets of sintered (Pu,U)02. The mixed-
oxide powder for pelletizing and sintering is prepared either by mechanical
mixing of Pu02 and U02 powders or by co-precipitation of uranium-piutonium
oxalate from an aqueous nitrate solution. Calcination of the mixed oxalate
results in a solid solution of Pu02 and U02, which has the advantage of a
homogenous mixture and less chance of segregation of PuCL. Also, the solid-
solution mixed oxide is easier to dissolve in later reprocessing operations.
The rate of dissolution of irradiated fuel prepared initially by mechanically
mixing Pu02 and U02 powders has been found to be very low.
The alternate process of mechanically mixing the two oxide powders is the most
straightforward if the plutonium has previously been converted to the oxide
prior to shipping from the fuel reprocessing plant. Although Pu(NO.,)A solution
O i
is now shipped from reprocessing to fabrication in 3-liter polyethylene bottles,
(2}
it is contemplatedv ' that regulations may soon require that plutonium be
/
shipped only as a dry stable solid, such as Pu02, so that the conversion of
Pu(N03), to the oxide would be done at the fuel reprocessing plant.
In either event, fabrication requires the handling of Pu02 as a powder, either
as pure oxide or diluted with about twenty times as much U02- Controlling
For the equilibrium fuel cycle.
23
-------
and confining the solid particles containing plutonium and minimizing the
escape of even a very small fraction of these solid particles as airborne
aerosols is the principal environmental -control problem in fuel fabrication.
It has been shown'3' that in a typical fabrication plant capable of proces-
sing one metric ton per day of uranium-plutonium fuel, the fraction of the
Plutonium processed which is calculated to escape as an aerosol, resulting
in off -site concentrations well below the plutonium radiological standards,
1 3
is of the order of one part in 10 . To protect the process-plant workers,
the plutonium conversion and fabrication operations are carried out in
glove-box process lines which are carefully ventilated with air that passes
through multiple particulate filters before exhaust. The performance of
such a filtration system appears to be adequate for plutonium control,
although there continues to be uncertainty with regard to the means of pre-
dicting the performance of multiple filtration systems from data on single
f i 1 ters .
The amount of radioactivity associated with recycle plutonium during fuel
fabrication depends in part upon the time elapsed since the plutonium was
separated as a purified product in fuel reprocessing. Between the times of
24-1
reprocessing and fabrication, decay of 14.3-yr. Pu results in the build-
241
up of 433-yr. Am, resulting in more energetic and penetrating gammas than
241
from Pu alone. Also, the decay of 2.85-yr. Pu results in 72-yr. U,
228
which alpha decays to 1.91-yr. Th, an intermediate radionuclide in the
24
-------
232 99R
decay of natural Th. The several daughters of nh are all short-lived
212 208
and include Bi and Tl, both of which emit gammas with energies of a few
mev. These daughters from the decay of 236'241Pu will contribute to the
shielding requirements for shipping from reprocessing, fuel fabrication,
shipping the fabricated fuel to the reactor site, and handling the fabricated
fuel at the reactor site. Plutonium which has been stored for several years
prior to fabrication will be a special problem in this regard. However, the
principal public-health hazard from effluents will probably be from inhalation
of the small quantities of plutonium that are released and should not be
significantly affected by these plutonium decay daughters.
The effluents for the present flowsheet are based upon data for a fabrication
plant capable of fabricating 300 Mg/yr of uranium and plutonium into mixed-
oxide fuel. The conversion and fabrication emissions from such a plant are
(2}
given in Table 5^ . The emissions for the present flowsheet are scaled from
these data according to the uranium-plutonium throughput.
The liquid filtrate from co-precipitation conversion contains 0.5% of the
uranium and plutonium processed. This is solidified, packaged, and shipped
to land storage for solidified low-level radioactive wastes. Similarly, 0.5%
of the uranium and plutonium processed in fabrication appears as a low-level
solid waste. Process scrap amounting to 2% of the actinides processed in
conversion and B% of those processed in fabrication is shipped to fuel re-
processing for actinide separation and recovery.
25
-------
TABLE 5
Environmental Emissions for a Mixed-Oxide Fuel Fabrication Plant
(300 Mg/yr of Uranium and Plutonium)'2'
Chemical Conversion to Oxide
Gaseous Effluents
NOX 1350 kg/yr
NH3 37.5 kg/yr
Plutonium + americium alpha 1.37 x 10~4 Ci/yr
beta 2.75 x lO'3 Ci/yr
Liquid Effluents
PO| 60 kg/yr
N03 1250 kg/yr
Plutonium + americium alpha 2.06 x 10~4 Ci/yr
beta 4.12 x 10~3 Ci/yr
Solid Wastes
750 drums/yr @ 7.35 cu.ft/drum, containing 0.5% of the uranium and
Plutonium processed.
Fabrication
Gaseous Effluents
F~ 0.187 kg/yr
NOX 1350 kg/yr
NH3 37.5 kg/yr
Plutonium alpha 1.37 x 10~4 Ci/yr
beta 2.75 x 10'3 Ci/yr
Liquid Effluents
Plutonium alpha 2.06"x 10~4 Ci/yr
beta 4.12 x lO'3 Ci/yr
Solid Wastes
750 drums/yr @ 7.35 cu.ft/drum, containing 0.5% of the uranium
and plutonium processed.
26
-------
5. Nuclear Power Plant Operation
The non-radiological emissions from power plant operations would be similar
to those analyzed in Fuel Cycles - Part I. The radiological emissions
should also be substantially the same, except for 85Kr, which has a yield
0 *3Q
from "yPu fission which is less than half that from 235U fission. The 85Kr
emissions from the power plant are reduced in proportion to the calculated
reactor inventory of these radionuclides.
No environmental release of plutonium in the reactor fuel at the power plant
(2)
has been identifiedv ;. However, some environmental analyses indicate small
releases of rare-earth fission products to the reactor coolant. Consequently,
because of the generally similar chemical properties, some release of
plutonium to the coolant would be expected. More detailed study of this as
a possible pathway for plutonium in liquid effluents and solid wastes is
warranted.
6. Shipping
No environmental effluents from shipping discharge fuel have been identified
for normal shipping operations. The rate of heat generation and radioactivity
level are actually lower in plutonium-recycle water-reactor fuel than in fuel
shipped from a uranium-fueled water reactor*. Apart from consideration of
accidents, which is beyond the scope of the present study, shipping fuel from
uranium-plutonium fueled reactors should present no greater environmental impact
The rate of decay heat generation during the short period following a
loss-of-coolant accident is greater for plutonium-recycle fuel than for
uranium fuel, but during post-irradiation cooling plutonium-recycle fuel
decays to a lower level.
27
-------
7. Fuel Reprocessing
Reprocessing the fuel from the uraniurn-piutonium fueled reactors follows a
similar process as reprocessing irradiated uraniuri fuel. The fuel rods are
chopped into segments, exposing the mixed-oxide pellets which are then
(4)
dissolved in nitric acid. Purex solvent extractionv ' produces separate
streams of uranyl nitrate and plutonium nitrate and a third stream consisting
of the fission products and the remaining actinides. The plutonium is then
stored as nitrate solution, or it may be converted to the oxide for storage
and ultimate shipping. As has been mentioned in Section 3, difficulties
have been encountered in dissolving irradiated fuel which was initially
prepared as a mixed uranium-plutonium oxide. This has been attributed to
the relatively slow dissolution of the separate plutonium dioxide particles
remaining from mechanical blending of the mixed-oxide powder.
Also, the high concentration (ca 5%) of plutonium in the fuel will introduce
new problems of criticality control in dissolution and solvent extraction
and may also contribute to greater solvent degradation. There are several
alternative technical means of solving these problems, such as adding fluoride
to the dissolver solution. It is assumed that these solutions will result
in no significant changes in the environmental effluents from this reproces-
sing technology.
o or
The releases of H and Kr are calculated on the basis of 100% of the fission-
product tritium and krypton in the discharge fuel at the time of reprocessing.
28
-------
The krypton release is less than that for a uranium-fueled water reactor
because of the lower fission-yield of 85Kr from plutonium. Of the total
tritium released, 86% is released as tritiated water vapor in the gaseous
effluents and 14% is released as tritiated water in surface-water discharges^
It is assumed that the scrubbing process for recovering iodine evolved
during dissolution is 99.9% efficient, i.e., the decontamination factor is
1000. The plutonium releases are estimated from data in reference (2) and
scaled to the plutonium throughput. Other radionuclide releases are based
upon the data for the uranium fuel cycle^ ', scaled according to the throughput
oo c
of plutonium and uranium. The uranium product is stored, since its U
isotopic content of 0.327% does not justify chemical conversion and recycle.
A low-level waste stream containing an estimated 0.5% of the actinides pro-
cessed is concentrated to a solid and canned for land storage. The quantities
of intermediate-level liquids and buried solid wastes are scaled from data
in reference (1).
8. High-Level Waste Management
The high-level waste steam from fuel reprocessing contains the
non-volatile fission products, neptunium, americium, and curium, and
the small quantities of uranium and plutonium resulting from incomplete
partitioning in solvent extraction. These wastes may be stored for up
to five years at the reprocessing plant, thereafter they are to be
solidified and shipped to a Federal repository, as described in "Fuel
Cycles for Electric Power Generation"^ . As has been discussed
29
-------
in Section 1, the effect of plutonium recycle is to increase significantly
the actinide content of the high-level wastes (cf. Table 3). It is these
243 . 242 243 244
actinides, particularly Am, Cm, Cm, and Cm, which control the
ultimate level of radioactivity, and particularly alpha radioactivity, which
remains in these wastes after storage periods of hundreds of years. This
radioactivity ultimately appears as long-lived plutonium radionuclides, i.e.,
238Pu from 242Cm decay, 239Pu from the decay of 243Am and 243Cm and 240Pu
from the decay of Cm. Although these plutonium isotopes are present
in the high-level wastes when first separated in solvent extraction, the
amount of plutonium due to this incomplete partitioning is much less than
the amount of plutonium ultimately formed by americium and curium decay.
The calculated activities of the isotopes of americium, curium, and plutonium
produced in one year of operation at 1000 Mw, as a function of the storage
time after separation, are shown in Figures 4, 5, and 6. The increase with
time of the plutonium isotopes during the first few thousand years is due
to the decay of the americium and curium precursors. After a few thousand
years of storage the activity of plutonium exceeds that of americium and
curium.
The total radioactivity in plutonium, americium, and curium in high-level
waste is compared for uranium-piutonium fueling and uranium fueling in
Figure 7. At a time of about 300 years, when the actinide activity exceeds
the fission-product activity, the total alpha activity in these wastes is
30
-------
10*
0)
3
U
O
Q
<£
Figure 4
AMERICIUM ACTIVITY IN HIGH-LEVEL WASTES
1000-Mw U-Pu FUELED WATER REACTOR
T
TOTAL Am
m
E43
'Am
rn
10
One year operation
3077 Mw thermal
30 Mw/Mg
33,000 Mwday/Mg
80% load factor
0
10 I02 I03
STORAGE TIME, years
I04 I05
31
-------
Figure 5
CURIUM ACTIVITY IN HIGH-LEVEL WASTES
lOOOMw U-Pu FUELED WATER REACTOR
One year operation
3077 Mw .thermal
30 Mw/Mg
33,000 Mw day/Mg
80% load factor
TOTAL Cm
TOTAL Cm
0
10 I02 I03
STORAGE TIME, years
32
-------
Figure 6
PLUTONIUM ACTIVITY IN HIGH-LEVEL WASTES
1000-Mw U-Pu FUELED WATER REACTOR
One year ope ration
3077 Mw thermal
30 Mw/Mg
33,000 Mw doy/Mg
oad factor
0.5 % of Pu reprocessed
remains in high-level wastes
TOTAL Pu (a-n/3)
TOTALPua.
O.I
10 10* 10° 10'
STORAGE TIME, years
33
-------
Figure 7 •
ACTINIDES IN HIGH-LEVEL WASTES FOR
U FUELED AND U-Pu FUELED WATER REACTORS
One year operation
30 Mw/Mg
33,000 Mw'doy/Mg
80% load factor
0.5% of Pu processed
remains in high-level waste
U-Pu fuel
U fuel
10 I02 I03 I04
STORAGE TIME.yeors
34
-------
about nine times greater for uranium-piutonium fueling than for uranium
fueling. After a storage time of a few thousand years, when the actinide
activity is determined by the 239'240pu content, the radioactivity in
high-level wastes is about 35 times greater for uranium-piutonium fueling.
9. Low-Level Actinide Solid Hastes
In Figure 3 a process loss of 0.5% of the plutonium into low-level solid
wastes is indicated for each of the operations of reprocessing, conversion,
and fabrication. The total yearly amount of plutonium in these low-level
wastes is estimated to be 1.43 x 10 alpha curies and 3.31 x 105 beta curies.
239 ?40 3
The contribution of ' ^ Pu to the alpha activity is 1.42 x 10 curies.
This is a considerably greater amount of plutonium than that in the high-
level wastes at the time of reprocessing. Although these low-level plutonium
wastes do not contain the appreciable quantities of americium and curium
which account for the increase in plutonium in high-level wastes during
storage, the plutonium activity in these low-level wastes will remain within
an order of magnitude of the plutonium activity in the high-level wastes,
even after the americium and curium in the latter have decayed.
The long-term requirement of high-level waste management is to isolate the
actinides, and mainly plutonium, from the environment. In this sense the
low-level plutonium wastes are in the same realm of importance as are the
high-level wastes and should be subject to the same or similar ultimate
criteria for isolation. A principal physical difference between the two
wastes at the time of their origin is the degree of dilution with inert
35
-------
carrier material. However, with the degree of isolation that is probably
necessary to make the long-term management of any form of plutonium wastes
acceptable, it is not clear that the greater dilution of these low-level
wastes in any way simplifies the technology necessary to isolate the pluto-
nium from the environment. The greater dilution may, in fact, introduce
technological difficulties in putting the contained plutonium into a form
suitable for isolation that are not present with the high-level wastes. The
problems of suitable long-term management of low-level solid wastes contain-
ing plutonium warrant careful attention.
36
-------
REFERENCES
1. Pigford, T. H., M. J. Keaton, B. J. Mann, and P. M. Cukor and
G. L. Sessler, "Fuel Cycles for Electric Power Generation", Teknekron,
Inc. Report No. EEED 101, U.S. Environmental Protection Agency Contract
No. 68-01-0561 (rev. March, 1975).
2. U. S. Atomic Energy Commission, Fuels and Materials Division of
Licensing, "Generic Environmental Statement Mixed Oxide Fuel (Draft),"
WASH-1327 (August, 1974).
3. Pigford, T. H., "Radioactivity in Plutonium, Americium, and Curium in
Nuclear Reactor Fuel," Report to the Energy Policy Project, Ford
Foundation (June, 1974).
4. Benedict, M., T. H. Pigford, "Nuclear Chemical Engineering," McGraw Hill
(1957).
5. USAEC, D.O.L., Final Environmental Statement Related to Operation of the
Highland Uranium Mill, Docket #40-8102 (November, 1973).
6. Oak Ridge National Laboratory, Projections of Radioactive Wastes to
be Generated by the U.S. Nuclear Power Industry, ORNL-TM-3965
(February, 1974).
37
-------
FUEL CYCLE FOR 1000-Mw HIGH-TEMPERATURE GAS-COOLED REACTOR
Thomas H. Pigford*
Robert T. Cantrell*
K. P. Ang*
and
Bruce J. Mann**
Teknekron Report No. EEED 105
March, 1975
* Department of Nuclear Engineering, University of California, Berkeley,
California.
** Now at U.S. Environmental Protection Agency, Office of Radiation
Programs, Las Vegas, Nevada.
-------
ABSTRACT
This study presents an illustrative data base of material quantities and
environmental effluents in the fuel cycle for a high-temperature gas-cooled
reactor fueled with uranium and thorium. Data were calculated for a 1000 Mw
nuclear power plant operating on an equilibrium fuel cycle. Results are
shown in tables and on a fuel-cycle flowsheet.
-------
TABLE OF CONTENTS
1. Introduction 1
2. Reactor Characteristics 2
3. Mining, Milling and Concentration 19
4. Conversion of UsOs to UFs and Uranium Enrichment 23
5. Conversion and Fabrication of Initial Make-up Fuel 23
6. Fabrication of Recycle Fuel 23
7. Nuclear Power Plant Operation 29
7.1 Radionuclide Inventories 29
7.2 Tritium 29
7.3 Krypton and Xenon 36
7.4 Iodine ~ 37
7.5 Additional Airborne Releases 41
7.6 Solid Wastes 42
8. Shipment of Irradiated Fuel 43
9. Fuel Reprocessing and Conversion 43
10. High-Level Wastes 47
References 52
v
-------
LIST OF FIGURES
' •
2.
3.
4.
5.
6.
7.
8.
Art'iniHp Ph^in^ fVnim 1 1 VA n T i im Tvya^ia-f-Tnvi
i nnn MW HTHR FMPI Finw ^hppt vpa^i \/ nn^ntitioc
Fission Products in High-Level Wastes Produced in
Onp Ypay hv 1000 Mu/ MTf^R
UMC icar uy i uuu iviw n i UK --_ ________ _ --
Plutonium Radioactivity in High-Level Wastes Produced
in Onp Ypar h\/ 1000 Mui HTRR -
Actinide Radioactivity in High-Level Wastes Produced
in Ono Vpav hx/ 1000 MI«I HTHD
0
4
n
17
21
48
50
-------
LIST OF TABLES
1. HTGR Fuel Particle Descriptions ------------------------------- 6
2. Calculated Uranium Composition of HTGR Fuel Particles --------- 8
3. Gaseous Effluents from Milling and Concentration of
2000 ton/day of Uranium ------------------------------------ 19
4. Effluents and Solid Wastes from HTGR Fuel Refabrication ------- 26
5. Radionuclides in 1000 Mw HTGR Reactor and in Discharge
..... ----------------------- ..... ------------------- 30
6. Actinides in 1000 Mw HTGR Reactor and in Discharge Fuel ------- 32
7. Estimated Rate of Release of Tritium to Helium Coolant
in 1000 Mw HTGR -------------------------------------------- 34
8. Estimated Yearly Environmental Releases of Tritium for
a 1000 Mw HTGR -------------------------------------- - ------ 35
9. Estimated Yearly Releases of Noble-Gas Radionuclides as
Gaseous Effluents from 1000 Mw HTGR ------------------------ 38
10. Calculated Inventories of Tellurium and Iodine Radio-
nuclides in Helium Coolant for 1000 Mw HTGR ---------------- 39
11. Calculated Inventories of Iodine Radionuclides in Reactor
Containment Building Air, 1000 Mw HTGR ------- ..... --------- 40
12. Calculated Annual Releases of Airborne Strontium from
Reactor Containment Building Purge, 1000 Mw HTGR ----------- 4I
13. Gaseous Chemical Releases from HTGR Fuel Reprocessing
Pilot Plant ---------- ..... ----------------- ......
-------
FUEL CYCLE FOR 1000 Mw HIGH-TEMPERATURE GAS-COOLED REACTOR
1. Introduction
This study presents estimates of the environmental effluents from a high-
temperature gas-cooled power reactor (HTGR) fueled with uranium and thorium
and from the associated fuel cycle operations. The study is based upon an
adaptation of current reactor designs, of which the first unit has recently
begun operation and several more are under construction and on order by
U.S. electrical utilities.
A number of thermal-electrical power-generating technologies were examined
in "Fuel Cycles for Electric Power Generation"^ ''. The approach followed
herein is similar. A flowsheet has been developed for a 1000 Mw nuclear
generating plant and its associated fuel-cycle operations. Representative
quantities for material throughput and environmental release are estimated
for the operation of the nuclear plant for one year at 80% load factor*.
Many quantities are the results of original calculations performed for this
study. Others are derived from various references and are scaled to the
current flowsheet. Variations from the quantities indicated herein may be
expected for particular installations.
* Most of the non-radiological quantities are given in metric tons (Mg),
Radiological quantities are given in curies (Ci).
-------
The flowsheet shows waste-heat rejection at the nuclear power plant by
evaporative cooling. Water requirements for the cooling system are scaled
from data developed in "Fuel Cycles for Electric Power Generation".
2. Reactor Characteristics
The high temperature gas cooled reactor (HTGR) is a helium-cooled graphite
pop
structure fueled with a mixture of natural thorium ( TH) and uranium of
high fissile content. Part of the uranium in the reactor fuel consists of
make-up highly enriched uranium (93.5% 235U), obtained by enriching natural
uranium in an isotope separation plant. The discharged fuel is processed
poc
to recover the uranium remaining from the initial make-up U, which is
then recycled for one more pass through the reactor. Also recovered from
poo
recycling is the uranium, largely fissile "°U, formed by neutron-capture
reactions in thorium. The thorium is too radioactive to be recycled. The
fuel cycle considered in this study is the equilibrium fuel cycle, such
that the composition of a given fuel charge consisting of thorium* make-up
"5u, ancj recycled uranium, is the same as previous and subsequent fuel
charges. This equilibrium fuel cycle is reached only after several years
of operation. The fuel life for the equilibrium fuel cycle is four years.
The principal actinides involved in using thorium-uranium fuel are shown
in Figure 1. Neutron absorption in 237Np results in 238Pu; higher-mass
Plutonium isotopes result from neutron absorption in the small amount of
238U (6.5%) present in the highly enriched make-up uranium, as shown in
Figure 2.
-------
Figure 1
Nuclide Chains from Thorium Irradiation
237
237,,
6.75d
236,,
(n,Y)
(n,y)
(n,Y)
(n,Y)
(n,Y)
228,
90
Th
-------
Figure 2
Nuclide Chains from Uranium Irradiation
4.51 x I09y
toTh234
.242
2.37 x I07y
to Th232
7.lxl08y
to Th23'
232
T. H. Pigford
8/73
-------
Each of the three types of uranium in the fresh fuel is formed into micro-
spheres from 540 to 740 microns in size, which are then mixed with 820-
micron microspheres of thorium and embedded in a carbonaceous matrix to
form a fuel "stick"(2). The resulting fuel sticks are sealed into holes
in blocks of high-purity, nuclear-grade graphite, which acts as neutron
moderator and structural support. Heat generated in the fuel sticks is
conducted through the adjacent graphite into helium coolant, which flows
through longitudinal holes penetrating each graphite fuel block.
Each fuel block contains only one of the three types of uranium-thorium
fuel, so that the spatial arrangement throughout the reactor of blocks
containing different types of fissile uranium provides a means of control-
ling the spatial distributions of neutron flux and power density.
The material properties of each of the three fuel types are given in Table
1. The initial make-up (IM) fuel elements, containing the highly enriched
(93.5%) make-up uranium, are formed by 200-micron microspheres of UC2 and
500-micron microspheres of Th02- The uranium microspheres in the IM fuel
are each coated with an inner layer of low-density pyrolytic carbon to
provide voids for fission products and to act as a buffer layer for fission-
product recoil. Surrounding this is a layer of high-density pyrolytic car-
bon, a layer of silicon carbide, and then another layer of high-density
pyrolytic carbon to reduce the diffusional escape of uranium and fission
products from the fuel microspheres. The fuel elements of recycled 235U
and make-up thorium are formed from microspheres similar to those described
above. The recycled 233U is formed into mixed thorium oxide-uranium oxide
-------
Table 1
HTGR Fuel Particle Descriptions
(2)
Elements
233U Recycle Elements 235U Recycle Elements
Property
Isotope
Kernel Composition
Kernel Diameter (ym)
Type Coating (b>c)
Coating Thickness (ym)
Buffer Carbon
Inner Dense Carbon
Silicon Carbide (SiC)
Outer Carbon
Total Particle Diameter (urn)
(a) For initial and make-up
(b) A TRISO coating consists
by successive layers of
Fissile
Particle
235U
UC2
200
. TRISO
85
25
25
35
540
loadings.
of a buffer 1
dense pyrolyti
Fertile
Particle
Th
Th02 (4
500
BISO
85
75
820
Fissile
Particle
233U-Th
.25Th,U)02
400
BISO
90
80
740
Fertile
Particle
Th
Th02
500
BISO
85
.75
820
Fissile
Particle
235U
UC2
200
TRISO
85
25
25
35
540
Fertile
Particle
Th
Th02
500
BISO
85
75
820
ayer surrounding the DC? kernel, followed
c carbon, silicon carbide, and dense pyrolytic carbon.
(c) A BISO coating consists of a buffer layer and a single layer of dense pyrolytic carbon.
-------
microspheres with a thorium-to-uranium ratio of 4.25. The steam generated
by the hot helium coolant from the reactor is at higher temperature and
pressure than the steam generated in water reactors, resulting in an over-
all thermal efficiency of 38.7%. For a net electrical output of 1000 Mw
the resulting thermal power is 2583.9 Mw.
The average thermal specific power in the reactor core is 64.57 Mw per Mg
of uranium and thorium in the fresh fuel. Each year one fourth of the
reactor fuel, contained within 900 graphite fuel blocks, is discharged and
replaced with fresh fuel, so that each fuel element remains within the
reactor for four years^ ' '. At an average load factor of 80% the resulting
average thermal exposure is 94,270 Mw days per Mg of uranium and thorium
charged. Calculated^5' compositions of make-up uranium and recycled uranium
are listed in Table 2. Also listed are the calculated isotopic compositions
of the fresh fuel and discharge fuel for each of the three fuel types.
The quantities of make-up thorium and make-up enriched uranium required for
yearly operation then provide the basis for calculating the required amounts
of natural uranium and thorium that must be mined and processed to sustain
the fuel cycle. Figure 3 is a flowsheet which presents the overall material
and environmental effluents. A more detailed flowsheet of the fuel actinides
is shown in Figure 4.
-------
TABLE 2
Calculated Uranium Composition of HTGR Fuel Particles
235
Fresh Make-up U Particles
Reactor Input Composition
Nuclide %_
U 0.84
234,
235
238,
U
93.5
5.66
100.00
Recycled
235
*°°
Particles
Reactor Input Composition
Nuclide % '
U 3 x 10
0.03
232
234
235L
236,
238,
-6
21.9
55.8
22.3
100.0
Discharge Composition
Nuclide %
U 3 x 10
U 0.03
U 21.7
U 55.7
232
234
235
236
-6
237
238,
U
"0.23
22.3
TOO.O
Discharge Composition
Nuclide %_
U 7 x 10
U 0.07
U 1.96
U 63.7
232
234
235
236,
237
238,
U
-6
0.3
34.0
100.0
-------
TABLE 2 (continued)
Recycled "^U Particles
Reactor Input Composition Discharge Composition
Nuclide
232U
233U
234U
235U
236U
238U
0.03
55.4
23.3
9.5
11.5
0.3
100.0
Nuclide
232U
233U
234u
235u
236u
237u
238u
0.03
52.8
24.5
10.1
12.2
0.05
0.3
100.0
-------
FLOW QUANTITIES ARE STATED IN METRIC TONS/YEAR
UNLESS OTHERWISE INDICATED
80% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Mg = METRIC TONS
Ci = CURIES
kwh = KILOWATT-HOURS
Mw = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
10
-------
Figure 3 (a)
Uranium-Thorium Fueled Gas-Cooled Reactor
Basis: I Year, 8O% Load Factor
IOOO Mw
Gaseous
O.O09 Ci
U
24.7O Ci Z22Rn
Uranium
Mining
1
0.2 % ore
I
V
l.lxlO6 Mg
overburden
0.004 Ci
O.004 Ci
6. 18 Mg
0.01 Mg
0.09 Mg
t
1
I
|
Milling
226Ro
230Th
NOX
SOX
NH3
Gaseous Gaseous
O.OOSCiU 0.001 CiU
3.88MgNOx 5.40 Mg NOX
1 .30 Mg SOX 9.89 Mg SOX
0.04 Mg fluorides 0 30 Mg fluorides
t
1
1
i
t
1
1
i
Enriched Uranium
Conversion Isotope (QS uFfi)
and
U (as U308)
.4 acres
I
7O.9Mg
V
Liquid
0.786 CiU
O.O2I Ci 226RO
1.352
' '
Solid Tailings
InPut 37.2OO Mg
20 acres n
37,300 Mgore u
.009 CiU
.|x|06Mg overburden 24.446 C. "-R
C 230Th
SeP°ration 0.35 Mg 93.5% 235U ^
38 ° U(osUF6) (SePk0I0t'VMa\ (to Conversion and Fabrication)
1 acre 7O.5Mg 0
D7I% 235n
! t
. ./. Electrical
oacfu Energy
OJOCi230Th
' '
5 acres
|
Liquid
O.OOICiU
10.80 MgNoCI
3.50 Mg Co2 +
3.5O Mg SC-4
0.23 Mg Fe
r 1.75 Mg NO5
Stored Solid Depleted Uranium
15.5 Mg osh Stored
0.104 Ci U-Th 70.2 Mg
a
as UF6
0.25%235U
24.383 Ci 230Th
-------
Figure 3(b) Uranium-Thorium Fueled Gas-Cooled Reactor 1000 Mw
Basis: I Year, 80% Load Factor
Gaseous
0.846 Ci 220Rn
-
Thorium
Mining
0.2 % ore
Thorium ore
3883 Mg
1 2 68 MgTh
Th
Mining
and
Concentration
1
t
l.!5x|05Mg
overburden
232Th
{as Th (N03)4)
7.37 Mg
Solid Tailings
3876 Mg containing ,
, -rr\ r; 224. 228 o-
5.94 MgTh
Th02
Microsphere
Preparation
(for fabrication with make-up "°U)^
3.21 MgTh
(for fabrication with recycled U)
I
0.75 % Th Loss
44.5 kg Th
0.004 Ci
1 43 MgTh
1 . (for fabrication with recycled 235U)
Input
0.71 acres
3883 Mg ore
l.l5*IOsMg overburden
3.38 Ci 2I2,2I6PO + 2I2BJ
2l2
Pb
228
Ac
0.085 Ci 228-232Th
-------
Figure 3 (c) Uranium-Thorium Fueled Gas-Cooled Reactor lOOOMw
Basis; I Year, 8O% Load Factor
0.35 Mg 93.5%
Gaseous
2MO-6CiU
O.03 Mg NOx
0.04 Mg CO
4«IO"5Mg fluorides
Delivered Electrical Energy. 6.387«l09Kwh
Electrical
Energy
7,OI*l09kwh
(os UF6)
2.68 Mg Th
(os Th02 microspheres)
Solid
O.OO5 CiUl
0.33 MgCoF2.
Transmission Losses: O.62I » I09 Kwh
Gaseous
83 Ci 3H
4200 Ci Kr, Xe
T Stored Solids
I 46000 Ci 3H (os TiH2)
I |46,500 Ci other
I
r
1
Liquid
2*IO'4CiU
O.08 MgNH3
O.O5 Mg N03
O.OO3 Mg fluorides
Nuclear
Steam-Electric
Generating Plant
1000 Mwe
38.7% Thermal Efficiency]
Plant Area 206 acres
1.811 xlOIOkwh/year
Irradiated Fuel
Make-up Water
12,720 gal/min.
Circulating Water
639,000 gal/min.
Cooling Tower
0.44 Mg U
0.016 Mg Pu
3.2UI09Ci
Slowdown Water. 4769 Mg
4750 Mg dissolved solids
12.30^ (asHTO)
To Shipment
0.46MgU
O.OI6 MgPu
8.2lxlO7Ci
3.21 MgTh
(os ThOz microspheres)
1.43 MgTh
(as Th(N03)4)
Stored Solids I
ll,7OOcu.ft.[
34.38 Ci
Actim'des
Recycle
from reprocessing
Recycle 235U from reprocessing (§)
•-»• Drift: 319 gal/min.
318 Mg dissolved solids
JSL
.^.Humidified Air
1.5 MO7 MgH2O evaporated
l.22*IO'°kwh waste heat
61.4 Ci 3H (as HTO)
LKiuid
0.295 Ci
Actinides
2.68 MgTh
0.349 MgU
(93.5%235U)
19.1 Ci
O.6O MgTh
0.07 MgU
(2I.8%235U)
4.2 Ci
3.97 MgTh
0.33 Mg U
(55.38 %233U)
4495 Ci
0.338 MgU
(55.38 %233U)
4575 Ci
O.O7 MgU
(2I.8%235U)
4.2 Ci
-------
Figure 3 (d) Uranium-Thorium Fueled Gas-Cooled Reactor 1000 Mw
Basis: I Year, 80 % Load Factor
Surface Water
3597gal.HN03
A
From Storage
0.46 MgU
O.OI6 MgPu
8.2lx|07Ci
0.47 MgU
-O.OI6 MgPu
3.6x|07Ci
0.33 MgU (55.38% 233U)
I »• Gaseous
225 Ci *H
4651 Ci 85Kr
0.01 Ci I29-|3II
296 Ci I4C
1.48 Mg NOX
0.97 Mg P205 _
2.29 Mg Hydrocarbons
'"^.eSxlO5 Ci 85Kr
as compressed gas to storage
To
Conversion
and
Fabrication 007 MgU (2|.8%235U)
High Level
Waste
3.6x.|O7Ci,FP.
0.016 MgPu
2.76x|05 CiPu
99cu.ft.FP
268"cu"ft. other solids
78x|Q6Ci FR"^
O.OI5 MgPu
2.2x|05CiPu
367cu.ft.solids
7.8x|06CiFP
O.OI5 MgPu
2.2xl05CiPu
367cu.ft. solids
l.62xl04Ci 'H as hydrate
Ci I3II as powder
to storage
. 6.78 MgTh to storage
1536 Ci
Storage Area
0.4 to 3.0 acres
^.Buried solid wastes 730O cu.ft.-, 0.14acres
2.15 Mg SiC hulls
^ SOile of recycled 235U to LWR
46.2 kg U (1.96% 235U; 63.86% 236U)
-------
FLOW QUANTITIES ARE STATED IN METRIC TONS/YEAR
UNLESS OTHERWISE INDICATED
80% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
AIRBORNE RELEASE
LIQUID EFFLUENT
SOLID EFFLUENT
Mg = METRIC TONS
Ci = CURIES
kwh = KILOWATT-HOURS
Mw = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
15
-------
Figure 4
lOOOMw HTGR FUEL FLOWSHEET
Yearly Quantities
80% Load Factor
Natural Uranium Make-up
Total U
Total U
70,220.5 29.34
0.75% Loss
44.5 kg Th
0.004 Ci
2.68 Mg
Th
(microspheres)
0.75% U Loss
0.005 Ci
7.378 Mg 100% 232Th os Th(N03)4 • 4 H20
HTGR
1000 Mwe
Average Burn-up-94,272Mwd/Mg
Fuel Exposure Time = 4 yr.
.Capacity Factor = 0.80
Thermal Efficiency = 0387
Discharge Fuel
Shipment
3.21 Mg Th
(microspheres)
1.43 Mg Th
I % Scrap Recycle
4.2 kg U
46 kg Th
45.6 Ci
Recycle 233U (§)
Recycle 35U
0.5% Loss
2.1 kg U
23.2 kg Th
22.83 Ci
Total E32Th 100
234U 0.84
23jU.93.5
238U 5.66
Total U iOO
Total
348.98 19.14
232Th
232u
233U
23^
235u
236u
238U
%
100
6 MO"6
I.2«O'5
0.07
21.78
55.82
22.33
603.4
5»IO-6
UIO'5
0.05
17.1
43.8
17.5
Ci
0.06
0.11
9x|0'5
0.33
0.03
2.77
5xlO'3
Total U IOO 78.4 4.11
%
o!232Th IOO
232U 0.03
233U 55.39
234U 23.23
2»U 9.53
236U 11.51
238U 0.31
Total U IOO
kg CI
3975 0.43
O.I 2267
184.3 1747
77.3 478
31.7 0.06
38.3 2.43
1.0 3xlO'4
332.7 4495.3
kg
Th 6734
Pa 18.1
U 445
Np 25.8
Pu 16.1
Am 0.3
Cm 0.2
F.P 792
Ci
3.8lx(08
3.81 x|08
4.44xO7
3.59xl07
I.82xl05ar
l.29xi06/3
300 a
7.05xJ05£
6.l2x(04a
2.36xl09
kg
Th 6734
Pa 0.5
U 462
Np 26.1
Pu 1 6.2
Am 0.4
Cm 0.2
F.P 792
Ci
2141
8.2x(06
4577
84
l.79x|05a
2.80xl050
3. la
2070
4.0x|04a
7.34xl07
kg
Pa O.I
Np 26.1
Pu 161
Am 0.4
Cm 0.2
F.P. 792
Ci
3.6 x(04
84
9 9 x 1 04a,
3. la
304. 8 0
3.64xl07
232U
233(j
234u
235y
236ij
237n
238u
Total U
%
I.2xl0'5
I.I xlO'5
0.12
1.97
63.84
2 x|0'8
34.07
IOO
kg Ci
6x|Q'6 013
5x|Q"6 5xlO'3
0.06 0 35
0.9 2»IO"3
29.5 L87
I.UIO'8 0.91
15.74 5»IO'5
46.2 3.27
%
232U 0.03
233U 55.39
234U 23.23
23»U 9.53
236U 11.51
237U 2XIQ-9
238U 0.31
Total U IOO
kg Ci
O.I 2307
1876 1778
78.7 487
32.3 0.07
39.O 2.47
7XIO"9 0.60
1.0 3xlO'4
338.8 4575
0.75% U Loss
3.14 kg U
34.45 Ci
232,
235 u
Radioactive
Thorium
6780kg
I536CJ
Depleted
Uranium
%
6x|0~6
l.2xKT5
0.07
21.78
55.82
|x|0"8
22.33
5xO'6
.UIO'5
0.05
17.4
44.6
UIO"8
17.83
Ci
0.11
9x|Q'5
0.33
003
2.82
0.86
Total U IOO
79.8
4.16
17
-------
3. Mining, Milling, and Concentration
Environmental effluents from mining uranium ore are calculated from the data
presented in the Part I report, "Fuel Cycles for Electrical Power Genera-
tion"^ ', scaled according to uranium throughput. Solid and liquid effluents
from milling and concentration are also based upon the Part I data, but the
gaseous effluents are derived in part from the data for a plant operating at
a capacity of 2000 ton/day (1814 Mg/day)^6), with the following estimated
gaseous releases:
TABLE 3
Gaseous Effluents from Milling and Concentration of
2000 ton/day of Uranium
uranium 439 Ci/day
226Ra 185 Ci/day
230Th 185 Ci/day
S02 460 Ib/yr
N02 3.5 x 104 Ib/yr
NH3 3.5 x 103 Ib/yr
The effluents on the present flowsheet are then scaled from the data in
Table 3 according to uranium throughput. A 5% loss in uranium milling
and concentration is assumed^ '.
19
-------
Material quantities of thorium ore mined yearly are based upon an assumed^ '
thorium concentration of 0.2%, the same as in uranium ore, although some
domestic ores contain thorium at concentrations as high as 2%v8)_
Thorium is extracted from the ore by a sulfuric-acid process or by a caustic-
treatment process. The thorium concentrate is purified by solvent extraction
from an aqeuous nitrate solution. The radioactive effluents from thorium
pop
milling and concentration are calculated from the quantities of Th decay
pop
daughters, according to the decay scheme in Figure 5. The "^Th half life
of 1.41 x 1010 yr corresponds to a radioactivity level of 0.109 Ci of 232Th
per metric ton (Mg) of thorium. When in secular equilibrium the 228Th con-
tent is also 0.109 Ci per metric ton of total thorium. Similarly, for each
metric ton of thorium processed, 0.109 Ci of gaseous 22^Rn is released and
0.218 Ci of 224Ra and 228Ra appear as radium salts in the solid tailings.
pop
Because of the relatively long half life of Th, the amount of radium
activity per unit mass of heavy metal processed is less than in the proces-
ppo
sing of natural uranium. Because of the 5.75-yr half life of Ra, the
radioactivity in the radium salts from thorium concentration will persist
for only a few decades, whereas the 1622-yr 226Ra from uranium concentration
presents a far more persistent radioactive waste. However, the decay of the
radium daughters from thorium is accompanied by the very energetic and pene-
trating gamr
with 224Ra.
212
trating gammas from Bi and tu°Tl, which remain in secular equilibrium
20
-------
FIGURE 5
Radioactive Decay of Natural Thorium
216,
208 T |
81 3.10m 82
-------
After purification the thorium radioactivity begins to increase due to
the build-up of the decay daughters of Th. Since these have short half
lives the radioactivity reaches a maximum after about 3 years and then
228
declines, due to the decay of 1.91-yr Th. Finally, after about 10
228
years the activity level increases again as Ra and its decay daughters
220
begin to approach equilibrium. The release of gaseous Rn from materials
containing purified thorium is a health hazard, requiring adequate ventila-
tion. Purified uranium does not have this problem because of the long half
life of 230Th.
Some ores may contain both uranium and thorium, and the resulting thorium
230 238
concentrate may contain trace quantities of the Th formed by U decay,
This can contribute appreciably to the activity level of pure thorium. For
example, 100 ppm of Th in Th contributes 1.9 Ci to the alpha activity
232 232
of a metric ton of purified Th, as compared with 0.218 Ci from Th
228 230
and Th. However, the decay daughters of Th do not build up to any
230
appreciable quantities in the purified thorium. The trace Th is most
232
important in affecting the amount of 72-yr U that is formed in irradiated
thorium, as explained in Section 6.
22
-------
4. Conversion of U?QR to UF^ and Uranium Enrichment
The effluents due to chemical conversion of U30g to UF6 are based upon data
in Fuel Cycles - Part I^> for similar operations, scaled to the uranium
throughput. The effluents from uranium isotope separation are scaled accord-
ing to separative work^). For an enrichment of 0.25% for depleted uranium
the yearly separative work is calculated to be 76 Mg, corresponding to a
yearly electrical energy requirement of 1.85 x 108 kwh. This represents
2.3% of the net electrical output of the HT6R power plant*.
5. Conversion and Fabrication of Initial Make-Up Fuel
The highly enriched (93.5%) uranium hexafluoride from isotope separation
is fabricated into 200-micron microspheres by the Sol-Gel Process^ '.
Fabrication wastes are calculated on the basis of a 0.75% fuel loss^2'.
6. Fabrication of Recycle Fuel
After a four-year irradiation cycle the fuel blocks containing the make-up
^U are discharged for reprocessing. The uranium remaining in the initial-
make-up microspheres is recycled for one more irradiation cycle, after which
* These data refer to the equilibrium fuel cycle wherein much of the fissile
.content of fresh fuel results from recycled ^U. The start-up fuel cycles
require greater yearly quantities of make-up "DU and greater amounts of
separative work.
23
-------
it is discharged because of its low 235U content (1.96%) and high 236U
content (63.7%). The thorium in each of the three fuel types generates
233
fissionable U by the neutron-capture reactions shown in Figure 1:
233Th _BT 233pa
22.2m 27. Od
ooo
Neutron-capture reactions in U generate U, U, and U. The dis-
charge isotopic composition is shown in Table 2. The uranium recovered"
from the thorium microspheres and from the microspheres formed from
233
thorium and recycled U is recycled for fabrication. The fabrication of
233
recycled U requires semi-remote fabrication and careful confinement to
232
minimize effluents because of the content of alpha-emitting U and its
232
decay daughters. The U is formed by fast-neutron (n, 2n) reactions in
poo
and "JU according to:
232T, (n. 2n) 231T. (T 231 p (n, yL232p (T 232..
Th - +• Th 25.>5h». Ha >• Ha 1>32cL> U
and 233u (n» 2n)>
235
It is also formed by the chain initiating with U
235,
Although chemical processing yields essentially pure uranium, storage after
separation and time elapsed in shipping to fabrication allow the build-up of
ppo
1.91-y Th, the decay daughter of U, which is in secular equilibrium with
232
its decay daughters as shown in- Figure 5. The total activity level from U
24
-------
and its daughters increases continuously after uranium separation until it
reaches a maximum at about ten years after separation. The energetic gammas
pi p
accompanying the decay of Bi and the 2.6-Mev gamma from 208T1 will
require special shielding in handling and fabricating recycled uranium con-
pop
taining toHl. Shielding is also to attenuate neutrons formed by (a3n)
reactions of the alphas in the 232»233u chains with the light elements, e.g.,
oxygen, present in processing and fabrication operations.
The 232U content in the recycle 233U is calculated(5) to be 318 ppm*,
pop
resulting in a "HI alpha activity of 2307 Ci in the yearly amount of
poo
recycle uranium. The recycle uranium also contains 1778 Ci/yr of U.
The Sol-Gel refabrication operations include sol preparation from the 1103
feed, microsphere preparation, microsphere coating, fuel-stick fabrication,
and assembly into graphite fuel blocks. Uranium losses to process wastes
are estimated at 0.5% of the throughput^''. Reject of finished fuel
results in recycle of 1% of the fuel as scrap for reprocessing^ '. Envi-
ronmental effluents and solid wastes are based upon estimates in the 1974
environmental statement^10' for the HTGR Fuel Refabrication Pilot Plant to
be constructed in Idaho, scaled according to uranium throughput from the
data listed in Table 4.
* Calculated on the basis of 100% 232Th in natural thorium. Some natural
thorium contains trace quantities of 230Th, a decay product of 23«U and
evidently occurring because of co-existing uranium deposits. Neutron-
capture in 23°Th leads eventually to 232U, according to the reactions
illustrated in Figure 1. A typical concentration of 100 ppm of «0rii
in the thorium makeup is calculated to increase the equilibrium "^U
concentrations in the recycled uranium to 876 ppm, resulting in an
increase in the 232U activity to 6355 Ci/yr.
25
-------
Table 4
Effluents and Solid Wastes from HTGR Fuel RefabricationOO)
(Based on 25 Kg of U+Th/day)
GASEOUS EFFLUENTS
Chemical
CO
NOX
co2
H2
Surfactant
Radionuclides
U
212Bi
212,216po
228,224Ra
220Rn
228,232Th
208T]
Annual Release Rate
(Mg/yr)
2.7
0.124
53.0
1.8
0.0033
Annual Release Rate
(Ci/yr)
-3
5,0 x 10
4.0 x 10"7
4.02 x 10'5
4.0 x 10"5
4.0 x 10"5
4.09 x 10
1.5 x 10"7
-6
26
-------
Table 4 (Continued)
LIQUID EFFLUENTS
Radionuclides
212Bi
212,216po
220Rn
224Ra
228,232Th
208T1
Annual Release Rate
(Ci/yr)
2.55
0.02
0.033
0.02
0.02
0.006
0.073
SOLID WASTES
Chemical
Ash
Nad
SiC
NaN03
NaHC03
Volume of a-contaminated solids
Annual Release Rate
(Mg/yr)
0.004
3.3
0.21
5.2
2.6
3 x 103 cu. ft/yr
27
-------
Table 4 (Continued)
Annual Release Rate
Radionu elides (Ci/yr)
U 25.5
?1?
^Bi 0.20
919
^Pb 0.20
212'216Po 0.33
224Ral 0.20
220Rn 0.20
228,232Jh 0>2Q4
208T1 0.073
28
-------
7. Nuclear Power Plant Operation
7.1 Radionuclide Inventories
The inventories of radionuclides calculated^ ' for the 1000 Mw HTGR operat-
ing with an equilibrium fuel cycle are shown in Tables 5 and 6. The inven-
tories are calculated on the assumption that all fuel blocks are at the
discharge composition. Also tabulated are the calculated material and
radioactivity quantities in the fuel discharged yearly, calculated at the
time of discharge, after one year of pre-processing cooling, and after ten
years.
7.2 Tritium
The tritium inventory listed in Table 5 is that calculated from ternary
fission only. Tritium is also formed by fast-neutron reactions with boron
control absorbers, with lithium impurities in the graphite, and by (n,p)
reactions with ^He present at 200 ppb in the helium coolant. The rates
of release of tritium to the coolant, estimated from data supplied by
Goodjohn^ ', are given in Table 7.
29
-------
Table 5
RadionucTides in 1000 Mw HTGR Reactor and in Discharge Fuel*
Radionuclides
Half Life
Reactor
Inventory
106 Curies
In Discharge Fuel
105 Ci./yr.
At Discharge
365 Days Decay
10 Yrs.- Decay
Fission Products
Tritium 3H
Krypton 83m
85m
85
87
88
89
90
TOTAL*
Strontium 89
90
TOTAL*
Iodine 129
131
132
133
134
135
136
TOTAL*
Xenon 131m
133m
133
135m
135
137
138
139
TOTAL*
Cesium 134
137
TOTAL*
Rb, Y, Zr, Hb, Mo,
Tc, Ru, Rh, Pd, Ag,
Cd, In, Sn, Sb
12.26 yr.
1.86 hr.
4.4 hr.
10.76 yr.
76 m.
2.8 hr.
3.18 m.
33 sec..
52.7 d.
27.7 yr.
1.7 x 107 yr.
8.05 d.
2.26 hr.
20.3 hr.
52.2 m.
6.68 hr.
83 sec..
11.8 d.
2.26 d.
5.27 d.
15.6 m.
9.14 hr.
3.9 m.
17.5 m.
43 sec.
2.046yr.
30.0 yr.
0.095
13.088
35.579
2.003
67.369
81.691
88.531
83.040
469.790
93.380
9.318
566.446
3.96 x 10"6
49.515
76.328
100.765
105.100
86.219
35.194
766.500
0.401
2.463
100.605
26.363
13.958
107.123
104.394
89.687
533.050
25.319
9.777
535.619
4057.222
0.023
3.272
8.894
0.500
16.842
20.422
22.132
20.760
117.447
23.345
2.329
141.611
9.914 x 10"7
12.378
19.083
25.191
26.275
21.554
8.798
191.625
0.100
0.615
25.151
6.590
3.489
26.780
26.098
22.421
133.262
6.329
2.444
133.904
1014.305
0.022
0
0
0.469
0
0
0
0
0.469
0.179
2.273
2.453
9.986 x 10"7
2.86 x 10"13
2.96 x 10"33
0
0
0
0
9.986 x 10"7
1.55 xlO-10
-49
2.43 x 10
4.38 x 10"20
0
0
0
0
0
1.55 xlO-1"
4.514
2.389
6.903
6.188
0.013
0
0
0.263
0
0
0
0
0.263
1.73 xlO-20
1.820
1.820
9.986.x 10'7
0
0
0
0
0
0
9.986 x 10"7
0
0
0
0
0
0
0
0
0
0.215
1.940
2.155
1.838
30
-------
Table 5 (continued)
Radionuclides in 1000 Mw HTGR Reactor and in Discharge Fuel
Radionuclides
Half Life
Reactor
Inventory
106 Curies
In Discharge Fuel
106 Ci./yr.
At Discharge
365 Days Decay
10 Yrs. Decay
Fission Products
Rare Earths:
La, Ce, Pr, Nd, Pm,
Sm, Eu, Gd, Tb, Dy,
Ho
TOTAL Fission Products
1570.843
9456
(3.169 Mg)
392.710
18.912
36.454
0.193
8.100
Actinides
Thorium
Protactinium
Uranium
Plutonium
Am, Cm, Bk,
Cf, Es
TOTAL Actinides
1525.295
(26.938 Mg)
1527.542
(0.072 Mg)
177.640
(1.782 Mg)
5.900
(0.064 Mg)
3.065
(0.002 Hg)
3381
(28.962 Mg)
381.323
381.885
44.434
1.477
0.767
846
0.001
0.035
4.560 x 10"3
0.276
0.026
0.354
0.002
2.499 x 10"5
4.374 x 10~3
0.230
0.012
0.262
Light Elements
Be, C, Cr, Hn,
Fe, Co, Hi, Cu
0.113
(257.56 Mg)
0.028
0.003
0.0006
Total Fuel and Block
Fission Products,
Actinides and Light
Elements
12,838
(289.697 Mg)
3210
36.811
_
8.362.
* Total radioactivity includes short-lived species not listed in the table. Calculated for 38.72 thermal efficiency,
average thermal exposure of 94,270 Mw days per Mg of uranium and thorium charged, equilibrium fuel cycle. Tritium
quantities are for ternary fission. Fission-product quantities are not corrected for releases during reactor operation.
31
-------
Table 6
Actinides in 1000 Mw HTGR Reactor and in Discharge Fuel*
Radionuclides
Thorium 227
228
229
230
231
232
233
234
TOTAL
Protactinium 231
232
233
234m
234
TOTAL
Uranium 232
233
234
235
236
237
238
239
TOTAL
Neptunium 236
237
238
239
240m
240
TOTAL
Half Life
18.2 d.
1.91 yr.
7340 yr.
8.0 x 104 yr.
25.52 hr.
1.41 x 1010 yr.
22.12 n, .
24.1 d.
3.25 x 104 yr.
1.31 d.
27.0 d.
1.175 m.
6.75 hr.
72 yr.
1.62 x 105 yr.
2.47 x TO5 yr.
7.1 x 108 yr.
•2.39 x 109 yr.
6.75 d.
4.51 x 109 yr.
23.54 m.
22 h.
2.14 x 106 yr.
2.1 d.
2.346 d.
7.3 m.
63 m.
Reactor Inventory
Kg.
5.42 x 10"8
5.818 x 10~3
1 .298 x 10~2
2.146 x 10~2
1.500 x 10~3
2.693 x 104
4.171 x 10~2
1.019 x 10~2
2.693 x 104
0.549
1.504 x 10"3
71.769
c
4.315 x 10 s
1.114 x 10~2
72.315
0.431
674.983
313.417
201 .396
451.680
1.852
138.458
7.873 x 10"4
1782.508
9.57 x 10"7
102.663
0.449
0.113
3.73 x 10-24
4.96 x 10"6
103.238
Curies
1.714
4778.321
2.773
0.417
7.957 x 105
2.945
1.523 x 109
2.361 x 105
1.524 x 109
26.151
6.419 x 105
1.468 x 109
7
2.964 x 10
2.806 x 107
1.526 x 109
9.242 x 103
6.396 x in3
1.939 x 103
0.431
28.640
1.512 x 108
0.046
2.637 x 107
1.776 x 108
578.391
72.388
1.175 x 108
2.630 x 107
4.0 x 10"13
6.176 x If)4
1.438 x 108
In Discharge Fuel
Kq./Yr.
1.35 x 10"8
1.454 x 10~~3
3.245 x 10"3
5.365 x 10"3
3.752 x 10"4
6734.579
1.042 x 10"2
2.548 x 10"3
6734.579
0.137
3.761 x 10'4
17.942
r
1.078 x 10
3.535 x 10~3
18.078
0.107
168.745
78.354
50.349
112.920
0.463
34.614
1.968 x 10~4
445.627
2.394 x 10"7
25.665
0.112
2.827 x 10"2
9.32 x 10"25
1.241 x 10"6
25.809
Ci./Yr.
0.428
1194.458
0.694
0.104
1.989 x 105
0.794'
3.808 x 108
5.903 x 104
3.810 x 108
6.537
1.604 x 105
3.670 x 108
c
7.412 x 10°
7.017 x 106
3.816 x 108
2310.547
1599.151
484.844
0.107
7.160
3.780 x 107
0.011
6.592 x 106
4 .'441 x 107
144.597
18.097
2.938 x 107
6.576 x 106
1.00 x 10'13
1.544 x 104
3.597 x 107
Shipped to Reprocessing
(365 "ays)
Kq./Yr.
1.95 x 10"8
1.866 x 10~3
4.021 x 10"3
5.582 x 10"3
2..03 x 10"10
6734.597
0
7.08 x 10'8
6734.597
0.137
0
1.754 x 10"3
-12
2.37 x 10 tf-
8.26 x 10"13
0.139
0.107
186.729
78.440
50.349
112.920
2.92 x 10"8
34.614
0
463.120
0
26.125
0
2.837 x 10"7
3.43 x 10"24
0
26.125
Ci./Yr.
0.618
1532.602
0.860
0.108
0.107
0.736
0
7.640
1536.666
6.555
0
3.590 x 104
1.640
0.001
3.591 x 104
2296.220
1769.343
485.414
0.107
7.160
2.378
0,011
0
4560.071
0
18.423
0
65.981
3.68 x 10"13
0
84.413
32
-------
Table 6 (continued)
Actinides in 1000 Mw HTGR Reactor and in Discharge Fuel
Radionuclides
Plutonium 236
238
239
240
241
242
243
244
245
TOTAL
Americiuir, 241
242m
242
243
244
245
TOTAL
Curium 242
243
244
245
246
247
248
249
250
TOTAL
Berkelium 249
250
TOTAL
TOTAL
ACTINIDES
Half Life
2.85 yr.
86.4 yr.
24390 yr-
6580 yr.
13.2 yr.
3.79 x TO5 yr.
4.98 h.
7.6 x 107 yr.
10.1 h.
458 yr.
152 yr.
16.01 h.
7.95 x 103 yr.
10.1 h.
2.07 h.
162.5 d.
32 yr.
17.6 yr.
9.3 x 103 yr.
5.5 x 103 yr.
1.6 x 107 yr.
4.7 x 105 yr.
64 m.
1.7 x 104 yr
314 d.
193.3 m.
Reactor Inventory
Kg.
1.666 x ID'4
41.834
9.195
5.472
4.082
4.028
1.844 x 10"3
2.26 x 10'11
1.01 x 10"16
64.617
8.266 x 10~2
1.278 x 10~3
3.687 x 10~4
1 .370
8.507 x 10~5
1.73 x 10"15
1.454
5.357 x 10~2
9.054 x 10"4
0.832
4.247 x 10"2
1.487 x 10"2
2.715 x 10"4
3.423 x 10~5
4.56 x 10~10
7.38 x 10~13
0.945
4.23 x 10~7
6.29 x 10~10
4.24 x 10"7
2.896 x 104
Ci.
88.605
7.063 x 105
563.973
1.206 x 103
4.148 x 105
15.712
4.776 x 106
4.01 x 10~13
1.22 x 10"7
5.900 x 106
283.255
12.437
2.986 x 105
253.635
2.522 x 106
1.07 x 10"5
2.821 x 106
1.774 x 105
41 .638
6.746 x 104
7.503
4.590
2.397 x 10"5
1.402 x 10~4
5.384
6.07 x 10"11
2.449 x 105
0.707
2.474
3.182
3.380 x 109
In Discharge Fuel
Kg./Yr.
4.165 x 10"G
10.458
2.298
1.368
1.020
1.007
4.610 x 10"4
5.66 x 10'12
2.53 x 10"17
16.154
2.066 x 10"2
3.197 x 10~4
9.218 x 10"5
0.342
2.126 x 10"5
4.34 x 10"16
0.363
1 .339 x 10"2
2.263 x 10"4
0.208
1.061 x 10"2
3.718 x 10"3
6.788 x 10"5
8.557 x 10~6
1.14 x 10"10
1.84 x 10"13
0.236
1.059 x 10"7
1.57 xlO-10
1.060 x 10"7
7240.399
Ci./Yr.
22.151
1.765 x 105
U0.993
301.566
1.037 x 105
3.928
1.194 x 106
1.00 x 10"13
3.05 x 10"8
1.475 x 106
70.813
3.109
7.465 x 104
65.908
6.305 x 105
2.686 x 10"6
7.054 x 105
9.435 x 104
10.409
1.686 x 104
1.875
1.147
5.993 x 10"6
3.506 x 10"5
1.346
1.51 x 10"11
6.123 x 104
0.176
0.618
0.795
8.456 x 108
Shipped to Reprocessing
(365 Days)
Kg./Yr.
3.277 x 10"5
10.498
2.326
1.375
0.973
1.007
2.31 x 10"15
2.08 x 10"11
0
16.183
6.787 x 10~2
3.183 x 10"4
3.822 'x 10"9
0.342
1.61 x 10'26
1.92 x 10"16
0.411
2.853 x 10"3
2.214 x 10"4
0.200
1.061 x 10~2
3.718 x 10"3
6.788 x 10"5
8.562 x 10"6
2.87 x 10~22
1.85 x 10"13
0.217
4.74 x 10"8
3.90 x 10"21
4.74 x 10"8
7235.237
Ci./Yr.
17.429
1.772 x 105
142.735
303.236
9.891 x 104
3.928
5.993 x 10"6
3.69 x 10"13
0
2.767 x 105
232.607
3.094
3.094
65.981
4.80 x 10"16
1.189 x 10"6
304.802
9449.605
10.786
1.623 x 104
1.875
1.147
5.993 x 10"6
3.508 x 10"5
3.39 x 10"12
1.52 x 10'11
2.570 x 104
0.079
1.52 x 10"11
0.130
3.447 x 105
* Total radioactivity includes short-lived species not listed in the table. Calculated for 38.7% thermal efficiency,
average thermal exposure of 94,270 Mw days per Mg of uranium and thorium charged, equilibrium fuel cycle.
33
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Table 7
Estimated Rate of Release of Tritium to Helium Coolant in 1000 Mw HTGR
Ternary Fission
Boron (n,T)
3He (n,p)
Ci/yr
4800
1000
3300
Total 9100
Most of the tritium released to the helium coolant is removed as solid tri-
tide formed by reaction with hot titanium in the helium purification system.
The main environmental release of tritium in the HTGR results from the
diffusion of tritium from the helium stream through the heat exchange sur-
faces in the steam generator and thence into the steam system. Since the
tritium reaches the steam as atomic and molecular hydrogen, and since, in
the absence of catalysis by radiation or by activated surfaces, the rate of
isotopic exchange between gaseous hydrogen and water is slow^"', the tritium
reaching the steam is likely to escape as gaseous hydrogen effluent through
the ejector which continuously removes noncondensables from the turbine
exhaust. However, estimates in reference (4) indicate that much of the
tritium escaping to the steam system appears ultimately as tritiated water
(HTO). For the purpose of the present flowsheet, it is assumed that this
tritiated water follows steam-condensate blowdown and other liquid wastes
from the steam system. It is assumed that these liquids are discharged into
the circulating water in the evaporative cooling system. The tritium is
34
-------
ultimately released to the environment as tritiated water by evaporation in
the cooling tower and by blowdown of circulating water in the evaporative
cooling system. Using data for tritium releases in reference (4) and the
cooling-system evaporation and blowdown calculated for this study, the tri-
tium releases for a 1000 Mw plant have been estimated and are listed in
Table 8*.
Table 8
Estimated Yearly Environmental Releases of Tritium
for a 1000 Mw HTGR
Gaseous Ci/yr
from reactor containment building 3.7 x 10~4
from gaseous rad-waste system 73.6
off gas from main condenser air
ejector 9.19
evaporation in cooling tower 61.4
Liquid
cooling tower blowdown 12.3
* In the more recent environmental impact statement^12) for the 1160-Mw
Fulton HTGR's it is stated that about 90 Ci/yr of tritium leaks to the
steam from the primary system. Most of this tritium is expected to be
released to the atmosphere through the turbine building vent, part via
the air ejector and deaerator and the remainder by the evaporation of
all liquid wastes from the steam system. About 10 Ci/yr of tritium is
expected in the cooling-tower blowdown from each of these plants.
35
-------
7.3 Krypton and Xenon
Fission-product krypton and xenon escape to the coolant by diffusion through
the coated fuel particles and by escape from fuel particles with defective
coatings. The expected failed-fuel fraction is 0.5% or less, whereas the
radionuclide control system is designed on the basis of an assumed failed-
fuel fraction of 5%'4'- These noble gases are removed from the coolant by
charcoal adsorbers in the helium purification system, operating at liquid
nitrogen temperature. These adsorption beds must be regenerated periodi-
cally, typically about five times a year, by passing hot helium through the
beds. This regeneration gas is vented to the waste-gas purification system.
In the Summit plants^' most of the noble gases in this regeneration gas is
finally released through the plant vent and constitutes the major source of
noble-gas effluents in normal operation. In the more recent Fulton
(121
plantsv ' most of the noble gases from regeneration are recycled to the
primary coolant system.
Another source of environmental release of noble-gas radionuclides is the
leakage of helium coolant into the containment, and subsequent release to
the surroundings by containment leakage and purging. The fractional leak
rate of helium from the primary coolant circuit, as quoted by the
designers^4', is 1% per year*, so there should be no appreciable loss of
noble-gas radionuclides by this pathway. Other pathways for noble-gas
* The release estimates in Table 9 are scaled from AEC estimates based
upon a leak rate of 3.65% per year(12,13).
36
-------
released are leakage from the gas-treatment systems and gas vented from fuel
handling., from liquid-waste receivers, and from instrumentation systems.
Estimates of the noble-gas releases expected for a 1000 Mw plant, scaled
from the expected releases quoted for the Summit and Fulton technologies,
are listed in Table 9. The releases would be about ten times greater than
those listed if the failed-fuel fraction is the design value of 5% instead
of the expected value of 0.5% on which these estimates are based.
7.4 Iodine
The HTGR fuel temperatures are high enough that fission product iodine is
released from the fuel particles with essentially the same rate constant as
the noble-gas fission products^' '4,15,16,17)_ yp,e grapnite temperature is
high enough in most of the reactor core that absorption of the iodine in
graphite can be neglected. Tellurium, the iodine precursor, is also vola-
tile at these temperatures, and experimental data'4'18'19) indicate a
release rate constant only slightly lower than that for iodine.
Most of the iodine and tellurium released to the helium coolant are plated
out in the primary system or are recovered in the helium purification system,
The inventories of tellurium and iodine radionuclides in the helium coolant,
calculated from data in the Delmarva Environmental Statement'4', are listed
in Table 10.
37
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Table 9
Estimated Yearly Releases of Noble-Gas Radionuclides as
Radionuclide
83mKr
85mKr
85 Kr
87 Kr
88 Kr
89 Kr
90 Kr
91 Kr
Total
1 33mXe
133 Xe
135mXe
135 Xe
137 Xe
138 Xe
139 Xe
141 Xe
Total
Gaseous Effluents from 1000 Mw HTGRa
Based Upon
Summit Plant Technology^ Fulton
Ci/yr
44
57
3640
93
127
39
15
5
Krypton 4020
1
24
46
46
14
26
5
3
Xenon 165
Based Upon
Plant Technology1
Ci/yr
4
6
0
8
13
3
1
35
—
8
4
6
1
2
0
0
21
a Based upon 0.5% of fuel particles with failed coatings.
Scaled to 1000 Mw from data in reference (13).
c Scaled to 1000 Mw from data in reference (12).
38
-------
Table 10
Calculated Inventories of Tellurium and Iodine Radionuclides in
125mTe
127mTe
127 Te
1 29mTe
129 Te
131mTe
131 Te
132 Te
1 33mTe
133 Te
134 Te
131 !
132 j
133 i
134 i
135 j
136 T
Helium Coolant for 1000 Mw HTGR
Expected3, Ci
4.81 x 10"5
8.20 x 10"4
8.99 x TO"2
1.14 x TO-2
9.77 x ID-1
5.89 x TO-2
2.87
3.31 x 10-1
3.20
2.38
5.14
1.54 x ID-1
2.04
9.06 x 10'1
4.88
1.39
1.48 x 10-1
Design3, Ci
2.93 x 10"2
7.14 x 10"1
8.04 x 10"1
1.00 x lO'1
7.31 x 102
3.85 x 101
1.69 x 103
2.12 x 102
1.98 x 103
1.33 x 103
3.09 x 103
1.04 x 102
1.30 x 103
6.21 x 102
3.36 x 103
1.00 x 103
4.92 x 103
a Expected releases are based upon failed coatings in an average
of 0.5% of the fuel particles. Design releases are based upon
5% failed coatings.
39
-------
The possible leakage of helium coolant is a mechanism by which gaseous
radionuclides can be transported to the containment. The containment air
is continuously treated by a kidney-type air purification system, including
HEPA filters and charcoal absorbers. The estimated inventories of iodine
radionuclides in the containment, scaled from data for a 2000 Mwt plant^4',
are listed in Table 11.
Table 11
Calculated Inventories of Iodine Radionuclides in Reactor
Containment Building Air, 1000 Mw HTGR
!31l 5.46 x 10"9
132I 4.75 x 10'8
133I 3.42 x 10'8
134I 9.92 x 10~8
135I 3.95 x 10'8
Leakage of containment building air to the surroundings is estimated^ ' to
result in off-site concentrations of radioiodine which are less than
MPC x 10"5*. The calculated yearly release of I which would result in
MPC x ID'5 is 0.0045 Ci/yr, based upon an average dilution factor^4) of
6.64 x 10'6 sec/m3-
* The AEC guidelines for as-low-as-practicable releases of radionuclides
for water reactors have specified off-site concentrations of radioiodine
at levels of 104 to 105 below the MPC for unrestricted exposure.
40
-------
7.5 Additional Airborne Releases
The leakage of primary coolant into the reactor containment building and
the periodic purging of the containment building air result in additional
releases of radionuclides, most of which are probably in the form of parti-
culates. The most significant airborne radionuclides other than radioiodine
are the strontium isotopes. The calculated yearly releases of airborne
strontium, scaled to a 1000 Mw plant from data in the Delmarva PSAR^4\ are
given in Table 12.
Table 12
Calculated Annual Releases of Airborne Strontium from
Reactor Containment Building Purge*, 1000 Mw HTGR
Ci/yr
89Sr 2.12 x lO'5
90Sr 1.23 x 10'8
91Sr 2.22 x 10"5
92Sr 4.06 x 10'7
93Sr 1.36 x 10'6
94Sr 1.15 x 10~6
* Based upon a leak rate of helium coolant to the containment
of 1%/yr.
41
-------
If air containing these strontium particles is inhaled, the greatest bone
dose results from 8%r. For a typical annual average atmospheric dilution
factor 6.64 x 10"^ sec/m3' *, these calculated releases of strontium would
result in off-site concentrations about 1000 times lower than the particu-
late concentrations specified in the 10 CFR 50 Appendix I guidelines. The
calculated allowable annual release under these guidelines is 0.014 Ci/yr
for 89Sr.
7.6 Solid Wastes
The principal sources of radioactive solid wastes are the solids which have
been used to remove radionuclides in the helium purification system and in
the radioactive gas-recovery system. From data in the Delmarva PSAFo ' it
is estimated that for a 1000 Mw generating plant 6000 Ci of tritium are
removed per year as solid titanium tritide on 6980 Ib of titanium sponge*.
The sponge will be packaged and shipped for off-site solid burial. Other
radioactive solid wastes consist of replaceable graphite reflector blocks,
discarded in-core instrumentation, charcoal adsorbers, HEPA filters, dis-
carded control absorbers, soda-lime absorbent from the radioactive gas
recovery system, spent radwaste demineralizer resin, spent filter cake,
solidified liquid waste, and miscellaneous dry wastes. Most of this is in
the form of low-level (0,y) waste. Included are 152 graphite reflector
blocks shipped yearly, containing 46,500 Ci**.
* A material balance using data in Tables 7 and 8 leads to an estimated
9000 Ci/yr of tritium removed on titanium sponge.
** These quantities are scaled from data in reference (12). Data in
reference (13) scale to 227 blocks and 69,700 Ci/yr.
42
-------
8. Shipment of Irradiated Fuel
The discharge HTGR fuel is shipped to a reprocessing plant after storage
on the power plant site for 150 days for radioiodine decay. The quantities
of radionuclides in the discharge fuel shipped yearly are shown in Table 5.
Because of the longer fuel life in the reactor and the higher thermal
efficiency, the radioactivity level in HTGR discharge fuel is about 40%
less than in fuel from a water reactor, for the same preprocessing cooling
period^ . The HTGR fuel blocks are shipped in a 100-ton railroad cask
with a typical capacity of 48 fuel blocks per shipping cask. For an assumed
1000-mile shipment and the use of only one shipping cask, the total hold-up
time for preprocessing cooling and shipment is about one year, during which
the irradiated fuel has decayed to 1.15% of its discharge radioactivity^ '.
This period is ample for the decay of 27 -day °Pa to U.
9. Fuel Reprocessing and Conversion
The reprocessing operations are those outlined for an interim phase of a
(2)
model HTGR fuel reprocessing facility^ . The three types of discharge
fuel blocks, as described in Section 2, are reprocessed separately to avoid
mixing the three streams of fissile uranium. The graphite fuel blocks are
crushed and then burned in a fluidized bed to expose the fuel microspheres.
These fuel particles are separated by air elutriation into four fractions
according to particle size: (1) particles formed originally from the make-up
43
-------
93.5% 235U, (2) particles formed from the once-recycled 235U, (e) particles
233
formed from recycled U, and (4) thorium particles. The particle coatings
are then fractured to expose the actinide cores for dissolution in nitric
acid. Uranium, thorium, and fission products are partitioned by aqueous-
(8)
organic extraction in the Thorex process^ ' .
The aqueous stream of purified thorium nitrate is concentrated by evapora-
tion and stored at the site for future calcination. The crushed SiC hulls
from the TRISO triply-coated fuel particles are combined with other solid
wastes for land storage in sealed 55-gal . drums. The uranyl nitrate solu-
tions containing uranium to be recycled is converted to UC^, which is
deposited on the surface of A^Os carrier particles for packaging and ship-
ment to refabrication facilities. The uranium process loss is typically
about 0.25% of the uranium throughput^ ' .
Non-radiological effluents from a proposed HTGR fuel -reprocessing pilot
plant with a capacity of 0.249 Mg of actinides per day are listed in
(2)
Table 13V . Quantities of non-radiological effluents on the flowsheet are
derived from these data, scaled according to fuel throughput.
The only liquids released will be cooling water and water from service
wastes. The only chemical expected in this liquid waste is some undeter-
mined quantity of nitric acid. All organic liquids are burned at the site
or, if they contain appreciable radionuclides, are calcined and stored with
solid wastes^ ' .
44
-------
Table 13
Gaseous Chemical Releases from HTGR Fuel Reprocessing Pilot P1ant
Plant Capacity = 0.249 Mg U + Th per day
Annual Release
cu. ft. (STP)
N2 2.8 x 108
QZ 7.3 x 107
CO 5.7 x 106
C02 6.4 x 107
NOX 1.7 x 105
\\2 and hydrocarbons 9.0 x
Annual Release
Ib.
1.5 x 10"
45
-------
The gaseous fission products Kr, ' I, H and the remaining stable
xenon evolve during the crushing and burning operations of the head-end
process. The proposed HTGR fuel reprocessing pilot plant includes a
system to recover the krypton and xenon noble gases^ . In the KALC pro-
cess these gases are absorbed in cold liquified CCL and then stripped
and stored in cylinders as compressed gas. Krypton effluents are calcu-
lated on the basis of 99% release of krypton in the head-end process and
1% loss of this krypton from the KALC absorption process^ ' .
Radioiodine is trapped in fuming nitric acid and converted to a dry powder
for storage'2^. Environmental releases are calculated on the basis of 1%
of all radioiodine in the fuel at the time of reprocessing^''.
The tritium is evolved as tritiated water vapor, which may be condensed
and sold for the tritium content or converted to a dry hydrate for storage.
Gaseous releases of tritium are calculated on the basis of 1% of all tritium
present in the fuel at the time of reprocessing.
The carbon monoxide and carbon dioxide evolved from combustion of the crushed
fuel blocks will contain 5730-year C, which resulted from neutron absorption
in carbon. It is estimated that 96% of this C in the fuel blocks will be
released to the atmosphere as CO and C02, resulting in a yearly release of
T A
297 Ci. This large C release is unique to HTGR fuel reprocessing.
46
-------
10. High Level. Wastes
The high level wastes from reprocessing HTGR fuel contain all the fission
products, other than tritium, iodine and the noble gases. They also con-
tain all the plutonium present in the fuel and 0.5% of the uranium^2'7).
The fission-product activity at the time of reprocessing is two orders of
magnitude lower in the HTGR wastes than in the high-level wastes from a
water reactor of the same electrical power rating^1). This is due to the
higher thermal efficiency of the HTGR and the longer preprocessing cooling
of its discharge fuel. After several years storage of the separated fis-
sion products the effect of the longer preprocessing cooling disappears.
The total fission product activity is then closer to that from water
reactors. The calculated activity of the fission products in the high
level wastes produced in one year of power generation, as a function of
storage time, is shown in Figure 6.
Because all plutonium in the HTGR fuel appears in the high-level wastes,
the mass of plutonium contained in these wastes is over twelve times greater
*
than in uranium-fueled water-reactor wastes which have been partitioned
ft
' from plutonium. The radioactivity of plutonium in the HTGR wastes at the
time of reprocessing separation in reprocessing is 27 times greater than,
in the high-level wastes from the uranium-fueled water reactor.
* This comparison refers only to a water reactor operating with slightly
enriched uranium fuel and without plutonium recycle. It has been
demonstrated that considerably greater quantities of actinides are
present in the high-level wastes from water-reactor fuel when plutonium
is recycled"' >221.
47
-------
FIGURE 6
Fission Products in High-level Wastes
Produced in One Year by 1000 Mw HTGR
i i
RE "rare earths: La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd.Tb, Dy.Ho
64 Mw/Mg
94272 Mw days/tog
2584 Mw thermal
00% load factor
Based on;
TOTAL
SSION
PRODUCTS
0 I 10 I02 I03 I04
TIME AFTER REPROCESSING, years
48
-------
The actinide content of these high-level wastes is important because, as in
the case of the high-level wastes from water reactors, actinides dominate the
total waste activity after storage periods of a few hundred years. However,
the long-term storage problem is no greater for the HT6R, even though the
plutonium content is considerably greater at the time the wastes are sepa-
rated. As shown in Figure 7, the plutonium activity in the HTGR wastes
238
arises mainly from the Pu, one of the end products of the chain initiated
235
by neutron capture in U. Because of the relatively small quantities of
poo
U in HTGR fuel, relatively little plutonium of mass 239 and higher is
formed, and relatively little americium and curium are formed. However,
because of their longer half lives, it is still the Pu and Pu, present
in the discharge fuel and formed later by the decay of americium and curium,
243
as well as 7950-year Am, which contribute most significantly to the long-
term storage problem of high-level wastes. This is illustrated in Figure 8
which is a plot of the total actinide activity in the high-level wastes as
a function of waste storage time. Because of the relatively low content of
OOQ OAf) 70_~J
""• HUPu and HOAm in HTGR fuel, the long-term actinide activity of the
HTGR wastes is less than for the uranium-fueled water reactor.
The high-level liquid wastes are converted to solids and stored at the repro-
cessing facility in air-cooled, stainless steel bins contained in concrete
vaults^2'. Storage may continue in this manner for up to 10 years, after
which the high-level wastes are to be shipped to a federal repository. The
waste volumes and land use are calculated from data in Fuel Cycles - Part lO
49
-------
FIGURE 7
Plutonium Rodiooctivity in High-level Wostes
Produced in One Yeor by ICOOfViw HTGR
b 4 Mw/Mg
2584 Mw thermo
80% copocity facto
10
0 I 10 I02 I03 I04
TIME AFTER REPROCESSING, years
50
-------
FIGURE 8
Aclinide Radioactivity in High-level Wastes
Produced in One Year by 1000 Mw HTG R
TOTAL Actinides
TOTAL -I
Actinides
(Bi.Po.Pb.Rn.RaH
from ^Th decoy
64 Mw/Mg
2584 Mw thermal
80 % capacity factor
0.5% of U remains
with high-level waste
10"
N-4
0 | 10 10* D I0
TIME AFTER REPROCESSING, years
51
-------
REFERENCES
1. Pigford, T. H., M. J. Keaton, B. J. Mann, and P- M. Cukor and
G. L. Sessler, "Fuel Cycles for Electric Power Generation", Teknekron,
Inc. Report No. EEED 101, Environmental Protection Agency Contract No.
68-01-0561 (rev. March, 1975).
2. National Reactor Testing Station, Idaho, Environmental Statement, HTGR
Fuels Reprocessing Facilities (January, 1974) (WASH-1534). ~~
3. Oak Ridge National Laboratory, National HTGR Fuel Recycle Development
Program Plan (August, 1971) (ORNL-4702).
4. Delmarva Power & Light Co. of Hilmington, Delaware, Preliminary Safety
Analysis Report and Environmental Report for the Summit Power Station,
1974.
5. Ang, K. P., Dcctoral Dissertation in Nuclear Engineering, University of
California, 1975.
6. USAEC, D.O.L., Final Environmental Statement Related to Operation of
the Highland Uranium Mill. Docket #40-8102 .(November, 1973).
7. Oak Ridge National Laboratory, Projections of Radioactive Wastes to be
Generated by the U.S. Nuclear Power Industry (February, 1974) (ORNL-
TM-3965).
8. Benedict, M. , and T. H. Pigford, Nuclear Chemical Engineering, McGraw
Hill, New York (1958).
9. Kosiancic, E. J., R. H. Dodd, C. J. Halva, "Direct Preparation of
233U02 Fuel by the Sol -Gel Process," Thorium Fuel Cycle; USAEC, Div. of
Tech.. Information, 12th Symposium Series, February, 1968.
10. Oak Ridge National Laboratory, Environmental Statement, HTGR Fuel Refa-
brication Pilot Plant (January, 1974) (WASH-1533).
11. Goodjohn, A. J.5 Control of Radionuclide Releases from Gas-Cooled
Reactors, Conference on Environmental Analysis and Environmental Moni-
toring for Nuclear Power Generation, University of California, Berkeley,
1974.
12. USAEC, Draft Environmental Statement by Directorate of Licensing Rele-
vant to Proposed Fulton Generating Station, Units 1 and 2, Philadelphia
Electric Co., Docket 50-463, 50-464, May, 1974.
52
-------
13. USAEC, Final Environmental Statement Related to the Proposed Summit
Power Station Units 1 and 2, Delmarva Power and Light Company, Docket
Nos. 50-450 and 50-451, July, 1974
14. Gulf General Atomic, 40 Mw(e) Prototype High-Temperature Gas-Cooled
Reactor Postconstruction Research and Development Program, Quarterly
Progress Report for the Period Ending January 31, 1968, USAEC Informal
Report GAMD-8500.
15. Turner, R. F., et al, Irradiation Test of the GAIL IIIB Fuel Element
in the General Atomic In-Pile Loop, USAEC Report GA-5314, General
Dynamics Corporation, General Atomic Division, 1964.
16. Winkler, E. 0., et al, Irradiation Test and Post Irradiation Examina-
tion of the GAIL IV Fuel Element in the General Atomic In-Pile Loop,
USAEC Report GA-7997, General Dynamics Corporation, General Atomic
Division, 1967.
17. Vanslager, F. E., G. B. Engle, D. R. Lofing, and C. S. Luby, Final
Report on the GA2-284-6F2 Fuel Irradiation Experiment, General Atomic
Report GAMD-5925, February 16, 1965.
18. Zumwalt, L. R., P. E. Gethard, and E. E. Anderson, "Fission Product
Release from Monogranular UC2 Particles," Nucl. Sci. Eng., 21, 1-12,
1965.
19. Zumwalt, E. E. Anderson, and P- E. Gethard, Fission Product Release from
(Th,U)C? Graphite Fuels, USAEC Report GA-3599, General Dynamics Corpora-
tion, General Atomic Division, 1962.
20. Gulf General Atomic, HTGR Fuel and Fuel Cycle Summary Description.
.(GA-10233).
21. Pigford, T. H., Radioactivity in Plutonium, Americium and Curium in
Nuclear Power Reactors, Report to Ford Foundation Energy Policy Project,
June, 1974.
22. Pigford, T. H., R. T. Cantrell, K. P. Ang, Fuel Cycle for Uranium-
Plutonium Fueled Water Reactor, Environmental Residuals From Fuel
Cycles for Electric Power Generation, Part II, Teknekron, Inc.
Report No. EEED-104, Environmental Protection Agency Contract No.
68-01-0561 (March, 1975).
53
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FUEL CYCLE FOR COMBUSTION TURBINE-STEAM TURBINE COMBINED CYCLE POWER PLANT
Peter M. Cukor
Teknekron Report No. EEED 106
March, 1975
-------
ABSTRACT
This study presents an illustrative data base of material quantities and
environmental effluents in the fuel cycle for a combustion turbine-steam
turbine combined cycle power plant. Data were calculated for a 1000 Mw
power plant fueled with either distillate fuel oil or natural gas. Results
are shown in tables and on a fuel cycle flowsheet.
-------
TABLE OF CONTENTS
1. Introduction 1
2. Fuels Utilized-- 9
2.1 Natural Gas Fuel: Extraction, Transmission and Processing -
Material and Environmental Releases 9
2.2 Distillate Fuel Oil: Extraction, Transportation and Refining -
Material and Environmental Releases 10
3. Power Plant Operation 12
3.1 Air Pollutants 12
3.2 Water Pollutants 12
3.3 Condenser Cooling 14
References 17
-------
LIST OF FIGURES
1. Combined Cycle Generating Unit-
2. Combustion Turbine - Steam Turbine Combined Cycle
Power Plant - 1000 Mw(e)
wii.
-------
LIST OF TABLES
1. Combined Cycle Power Plant 1000 Mw(e) Environmental
Releases Associated with Crude Oil Refining (Te/yr) 11
2. Air Pollutants from Combined Cycle Power Plant -
1000 Mw(e) 13
3. Boiler Slowdown Releases of Liquid Wastes Combined
4w(e) 15
4. Cooling Tower Quantities for Combined Cycle Power Plant -
1000 Mw(e) 16
^x
-------
FUEL CYCLE FOR COMBUSTION TURBINE-STEAM
TURBINE COMBINED CYCLE POWER PLANT
1. Introduction
The rapid growth of peak electrical loads over the last decade has necessi-
tated the installation of increasing numbers of generating units capable
of responding quickly to shifts in power demand. In the majority of cases,
utilities have purchased combustion turbine units to fulfill this require-
ment. In addition to their excellent load following characteristics, com-
bustion turbines can be quickly started in the event that sudden equipment
failures elsewhere in the electric supply system require that emergency
power be provided. Because of the relatively short lead times required for
installation, utilities faced with unexpected delays in the commissioning
of new nuclear and fossil steam units have been forced as a stop-gap measure
to install additional combustion turbine capacity in order to maintain
system reliability. In these cases, the combustion turbines have frequently
been operated as intermediate or base load units rather than as peaking
units. Under such conditions, required maintenance increases rapidly thereby
increasing total generation costs and decreasing system reliability.
While the capital costs for combustion turbines are considerably lower than
those for fossil steam units, the operating costs are considerably higher.
The high operating cost is primarily the result of the low efficiency of
— t
* Combustion turbines, which may burn a variety of gaseous and liquid
fuels, are also frequently referred to as gas turbines.
-------
conversion of thermal energy to electrical energy. While modern fossil
steam units may have efficiencies approaching 38 percent, combustion tur-
bines typically have thermal efficiencies in the vicinity of 24 to 27
percent. This low efficiency results from the high temperature, typically
1000°F, at which the exhaust gases exit from the turbine. While the thermal
efficiency of a combustion turbine does increase as the firing temperature
rises, metallurgical considerations limit the maximum firing temperature of
modern combustion turbines to about 2000°F.
The use of a heat recovery boiler to recover part of the thermal energy
contained in the combustion turbine exhaust gases greatly increases the
efficiency of conversion to electricity of the fuel burned in the turbine.
The heat recovery unit is similar to, but somewhat larger than, a conven-
tional boiler. Some units are equipped with supplemental burners which
add heat to the combustion turbine exhaust. The superheater and evaporator
sections provide superheated steam for the steam turbine generator. An
economizer and low-pressure coil heat the feedwater for the steam system.
Since this type of power plant produces electricity both by expansion of
combustion gases in a gas turbine and by expansion of steam in a steam
turbine, it is called a combined cycle unit. Present generation combined
cycle units have thermal efficiencies of about 40 percent. Figure 1 is
a diagram of a typical combined cycle generating unit.
-------
FIGURE I
COMBINED CYCLE GENERATING UNIT
FUEL
AIR '
COMPRESSOR
BURNER
COMPRESSOR
TURBINE
POWER TURBINE
STEAM
BOILER
TO STACK
L_
ELECTRIC
GENERATOR
ELECTRIC
GENERATOR
-------
The configuration shown in Figure 1 is only one of a number of possible
combined cycles. Other possibilities now being investigated include pres-
surized boiler furnaces combined with gas turbine ..ets. In such a system
the gas turbine provides the energy to compress combustion air for the fur-
nace. A part of the thermal energy released by fuel combustion in the
furnace is converted to steam which is expanded in a steam turbine to pro-
duce electricity. The remaining hot gases are expanded in a gas turbine
where additional electricity is generated. While this type of configura-
tion promises further increases in thermal efficiency, the only commercially
operating combined cycle plants in the United States are of the type des-
cribed earlier. The following discussion refers solely to this type of unit.
Figure 2 is a material and environmental release flowsheet for a hypotheti-
cal 1000 Mw(e) combined cycle power plant. The entries are normalized for
operation at 100% of capacity for one year. The largest combined-cycle
units now operating have a total generating capacity of about 250 Mw(e).
Such a unit consists of three combustion turbines having a total output of
about 170 Mw(e) and a heat recovery boiler and steam turbine having an out-
put of about 80 Mw(e). Hence a 1000 Mw(e) combined cycle power plant would
be composed of four of these 250 Mw(e) units. Based on a heat rate of
8460 Btu pf fuel input per kilowatt hour produced, the average thermal effi-
ciency is 40.3 percent^ '. Refinements in combustion turbine technology
will lead to lower heat rates for combined cycle units. By the late 1970's
it is expected that newly installed combined cycle plants using distillate
oil as fuel will have heat rates of about 8050 Btu per kilowatt hour. This
is equivalent to a thermal efficiency of 42.4 percent^.
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FLOW QUANTITIES ARE STATED IN METRIC TONNES/YEAR
UNLESS OTHERWISE INDICATED
100% CAPACITY FACTOR
EVAPORATIVE COOLING TOWER FOR WASTE HEAT REJECTION
ELECTRICAL ENERGY
*- AIRBORNE RELEASE
C> LIQUID EFFLUENT
SOLID EFFLUENT
Te = METRIC TONNES
Ci = CURIES
kwh = KILOWATT-HOURS
Mw(e) = MEGAWATTS ELECTRICAL
MPC = MAXIMUM PERMISSABLE
CONCENTRATION
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Transported distillate
fuel oil I.26xl07 bbls
Transported natural gos
7.06 x I010 cu. ft.
Transn
nission
• Delivered
Electrical
Energy
7.984 x I09
Electrical
Energy
876 xlO9 kwh
Transmission
Losses _
0.776 xlO9 kwh
Internal Thermal
Losses, 0.87xl09 kwh/yr.
Figure 2.
Combustion Turbine - Steam Turbine
Combined Cycle Power Plant
1000 Mwe
Material and Environmental Release Flowsheet
Combustion Turbme -
Steam Turbine
Combined Cycle
Power Plant
1000 Mwe
40.3% Thermal Efficiency
200-350 acres
21.74 x I09 kwh/yr
Liquid Waste
189 Te suspended solids
25 Te organics
0.9 Te BOO
31 Te H2S04
10 Te Cl?
15.8 Te Phosphates
126 Te Boron
0.9 Te Chromates
Drift
216 gal./min.
216 Te dissolved solids
Circulating Water
433,000 gal./min.
Humidified Air
103 xlO7 Te H20
8.33 xlO9 kwh waste heat
Makeup Water
8,620 gal./min.
Slowdown
3,240 gal/min.
3,220 Te dissolved solids
1 Flue Gas
3 78 xio" kwh waste heat
S02
NOX
Porticulotes
Hydrocarbons
CO
Natural gos
192 Te
19,200 T«
480 Te
1280 Te
Diitilatt fuel oil
680 Te
28,800 Te
2OOO Te
250 Te
880 Te
UNLESS
100 % -fl>'<
TONNES/ TtAt
1 REJECTION
1IRBGBNE HElEASE
LIQUID EFFLUENT
METRC TONNES
CURIES
KILOWATT-HOURS
CONCENTRATION
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2. Fuels Utilized
The combined cycle units can be designed to accept a wide variety of fuels
including clean power gases made from coal or oil, natural gas, methanol
and a range of fuel oils. The fuel oils that can be used range from light
distillates all the way to residual. In the case of the heavy fuels, pre-
treatment is necessary to remove metallic contaminants which may deposit
on the turbine blades. Since combined cycle units now operating are
designed to burn natural gas or distillate fuel oil, these two fuels have
been selected for the present analysis. Based on a thermal efficiency of
40.3 percent and heating values for natural gas and distillate fuel oil of
1050 Btu/ft and 140,000 Btu/gal respectively, the annual fuel requirements
for the model 1000 Mw(e) combined cycle power plant operating at 100 per-
cent capacity factor are 7.06 x 10'^ cubic feet of natural gas or 1.26 x
barrels of distillate fuel oil.
2.1 Natural Gas Fuel: Extraction, Transmission and Processing -
Material and Environmental Releases
The annual material and environmental releases due to extraction, transmis-
sion and processing of the natural gas consumed in the model 1000 Mw(e)
combined cycle power plant are simply the values presented in Chapter 5 of
"Fuel Cycles for Electric Power Generation"^ ' multiplied by the ratio of
the thermal efficiencies of the conventional steam and combined cycle power
plants: 38/40.3 = 0.94.
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2.2 Distillate Fuel Oil: Extraction, Transportation and Refining -
Material and Environmental Releases
The material and environmental releases due to the extraction, transporta-
tion and refining of the petroleum required for the production of the
annual volume of distillate fuel oil consumed in the reference combined
cycle power plant were calculated using the data presented in Chapter 4 of
(3)
"Fuel Cycles for Electric Power Generation"v ' as a basis.
Because of the average yield of distillate fuel oil from domestic refineries
is 21.7 percent, while the average yield for resid is only 6.8 percent, the
required crude oil throughput is much lower than that calculated previous-
ly'^^. The actual volume of crude required is equal to the annual fuel
consumption of the model combined cycle power plant (corrected for trans-
portation losses) divided by the refinery yield of distillate fuel oil.
Assuming that the distillate fuel is shipped to the power plant by pipeline
and that 0.04% of the fuel is lost due to spills, the annual volume of
crude which must be processed is 5.83 x 10 barrels per year or nearly
160,000 barrels per day. This is a typical size for a modern refinery.
Releases of air and water pollutants and solid wastes from the refinery
were calculated using the data in reference (3) as a base point and scaling
the quantities by the factor 160,000/500,000 = 0.32. These quantities are
summarized in Table 1. Releases resulting from crude oil extraction and
transporation are simply the values presented in reference (3) multiplied by
the same scale factor, 0.32.
10
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Table 1
Combined Cycle Power Plant 1000 Mw(e) Environmental
Releases Associated with Crude Oil Refining (Te/yr)
Air Pollutants
Particulates 900
S02 6700
Organics 7400
NOX 5800
CO 1400
Ammonia 700
Water Pollutants
o
4.5 x 10 Te waste water containing:
Phenol 1
Chlorides 770°
Chromium 2
Lead ]
Zinc 2
Copper
Grease 19°
Ammonia Nitrogen 19°
Phosphates
BOD 32°
COD 190°
Suspended Solids 64°
Dissolved Solids 3200°
11
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3.0 Power Plant Operation
3.1 Air Pollutants
Assuming that no fuel is burned in the heat recovery boiler, releases of
air pollutants from the reference combined cycle power plant occur due to
the burning of fuel in the combustion turbine. Further, since all gases
from the combustion turbine stage pass through the heat recovery boiler and
are subsequently discharged through the smokestack, the annual release of
air pollutants is the same as that for a conventional combustion turbine
of equivalent size. Based upon combustion turbine emission factors com-
piled in reference (4), annual releases of air pollutants were calculated.
Additional data for releases of carbon monoxide and organic materials were
obtained from reference (1). The results are shown in Table 2 and in the
flowsheet.
3.2 Water Pollutants
Combustion turbines are air cooled. Hence no liquid wastes are released
because cooling system blowdown is not necessary.
However, blowdown of the heat recovery boiler is a source of liquid wastes.
The blowdown contains chemicals added for control of boiler organic growth
as well as corrosion. The release rates for the various pollutants in
liquid wastes were obtained by scaling on the basis of the steam rates for
the reference combined cycle plant and a conventional 1000 Mw(e) coal-fired
12
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Table 2
Air Pollutants from Combined Cycle Power Plant - 1000 Mw(e)
Emission factor Effluents
Fuel Ib/lp6 ft3 (Natural gas) Te/yr
Natural Gas:
Particulates - 480
NOX 600 19200
SOX 0.6 19.2
Hydrocarbons - 1280
Distillate Fuel Oil:
Particulates 8.4 2000
NOX 120 28800
SOX 1425 680
Hydrocarbons — 250
13
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plant(5). On the basis of a steam rate of 106 Ibs/hr for a 400 Mw(e) com-
bined cycle plant^), the reference plant would have a steam rate of
2.5 x 106 Ibs/hr. This is approximately 38% of the steam rate for a conven-
tional 1000 Mw(e) coal-fired plant. The resulting release rates for pollu-
tant contained in the boiler blowdown for the model combined cycle plant
are presented in Table 3.
3.3 Condenser Cooling
It is assumed that the condenser cooling for the steam cycle phase of the
1000 Mw(e) combined cycle power plant is provided entirely by evaporative
cooling towers. The characteristics of the towers are scaled on the basis
of the circulating water rate (see Chapter 6 of reference(3)) and are
summarized in Table 4.
In the present example, the circulating water rate was calculated on the
basis of data presented for a 472 Mw(e) combined cycle plant having a change
in temperature of 20°F across the condenser and an overall thermal effi-
ciency of 38.6%(7). For this smaller plant the circulating water rate was
stated to be 160,000 gal/min. Scaling to 1000 Mw(e) and correcting for the
differences in condenser temperature rise and thermal efficiencies yields a
circulating water rate of 433,000 gal/min for the present example. The
flowsheet entries (also shown in Table 4) were calculated on the basis of
* A 15°F temperature rise across the condenser has been assumed.
14
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data for cooling tower releases presented in reference (3) adjusted by the
ratio of the circulating water rates for the 1000 Mw(e) combined cycle and
1000 Mw(e) coal-fired power plants.
Table 3
Boiler Slowdown Releases of Liquid Wastes
Combined Cycle Power Plant - 1000 Mw(e)
Componejit
Suspended solids
Non-degradable organics
BOD
Acids
Alkalinity
Chlorine
Phosphates
Boron
Chromates
Releases(8)
Ib/day
380
152
6
190
24
61
95
760
5.7
Releases
Te/yr
189
25
0.9
31
3.9
10
15.8
126
0.9
15
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Table 4
Cooling Tower Quantities for Combined Cycle Power Plant - 1000 Mw(e)
Thermal load
Circulating coolant
Slowdown discharge rate
Dissolved solids released in blowdown
Make-up water rate
Drift rate
Dissolved solids released in drift
Evaporated water
8.35 x 10y kwh/yr
433,000 gal/min
3240 gal/min
3220 Te/yr
8620 gal/min
216 gal/min
216 Te/yr
1.03 x 1O7 Te/yr
16
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REFERENCES
1. Private communication; Warren Davis, General Electric Company;
San Francisco; June, 1974.
2. Private communication; John Gerrity; Gas Turbine Products Division;
General Electric Company; Schenectady, New York; December, 1974.
3. Pigford, T. H., M. J. Keaton, B. J. Mann, and P. M. Cukor and
G. L. Sessler, "Fuel Cycles for Electric Power Generation", Teknekron
Report No. EEED 101, EPA Contract No. 68-01-0561, rev. March, 1975.
4. Compilation of Air Pollutant Emission Factors; United States Environ-
mental Protection Agency; 2nd Edition, April, 1973.
5. "Steam Generation - a Power Special Report;" McGraw Hill; June, 1964.
6. Private communication; Gary Squires; General Electric Company;
San Francisco; August, 1974.
7- "Draft Environmental Impact Report - Coolwater Combined Cycle Units 3
and 4;" Southern California Edison Company; submitted to California
Public Utilities Commission; June 8, 1973.
8. Aynsley, E. and M. R. Jackson; "Industrial Waste Studies: Steam Gene-
rating Plants;" United States Environmental Protection Agency, Water
Quality Office; 1971.
17
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/9-78-013
3. RECIPIENT'S ACCESSI Of* NO.
4. TITLE AND SUBTITLE
Comprehensive Standards: The Power Generation Case
5. REPORT DATE
June 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
K.P. Ang* Peter M. Cukor
Robert T. Cantrell* Michael
8. PERFORMING ORGANIZATION REPORT NO.
Thomas H. Pigford*
J. Keaton, Bruce J. Mann**
PERFORMING ORGANIZATION NAME AND ADDRESS
nergy and Environmental Engineering Division
eknekron, Inc.
118 Milvia St.
erkeley, Ca. 94704
10. PROGRAM ELEMENT NO.
1HA091
11. CONTRACT/GRANT NO.
68-01-0561
2. SPONSORING AGENCY NAME AND ADDRESS
Office of Research and Development
U.S. Environmental Protection Agency
401 M St. SW
Washington, DC 20460
13. TYPE OF REPORT AND PERIOD COVERED
Criteria nocunient
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
= Dep't of Nuclear Engineering, University of California, Berkeley, Ca.
** = Office of Radiation Programs, U.S. EPA, Las Vegas, Nevada
16. ABSTRACT
This study presents an illustrative data base of material quantities and
environmental effluents in the fuel cycles for alternative technologies of
thermally generated power. The entire fuel cycle for each of the alternative
ten technologies is outlined for a representative power plant generating
1000 Mw of electrical power. The required utilization of material resources
and the fuel-cycle material quantities are indicated on a flow sheet for each
technology. The technologies considered are: 1) Light Water Nuclear Reactor;
2) Coal: Appalachian Bituminous and Northwestern Sub-bituminous; 3) Residual
fuel oil; 4)Natural Gas; 5) High Sulfur Coal, with Coal Gasification and Sulfur
Removal; 6) High Sulfur Coal, with S0? recovery by Wet-Limestone Scrubbing;
I) Geothermal Steam; 8) Breeder Fission Reactor; 9) Solar Energy; and
10) Thermonuclear Fusion.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Coal Gasification
Geothermal Power Generation
Nuclear Power Generation
Solar Power Generation
Thermonuclear Power Generation
Electric Power Generation
Alternative Energy
Technologies,
Futre Energy
Technologies,
"Hard Path" Energy
Technologies
3. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
AU.S. GOVERNMENT PRINTING OFFICE: 1978 O— 720-335/6l37 REGION 3-1
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