United States
Environmental Protection
Agency
Office of Radiation Programs
Eastern Environmental
Radiation Facility
P 0 Box 3009
Montgomery AL 36109
EPA-520/5-80-004
March 1981
Radiation
&EPA
Health impact Assessment of
Carbon-14 Emissions from
Normal Operations of
Uranium Fuel Cycle Facilities
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EPA 520/5-80-004
HEALTH IMPACT ASSESSMENT OF CARBON-14
EMISSIONS FROM
NORMAL OPERATIONS OF URANIUM FUEL CYCLE FACILITIES
Ted W. Fowler*
Christopher B. Nelson
June 1979
* U. S. Environmental Protection Agency
Office of Radiation Programs
Eastern Environmental Radiation Facility
P. 0. Box 3009
Montgomery, Alabama 36193
i"U. S. Environmental Protection Agency
Office of Radiation Programs (ANR-460)
Criteria and Standards Division
401 M Street, SW
Washington, DC 20460
Publication Date: March 1981
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TABLE OF CONTENTS
List of Figures
List of Tables
Preface
Acknowledgments
Abstract
Introduction
Carbon-14 Source Terms
Theoretical LWR Production Rates
C-14 Source Terms for LWR Facilities
Comparison of Theoretical and Measured C-14
Emission Rates
Other Sources of C-14 Releases to the Atmosphere
LWR Nuclear Power Growth Estimates
Comparison of Cumulative
to the Atmosphere
Carbon-14 Dose Equivalent and
Environmental Transport
The Killough Model
Fossil Fuel Scenario
World Population Scenario
Internal Dosimetry
Environmental Dose Commitment
Releases of C-14
Environmental Dose Commitment
Dose Equivalent and
Health Impact Assessment
Nuclear Power Industry
Summary
Dose Equivalent Rate
of C-14 Discharges from the LWR
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Table of Contents (Cont1d.)
References
Appendi x 1.
Appendi x 2.
Appendi x 3.
Appendix 4.
Paqe
--"'--
46
US LWR Nucl ear Indus try Carbon-14 Rel eases
1976-2000
World LWR Nuclear Industry Carbon-14 Releases
1976-2000
53
54
55
56
Cosmic Carbon-14 Produced During 1976-2000
Weapons Testing Carbon-14 Releases 1945-1974
i i i
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LIST OF FIGURES
Figure
1
Comparison of Cumulative Releases of Carbon-14
to the Atmosphere
Comparison of Production Rates of Carbon-14
from the LWR Nuclear Power Industry
Annual Atmospheric Injection Rate of Fossil Fuel
12CO
2
2
3
4
5
World Population Projection
Buildup of the Total Body Environmental Dose Commitment
to the World Population for a Release of 1 Ci of C-14
to the Atmosphere in 1985
Buildup of the Total Body Environmental Dose Commitment
to the World Population for a Release of 1 Ci of C-14
to the Atmosphere in 1985
Average Individual Total Body Dose Equivalent Due to
Carbon-14 Releases for the Years 1976-2000 from the
U. S. LWR Nuclear Power Industry
6
7
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13
16
18
22
23
29
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LIST OF TABLES
Table
1
2
3
4
Carbon-14 Production Rates in LWR Facilities (Da77)
Nuclear Weapons Testing C-14 Source Terms (Ki78)
Installed Nuclear Capacity Projections
Carbon-14 Specific Activity Dose Equivalent Rate
Conversion Factors
Carbon-14 lOa-Year Environmental Dose Commitment Factors
Release Rate of Carbon-14 from the U.S. LWR Nuclear
Power Industry - Low Case
Average Worldwide Individual Total Body 70-Year
Lifetime Dose Equivalent Due to Carbon-14 Releases
World Population Total Body Environmental Dose
Commitment Due to Carbon-14 Releases
World Population Total Body Environmental Dose
Commitment per Century after 1976 Due to U. S. LWR
Nuclear Industry Carbon-14 Releases 1976-2000
Maximum Individual Carbon-14 Total Body Dose
Equivalent Rates for LWR Facilities
Assumptions Used for the Calculation of the
Maximum Individual Carbon-14 Total Body Dose
Equivalent Rates for LWR Facilities
Total Body Dose Equivalent Rates for Airborne
Emissions from BWR and PWR Facilities
Carbon-14 Health Effect Risk Coefficients
Average Worldwide Individual Lifetime Risk of Fatal
Cancer and Health Effects Committed to the World
Population from Carbon-14 Sources
Local Individual Lifetime Risks of Fatal Cancer and
Health Effects Committed to the Regional and World
Populations Due to Carbon-14 Emissions from Model
BWR and PWR Facilities
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PREFACE
The Eastern Environmental Radiation Facility (EERF) helps solve prob-
lems defined by the Office of Radiation Programs. The Facility provides
analytical capability for evaluating and assessing radiation sources through
environmental studies and surveillance and analysis. The EERF provides
special analytical support for Environmental Protection Agency Regional
Offices and other federal government agencies as requested as well as
technical assistance to the radiological health programs of state and local
health departments.
Currently, the Environmental Protection Agency is evaluating the need
for a national environmental standard for carbon-14 emissions from normal
operations of uranium fuel cycle facilities. The study reported on here was
performed to provide information on the health impact of carbon-14 and the
methodology being used to estimate it. Readers of this report are encouraged
to comment freely. Comments may be directed to the EERF directly or to the
Office of Radiation Programs in Washington, DC.
D~re~ ::r~~
Eastern Environmental Radiation Facility
vi
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ACKNOWLEDGMENTS
The authors gratefully acknowledge Neal S. Nelson's contribution to
the development of the carbon-14 internal dosimetry factors and health im-
pact risk coefficients. The assistance of George G. Killough in the use
of his diffusion model of the global carbon cycle is also much appreciated.
Comments provided by James M. Gruhlke and John L. Russell were very useful
in the final editing of the report. Finally, we thank Annette B. Fannin for
typing many drafts and Chuck Petko for his editorial assistance in the
preparation of the manuscript.
vii
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ABSTRACT
A 1976 study by the U. S. EnvirranmentalPratectiO,r:lA,g,encyes,t;,ma,ted the
public health impact af C-14 discharges fram thelight-water-caoled r~actor
(LWR) nuclear pawer industry. ,The studyrep,arted an here evaluates the
enviranmental impact af C-14 discharges from LWR's and LWR fuel repracessing
facilities and updates the 1976 EPA estimates. The results af this study
will be used to. help deliberate the need far a natianal enviro.nmental
standard far carban-14 emissians fram narmal operatians afuranium fuel cycle
facilities.
Far a given release af C-14 to. the atmasphere, 5 percent af the environ-
mental do.se cammitment is delivered in the first 100 years after release, 50
percent in 5,000 years, and the balance tens to. thausands af years after
release. The additianal fatal cancer risk to. any single individual due to.
C-14 emissians fram LWR facil ities is estimated to. be small. The fatal
cancers and genetic effects cammitted to. the warld papulatian due to. C-14
emissians fram LWR facilities is also. small campa red to. the fatal cancers and
genetic effects fram enviranmental C-14 saurces such as casmic C-14 ar C-14
rel eased during nucl ear weapans testing. The primary cancern aver uncan-
tralled discharges af C-14 from LWR facilities is the cumulative fatal cancers
and genetic effects cammitted to. the warld papulatian aver lang periads af
time.
Carbon-14 risk coefficients indicating fatal cancers cammitted to. the
world papulatian per curie af C-14 released to. the atmasphere are estimated
to. be 4.1E-3 fatal cancerslCi for 100 years after release and 7.8E-2 fatal
cancerslCi for infinite time. We assume that all C-14 pro.duced by U. S. LWR
facil iti es from 1976 to. the year 2000 wi 11 be rel eased to. the atmosphe're.
From that release, we estimate that there will be 390 patential serious
health effects committed to. the warld papulatian during the next 100 years
and 7500 over the next 40,000 years.
viii
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In addition to considering these findings on health impact, we recommenJ
further study before deliberating the need for a national C-14 standard. Car-
bon-14 control technology. costs for LWR facilities, and the significance of
summing very small doses to large numbers of people over long time periods tv
cumulate health effects should be addressed in additional studies.
ix
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INTRODUCTION
Carbon-14 discharges to the atmosphere are not likely to be a problem in
the immediate future, but they can be in the more distant future. Carbon-14
has a long physical half-life, 5730 years. As such, C-14 released to the
a tmosphere becomes a permanent contami na nt to the worl dwi de envi ronment.
Though, at present, there are only small environmental burdens of C-14 from
nuclear power operations and only small estimated dose equivalents committed
to any single individual, there is a clear concern about the cumulative risk
from C-14 over long periods of time.
This report presents estimates of health impacts from uncontrolled dis-
cha rges of C-14 from 1 i ght-wa ter-reactor (LWR) fac il iti es and compa res the
health impacts from those C-14 discharges with discharges from other sources.
To derive the individual lifetime and population dose commitments from dis-
charges of C-14 to the atmosphere, we used a diffusion-type model of the
global carbon cycle developed by G. G. Killough (Ki77a).
A previous EPA study (F076) also estimated health impacts from C-14
discharged to the atmosphere by the LWR industry. The study reported on here
is different from the 1976 study in two main ways. First, whereas the 1976
study did not calculate the C-14 environmental dose commitment beyond 100
years after its release to the atmosphere, this study calculates the
environmental dose commitment over the 1 ife of C-14 in the environment.
Secondly, this study estimates C-14 heal th risk coefficients for somatic
effects considering only the dose to the lean body mass, since the dose to
adipose tissue is not effective in producing cancer. The 1976 study
considered the dose to both the lean body mass and adipose tissue.
CARBON-14 SOURCE TERMS
Theoretical LWR Production Rates
Carbon-14 is produced in LWR's by the activation of the fuel, cladding,
core structural material s, and coolant. Most carbon-14 in the fuel is pro-
duced by the (n,p) reaction with nitrogen-14 that is present as a fuel im-
-------
purity; whereas, most carbon-14 in the coolant is produced by the (n, alpha)
reaction with oxygen-17, which is only present in its natural abundance of
0.037%. Table 1 presents carbon-14 production rates calculated for LWR
facilities by Davis (Da77a) using the ORIGEN code (Be73). Carbon-14 produced
in the coolant and fuel is potentially available for release at the reactor
and fuel reprocessing facility, respectively. We assume that carbon-14
produced in the cladding and core structural materials is unavailable for
release to the air or water but contributes to the amount of carbon-14
disposed in radioactive waste.
C-14 Source Terms for LWR Facilities
The C-14 source terms for LWR facilities that we used in this evaluation
are as foll ows:
LWR fuel cycle - 25 Ci/GWe-yr
LWR fuel reprocessing facility
PWR-5 Ci/yr (5 Ci/GWe-yr)
BWR-10 Ci/yr (10 Ci/GWe-yr)
- 830 Ci/yr (18.4 Ci/GWe-yr)
Our LWR values are based on an analysis of measured values (Fo76) rather than
theoretical estimates. The LWR values are supported by measured values re-
ported by Riedel and Gesewsky (Ri77) and are similar to values used by the U.
S. Nuclear Regulatory Commission (USNRC) in their regulatory guides
NUREG-0016 (USNRC76a) and NUREG-0017 (USNRC76b). The NRC estimates
(USNRC76a, USNRC76b) that the annual quantity of carbon-14 released from a
reference boil ing water reactor and pressurized water reactor is 9.5 Ci/yr
and 8 Ci/yr, respectively. Their estimates are based on a simple activation
calculation; however, the values are in reasonable agreement with the values
selected for this analysis and with measurements to date of C-14 emissions at
operating LWRls.
The C-14 source term for an LWR fuel reprocessing facil ity was
calculated using Davis's (Dan) fuel production rates (see Table 1). To
calculate average fuel production (18.4 Ci/GWe-yr), we assumed that the PWR
accounts for approximately twice the produced power of the BWR. The
reference LWR fuel reprocessing facil ity (Fo76) has a throughput capacity of
1500 metric tons heavy metal (MTHM) per year and an annual capacity to
2
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Table 1.
Carbon-14 production rates in LWR facilities (Da77)
Reactor
type
Region of carbon-14 formation
Carbon-14 production rate
Ci/(GWe-yr)
Boil i ng
Water
Reactor
Cladding and core structural
materials *
Fuel
Coolant
43.3-60.4
17.6
4.7
Pressurized
Water
Reactor
Cladding and core structural
materials *
Fuel
Coolant
30.5-41. 6
18.8
5.0
*According to Davis (Da77), the calculated values for C-14 in the hard-
ware are conservatively high, since they are based on the assumption that all
core hardware - not just the cladding - is in an intense a flux field as is
the cladding.
tThese are median production rates based on a median nitrogen impurity
of 25 ppm in the fuel. Lower or higher values depend on whether or not pro-
cess precautions are taken to minimize nitrogen inclusion during fabrication.
3
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process fuel which produced a nominal electric power output of 45 GWe-yr for
a burnup of 33,000 MWt-days/MTHM at 33% thermal efficiency. Therefore, 830
curies of C-14 can be released annually from the LWR fuel reprocessing
facility. For this evaluation, we assume that the C-14 released from the
fuel reprocessing facil ity and the BWR is in the chemical form of carbon
dioxide and in the non-C02 form (hydrocarbons) at the PWR (Fo?6, Br??). The
assumed chemical species of C-14 emissions at LWR's have been confirmed by a
few measurements, but confirmation at the LWR fuel reprocessing facility
awaits necessary laboratory data and/or actual field measurements.
Comparison of Theoretical and Measured C-14 Emission Rates
The carbon-14 production rates in Table 1 are based on theoretical
calculations, and they are uncertain values. A few measurements of C-14
emission rates at LWR's have been compared to theoretical estimated emissions
(Da77b, Fo?6, Ri?6). There is reasonable agreement between theoretical and
measured C-14 gaseous emission rates at pressurized water reactors (PWR's);
however, for boiling water reactors (BWR's), theoretical production rates are
often lower than measured values by a factor of at least two. The
theoretical values in Table 1 for the BWR appear low even without correcting
for the large number of steam voids in the BWR reactor core coolant. By not
correcting for the void fraction, the BWR core water mass is overestimated
and the carbon-14 production by neutron (n, alpha) reaction with oxygen-I?
will be overestimated.
The contribution by the neutron reaction with nitrogen-14 to measured C-
14 emissions is unknown, since the nitrogen content of the coolant water at
the time of the measurements was not reported. Measurements of the sources
of C-14 production such as the nitrogen level in the coolant of LWR's are
Iherefore needed. Another possible contribution to the higher measured BWR
C-14 emission rates could be C-14 leaking from fuel tubes into the coolant
water, since this source was not considered in the theoretically calculated
C-14 gaseous emission rate.
Because of the uncertainties, we suggest that the following information
be collected from several representative PWR's and especially BWR's:
1. measurements for each di scharge stream of C-14 emissions (quantity
di scharged to the environment) concentration of C-14 and chemical
form (carbon monoxide, carbon dioxide, hydrocarbons, etc.)
4
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2.
measurement where practicable of in-plant C-14 concentrations
that input to the facility release of C-14 to the environment
measurements of contributing sources (e.g., nitrogen levels in
the coolant, etc.) to the production of C-14 at the time of the
C-14 emission measurements so that measured emissions can be
compared to theoretical estimated emissions
collection of additional facility information pertinent to a
theoretical calculation of the C-14 emission rate (e.g., mass
of water in the BWR core accounting for any necessary correction
for void fractions, effective neutron flux, etc.)
measurements of C-14 in ambient air surrounding the facility
3.
4.
5.
In addition to measurements at LWR's, measurements of nitrogen in U02 fuel
and C-14 liberated during fuel dissolution are needed to validate the C-14
LWR reprocessing plant source.
Davis (Da77a) has presented information supplied by five LWR-fuel
manufacturers of nitride nitrogen and gaseous nitrogen in their fuel sand
fuel-rod void spaces. Based on Davis's (Dana) analysis, it appears that
production of C-14 in the fuel could be controlled by limiting the amount of
nitrogen impurity during fuel fabrication. As for actual measurements of C-14
in spent LWR fuel, Davis (Dana) refers to an experimental program (Ca76)
that may confirm the theoretically calculated source terms.
Other Sources of C-14 Releases to the Atmosphere
There are other fuel cycl e sources of C-14 rel eases to the atmosphere
(e.g., thorium fuel cycle [high temperature gas-cooled reprocessing plant])
besides the LWR nuclear power industry, but we did not evaluate these. We
estimate that the major nuclear industry releases of C-14 to the atmosphere
to the year 2000 will be from the LWR fuel cycle. However, Killough (Ki78)
evaluated the worldwide impact of C-14 from the world nuclear power industry
and noted that the water cooled graphite-moderated reactor (GMR), which is
being constructed in the Soviet Union, has a potential for releasing signi-
ficant amounts of C-14 to the environment (800 :t 300 Ci/GWe-year, Dana),
even though its contribution to the wor1d's total nuclear energy production
is expected to be small. We hope that improvements will be made in the GMR
design and control technology to minimize C-14 releases to the environment
5
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once the prOduction sources of C-14 are identified and an international
awareness for the potential environmental impact of C-14 releases is
ach i eved.
We did evaluate the potential health effects from cosmic C-14 and
nuclear weapons testing C-14 to provide a perspective on C-14 discharges from
the U. S. LWR nuclear power industry. Cosmic C-14 is produced at a rate of
approximately 4x104 Ci/yr (Li76, Dana), which sustains an environmental
steady state inventory of about 3x108 Ci (Kina). Nuclear weapons testing
can al so produce C-14 by reactions of neutrons produced at the time of the
explosion with nitrogen in the atmosphere. An aboveground burst will produce
about twice as much C-14 as a surface burst since surface bursts "lose" about
one-half of their neutrons to the ground (Du64). Table 2 presents nuclear
testing C-14 source terms that we adopted from Killough (Ki78). To calculate
the C-14 nuclear weapons testing source terms, Killough assumes that a 1-MT
burst above the ground releases 2.07x104 Ci of C-14 to the atmosphere and
that all atmospheric detonations are air bursts. The assumption, which
Killough made and we adopted, that all detonations are aboveground was made
to help offset the possible underestimation that results from unreported
yields and unannounced events.
LWR Nuclear Power Growth Estimates
In this study, we used 1976 U.S. Energy Research and Development
Administration (ERDA) (Han76) projections for the growth of nuclear power in
the U. S. and the world (see Table 3). We calculated installed nuclear
capacity for the 25-year period 1976 to 2000 using ERDA projections for the
years 1975, 1980, 1990, and 2000 and estimated capacities for intermediate
years by linear interpolation. We assumed that the nuclear capacity consists
entirely of LWR's and that the PWR will account for approximately twice the
installed capacity projected for the BWR. Foreign nuclear capacities include
all countries except the U. S. and Eastern Bloc countries. World capacities
are sums of U. S. and foreign nuclear capacities and, therefore, do not
include Eastern Bloc countries.
Recent estimates (OECD77a,
OECD77b, Ha79, Li79) that consider the
6
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Table 2. Nuclear weapons testing C-14 source terms (Ki78)
Year 14C Released (Ci) Year 14C Released (Ci)
1945 1. 2x103 1960 3
2.1x10
1946 4.1x102 1961 6
1. 5x 1 0
1947 * 1962 6
2.2x10
1948 2.2x103 1963 *
1949 * 1964 2
4.1x10
1950 * 1965 2
4.1x10
1951 3.3x103 1966 4
1. 4x10
1952 2.4x105 1967 4
6.4x10
1953 4.7x104 1968 5
1.2x10
1954 3.1x105 1969 4
6.2x10
1955 2.4x104 1970 5
1.1x10
1956 3.3x105 1971 4
1.6x10
1957 2.0x105 1972 3
2.7x10
1958 5 1973 5.2x104
6.6x10
1959 * 1974 1. 2x104
Total (1945-1974) = 5.8x106Ci
*Killough (Ki78) did not present an estimated C-14 yield from nuclear
weapons tests in the atmosphere for these years.
7
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Table 3. Installed Nuclear Capacity Projections
(GWe)
United States Foreign Worl d**
Year Low Case High Case Low Case* High Caset Low Case High Case
1976 43 46 43 46 86 92
1977 47 52 57 62 104 114
1978 52 58 72 79 124 137
1979 56 65 86 95 142 160
1980 60 71 100 112 160 183
1981 73 90 126 155 199 245
1982 87 109 152 197 239 306
1983 100 128 178 240 278 368
1984 114 147 204 282 318 427
1985 127 166 230 325 357 491
1986 141 191 269 384 410 575
1987 154 216 308 443 462 659
1988 168 240 347 501 515 741
1989 181 265 386 560 567 825
1990 195 290 425 619 620 909
1991 214 323 486 705 700 1028
1992 232 356 546 791 778 1147
1993 251 389 606 877 857 1266
1994 269 422 667 963 936 1385
1995 288 455 728 1050 1016 1505
1996 306 488 788 1136 1094 1624
1997 324 521 848 1222 1172 1743
1998 343 554 909 1308 1252 1862
1999 362 587 969 1394 1331 1981
2000 380 620 1030 1480 1410 2100
tOECD/IEA Modified by USA evaluation
OECD/IAEA
**These projections are for the free world since Eastern Bloc countries
were not included
8
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announced delays in constructing planned nuclear facilities present even
lower nuclear power growth estimates than the low cases presented in Table 3.
Therefore, we expect that the nuclear growth scenarios in Table 3 will not be
exceeded and that actual growth rates will be lower than the estimated low
case. The low case is used to represent a conservative estimate of the LWR
nuclear power capacity to the year 2000. Where appropriate, the results of
analyses using more recent nuclear growth scenarios are discussed in the
text.
In order to estimate the total impact of C-14 from U. S. LWR's, we used
the Oak Ridge Associated Universities (ORAU) estimate (Wh76) of potential
power production: 2.25x104 GWe-yr. This estimate is based on an estimated
3x106 tons of uranium available to the U. S. at costs that can be afforded in
an LWR and assumes a 1 GWe LWR with recycle that requires about 4000 tons of
natural uranium during its 30 years of operating life.
Comparison of Cumulative Releases of C-14 to the Atmosphere
Figure 1 shows a comparison of cumulative releases of cosmic C-14,
nucl ear weapons testing C-14, and LWR nucl ear industry C-14 rel eases to the
atmosphere. We employed the following assumptions to generate the C-14
release rate comparison presented in Fig. 1.
1. The low case installed nuclear capability projections for the
25-year period 1976-2000 are those in Table 3. We believe the low case is a
realistic conservative estimate of the future growth of the LWR industry to
the year 2000.
2. The capacity factor (GWe produced electrical power/GWe installed
electrical power) is 0.69.
3. The potential power production of U. S. LWR facilities is 2.25x104
GWe-yr (Wh76).
4. The annual discharge of C-14 from the LWR nuclear power industry is
equal to the LWR produced electrical power in GWe-yr times 25 Ci/GWe-yr (see
p. 2). Carbon-14 produced in the fuel and coolant is released to the
atmosphere in the year that the electrical power is produced. (These assump-
tions result in a conservatively high C-14 release rate since the U. S. does
not currently have commerci a 1 LWR fuel reprocess i ng, and fuel reprocess i ng
constitutes 18.4 of the 25 Ci/GWe-yr.)
9
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5. We used the yearly C-14 source tenns in Table 2 to calculate the
nuclear weapons testing C-14 cumulative releases for the period 1945-1974.
6. The cosmic C-14 production rate is 4x104Ci/yr, which sustains a
steady-state environmental inventory of about 3x108 Ci (4x104Ci/
yrx5730yr/0.693).
As illustrated by the curves in Fig. 1, we project that the cumulative
environmental burden of C-14 to the end of the twentieth century from the LWR
nuclear industry will be only a small fraction of the cumulative environ-
mental burden of nuclear weapons testing C-14 or cosmic produced C-14. The
cumulative atmospheric injection of C-14 from nuclear weapons testing was
5800 kCi for the years 1945 to 1974. The cosmic C-14 annual production rate
of 40 kCi resulted in a cumulative atmospheric injection of 1,000 kCi after
the 25-year period 1976 to 2000. Cumulative releases of C-14 from the LWR
nuclear power industry after the 25-year period 1976 to 2000 are estimated to
be 78.8 kCi for the U.S., 182 kCi for foreign facilities, and 261 kCi for the
world. Using more recent energy production estimates (Ha79) for the U.S.,
about 49 kCi of C-14 will be released by U. S. LWR facil ities between 1976
and the year 2000.
These release estimates for the U.S. industry are especially conser-
vative since there are no operating commercial reprocessing plants in the
United States. President Carter's nuclear energy policy included a decision
to defer indefinitely the commerci al reprocessing and recycl ing of pl utonium
in the U.S. Subsequently. the NRC issued a policy statement (USNRC77)
terminating applications for reprocessing facility licenses. In light of the
lack of current operating LWR fuel reprocessing facilities, the impact of
C-14 releases from this portion of the uranium fuel cycle is currently zero.
However, we have included an estimate of the health impact of C-14 emissions
from LWR fuel reprocessing facilities to give a complete presentation of LWR
facilities. Such infonnation will be useful should the U.S. begin to
reprocess fuel in the future.
The potential cumulative C-14 release to the atmosphere from the world
LWR industry for the period 1976-2000 is about 25% of the cosmic C-14 pro-
duced during the same period, about 0.1% of the cosmic C-14 sustained steady
state environmental inventory, and about 4% of the C-14 produced by nuclear
weapons testing from 1945 to 1974. The U.S. LWR nuclear industry will
release about 30% of the C-14 release from the world LWR industry.
10
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106
105
104
en
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52
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(J)
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(J)
o
E
:c
U)
>
~
~
E
~
o
103
I
I
102,
I
101
Figure 1
Comparison of Cumulative Releases of Carbon-14 to the Atmosphere
Cosmic C-14 Sustained Steady State Environmental Inventory
Nuclear Weapons Testing C-14 (1945-1975)
7,Qr:f))
:10./
~ \.",9
C/'
i:-'v
0""
'-.0
1975
1980
1995
2000
1985
1990
Year
-------
Using a potential power production of 2.25x104 GWe-yr (Wh76) for U. S.
LWR facilities, we estimate a potential C-14 release of 562 kCi. By the year
2000, the U. S. LWR nuclear industry will have produced about 14% of the C-14
that will be produced during the estimated life of the industry. The
production of C-14 from the LWR industry will equal the production of C-14 by
cosmic reactions when the electrical production of the industry is 1600
GWe-yr or an installed capacity of 2319 GWe-yr using a capacity factor of
.69.
Figure 2 presents a comparison of production rates. We estimate that
the world and U. S. LWR nuclear industry in the year 2000 will produce about
61% and 16% respectively, of the cosmic C-14 natural production rate. Using
more recent energy production estimates for the U. S. (Ha79), we estimate
that the U. S. LWR nuclear industry in the year 2000 will produce about 8
percent of the cosmic C-14 natural production rate. We used the same
assumptions for the comparisons shown in Fig. 2 and Fig. 1. In both cases,
we maximized the potential LWR nuclear industry C-14 release rates by
assuming no control of C-14.
CARBON-14 DOSE EQUIVALENT AND ENVIRONMENTAL DOSE COMMITMENT
Environmental Transport
The worldwide environmental transport of carbon-14 atmospheric dis-
charges was evaluated using a diffusion-type model of the carbon cycle de-
veloped by Killough (Kina). The Killough model is a world multi-reservoir
model containing the atmosphere, slow turnover terrestrial biosphere, rapid
turnover terrestrial biosphere, the surface waters of the ocean (mixed
ocean), the thermocline, and the deep ocean. Based on a suggestion by
Kii10ugh (Ki77b), an extra layer was added to the deep ocean as represented
in 0RNL-5269 (Kina) 50 that the equilibrium level from natural cosmic C-14
would be reproduced by the model. The extra layer is the only change that we
made in the model described by Killough (Kina). A summary description and
discussion of some of the important features of his model follows.
The Killough Model
The Killough model treats the ocean
to vertical transport of carbon in the
Oeschger et ale (Oe75). Carbon dioxide
as a diffusive medium with respect
subsurface ocean as impl emented by
read ily di ssol ves in water to form
12
-------
105
4x104
10.
---..
....
~
"-
2
Q)
Ci;
cr::
Q)
CI)
en
Q)
Q;
cr::
'-'
-;:
Q)
.c:
Q
CI)
o
,S
-------
carbonic acid~ and this reaction involves so little energy change that it is
easily reversible and C02 can be readily released from the ocean when
condi ti ons are appropri ate. The trans fer of ca rbon between the atmosphere
and mixed ocean is calculated using the nonl inear relationship between the
partial pressure of C02 exerted by the ocean surface water and the total
inorganic carbon in this water as implemented by Bacastow and Keeling (Ba73).
The nonl inear model accounts for the decreasing capaci ty of the ocean to
absorb carbon dioxide from the atmosphere as the acidity of the ocean water
increases. Killough calculates exchanges of carbon between the atmosphere
and terrestrial biospheres using the Bacastow and Keeling (Ba73) logarithmic
growth term for the terrestrial biota and a fractional growth limit for the
terrestrial biota of 1.5 times the pre-industrial value.
.The Killough model estimates the specific activity of C-14 in the atmo-
sphere from the release of 14C02 into the atmosphere and includes a
calculation of the carbon-14 environmental dose commitment (USEPA74), which is
the sum of all doses to individuals over the entire time period that the C-14
persists in the environment in a state available for interaction with humans.
It is assumed that the specific activity of carbon in human tissues is equal
to the specific activity of carbon in the atmosphere, and the individual dose
equivalent and the environmental dose commitment are calculated using carbon-
14 specific activity dose equivalent rate conversion factors for the
different body organs.
The Killough model uses a worldwide popul&tion growth scenario and
assumes that increased amounts of atmospheric carbon dioxide are released to
the atmosphere due to the combustion of fossil fuels containing no carbon-14.
This assumption reduces the specific activity of C-14 in the carbon cycle
(the "Suess Effect") and thereby reduces the 1 ong-term envi ronmental dose
commitment from carbon-14. Scenarios for world population growth and
injections of fossil fuel 12C02 were included in the EPA modified Machta
model (Ma74, Fo76); however, the choice of the scenarios did not allow
calculations of the environmental dose commitment beyond 100 years after
release of C-14 to the atmosphere. The improved plausible scenarios
presented by Ki 11 ough (Ki 77a) allow the envi ronmenta 1 dose commitment to be
properly calculated over the life of C-14 in the environment.
14
-------
Fossil Fuel Scenario
The injection of 12C02 into the atmosphere from the burning of fossil
fuels is an important feature of the Killough model. Figure 3 is a plot of
the production rate of fossil fuel 12C02 used in this analysis. For the
years 1960 to 1974, production rates are computed by linear extrapolation of
historical data tabulated by Keeling and Rotty (see ORNL-5269). For years
beyond 1974, we used a logistic projection of the future release rate by
solving the differential equation
-,
.
P(t) = RP(t)
1
- (:~ t) ) n
P(to) = Po
where
.
p(t) =
R =
fossil fuel production rate (gCjyr) at time t,
adjustable parameter used to fit projections smoothly to
historical data,
P(t) = cumulative production (gC) prior to time t,
Poo = total fossil fuel ultimately released (gC),
n = shape parameter, with increasing values of n decreasing
the required time to exhaust the supply of fossil fuels, and
Po = cumulative production (gC) prior to a specified time
to (=1974).
We used Killough's reference values to solve the above differential
equation, and they are as follows:
17
Po = 1.34x10
18
Rx, = 3.08x10
\
n = 1
However, Killough (Ki77a) found that the parameters used in the fossil
fuel scenario had little effect on the environmental dose commitment for a
release of C-14 to the atmosphere. For example, he found during sensitivity
tests that doubling the total fossil-fuel projected to be ultimately
released, Poo (3.08x1018g to 6.16x1d-8 g), decreased by eight percent the
envi ronmental dose commitment for i nfi nite time, but did not s i gnifi cantl y
15
-------
Figure 3
Annual Atmospheric Injection Rate of Fossil FueI12CO~
3
o
2.5
>.
'-
N
"7
0
0'>
CD
0 2
~
Q)
-------
affect envi ronmental dose commitments ca 1 cul a ted for time peri ods 1 ess than
100 years after release of carbon-14 to the atmosphere. Similarly, in-
creasing the shape parameter n by 4 (0.5 to 2.0) did not affect the en-
vironmental dose commitment over infinite time, and the 100-year environ-
mental dose commitment was only decreased by about 4%.
World Population Scenario
The environmental dose commitment calculation must consider world popu-
lation growth over the next 40,000 years, since that is how long C-14 remains
in the environment and available for interaction with man. In Killough's
model (Ki77a), which we have adopted, the world population stabilizes at 12.2
billion from the year 2075 on. His reference world population growth scen-
ario, shown in Fig. 4, is the United Nations. "medium" variant projection to
the year 2075(UN74).
Infinite time environmental dose commitments calculated using Killough's
model can be scaled up or down in accordance with alternative world popu-
lation future growth scenarios. The United Nations' long-range projections
(UN74) assume that "where any human behavior is concerned, no accurate pre-
diction is possible" and lithe more distant the future, the more hazardous is
the venture. II As for the employed asymptotic level of 12.2 billion for the
world population, reports indicate that it may be high or low. According to
Kahn (Ka76), who projects a decreasing population growth rate, the world
population in 200 years "will total approximately 15 billion, give or take a
factor or two. II
Internal Dosimetry
An intermediate result of the Killough (Ki77a) worldwide C-14 environ-
mental transport model is the specific activity of C-14 in the atmosphere. In
order to convert this specific activity to a dose equivalent rate in man, we
assumed that the specific activity of C-14 in the atmosphere and in man are
the same. We derived carbon-14 specific activity dose equivalent rate con-
version factors by the method outlined by Fowler (Fo76). Table 4 presents
4
the resulting factors. Specific activity dose equivalent rate factors (DECF)
were calculated using the following equations:
17
-------
14'~
13
U)
c
.12
i5
12
11
c
o
~
6. 7
o
a..
"
~
:i:
5
,
,
;'
,
,
/
/
/
0/
0------
4
2
1925
1950
1975
,.
/
I
/
I
/
I
(;)
I
,
I
I
2000
Figure 4
World Population Projection
,
'"
'"
'"
..-
".
..-
0"
"
"
"
/
/
/
,
/
/
,
/
,
d
/-
I
,
I
,
I
I
I
2025
2050
Year
0----------------------------- ---
2075
3000
-------
Table 4.
Carbon-14 specific activity dose equivalent rate conversion factors
Organ
Dose equivalent rate conversion factor
( D(CF)
(mrem/yr per pCi C-14/gm C)
Body Fat
Adipose Tissue (body fat
plus yellow marrow)
Kidneys
Live r
Lungs
Cortical Bone
Trabecular Bone
Red Marrow
Yellow Marrow
Total Endosteal
0.68
0.59
Cells
0.12
0.13
0.09
0.13
0.12
0.38
0.58
0.33*
0.11
0.11
0.21
0.08
0.08
0.13
0.10
0.21
0.11
Lowe r La rge
Stomach
Skin
Testes
Intestine
Ovaries
Female Breasts
Thyroid
Total Body
Total Body Less
Adipose Tissue
*This conversion factor represents contributions from C-14 in cancellous
bone, cortical bone, red marrow, and yellow marrow using data from Snyder
(Sn74).
19
-------
OECF (mrem/yr per pCi C-14/gm C) = 0.919 Mc/MT
and
OECF (mrem/yr per pCi C-14/gm C) = 0.365 SM
c
where
Mc and MT are the mass of carbon and mass of tissue
respectively for the organ or tissue that the DECF
is being calculated.
0.919 is the product [3.7 E + 10 dis/sec-Ci] x [lCi/
1E+12 pCi] x [0.0493 MeV/dis] x [1.6 E-6 ergs/MeV] x
[lgm (tissue) rad/100 ergs] x [3.15 E+7 sec/yr1 x [1
rem/rad] x [1.0 E+3 mrem/rem]
S = dose equivalent per unit accumulated activity (rem~Ci-day)
0.365 is the product [1 E-6 lJ Ci/pCi] x [365 day/yr] x [lE+3
mrem/rem]
1\ a\'d ":r are from ICRP Publication 23 (ICRP75). The IISII factor is the dose
equivclent (rem) to a target organ per unit integrated activity ( lJ Ci-day) in
the source organ, which can be equated to the dose equivalent rate (rem/day)
per organ activity burden (lJ Ci) for steady state conditions.
In order to calculate OECF factors in Table 4, we obtained carbon-14 "SII
factors from Snyder (Sn74) for 22 source organs and 24 target organs, and M
c
vaiues are from !CRP Publication 23 (ICRP75). The dose equivalent rate to
the total endosteal cells per unit C-14 specific activity in cancellous bone,
cortic,l bone, red marrow, ar.d yellow marrow was calculated using the IISII
factor technique. The O~CF values for the GI tract in Table 4 do not include
the dcse equivalent contributed by the migrating contents of the GI tract.
The ~'S" factor method to calculate OECF factors for C-14 has also been
employed by ERDA (USEROA75); and contributions from the migrating contents of
the G1 tract were included in the ERDA calculated values. Considering C-14
in tissue and in the migrating contents within the stomach and intestine,
20
-------
.
DECF values of 0.14 and 0.16 mrem/yr per pCi C-14/gmC are inferred from ERDA
(USERDA75) methodology.
The carbon content in the female ovaries and breasts was calculated
using tissue composition and elemental carbon content data from ICRP Publi-
cation 23 (ICRP75). The female breasts (combined weight of 360 g) contained
46 grams of carbon, and the ovaries (combined weight of 11 g) contained 0.94
g of carbon. The specific activity dose equivalent rate conversion factor
presented in Table 4 for the female breasts may be low, since the tissue
composition in ICRP Publication 23 (ICRP75) is for pregnant females, who
would have a higher water content in the breast than nonpregnant females.
The C-14 DECF value for adipose tissue was also calculated using data from
ICRP Publication 23 {ICRP75).
A considerable portion of the C-14 dose to the total body is to adipose
tissue. However, since C-14 has not been shown to produce carcinoma in adi-
. .
pose tlssues, a DECF factor was calculated for the total body less adipose
tissue. And, since C-14 has a maximum beta energy of 0.156 MeV and a maximum
range in water (or tissue) of about 0.012 inches (305 microns) (USHEW70), the
C-14 deposited in adipose tissue is not expected to irradiate, to any signif-
icance, adjacent nonadipose tissue. Moreover, adipose tissue is located at
selected depots rather than dispersed uniformly throughout tissue. To cal-
culate the OE"CF factor for adipose tissue (see Table 4), we used a tissue
mass (MT) of 15,000 grams (13,500 grams body fat and 1500 grams yellow
marrow) and a carbon mass (M ) of 9600 grams (ICRP75).
c
Environmental Dose Commitment
As previously indicated, we used the Killough model (Ki77a) to estimate
the environmental dose commitment (EDC) from discharges of C-14 to the atmo-
sphere. The Ki llough model has a bui It-i n total body speci fic activity dose
equivalent rate conversion factor for C-14 of 2.08x108 rem/yr per Ci C-14/gC.
Thus, mc calculations with the Killough model will be for the total body.
Dose equivalent rates and the environmental dose commitments to other organs
.
are calculated by simple ratios using the organ specific DECFis in Table 4.
Figures 5 and 6 illustrate the buildup of the environmental dose commit-
ment to the world population for a release of 1 Ci of C-14 in 1985. Approxi-
mately 5 percent of the environmental dose commitment to infinite time is
delivered in the first 100 years after release; 22 percent within 1000 years;
and 99 percent within 40,000 years after release.
21
-------
en
E
~
,
c:
III
E
'E 100
(I)
~
E
E
8 50
(I)
tJ)
o
C
Iii
....
c:
(I)
E
c:
o
~
0:;;
c:
W
>-
-0
o
ID
Iii
(;
I-
1000
5001
10
5
Figure 5
Buildup of the Total Body cnvironmentai DostJ Commitment to the World Population
for a Release of 1 Ci of C-14 to the Atmosphere in 1985
EDC Fac;tors
30 yr EDC = 13 man-rems/Ci
100 yr EDC= 28 man-rems/Ci
1000 yr EDC= 120 man-rems/Ci
EDC (t) = 1 .609t 0.6221 for 10 yrs ~ t ~ 1000 yrs
( man({;ems )
infinite EDC=537 man-rems/Ci
5
10
100
1000
10,000
100,000
Time After 'Release (Years)
-------
Figure 6
Buildup of the Total Body Environmenta1 Dose Commitment to the World Population
for a Release of 1 Ci of C-14 to the Atmosphere in 1985
100
50'
....
c:
OJ
.~
E 10
E
o
0
OJ
1/1
0
0 5
-------
The environmental dose commitment for C-14 releases in 1985 as shown in
Fig. 5 can be represented approximately by a power curve fit between 10 and
1,000 years after the release of C-14 to the environment. The resulting
equation for the environmental dose commitment is
EDC(t)
= 1.609(t)0.6221 for 10 ~ t ~ 1000
where
EDC(t)
= total body environmental dose commitment for
C-14 releases in 1985 to the world population
for "t" years after the release of the C-14 to
the atmosphere (man-rems).
Resulting C-14 total body environmental dose commitments for time periods
after a release in 1985 are shown in Fig. 5. EDC factors regardless of year
of rel ease will be taken from Fig. 5 for time peri ods beyond 100 years after
release.
One-hundred-year EDC factors for the next twenty-five years vary
sl ightly with the year of release since the world population and stable
carbon concentration in world reservoirs are changing during this time
period. We made computer runs of the Killough model (Kina) for releases in
the years 1975, 1985, 2000, and 2025 to determine the sensitivity of the EDC
factor to year of release. The EDC factors were plotted on a graph, and EDC
factors for intermediate years were determined by graphical interpolation.
Table 5 presents the resulting total body C-14 100-year EDC factors for the
years 1976 to 2000. We used these factors to project environmental dose
commitments for different nuclear growth scenarios. C-14 environmental dose
commi tments for organs other than the total body are determi ned by multi-
.
plying the total body EDC factors from Table 5 with the ratio of the DECF
factor (see Table 4) for the organ for which the EDC is desired to the DECF
factor for the total body. Gonad EDC factors are presented in Table 5 using
this ratio technique. Tabulations such as. the one in Table 5 allow one to
use the resul ts of the Killough model to project impacts of C-14 releases
without installing and running the computer code.
24
-------
Table 5. Carbon-14 100-year environmental dose commitment factors
Year of Release
C-14 100-year EDC Factor (man-rems/Ci)
Total Body Gonads
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
25.5
25.7
25.9
26.2
26.4
26.6
26.8
27.1
27.3
27.6
27.8
28.0
28.2
28.4
28.6
28.8
29.0
29.2
29.4
29.5
29.7
29.8
30.0
30.1
30.3
9.71
9.79
9.87
9.98
10.1
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.7
10.8
10.9
11.0
11.0
11.1
11.2
11.2
11.3
11.4
11.4
11.5
11.6
25
-------
Dose Equivalent and Dose Equivalent Rate
Computer runs were done to estimate the total body dose equivalent rate
and lifetime dose equivalent to an average individual in the world population
from C-14 releases to the atmosphere. Comparisons were made of dose equi-
valent rates due to releases of C-14 from the U. S. and world LWR nuclear
power industry, cosmic C-14, and nuclear weapons testing C-14.
The C-14 source term from the U. S. LWR nuclear industry for the years
1976 to 2000 was developed using the installed nuclear capacity projections
for the United States low case in Table 3. Produced power for each year was
ca 1 cul a ted us i ng an assumed capaci ty factor of 69 percent for each je3~,
Carbon-14 was assumed to be produced at a rate of 25 curies per GWe-yr of
produced electrical energy, and it was further assumed that all C-14 produced
was released (e.g., no C-14 control) in the year that it is produced. We
used this conservative approach in order to scope the public health impli-
cations of C-14 discharges. The projected atmospheric release rates of C-14
are especially conservative considering the current absence of LWR fuel
reprocessing.
A subroutine was developed to describe the time dependent C-14 injection
rate from 1976 to the year 20('1. This subroutine develops the function
C14PRO(T). which is the C-14 so'rce term used in the Killough model environ-
mental dose commitment calculation. Appendix 1 lists the subroutine used to
evaluate the USLWR nuclear power growth scenario.
Table 6 lists the data base used to calculate the release rate of C-14
from the U. S. LWR nuclear power industry (low case). Electrical energy
production rates for the beginning of each year (LWRPRO) were calculated
assuming that the production rate changes 1 inearly with time during each
year. The values of LWRPRO are chosen to give an energy production in each
calendar year equal to those indicated as produced electrical energy in Table
6. The va 1 ue of LWRPRO for 1976 was chosen so that the difference between
the values for 1977 and 1976 would be the same as the difference between the
values for 1978 and 1977. The mathematical development of LWRPRO is as
fo 11 ows :
assume,
(ri + ri+1)/2 = Pi or ri+1 = 2Pi - ri
and
ro + r2 = 2r1
26
-------
where
r.
1
= electrical energy production rate at the beginning
of year i (GWe-yr/yr) = LWRPRO(I)
p.
1
= mean electrical energy production (GWe) during
year i (also has the same value as the electrical
energy produced for year i(GWe-yr))
i
= 0 for 1976, i = 1 for 1977, etc.
By mathematical manipulation, it can be shown that rO =
(3 Po - P1)/2 and ri = 2Pi-1 - ri-1.
Table 6 shows the resulting values of LWRPRO. The atmospheric injection
rate of C-14 in curies per year is calculated to be 25 Ci per GWe-yr times
LWRPRO (GWe). The injection rate in curies per year is multiplied by 0.2242
to convert it to grams per year. The C-14 annual atmospheric injection from
the U. S. LWR nuclear power (low case) is presented in Table 6. A similar
approach was used to calculate the release rate of C-14 from the world LWR
nuclear power industry using the installed capacities for the low case as
presented in Table 3. Appendix 2 lists the subroutine utilized to evaluate
the world LWR nuclear power growth scenario. Appendices 3 and 4, respec-
tively, list the subroutines used to estimate cosmic C-14 produced from 1976
to 2000 and nuclear weapons testing C-14 releases during the years 1945 to
1974.
Figure 7 and Tables 7, 8, and 9 present the resul ts of the computer
analysis of the various sources of C-14 discharges. Figure 7 shows the time
dependence of the average worldwide individual total body dose equivalent
rate due to C-14 releases for the years 1976 to 2000 from the U.S. LWR nu-
clear power industry. The peak total body dose equivalent rate is approxi-
mately 7.5x10-3 mrem/year. Using recent projections of the growth of the
U.S. LWR nuclear power industry to the year 2000 (Ha79), the peak total body
dose equivalent rate after 25 years of uncontrolled C-14 discharges is about
4.3x10-3 mrem/yr. Note that the dose equivalent rate decreases after the
27
-------
Table 6. Release rate of ca rbon-14 from the US LWR nucl ear power indus try -
low case
P. LWRPRO( I)
1 Energy Production C-14 Annual
I ns tall ed Produced* Rate at Beginning Atmospheric
LWR Nuclear Capacity Energy of the Year Injection
Year (GWe) (GWe-yr) (GWe) (KCijyr)t
1976 43 29.7 28.4 .742
1977 47 32.4 31.0 .811
1978 52 35.9 33.8 .897
1979 56 38.6 38.0 .966
1980 60 41.4 39.2 1.04
1981 73 50.4 43.6 1.26
1982 87 60.0 57.2 1.50
1983 100 69.0 62.8 1.72
1984 114 78.7 75.2 1.97
1985 127 87.6 82.2 2.19
1986 141 97.3 93.0 2.43
1987 154 106 102 2.66
1988 168 116 111 2.90
1989 181 125 121 3.12
1990 195 134 129 3.36
1991 214 148 140 3.69
1992 232 160 155 4.00
1993 251 173 165 4.33
1994 269 186 182 4.64
1995 288 199 190 4.97
1996 306 211 208 5.28
1997 324 224 214 5.59
1998 343 237 233 5.92
1999 363 250 241 6.24
2000 380 262 259 6.56
2001 265
*Assumed capacity factor is 69%.
tAtmospheric emission C-14 source term is 25 Ci/GWe-yr.
28
-------
10.0
9.0
...
>-
" 2.0
E
Q)
~
Q)
co
a:
C
Q)
(tj
.~
~
C"
UJ
Q)
(/)
0
0
(tj 1.0
~
"0 .9
:~
"0
c: .8
Q)
"0
~ .7
-b
::
0
~ .6
Q)
OJ
'"
CD .5
>
«
.4
Figure 7
8.0
Average Individual Total Body Dose Equivalent Due to Carbon-14 Releases
for the Years 1976-2000 from the US LWR Nuclear Power Industry
7.0
6.0
5.0
4.0
3.0
.3
.2
.1
1975
1985
1980
1990
1995
2000
2005
2010 2015
, Year
2020
2025
2030
2035
2040
2045
-------
Table 7.
Average world wide individual total body 70-year lifetime
dose equivalent due to carbon-14 releases
Carbon-14
Sou rce Term
Average
Lifetime
Individual Total Body
Dose Equivalent (mrem)
0.20*
US LWR
Nuclear Industry
Release 1976-2000
Worl d LWR
Nuclear Industry
Releases 1976-2000
0.67
Cosmic C-14
Produced
During 1976-2000
2.8
Cosmic C-14
Steady Sta te
91
Nucl ear Weapons
Testing
1945-1974
11
*Using more recent energy production estimates for the U. S. (Ha79),
this value is 0.13 mrem.
Note.--Dose equivalents in this table are for an individual born
in 1976.
30
-------
Table 8. World population total body environmental dose commitment (man-rems)
due to carbon-14 releases
--.-
Carbon-14 Source Term
US LWR World lWR Cosmic C-14 Nuclear Weapons
Nuclear Ind. Nuclear Ind. Procuced Testing
Yea rs Releases Releases Duri'19 Steady 1945-1974
after 1976 1976-2000 1976-2000 1976..2000 State
1.2x106 (7.3x105) 6 7 8 "1
W 50 3.8x10 1. 5x 1 0 4.2x10 9.1x10'
.......
100 2.0xl06 (1.2x106) 6 2.6x107 1. 2x 109 1.4x108
6.6xlO
500 6.2xl06 (3.8xl06) 7 7 .7.9xl09 8
2.1x10 7.9x10 4.6x10
1,000 9.4xl06 (5.9xl06) 3.1xl07 1.2x108 1.6x1010 7.0x108
10,000 3.1x107 (2.0x107) 1.0x108 8 1. 6x 1011 9
4.0x10 2.3x10
20,000 3.9x107 (2.4x107) 8 8 3.2)(1011 2.9x109
1.3xlO 5.0x10
40,000 7 7 1.4x108 8 6.4xl011 9
4.2x10 (2.6x10) 5.3xlO 3.1x10
infinite 4.2x107 (2.6x107) 1.4x108 8 3.1x109
5.4xlO co
*Va"ues in parentheses are those calculat.ed using more recent energy production
estimates for the U. S. (Ha79).
-------
Table 9.
World population total body environmental dose commitment per
century after 1976 due to U. S. LWR nuclear industry carbon-14
releases 1976-2000
Total Body
Environmental Dose Commitment
(man-rems)*
Years After 1976
0-100
100-200
200-300
300-400
400-500
500-600
600-700
700-800
800-900
900-1,000
9,900-10,000
19,900-20,000
39,900-40,000
2.0x106
1. 4x106
1.1x106
9.2x105
8.2x105
7.4x105
6.9x105
6.3x105
6.0x105
5.7x105
1.6x105
7.9x104
7.9x103
(1.2X106)
(9.4x105)
(6.6x105)
(5.8x105)
(5.1x105)
(4.6x105)
(4.3x105)
(3.9x105)
(3.7x105)
(3.6x105)
(9.8x104)
(4.9x104)
3
(4.9x10 )
*Values in parentheses are those calculated using more recent energy
production estimates for the U.S. (Ha79).
32
-------
last year that C-14 was released to the atmosphere from the evaluated u.s.
LWR nuclear industry growth scenarios. The dose equivalent rate due to C-14
releases from US LWR facilities will continue to increase after the year 2000
if the US LWR nuclear industry continues to release C-14 after this date.
Based on the ORAU estimate (Wh76), the potential electrical energy production
of US LWR's is 2.25x104 GWe-yr. From an analysis of the evaluated US LWR
nuclear growth scenario, it is estimated that approximately 3.15x103 GWe-yr
(1.96x103 GWe-yr for the 1979 projections (Ha79)) of electrical energy will
be produced by the year 2000. Therefore, unl ess C-14 control systems are
installed, C-14 releases from US LWR's will continue after the year 2000, and
the average individual dose equivalent rate will increase above the values
indicated in Fig. 7. The US LWR nuclear growth scenario evaluated in this
analysis only extends to the year 2000 because of the large uncertainty
associated with the estimated nuclear industry growth beyond the year 2000.
Cosmic C-14 is produced at a rate of approximately 4x104 Ci/yr, which
sustains an environmental steady state inventory of about 3x108 Ci and a
resul ting specific activity of approximately 6x10-12 Ci/gC in the biosphere,
from which the average worldwide individual receives a 1.3 mrem/yr total body
radiation dose equivalent (Kina). Environmental dose commitments from the
cosmic C-14 steady state level were calculated by multiplying the average
dose equivalent rate of 1.3x10-3 rem/yr by the average world population size
for the time period of interest and by the number of years of exposure. The
1 ifetime average individual total body dose equivalent from the C-14 steady
state level was simply calculated as 1.3 mrem/yr x 70 years = 91 mrems.
Table 7 shows the average worldwide individual, total body, 70-year
lifetime dose equivalent due to C-14 releases. An individual born in 1976 is
estimated to receive 102.67 mrem over hi s 1 ifetime due to C-14 rel eases from
the world LWR nuclear industry during the years 1976-2000, the cosmic C-14
steady state level, and C-14 releases from nuclear weapons testing during the
years 1945 to 1974. Releases of C-14 from US LWR nuclear industry for the
years 1976-2000 contribute 0.2 mrem of the estimated 102.67 mrem 1 ifetime
total body dose equivalent from C-140 Using more recent energy production
estimates for the U.S. (Ha79), the a'jerage worldwide in(jl'/idual total body
lifetime dose equivalent due to C-14 releases from the US LWR nuclear in-
dustry (1976 to 2000) is estimated as 0.13 mrem. The actual individual C-14
33
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dose equi va 1 ent will be higher if rel eases of C-14 from fuel cycl es other
than LWR's are considered and if releases from the LWR nuclear industry are
projected beyond the year 2000.
We assume the release of all the nuclear industry C-14 that is produced,
thus the lack of fuel reprocessing or any installed C-14 control technology
at LWR facilities would lower the estimated individual dose equivalent.
Also, an individual living in the vicinity of a nuclear facility that re-
leases large quantities of C-14 could receive a higher C-14 dose equivalent
than the average worldwide individual. The extent of the increased dose
equivalent to an individual residing in the vicinity of the nuclear facility
will be determined largely by the nature of the facility release (daytime
versus night), local meteorology (especially the frequency of daytime type A
stability) (Ki76), and the dietary habits of the individual to whom the dose
equivalent is being estimated.
Table 8 contains the world population total body environmental dose
commitments due to C-14 releases from several sources of C-14 discharges to
the envi ronment. The envi ronmental dose commitments for 50 and 100 years
after 1976 were taken di rectly from the computer pri ntout for computer runs
using the K.llough model. Except for the cosmic C-14 steady state source,
environmental dose commitments for times greater than 100 years after 1976
were calculated by multiplying the total C-14 curie release for the release
time period by the appropriate EDC factor. EDC factors regardless of year of
release were taken from Fig. 5, so the resulting EDC is approximate, but
accurate enough for the comparison purpose of this analysis.
The relative impacts of C-14 releases from LWR's, nuclear weapons
testing, and cosmic C-14 are shown in Table 8. For example, the C-14 due to
the world LWR nuclear industry releases for the 25-year period (1976-2000) is
about 25% of the EDC due to the cosmic C-14 produced during this same quarter
of a century, about 0.6% of the EDC due to the cosmic C-14 sustained steady
state environmental inventory, and about 4.7% of the EDC produced by nuclear
weapons testing C-14 from 1945 to 1974.
The EDC values in Table 9 for C-14 releases from the U. S. LWR nuclear
industry are for different lOa-year time periods after 1976. The impact is
greatest in the first lOa-year time period after 1976, and it decreases in
the following centuries. However, a potential impact, though reduced,
remains even at approximately 40,000 years after the release of the C-14 to
the environment.
34
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Estimated annual carbon-14 dose equivalent rates to individuals at the
offsite location where maximum air concentrations occur at light-water-cooled
reactors and fuel reprocessing plants are given in Table 10. Table 11 con-
tains the assumptions we used to calculate the local dose equivalent rates.
A specific activity model was used for the local maximum individual dose
equivalent rate calculation. This method assumes that carbon-14 specific
activity in the maximum individual is equal to the carbon-14 specific activ-
ity in the air at the maximum point of offsite concentration. Any food or
fluids that the maximum individual ingests that are uncontaminated or at a
lower C-14 specific activity than that at the point of maximum offsite con-
centration will lower C-14 dose equivalent rates below those in Table 10.
Table 12 shows the relationship of the C-14 dose equivalent rate to the
total body dose equivalent rate from all radionuclides released from LWR's.
The LWR impacts in Table 12 were estimated using the AIRDOS-II computer code
(Mo77). Except for carbon-14, the airborne radionuclide emissions were taken
from model BWR and PWR (with recirculating U-tube type steam generators)
facilities as developed by the NRC and described in the final generic environ-
mental statement on the use of recycled plutonium in mixed-oxide fuel in
light-water-cooled reactors (USNRC76c). The annual release rates of C-14
were 9 Ci/yr and 5 Ci/yr for the BWR and PWR, respectively. The estimates
represent a midwestern site in the United States. Food production and con-
sumption assumptions for the maximum individual are for a rural setting. A
20-meter fixed stack height with no plume rise was employed. The regional
population consisted of 2,486,049 people within an area having a radius of
80.4 kil ometers. The maximum i ndi vi dua 1 dose equi va 1 ent rate occurred 503
meters downwind. The dose equivalent rate from C-14 is a significant frac-
tion of the total body dose equivalent rate received from all airborne radio-
nuclides released from the model LWR facilities. The percentage of the
maximum individual total body dose equivalent rate due to carbon-14 emissions
is 22% for the BWR and 29% for the PWR. The percentage contribution by C-14
to the total body dose equivalent rate as obtained from data in Table 12 is
appropriate only for the total body as the target organ. Percentage contri-
butions for other target organs would have to be calculated separately. For
example, carbon-14 contributes 16.4 percent to the lungs, 7.2 percent to the
thyroid, and 18.5 percent to the ovaries of the maximum individual dose
equivalent rate for the model PWR.
35
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Table 10.
Maximum individual carbon-14 total body dose equivalent
rates for LWR facilities
Facil ity
Total Body
Dose Equivalent Rate
(mrem/yr)
LWR Fuel Reprocessing
Facil i ty
1.6
BWR
PWR
.86
.48
36
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Table 11.
Assumptions used for the calculation of the maximum individual
carbon-14 total body dose equivalent rates for LWR facilities
Carbon-14 source terms
LWR fuel reprocessing
PWR
BWR
facil ity
830 Ci /yr
5 Ci/yr
9 Ci/yr
Maximum offsite atmospheric dispersion factor - "X/Q"
LWR fuel reprocessing facility
PWR & BWR without stack
5.0E-8 sec/m3
2.5E-6 sec/m3
Concentration of carbon-14 in the troposphere
0.174 gm C-12/m3 (estimated for 1980)
Specific activity dose equivalent rate conversion factor
total body
0.21 mrem/yr per pCi C-14/gm C
37
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Table 12.
Total body dose equivalent rates for airborne emissions from
BWR and PWR facilities
Maximum Average Regional
Individual Individual Population
Faci 1 ity (mrem/yr) (mrem/yr) (man-rem/yr)
BWR
all radionucl ides 1.8 3.5x10-3 8.6
C-14 only .41 -4 1.4
5.6x10
PWR
all radionucl ides .78 2.3x10-3 5.7
C-14 only .23 -4 .78
3.1x10
38
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HEALTH IMPACT ASSESSMENT OF C-14 DISCHARGES FROM THE LWR NUCLEAR POWER
INDUSTRY
To project health impacts, we assumed a 1 inear, nonthreshold
relationship between the magnitude of the radiation dose received at
environmental levels of exposure and ill health produced (USEPA75). This
assumpti on is cons i stent with recommendati ons by the Nati ona 1 Academy of
Sciences - National Research Council's Advisory Committee on the Biological
Effects of Ionizing Radiation (BEIR72). The general health effect risk
factors that have been used previously by EPA in C-14 health impact assess-
ments are 400 cancers (200 fatal and 200 nonfatal) per 106 man-rem to the
total body and 200 serious genetic effects per 106 man-rem to the gonads
(F076). Since a large percentage of the total body dose from C-14 is to
adipose tissue and is not effective in producing cancer, we estimated new
C-14 health risk coefficients that consider the dose to lean body mass. Table
13 presents resulting C-14 health risk coefficients as derived from an internal
EPA memorandum (Ne78).
Since the average energy of a C-14 beta is 49 kev (median, 46 kev) and
almost 100% absorbed in 50 w , twice the diameter of a fat cell, no appreciable
radiation is expected to escape the tissue from C-14 deposited in adipose
tissue. If the C-14 beta radiation does not escape from adipose tissue, then
only the risk to adipose tissue needs to be accounted for in the case of
C-14 deposited in the tissue. The best evidence to date does not indicate
any increased susceptibility to develop lipomas or liposarcomas following
radiation exposure. Thus the risk to adipose tissue is considered to be
zero (Ne78).
Lean body mass is approximated by the total body less adipose tissue
target organ as described in the internal dosimetry section of this report.
The leukemia risk from irradiation of the red bone marrow is considered
separately, since it is two-thirds as great as the risk from all other
tissues in the lean body mass exposed to carbon-14 (Ne78). Carbon-14
health effect risk coefficients presented in Table 13 per 106 man-rems to
total body were calculated using the number of health effects per 106
man-rems to the target organ and the C-14 specific activity dose equivalent
rate conversion factors in Table 4 of this report. For 106 man-rem exposure
to the total body from C-14, the following health effects distribution was
estimated: 58 leukemia deaths, 88 other cancer deaths, 105 nonfatal cancers,
and 76 serious genetic effects.
39
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Table 13.
Carbon-14 health risk coefficients
Ta rget Organ &
Health Effect
Health Effect
(Number per 106
man-rems to
target organ)
Risk Coefficients
(Number per 106
man-rems to
total body)
Red bone marrow
fa ta 1 1 eu kemi as 32 58
Lean body mass
other fatal cancers 168 88
non-fatal cancers 200 105
Gonads
serious genetic effects 200 76
(all generations)
40
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The health effects estimates are for C-14 beta irradiation only. No
attempt was made to estimate the effect of 14C ~ 14N transmutation. The BEIR
committee (BEIR72) noted that when there are many carbon-14 decays per
nucleus that the radiation effects far outweigh the consequences of trans-
mutation. The general conclusion was that it was justifiable to consider the
main effect to come from the radiation emitted when the isotope disintegrates
(BEIR72).
Estimates of the average worldwide fatal cancer risk and potential
health effects committed to the world population from C-14 releases are in
Table 14. The average worldwide individual fatal cancer risk was calculated
using lifetime dose equivalents from Table 7 and the C-14 fatal cancer risk
coefficient of 146 fatal cancers per 106 man-rems to the total body as pre-
sented in Table 13. Potential health effects include fatal cancers, nonfatal
cancers, and seri ous genetic effects. The potenti al worl d popul ati on health
effects for 100 years after the C-14 release was calculated using the
100-year environmental dose commitments in Table 8 and the C-14 health effect
risk coefficients from Table 13.
Table 15 contains estimates of the local individual lifetime risks of
fatal cancer and health effects committed to the regional population due to
carbon-14 emissions from model BWR and PWR facilities. These health impacts
were estimated using the total body dose equivalent rates from Table 12 and
the carbon-14 health risk coefficients from Table 13. The lifetime fatal
cancer risk to the highest exposed group of individuals is estimated to be
4.2E-6 for the BWR and 2.4E-6 for the PWR. The lifetime fatal cancer risk to
the average individual in the region is estimated to be 5.7E-9 for the BWR
and 3.2E-9 for the PWR. To make these individual risk assessments, we
assumed that the exposure source would exist for at least 70 years. The
individual lifetime fatal cancer risks in Table 15 will be in addition to the
individual risk of cancer death from all causes of 0.15 (Bat79). The esti-
mated cancer death risk of 0.15 is based on the American Cancer Society
estimate that 25,000 out of 100,000 people will eventually develop cancer and
that about 15,000 will eventually die of cancer.
41
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Table 14.
Average worldwide individual lifetime risk of fatal
cancer and health effects committed to the world
population from carbon-14 sources
Carbon-14
Source Term
Average Worldwide
Individual Fatal Cancer
Lifetime Risk (over 70 yrs.)
Potential World
Population Health Effects
(100 yrs. after C-14 Release)
US LWR
Nuclear Industry
Releases 1976-2000
2.9E-8 (1.9E-8)t
6.5E+2* (3.9E+2)t
Worl d LWR
Nuclear Industry
Releases 1976-2000
9.8E-8
2.2E+3
Cosmic C-14
Produced
During 1976-2000
4.1E-7
8.5E+3
Cosmic C-14
Steady State
1.3E-5
3.9E+5
Nucl ear Weapons
Testing
1945-1974
1.6E-6
4.6 E +4
*The potential health effects committed to infinite time (essentially
over the next 40,000 years) is estimated to be 1.4E+4(7.5E+3).t
tValues calculated using more recent energy production estimates for
the U. S. (Ha79).
42
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Table 15.
Local individual lifetime risks of fatal cancer and health
effects committed to the regional and world populations
due to carbon-14 emissions from model BWR and PWR facilities
Individual Fatal Cancer Lifetime Risk (over 70 years)
Maximum Individual
Average Individual
BWR
4.2E-6
5.7E-9
PWR
2.4E-6
3.2E-9
Per year of plant operation
Population Health Effects (one-year
BWR
4.6E-4
impact)
PWR
2.6E-4
Regional
Per year of plant operation
Effects (IOO-year
BWR
8.2E-2
impact)
PWR
4.6E-2
Worldwide Population Health
43
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The number of health effects (fatal cancers, nonfatal cancers, and
serious genetic effects) committed per year of site operation to the regional
population is estimated to be 4.6E-4 for the BWR and 2.6E-4 for the PWR. The
number of health effects committed to the world population from the annual C-
14 release is estimated to be 8.2E-2 for the BWR and 4.6E-2 for the PWR. The
health effects committed to the world population considered the impact over a
100-year period of time after release from one year's source term of carbon-
14.
SUMMARY
The admonition of the National Environmental Policy Act of 1969 (NEPA69)
that each generation should be a responsible IItrustee of the environment for
succeeding generationsll is particularly germane to evaluating the health
impact of C-14, which has a physical half-life of 5730 years. For a given
release of C-14 to the atmosphere, 5 percent of the environmental dose com-
mitment will be delivered in the first 100 years after release, 50 percent in
5,000 yea rs , and the ba 1 a nce of the env i ronmenta 1 dose commitment over a
period extending tens of thousands of years after release.
The estimated health impact risk to any single individual from C-14
emissions from LWR facilities is small. The largest impact is the cumulative
risk to population groups over long periods of time. Existing burdens of
C-14 due to nuclear power operations are small, but the potential for future
radiation effects may be large in the absence of a standard to limit the
environmental burden of C-14. Assuming that all C-14 produced by U.S. LWR
facilities during 1976-2000 is released to the atmosphere, approximately 390
potential serious health effects will be committed to the world population
during the next 100 years. Seventy-five hundred potential health effects
will be committed to infinite time (essentially over the next 40,000 years).
Carbon-14 risk coefficients can be expressed on a per curie basis to aid
scientists in making evaluations of the impact of C-14 discharges to the
atmosphere. Carbon-14 risk coefficients indicating fatal cancers committed
to the world population per curie of C-14 released to the atmosphere are
estimated to be 4.1E-3 fatal cancers/Ci for 100 years after release and
7.8E-2 fatal cancers/Ci for infinite time.
44
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We recognize that the health impact due to C-14 emissions from LWR
facilities is very small compared to that from background radiation or
environmental C-14 sources such as cosmic C-14 or C-14 released during
nuclear weapons testing. However, we share the view expressed by Killough
and Till (Ki78) on comparisons of the health impact of C-14 emissions from
LWR facilities and the potential health effects from natural and
weapons-produced C-14: "These comparisons provide us with levels of exposure
which are accepted as inevitable because they cannot be reduced" (Ki78). The
comparisons provide perspective but should not be used to belittle the
importance of controll ing C-14 emissions if it could be done in a
cos t-effect ive manner. Carbon-14 control technology ava i 1 abil ity and cos ts
for LWR facilities must be considered in deliberations on the need for a
national C-14 standard.* This report outlines how the cumulative risk to the
world population as well as individual risk can be used with C-14 control
technology cost information to evaluate cost effective considerations.
Several issues besides cost effectiveness remain to be addressed. One
is the significance of summing very small doses to large numbers of people
over long time periods and cumulating health effects. Another is how
potential heal th effects beyond 100 years in the future are to be addressed.
*Two EPA contracted studies on this topic have been completed. Science
Applications, Inc. assessed C-14 control technology and cost for the LWR fuel
cycle (Br77). Nuclear Consulting Services, Inc., critically analyzed the SAI
contract report (Ko79a) and provided an updated and more detailed analysis of
C-14 control technology and costs for LWR facilities (Ko79b).
45
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in the Uranium Fuel Cycle - Final Environmental Statement, Volume I
and II, EPA 520/4-76-016 (U.S. Environmental Protection Agency. Office
of Radiation Programs, Washington, D.C.)
USEPA77 U.S. Environmental Protection Agency, 1977, Subchapter F -
Radiation Protection Programs, Part 190 - Environmental Radiation
Protection Standards for Nuclear Power Operations, Federal Register,
Vol. 42, No.9, Thursday, January 13, 1977.
USEPA78 Office of Radiation Programs, 1978, Radiation Protection Activities
1977, EPA-520/4-78-003 (U.S. Environmental Protection Agency, Office
of Radiation Programs, Washington, DC).
USERDA75 U.S. Energy Research and Development
Environmental Statement-Liquid Metal Fast
ERDA-1535 (National Technical Information
51
Administration, 1975, Final
Breeder Reactor Program,
Service, Springfield, VA).
-------
USERDA77 Energy Research and Development Administration, 1977, Nuclear
Reactors Built, Being Built, or Planned in the United States as of
June 30, 1977, TID-8200-R36 (National Technical Information Service,
Springfield, VA).
USHEW70 U.S. Department of Health, Education and Welfare, 1970, Radio-
logical Health Handbook (Public Health Service, Rockville, Maryland 20852).
USNRC76a U.S. Nuclear Regulatory Commission, 1976, Calculation of Releases
of Radioactive Materials in Gaseous and liquid Effluents from Boiling
Water Reactors, (BWR-GAlE CODE), NUREG-0016, Office of Standards Develop-
ment (National Technical Information Service, Springfield, VA).
USNRC76b U.S. Nuclear Regulatory Commission, 1976, Calculation of Releases
of Radioactive Materials in Gaseous and liquid Effluents from Pressurized
Water Reactors, (PWR-GAlE CODE). NUREG-0017, Office of Standards Develop-
ment (National Technical Information Service, Springfield, VA).
USNRC76 U.S. Nuclear Regulatory Commission, 1976, Final Generic Environ-
mental Statement on the Use of Recycle Plutonium in Mixed Oxide Fuel
in light Water Cooled Reactors, NUREG-0002, Vol. 3 (National Technical
Information Service, Springfield, VA).
USNRC77 U.S. Nuclear Regulatory Commission, 1977, Policy Statements -
Mixed Oxide Fuel, Federal Register, 42 FR 65374, December 30, 1977.
Wh76 Whittle, C.E., Allen, E.l., Cooper, C.l., MacPherson, H.G., Phung,
D.l., Poole, A.D., Pollard, W.G., Rotty, R.M., Treat, N.l., and Weinberg,
A.M., 1976, Economic and Environmental Implications of a U. S. Nuclear
Moratorium, 1985-2010, ORAUjIEA 76-4 (Oak Ridge Associated Universities,
Institute for Energy Analysis, Oak Ridge, TN).
52
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APPENDIX 1
US LWR NUCLEAR INDUSTRY CARBON-14 RELEASES 1976-2000
C14PRO
FUNCTION C14PRO(T)
C
C
C
C
C
C
C
C
C
C
C
C
LWRPRO = PRODUCTION RATE OF ELECTRICAL ENERGY BY LWRS AT THE BEGINNING
OF EACH YEAR FOR 1976 THROUGH 2001.
THE PRODUCTION RATE IS ASSUMED TO CHANGE LINEARLY WITH TIME DURING
EACH YEAR. VALUES OF LWRPRO ARE CHOSEN TO GIVE AN ENERGY PRODUCTION
IN EACH YEAR EQUAL TO THAT IN TABLE-3 (US LWR LOW CASE).
THE VALUE OF LWRPRO FOR 1976 WAS CHOSEN SO THAT THE DIFFERENCE BETWEEN
THE VALUES FOR 1977 AND 1976 WOULD BE THE SAME AS THE DIFFERENCE
BETWEEN THE VALUES FOR 1978 AND 1977. THE ATMOSPHERIC INJECTION
RATE OF CARBON-14 IS TAKEN TO BE XCI*LWRPRO (CI/YR). THE INJECTION
RATE IN CI/YR IS MULTIPLIED BY 0.2242 TO CONVERT IT TO GRAMS/YR.
REAL LWRPRO(26)/ 28.35, 31.05, 33.75, 38.05, 39.15, 43.65, 57.15,
* 62.85, 75.15, 82.25, 92.95, 101.65, 110.95, 120.85,
* 128.95, 140.05, 155.35, 164.85, 181.55, 189.65, 207.75,
* 214.45, 232.75, 240.65, 258.95, 265.45/
DATA XCI/25.0/
CI4PRO=0.0
IF (T.LT. 1976..0R.T.GE.2001.) RETURN
I=T-1975.
F=AMOD(T ,1.0)
C14PRO=XCI*((1.0-F)*LWRPRO(I)+F*LWRPRO(I+1))*0.2242
RETURN
END
53
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APPENDIX 2
WORLD LWR NUCLEAR INDUSTRY CARBON-14 RELEASES 1976-2000
FUNCTION C14PRO(T)
~
~
l
C
LWRPRO = PRODUCTION RATE OF ELECTRICAL ENERGY BY LWRS AT THE BEGINNING
OF EACH YEAR FOR 1976 THROUGH 2001.
THE PRODUCTION RATE IS ASSUMED TO CHANGE LINEARLY WITH TIME DURING
EACH YEAR. VALUES OF LWRPRO ARE CHOSEN TO GIVE AN ENERGY PRODUCTION
IN EACH YEAR EQUAL TO THAT IN TABLE-3 (WORLD LWR LOW CASE).
THE VALUE OF LWRPRO FOR 1976 WAS CHOSEN SO THAT THE DIFFERENCE
BETWEEN THE VALUES FOR 1977 AND 1976 WOULD BE THE SAME AS THE
DIFFERENCE BETWEEN THE VALUES FOR 1978 AND 1977. THE ATMOSPHERIC
INJECTION RATE OF CARBON-14 IS TAKEN TO BE XCI*LWRPRO (CI/YR).
THE INJECTION RATE IN CI/YR IS MULTIPLIED BY 0.2242 TO CONVERT
IT TO GRAMS/YR.
c
C
C
C
C
r
v
C
C
C
C
REAL LWRPRO(26)/
56.235, 66.585, 76.935, 94.185, 101.775, 119.025,
155.575, 174.225, 209.375, 229.425, 263.175, 302.625,
334.975, 375.825, 406.575, 449.025, 516.975, 556.625,
625.975, 665.625, 736.375, 773.425, 843.975, 883.825,
952.975, 992.825/
*
*
*
*
DATA XCI/25.0/
C14PRO=0.0
IF(T.LT.1976..0R.T.GE.2001.) RETURN
I=T-1975.
F=AMOD(T,1.0)
C14PRO=XCI*((1.0-F)*LWRPRO(I)+F*LWRPRO(I+1))*0.2242
54
-------
APPENDIX 3
COSMIC CARBON-14 PRODUCED DURING 1976-2000
C14PRO
FUNCTION C14PRO(T)
C
C
C
C
C
COMPUTES RATE (GRAMS PER YEAR) AT WHICH C-14 IS BEING
INTO THE ATMOSPHERE. THIS VERSION OF THE SUBPROGRAM
ESTIMATES THE COSMIC PRODUCTION FOR THE YEARS 1976-
2000 AS 40000 CIjYR (=8968 GMjYR).
C14PRO=0.0
IF(T.GE.1976. .AND. T.LT.2001.) C14PRO=8968.0
RETURN
END
55
INJECTED
-------
APPENDIX 4
WEAPONS TESTING CARBON-14 RELEASES 1945-1974
COMPUTES RATE (GRAMS PER YEAR) AT WHICH C-14 IS BEING INJECTED
INTO THE ATMOSPHERE. THIS VERSION OF THE SUBPROGRAM
ESTIMATES THE NUCLEAR WEAPONS TESTING PRODUCTION DURING THE YEARS
1945 - 1974. DATA IN CI/YR FROM KILLOUGH (Ki78) AS SHOWN IN
TABLE-2.
REAL BOMB(30) /1.2E3, 4.1E2, 0.0,
4.7E4, 3.1E5, 2.4E4,
1.5E6, 2.2E6, 0.0,
6.2E4, 1.1E5, 1.6E4,
FUNCTION C14PRO(T)
C
C
C
C
C
C
*
*
*
C14PRO=0.0
IF(T.LT.1945..0R.T.GE.1975.)
I=T-1944.
C14PRO=BOMB(I)*.2242
RETURN
END
RETURN
56
2.2E3, 0.0,
3.3E5, 2.0E5,
4.1E2, 4.1E2,
2.7E3, 5.2E4,
0.0,
6.6E5,
1.4E4,
1. 2E4/
3.3E3, 2.4E5,
0.0, 2.1E3,
6.4E4, 1.2E5,
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United States
Envinmmenial Protection
Agency
Office of Radiation Programs
. Eastern Environmental
Radiation Facility
P.O. Box 3009
Montgomery AL 36109
Postage and
Fees Paid
Environmental
Protection
Agency
EPA-G35
~
~
Official Business
Penalty for Private Use $300
Third Class
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