United
Environmcnt.il Prut
Agt-i
of Radiation Programs
. Facility
PO Box 18416
Las Vegas NV 89114
EPA 520 6 82 021
November 1982
Radi
Emissions Of Naturally
Occurring Radioactivity:
Monsanto Elemental
Phosphorus Plant
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EPA-520/6-82-021
November 1982
EMISSIONS OF NATURALLY OCCURRING RADIOACTIVITY FROM
MONSANTO ELEMENTAL PHOSPHORUS PLANT
Vernon E. Andrews
Office of Radiation Programs
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
Project Officer
Tom Bibb
Emission Standards and Engineering Division
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
This report was prepared with the technical support
of Engineering-Science Inc. under contract 68-02-2815,
Office of Radiation Programs - Las Vegas Facility
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
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DISCLAIMER
This report has been reviewed by the Office of Radiation Programs-Las Vegas
Facility, U.S. Environmental Protection Agency. Mention of trade names or
commercial products constitutes neither endorsement nor recommendation for
their use.
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FORWARD
The Office of Radiation Programs (ORP) of the U.S. Environmental Protection
Agency (EPA) conducts a national program for evaluating exposure of humans to
ionizing and nonionizing radiation. The goal of this program is to develop and
promote protective controls necessary to ensure the public health and safety.
In response to the 1977 amendments to the Clean Air Act the Las Vegas
Facility was given the responsibility to collect field data on emissions to the
atmosphere of natural radioactivity from operations involved in the mining,
milling, and smelting of minerals other than uranium and coal. This report is
one of a series which describes an individual facility and its associated
radioactive emissions.
ORP encourages readers of the report to inform the Director, ORP-Las Vegas
Facility, of any omissions or errors. Comments or requests for further infor-
mation are also invited.
Wayne A. Bliss
Acting Director
Office of Radiation Programs
Las Vegas Facility
iii
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CONTENTS
Page
Forward ii"j
Figures vi
Tables vi
Abbreviations and Symbols vii
1. Background 1
2. Introduction 3
3. Summary 4
4. Plant Operations 5
Production Process 5
Airborne Emission Sources 7
5. Sample Collection and Analysis 9
Sample Collection 9
Sample Analysis 9
Data Reporting 10
6. Sample Results 11
Process Samples 11
Ambient Air Samples 14
Emission Samples 14
7. Discussion of Results 26
References 27
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FIGURES
Number
Page
1 uranium and Thorium Radioactivity Decay Schemes ........... 2
2 Monsanto Chemical Plant Flow Diagram ................ 6
TABLES
Page
1 Radioactivity Concentrations in Process Materials .......... 12
2 Ambient Radon-222 Concentrations .................. 15
3 Ambient and Stack Particulate Radioactivity Concentrations ..... 16
4 Radon-222 Stack Emissions ...................... 18
5 Stack Flow and Particulate Emission Rates .............. 20
6 Particulate Radioactivity Emission Rates .............. 21
7 Particulate Radioactivity Annual Emission Rates ........... 23
8 Aerodynamic Particle Size Distribution ............... 25
vi
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
Ci curies: 3.7x10^ disintegration per second
Ci/y curies per year
kg/h kilograms per hour
km kilometer
mci/y millicuries (10~3Ci) per year
nCi/m^ nano (10~^Ci) curie per cubic meter
pCi/g picocuries (10~12Ci) per gram
pCi/1 picocuries per liter
pCi/m^ picocuries per cubic meter
ppm parts per million
TSP total suspended particulates
vm micrometer: 10~^meters
SYMBOLS
CO carbon monoxide
E-S Engineering Science, Inc.
EIC Eberline Instrument Company
FeP ferrophosphorus
vi i
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SECTION 1
BACKGROUND
The Clean Air Act, as amended in August 1977, required the Administrator
of the Environmental Protection Agency (EPA) to determine whether emissions of
radionuclides into ambient air should be regulated under the Act. In December
1979 the Administrator listed radionuclides as a hazardous pollutant under
Section 112 of the Clean Air Act.
The naturally occurring radionuclides most likely to be emitted in signif-
icant quantities are those in the uranium-238 and thorium-232 decay series
(Figure 1). These radionuclides and their daughter products occur naturally
in widely varying amounts in the soils and rocks that make up the earth's
crust. Average values for uranium-238 and thorium-232 in soils are approxi-
mately 1.8 ppm (0.6 pCi/g) and 9 ppm (1 pCi/g) respectively (1). The radio-
activity concentration of each of the daughter products in the two series is
approximately equal to that of the uranium-238 or thorium-232 parent.
Almost all operations involving removal and processing of soils and rocks
release some of these radionuclides into the air. These releases become
potentially important when the materials being handled contain above-average
radionuclide concentrations or when processing concentrates the radionuclides
significantly above the average amounts in soils and rocks.
Because mining and milling operations involve large quantities of ore, and
because there is little information about how these activities release radio
active emissions, EPA, in 1978, began to measure airborne radioactive emissions
from various mining, milling, and smelting operations.
Operations were selected for study on the basis of their potential to emit
significant quantities of naturally occurring radionuclides to the atmosphere.
Some of the factors in the selection included typical mine size, annual U.S.
production, measured working levels of radon daughters in underground mines
and associated ventilation rates, production rate and process of individual
facilities, and previous association with naturally occurring radionuclides.
Usually, we chose to look at large facilities in order to improve the chances
of obtaining emission samples with radioactivity contents significantly
greater than background.
These surveys were screening studies designed to identify potentially
important sources of emissions of radionuclides into the air. Any such
sources can then be studied in detail to determine whether or not a national
emission standard for hazardous pollutants is needed under the Clean Air Act.
-------
URANIUM - 238 DECAY SERIES
THORIUM - 232 DECAY SERIES
ro
238
U
4.5>10*vr
a
234
Th
24 da.
ra
6 75 he
s
/*.
134
U
!Si10*yr
/
a.x
230
Th
8(10* V
a.r
226
Ha
1620yr
a.t
222
no
3 8 da
a.X
218
Po
3 (T^IO.
a
214
Pb
27 min.
214 210
Po Po
IBxICfMC. 138d».
7 *-
21%, ^r-r "V ^ -"
19.7 min. 5
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SECTION 2
INTRODUCTION
As early as 1908 it was recognized that phosphate rock contained above
normal concentrations of uranium and thorium (2). Those concentrations have
been observed in the United States to range from 8 to 399 ppm (2.7 to 133
oCi/g) of uranium-238 and 2 to 19 ppm (0.22 to 2.1 pCi/g) of thorium-232 (3).
South Carolina ores had the highest concentrations, while the lowest were
found in Tennessee. During the 1950's uranium was recovered as a byproduct of
phosphate production.
Since 1974 the EPA has studied various aspects of the radioactivity
released to plant environs during benefication and processing of phosphate
ores The EPA had conducted a comprehensive radiological survey of a thermal
nhosphate (elemental phosphorus) plant in 1974 (4). However, problems with
the analysis of lead-210 had greatly reduced the accuracy of the measurements
of both lead-210 and polonium-210. Under the added emphasis provided by the
Clean Air Act Amendments the decision was made to include at least two
elemental phosphorus plants in this series of surveys. The two plants
selected were the Stauffer Chemical Company plant in Silver Bow, Montana, and
the Monsanto Company plant in Columbia, Tennessee. This report presents the
results of the Monsanto facility survey.
Engineering-Science, Inc. (E-S) under contract with the EPA, conducted the
survey and collected samples (5). Representatives of E-S and EPA visited the
niant before the survey to select sampling locations. During the period
December 4-14, 1979, E-S, accompanied by an EPA representative, conducted the
^amoling and measurement program. E-S collected particulate and gas samples
from plant emissions and ambient air as well as information on plant
operations. A meteorology station was installed at the ambient air monitoring
location.
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SECTION 3
SUMMARY
Engineering Science, Inc. (E-S) collected participate and gaseous emission
samples from the major emission points at the Columbia, Tennessee plant of
Monsanto. Where more than one stack served a process only one stack was
sampled. Ambient participate and gaseous samples were collected at a site 2
km northwest of the plant.
The thorium decay chain radionuclides, thorium-232 and -228, were found at
normal background levels in ore and emission samples. The uranium decay chain
radionuclides averaged 3.4 pCi/g in Tennessee ores and 47 pCi/g in ores from
Florida.
Kiln exhaust stacks were the major point of release of radioactivity from
the plant. Radon emissions from the kilns totaled 9.6 Ci/y. Lead-210
emissions from the kilns were 0.48 Ci/y and polpnium-210 emissions were
0.75 Ci/y. These were probably all released primarily from the molten
materials in the furnaces and carried to the kilns along with the CO used as
fuel.
Except for one source, the non-volatile nuclides, uranium-238 and -234,
thorium-230, and radium-226, produced annual releases of these nuclides,
averaging 0.24 to 1.5 mCi. The screening plant dust collectors were estimated
to release an average of 7.2 mCi/y of each of these nuclides. Possible
non-operation of a scrubber on the discharge may be the reason for the higher
emissions from this source which accounted for over half of the 13 mCi/y of
each nuclide released from all sources at the plant.
The majority of the suspended particulates emitted were found to be above
the respirable size range. This probably holds, as well, for the non-volatile
radionuclides.
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SECTION 4
PLANT OPERATIONS
PRODUCTION PROCESS
The Monsanto Company plant is located approximately 10 km northwest of
Columbia, Tennessee. Most of the ore comes from strip mines in the vicinity
of the plant, but part of the ore is shipped from Florida. The plant produces
elemental phosphorus. Ferrophosphorus (FeP) is an important by-product. At
the time of the survey a portion of the slag produced was sold as an aggregate.
Figure 2 is a schematic of the plant operation. Concentrates from the
washer and dust collected from the kilns and screening plant are stockpiled in
an open, raw materials craneway. From here the materials are sent to one of
two stockpiles. As one stockpile is built up - taking about 1 week - the
other supplies the kiln. Ores from various sources are initially blended by
the stockpiling process in the craneway and are further blended by the kiln
feed operation.
It is necessary to form the finely divided ore into larger, stable
agglomerates for proper operation of the reduction furnaces. This is accom-
plished by passing the ore through three rotary kilns. The kilns raise the
ore temperature to its incipient melting point and the tumbling action forms
it into the desired nodular form. The hot nodules pass through coolers and
are conveyed by a series of conveyors to the nodule storage craneway. A
clamshell bucket on an overhead crane moves the nodules to storage bins from
which they pass through the screening plant on their way to the burden scales
and on to the furnace stocking system. At the burden scales coke is added to
serve as the reducing agent and silica and lime are added, as needed, to
achieve the necessary balance of calcium and silicon to form a proper slag.
The approximate reaction in the furnace is:
2 Ca3(P04)2 + 10 C + 6 SiO£ *?4 + 10 CO + 6 CaSiOs
In addition, the iron naturally present in ore reacts with some of the
phosphorus to produce FeP. The blended furnace feed enters the furnaces con-
tinually from the top and progresses downward until reaching the molten layer
on the bottom. Phosphorus and carbon monoxide (CO) are driven off as gases
and are vented near the top of the furnace. The slag and FeP which are
continually collecting in the furnace are periodically "tapped off." Molten
slag is carried by bucket to a dump. Front-end loaders transfer the cooled
slag to a storage pile. At the time of the survey, slag was being sold from
storage for use as aggregate.
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LEGEND
HM DAWMATERItl-S
«- PROCESS MAttRlAl FLOW
-^ GAS FLOW
(T) STACK SAMPLE POINT
FIGURE 2. MONSANTO CHEMICAL PLANT FLOW DIAGRAM
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Furnace off-gases pass through dust collectors then through water spray
condensers. Phosphorus is cooled to the molten state in the condensers. The
mix of phosphorus and water - phossy water - and mud go to a processing system
where phosphorus is separated and piped to storage. The clean off-gases leav-
ing the condensers contain a high concentration of CO and are used as fuel in
the kilns to supplement the coal fuel.
AIRBORNE EMISSION SOURCES
The Monsanto emission inventory includes 54 controlled and uncontrolled
sources. Thirty-one sources treat emissions from coke handling, boilers,
short-term intermittent operations, or emergency release emissions. Open
sources, such as craneways and open-belt conveyors are not easily sampled.
Eight stacks were selected as representing the important emission sources
based on reported mass emission rates or process involved. These sources are
shown in Figure 2, keyed to the following descriptions.
Kilns (1)
The three kilns discharge emissions through individual dust collection
chambers and spray scrubbers. Lime is added to the scrubber spray to aid in
removal of fluorine and sulfur dioxide. Entrained water in the exhaust gases
is removed in two demister stacks. One demister stack serves emissions from
kilns 1 and 2. The other demister stack serves kiln 3. The 5.4-m diameter
stack discharges about 35 m above ground level. An existing Monsanto sampling
system was used to collect samples from the top of the stack serving kiln 3.
Nodule Coolers (2)
Each nodule cooler has an emission control system and discharge stack.
Emissions are controlled by jet eductors. The exhaust stack on the nodule
cooler at kiln 3 was sampled. Samples were collected on both inlet and
exhaust of the jet eductor to determine the fraction removed. The 4.4-m
diameter stack discharges 25 m above ground.
Nodule Transfer Points (3)
Particulate emissions from the screening plant operations are controlled
by three "Type R" rotoclones composed of nine "clones" each. "Type R" roto-
clones combine water scrubbing with multiclone separation. For purposes of
this survey the screening plant dust collectors were identified by emission
source. One dust collector served the nodule transfer points on the pan
conveyors. The others controlled emissions from other screening plant points.
Nodules from the coolers are diverted at several points to other conveyors for
delivery to multiple entires into the nodule storage craneway. Dusts generated
at these transfer points are collected by hooding systems and treated for
removal of particulates by a "Type R" rotoclone. The 1-m diameter stack
discharges at a height of 29 m.
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Screening Plant Dust Collector (4)
Two dust collectors control emissions from the screening plant other than
the nodule transfer points. The two "Type R" rotoclone dust collectors and
their emissions are essentially identical so only one source was sampled Test
results indicated that the water to the rotoclone was off during testing
This has been corrected by Monsanto. The 1-m diameter stack discharges at
height of 29 m. s
a
South Scale Room Dust Collector (5)
Nodules, coke, and silica are weighed and fed into the furnace stocking
system by means of weighing belt conveyors. Two dust control systems are in
use in this area. The south scale room Luhr baghouse dust collector controls
emissions from the area where nodules are weighed. Because of the dissimilar-
ity of the emissions this was considered to be a single stack source. The other
stack was not sampled. The 0.9-m diameter stack exhausts at a height of 13 m.
Stocking System Belt Dust Collector (6)
The stocking system belt conveyor moves the blended furnace feed from the
scale room to the furnace stocking system. The conveyor and transfer points
are hooded and particulate emissions are controlled by two similar systems
une stack was selected as representative of the two stacks. Particulate
emissions are controlled by a Luhr baghouse dust collector. The 0.75-m
diameter stack discharges at a height of 21 m.
Central Furnace Stocking System (7)
The stocking system belt conveyor transfers furnace feed to the central
furnace stocking system. From there, three pivoting belt conveyors stock the
six furnace stocking bins. Emissions from the central furnace stocking system
are controlled by a Buell bag dust collector. The 0.9-m diameter stack
exhausts at a height of 48 m.
Furnace Taphole Fume Collector (8)
Each of the six furnaces has a hood, emission control system, and stack.
Slag is tapped from each furnace for 20 to 25 minutes with approximately 20
minutes between taps. Ferrophosphorus is tapped once or twice daily. Fumes
in the stack effluent are controlled by a venturi scrubber. The stacks are
1.1 m in diameter and discharge at a height of 38 m.
Other Sampling Points
In addition to the eight controlled sources sampled, high-volume air
samplers were operated near the slag dump and adjacent to the Florida ore rail
car dump and stockpile. The Florida ore pile is located close to the slaq
storage pile.
8
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SECTION 5
SAMPLE COLLECTION AND ANALYSIS
SAMPLE COLLECTION
Most stack samples were collected using EPA reference methods for
stationary sources (6). Stack sampling points were selected according to EPA
Method 1, Sample and Velocity Traverses for Stationary Sources. Stack gas
velocity and volumetric flow rate were determined by EPA Method 2, Determina-
tion of Stack Gas Velocity and Volumetric Flow Rate (Type S pilot tube). Gas
samples for radon-222 analysis were collected using EPA Method 3, Gas Analysis
for Carbon Dioxide, Oxygen, Excess Air, and Dry Molecular Weight. Total
suspended particulates (TSP) in ducts and exhaust stacks were determined using
EPA Method 5, Determination of Particulate Emissions from Stationary Sources,
or EPA Method 17, Determination of Particulate Emissions from Stationary
Sources (In-stack Filtration Method). High volume ambient TSP samples were
collected in accordance with the Reference Method for the Determination of
Suspended Particulates in the Atmosphere (7).
E-S collected Method 5 TSP samples on 7.6-cm (3-inch) diameter glass fiber
filters and Method 17 TSP samples on 5- by 12.7-cm (2- by 5-inch) glass fiber
filters. Ambient TSP samples were collected on 20.3- by 25.4-cm (8- by
10-inch) Microsorban polystyrene fiber filters. Stack gas and ambient whole
air samples for radon analysis were collected in 30-liter Tedlar bags.
E-S sampled each of the emission points described in Section 4-B. They
collected two to four samples each of TSP and gas samples from each point.
Two samples were collected simultaneously on the south scale room dust
collector stack as part of the quality assurance program. Two size-
fractionated samples were collected from each of the sources except the kiln
demister, nodule cooler, and furnace taphole fume scrubber.
Samples of process materials were collected to relate radionuclide
emission rates to the radioactivity of the material handled at each emission
point and to permit a radionuclide balance through the process.
SAMPLE ANALYSIS
E-S made mass determinations on TSP samples before forwarding them to
Eberline Instrument Corporation (EIC) for radiochemical analysis. Stack and
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ambient gas samples were shipped to EIC for arrival within 2 days of
collection.
EIC analyzed process and TSP samples by dissolving the samples and sepa-
rating the elements of interest by chemical techniques. The separated uranium
and thorium fractions were counted on alpha spectrometers for individual iso-
topic quantisation. An alpha scintillation counter measured the polonium-
210. Lead was separated and set aside for about 2 weeks to allow for ingrowth
of bismuth-210 from lead-210. After the ingrowth period the bismuth-210 was
separated from the lead and was counted on a beta counter to quantitate lead-
210. Radium was separated and enclosed as a solution in a sealed tube to
allow for ingrowth of radon from radium-226. After 3 weeks of ingrowth the
radon gas was evolved and collected in an alpha scintillation cell to be
counted. Stack and ambient gas samples were transferred to alpha scintilla-
tion cells and counted for radon.
DATA REPORTING
The radioactivity reported for each sample, is the net radioactivity plus
or minus twice the standard deviation due to counting statistics. Net
radioactivity is the gross sample radioactivity minus the counting equipment
background and minus either a) for filter samples, an average value for the
radioactivity content of a blank filter, or b) for stack radon samples, the
ambient radon concentration. The standard deviation is based only on the
random variations inherent in radioactivity counting and is propagated through
the various steps to the final result. This random variation, plus the
variable radioactivity content of individual filters, occasionally results in
a net radioactivity of less than zero. Of course, there is no negative
radioactivity. In these cases, as with all others, the net result must be
considered along with the standard deviation. Averages of multiple samples
from a source are given with a standard deviation due to counting statistics.
This uncertainty is propagated from the sample standard deviations.
10
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SECTION 6
SAMPLE RESULTS
PROCESS SAMPLES
Process sample radioactivity concentrations are given in Table 1. Ore
from the six Tennessee sources had similar radioactivity contents. The
average concentration of uranium decay chain radionuclides was 3.4 pCi/g.
Tailings solids averaged 3.0 pCi/g. The washed ore kiln feed averaged 4.0
pCi/g in the 1st shift sample and 6.6 pCi/g in the 2nd shift sample. This
indicates that the uranium and its decay products are more closely associated
with the phosphate ore than with the barren fines. As expected, Florida ore
had a higher radioactivity content with uranium decay chain nuclides averaging
47 pCi/g. Thorium decay chain nuclide concentrations of about 1 pCi/g in
Tennessee ores and 0.5 pCi/g in kiln feed were in the range expected for
normal rock. Thorium-232 and -228 were at normal concentrations in ore and
were generally not found at levels significantly different from background in
emission samples. Therefore, the remainder of the sample results discussion
will include only uranium decay chain nuclides. Thorium-232 and -228 results
are included in the data tables, however.
Nodule samples were collected from the conveyor belt and from the craneway
storage area at the same time as the 1st shift kiln feed samples. Nodules
from the conveyor had an average radionuclide concentration of 7.4 pCi/g, not
including the more volatile polonium-210. The craneway composite sample
averaged 3.5 pCi/g for the same nuclides. The differences in concentrations
in the kiln feed and nodule samples is probably due to some inhomogeneity
resulting from blending of Tennessee and Florida ores. Although blending
provides large scale homogeneity sufficient for production, it apparently is
not complete on the small scale of a sample prepared for analysis.
Coal, coke, and silica all had normal, background concentrations of
radioactivity. Slag and FeP had approximately the same concentrations of
uranium, however, about 90 percent of the total uranium was in slag due to the
relative amounts produced. Thorium from both decay chains was found primarily
in slag, as was radium. Lead-210 and polonium-210 were found in higher
concentrations in the FeP (3.9 ± 0.5 and 1.0 ± 0.9 pCi/g) than in slag (1.5 ±
0.5 and <0.8 pCi/g). Most of the lead-210 and polonium-210 originally in the
ore, however, is volatilized in the kiln. The kiln emission control systems
show high concentrations of these isotopes in their discharge water.
11
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TABLE 1. RADIOACTIVITY CONCENTRATIONS IN PROCESS MATERIALS
Radlonuclide Concentrations (pCi/g)
rv>
Sample
Ore-WcEvens Muck
Ore-Paisley Muck
Ore-Henson's Muck
Ore-Kincaid Tract
Ore-Gilbert's
Ore-Jones Tract
Average
Ore Washer Tailings
Water (pCi/1)
Ore Washer Tailings
Suspended Solids
Ore-Florida ftockb
Ore-Florida Stockpile
Florida Ore Average
Kiln 3 Feed, 1st Shift6
Kiln 3 Feed, 2nd Shiftb
Kiln 3 Feed Average
Nodules'1
Craneway Nodules
Compos i te°
Coal - Kiln Fuel
Silcab
Coke
Slagb
(continued)
U-238
2.6
2.2
2.7
3.2
2.7
2.5
2.7
1.2
3.1
39
46
43
3.5
6.3
4.9
7.5
2.8
0.49
0.32
0.42
11
4 0.4
* 0.3
* 0.3
* 0.4
4 0.4
4 0.3
4 0.3
4 0.4
* 0.4
* 3
* 5
* 5
* 0.3
* 0.5
* 2.0
4 0.6
4 0.3
* 0.15
4 0.1
4 0.10
* 1
U-234
2.5
2.3
2.7
3.5
2.5
2.8
2.7
0.69
2.8
40
47
44
3.7
6.5
5.1
7.7
2.9
0.34
0.38
0.47
11
* 0.4
* 0.3
* 0.3
* 0.5
* 0.4
± 0.4
* 0.4
* 0.29
* 0.4
* 3
4 5
* 5
* 0.3
* 0.5
* 2.0
4 0.6
* 0.3
4 0.12
* 0.07
* 0.11
* 1
Th-230
4.2
1.8
2.6
6.1
2.2
4.8
3.6
2.4
1.3
54
21
38
4.1
7.4
5.8
7.1
4.0
0.46
1.1
0.56
22
4 1.5
* 0.7
* 1.0
4 2.5
4 0.9
* 1.6
* 1.7
* 1.1
* 0.6
4 10
4 7
4 23
4 0.9
4 1.6
4 2.3
4 1.6
4 0.9
40.35
4 0.4
4 0.27
4 4
Ra-226
2.8
2.9
3.1
3.4
3.0
3.2
3.1
1.8
3.7
50
49
50
3.8
6.8
5.3
7.7
3.1
0.39
0.35
0.51
12
4 0.8
* 0.9
4 0.9
* 1.0
4 0.9
4 1.0
4 0.2
4 0.5
4 1.1
4 11
4 15
4 1
4 0.8
4 1.5
4 2.1
4 1.6
4 0.6
* 0.12
4 0.08
4 0.15
4 3
Pt>-210
4.1
5.5
2.0
3,9
5.4
4.5
4.2
26
3.6
44
56
50
4.0
5.0
4.5
7.2
4.6
1.2
0.99
0.91
1.5
* 0.8
4 0.8
4 0.7
4 0.8
* 0.8
4 0.8
4 1.3
4 22
4 0.3
4 1
4 2
4 8
4 0.5
4 0.5
4 0.7
4 0.6
4 0.6
* 0.6
4 0.47
* 0.63
± 0.5
Po-210
4.3 4
4.1 4
2.8 4
5.0 4
3.3 4
5.3 4
4.1 4
<11
3.6 4
57 4
62 4
60 4
4.8 4
7.4 4
6.1 4
3.3 4
3.6 4
1.1 4
<0.
<0.
<0.
1.0
1.0
0.9
_1.1
0.9
1.1
1 0
L
0.9
2
3
4
0.7
0.9
1.8
1.5
1.4
1.0
8
8
8
Th-232
1.4 4Q.7
0.20 4 0.18
0.89 4 Q.51
1.6 * 0.9
0.58 4 0.38
0.23 4 0.24
0.82 4 0.6
0.12 4 o.l7
0.77 4 o.45
0.31 4 0.20
-0.18 4 0.13
0.07 4 o.35
0.57 4 0.25
0.49 4 o.25
0.53 4 0.06
0.57 4 0.27
0.69 4 o.30
0.23 4 0.24
0.26 4 0.15
0.26 4 0.18
0.87 4 0.33
Th-228
1.4 4 0.7
0.72 4 0.37
0.95 4 0.53
1.5 * 0.8
0.58 4 0.38
1.2 4 0.6
1.1 4 0.4
0.12 4 0.17
0.11 4 0.16
0.44 4 0.23
-0.19 4 0.22
0.13 4 0.45
0.40 4 0.20
0.68 4 0.29
0.54 4 0.20
0.62 4 0.30
0.72 4 0.30
0.23 4 0.24
0.65 4 0.47
0.32 4 0.20
1.1 4 0.5
-------
CO
TABLE 1(continued)
Radlonuclide Concentrations (pC1/g)a
Sample
Ferrophosphorusb
Kiln 3 Spray Lime Slurry
Dissolved Solids (pCi/1)
Kiln 3 Spray Lime Slurry
Suspended Solids (pCi/1)
Kiln 3 Spray Lime Slurry
Total Solids (pCi/1)
Kiln 3 Spray Water
Dissolved Solids (pCi/1)
Kiln 3 Spray Water
Suspended Solids (pCi/1)
K1ln 3 Spray Water
Total Solids (pCi/1)
Kiln 3 Spray Discharge
Dissolved Solids (pC1/l)
Kiln 3 Spray Discharge
Suspended Solids (pCi/1)
Kiln 3 Spray Discharge
Total Solids (pCi/1)
U-238
9.7
2.3
.36
38
1.7
3.1
4.8
1.5
54
56
* 1.4
± 0.8
± 13
* 13
± 1.0
* 1.3
* 1.6
* 0.8
* 9
* 9
U-234
9.8
3.5
39
43
1.0
3.5
5.5
2.1
55
57
* 1.4
± 0.9
± 14
* 14
* 1.1
* 1.4
* 1.8
* 0.9
* 9
* 9
Th-230
0.05
1.1
28
28
0.56
2.0
2.6
0.82
24
25
* 0.07
± 0.9
* 19
* 19
* 0.46
* 1.3
* 1.4
* 0.68
* 10
* 10
Ra-226
0.19
4.7
45
50
1.0
4.0
5.0
0.78
59
60
* 0.04
± 1.4
± 13
* 13
± 0.5
* 1.2
* 1.3
* 0.23
± 18
* 18
Pb-210 Po-210
3.9
3.1
-20
-17
1.5
130
130
4.9
990
990
± 0.5 1.0 ± 0.9
* 6.8 <5
* 90 <40
± 90 <45
± 12 <5
* 20 130 * 35
± 23 130 ± 35
* 6.8 <5
* 60 1700 * 170
* 60 1700 * 170
Th-232
0.12
1.4
17
18
0.09
1.5
1.6
0.14
6.5
6.6
* 0.3
± 1.0
± 15
* 15
± 19
* 1.2
* 1.2
± 0.27
± 4.7
* 4.7
Th-228
0.21
1.4
26
27
0.09
1.5
1.6
0.14
5.2
5.3
± 0.14
± 1.0
± 20
± 20
* 0.19
± 1.2
± 1.2
± 0.27
* 4.0
* 4.0
a) Picocuries (10~^ curies) per gram plus or minus twice the standard deviation based on counting statistics.
Units in plcocuries per liter (pC1/l) where Indicated in sample description.
b) The results are derived from duplicate analyses.
-------
Waste water from phossy water processing and kiln spray chamber discharges
is recycled through a pond, which serves as a settling pond for suspended
solids. This water is used to make lime slurry and spray for the kiln spray
chambers. Uranium-234 and -238, thorium-230, and radium-226 concentrations in
the spray water averaged 4.5 pCi/1. Lead-210 and polonium-210 concentrations
were 130 pCi/1. Lime normally has uranium-234 and -238, thorium-230, and
radium-226 concentrations of 0.3 to 0.5 pCi/g and very low concentrations of
lead-210 and polonium-210 which are volatilized during the calcining process.
This natural radioactivity of lime is reflected in the lime slurry which
averaged 40 pCi/1 for the non-volatile radionuclides. There is no obvious
reason for the difference in lead-210 and polonium-210 concentrations between
the kiln spray water and lime slurry samples. Radioactivity concentrations of
the kiln spray chamber discharge demonstrate the removal of radioactivity at
that point. The average non-volatile radionuclide content was 50 pCi/1, or
about 38 pCi/1 above the weighted concentration expected from spray water and
slurry alone. Lead-210, with 990 ± 60 pCi/1, and polonium-210, with 1,700 ±
170 pCi/1, were the major radionuclides in the discharge.
AMBIENT AIR SAMPLES
Airborne radon concentrations measured at the ambient station are shown in
Table 2. Ambient radon concentrations typically vary from less then 0.1 to
about 1 nCi/m3, depending on time of day, season, and meteorology (1). All
ambient radon measurements were within the expected normal range.
Ambient airborne particulate radioactivity concentrations are reported in
Table 3. All results are within the range expected for normal ambient air (1).
Meteorological measurements at the ambient station show that the station was
downwind of the plant less than 15 percent of the time during collection of
the first particulate sample reported and less than 5 percent of the time for
the second sample reported. No effect of plant emissions is apparent on
either sample.
EMISSION SAMPLES
Radon
Of four sources sampled for radon only the kiln demister was found to
release radon in quantities signficantly different than background. The net
concentration above ambient, shown in Table 4, averaged 1.8 ± 0.3 nCi/m3.
On this basis, the total radon released annually from the three kilns was
projected to be 9.6 Ci.
14
-------
TABLE 2. AMBIENT RADON-222 CONCENTRATIONS
Time Radon-222
pate On - Off Concentration (nCi/m )a
12/4 1330 - 1615 0.14 ± 0.06
12/5 1130 - 1330 0.14 ± 0.06
12/6 1030 - 1300 0.08 ± 0.04
12/6 1300 - 1540 0.17 ± 0.04
12/10 1130 - 1400 0.15 ± 0.06
12/10 1400 - 1600 0.16 ± 0.05
12/11 1030 - 1420 0.09 ± 0.04
12/11 1430 - 1600 0.08 ± 0.03
12/12 0915 - 1215 0.60 ± 0.07
12/12 1425 - 1708 0.34 ± 0.05
12/13 0800 - 1115 0.26 ± 0.05
12/13 1115 - 1630 0.27 ± 0.07
a) Nanocuries (10~9 curies) per cubic meter plus or minus twice the
standard deviation based on counting statistics.
Total Suspended Particulates
Each of the processes sampled generates large quantities of airborne
particulates, primarily from comminution of materials during handling. It
would be expected, then, that particulate emissions would reflect the radio-
activity of the process materials. This was found to be the case, within the
limits of sample variability and analytical accuracy, for the non-volatile
radionuclides for all sources, with the possible exception of the furnace tap-
hole fume collector. The fume collector emits fumes resulting mainly from the
small amounts of phosphorus released and which are very low in radioactivity
Stack exhaust gas flow rates and TSP concentrations are given in Table 5.
Kiln Emissions
As shown in Table 3, uranium chain nuclides were in approximate equilib-
rium, with concentrations of about 0.4 pCi/m3, except for lead-210 and
polonium-210. Polonium was partially volatilized, as shown by its depletion
in nodules, and both lead and polonium were nearly completely volatilized in
the furnaces and returned to the kiln with the CO fuel. Most of these two
nuclides was removed in the spray chamber and demister, but they were still
measured at concentrations of 33 to 120 pCi/m3 for lead-210 and 64 to 280
for polonium-210. Emission rates determined from individual samples
15
-------
TABLE 3. AMBIENT AND STACK PARTICULATE RADIOACTIVITY CONCENTRATIONS
.3,a
Radioactivity Concentration (pCi/m )'
Source
Antoient
Station
Ambient
Station
Florida Ore,
Slag Storage
Slag Dump
Slag Dump
No. 3 Kiln
Demisterb
No. 3 Kiln
Demister15
No. 3 Kiln
Demister6
No. 3 Nodule
Cooler
No. 3 Nodule
Cooler
Nodule Transfer
Point Exhaust
Noifute Transfer
Point Exhaust
Nodule Transfer
Point Exhaust
Screening Plant
Dust Collector
Screening Plant
Oust Collector
Screening plant
Dust Collector
South Scale Room
Oust Collector
South Scale Room
Oust Collector
South Scale Room
Oust Collector
South Scale Room
Collected
1600 - 12/06
1830 - 12/07
0910 - 12/12
1030 - 12714
1440 - 12/07
1915 - 12/08
1200 - 12/10
0800 - 12/12
0800 - 12/12
1220 - 12/12
1340 - 1540
12/06
1720 - 1920
12/06
0952 - 1152
12/07
1338 - 1643
12/11
1012 - 1243
12/14
0922 - 1034
12/06
1208 - 1320
12/06
1505 - 1617
12/06
1057 - 1240
12/07
1408 - 1520
12/07
0933 - 1045
12/10
0913 - 1133
12/04
1522 - 1820
12/04
1524 - 1822
12/04
0928 - 1202
U-238
0.00005
0.00007
0.0022
0.00047
0.0021
0.39
0.43
0.34
0.38
0.42
1.9
3.2
0.93
3.4
13
1.4
1.1
2.0
1.4
2.0
* 0.00011
* 0.00008
* 0.0005
* 0.00016
* 0.0010
* 0.18
* 0.16
* 0.15
* 0.34
* 0.37
* 0.4
* 0.6
* 0.350.
* 0.4
* 1
* 0.5
* 0.4
* 0.5
* 0.4
* 0.5
U-234
-0.00001
0.0
0.0053
0.00071
0.0021
0.42
0.90
0.41
0.19
0.35
2.0
3.5
0.78
4.1
13
1.9
1.6
2.2
1.8
1.8
* 0.00016
* 0.0001
* 0.0005
* 0.00020
* 0.0013
* 0.21
* 0.24
± 0.20
<* 0.39
± 0.45
* 0.5
* 0.8
* 0.41
t 0.7
* 1
* 1.3
* 0.5
* 0.6
* 0.5
* 0.6
Th-i30
0.00015 * 0.00055
0.0002 * 0.0004
0.0086 * 0.0016
0.00077 * 0.00056
0.0025 * 0.0040
0.38 * 0.51
0.21 * 0.40
0.22 * 0.39
0.09 * 0.88
0.6 * 1.1
2.7 * 1.3
5.6 * 2.4
0.50 * 0.89
3.7 * 1.6
15 * 5
1.0 * 0.6
1.7 * 1.0
2.7 * 1.3
1.4 * 0.9
1.0 *1.2
Ra-226
-0.00024 * 0.00056
0.00024 * 0.00032
0.0038 * 0.0009
0.00001 * 0.00035
0.0023 * 0.0038
0.40 * 0.288
0.47 * 0.27
0.26 * 0.22
-0.12 * 0.52
-0.05 * 0.55
1.8 * 0.7
4.3 * 1.5
2.0 * 3.1
4.0 * 1.4
13 * 4
0.9 i 5.5
1.1 * 0.6
2.3 * 1.0
1.2 * 0.6
2.0 * 0.9
Pb-210
0.024 * 0.020
0.0081 * 0.0019
0.0032 * 0.0030
0.017 * 0.002
-0.013 * 0.018
110 * 8
33 * 3
120 * 5
-0.2 * 4.9
-1.6 ± 5.3
-2.7 * 5.0
1.1 * 8.4
-1.0 * 4.8
-3.3 * 5.3
9.0 * 5.3
0.5 * 2.1
-0.5 * 3.2
0.7 * 5.8
-3.5 * 4.9
-1.3 * 5.7
Po-210
0.010 * 0.019
0.006 * 0.003
0.0078 * 0.0042
0.0066 ± 0.0038
0.011 * 0.017
280 ± 15
64 * 9
67 ± 8
0.7 * 2.1
-0.4 * 2.0
0.6 * 1.7
2.1 * 3.2
0.01 * 1.7
1.4 * 2.2
1.6 * 5.1
0.5 * 2.1
-0.03 * 1.7
-1.0 * 2.1
0.3 ± 1.8
-0.4 * 2.3
Th 232
-0.00009 * 0.00029
-0.00004 * 0. 00018
0.0 * 0.00036
-0.00005 * 0.00019
0.0005 * 0.0024
-0.35 ± 0.32
0.02 * 0.25
0.05 * 0.2H
-0.17 * 0.53
-0.14 * 0.58
0.10 * 0.56
-0.05 * 0.55
-0.02 * 0.52
-0.05 ± 0.57
1.6 * 1.5
0.13 * 0.63
-0.16 * 0.48
-0.10 * 0.64
0.13 * 0.52
-0.21 * 0.64
Th-228
-0.00006 * 0.00023
-0.00003 * 0.00015
0.00003 * 0.00030
-0.00003 * 0.00015
0.0007 * 0.0021
0.33 * 0.31
0.04 * 0.24
0.07 * 0.24
-0.10 * 0.51
-0.07 * 0.56
0.01 * 0.50
-1.2 * 1.0
-1.8 * 0.9
-1.1 * 0.8
1.9 * 1.6
0.11 » O.S9
-0.10 * 0.46
-0.03 * 0.59
0.19 ± 0.50
-0.13 * 0.55
(continued)
-------
TABLE 3. (Continued)
Radioactivity Concentration (pC1/m3)a
Source
Stocking System
Oust Collector
Stocking System
Dust Collector
Stacking System
Dust Collector
Central Furnace
Stocking System
Central Furnace
Stocking System
Centra] Furnace
Stocking Systen
Furnace Tapehole
Fume Collector
Furnace Tapehole
Fine Collector
Furnace Tapehole
Fine Collector
Furnace Tapehole
Fume Collector
Collected
1040 - 1309
12/04
H53 - 1705
12/04
0905 - 1117
12/05
1351 - 1609
12/06
0658 - 1145
12/07
120S - 15*6
12/07
1355 - 1545
12.04
13S6 -1546
12/04
0844 - 1506
1525 -1808
12/05
0-236
0.80 *
0.95 *
0.66 *
0.51 *
0.90 *
0.93 *
-0.24 *
' -0.15 *
-0.001 *
-0.06 *
0.29
0.31
0.28
0.21
0.27
0.29
0.32
0.36
0.17
0.16
U-234
0.97
0.87
0.98
0.65
0.80
0.73
-0.10
0.05
-0.06
-0.06
* 0.34
* 0.36
* 0.33
* 0.27
* 0.31
* 0.30
* 0.42
* 0.42
* 0.20
* 0.20
Th-230
1.4
0.97
0.55
0.83
1.9
0.47
0.03
-0
-0.10
0.10
* 1.5
* 0.71
* 0.67
* 0.60
* 0.7
* 0.56
* 0.93
« 1.0
* 0.44
* 0.47
Ra-226
0.57
0.81
0.67
0.59
0.78
0.47
-0.04
-0.10
-0.09
-0.04
* 0.43
* 0.46
* 0.43
* 0.36
* 0.43
* 0.35
* 0.54
* 0.58
* 0.26
* 0.26
Pb-210
-0.8
0.1
0.7
-1.4
0.5
-0.3
-3.0
2.4
15
3.2
* 3.5
* 2.6
* 4.3
* 3.0
* 3.3
* 3.0
* 5.8
* 6.9
* 3
* 3.1
Po-210
-0.2
-0.7
-0.4
-0.2
0.3
0.2
0.6
1.5
0.001
1.1
* 1.4
* 1.3
* 1.3
* 1.1
* 1.3
* 1.2
* 2.2
* 2.5
* 0.38
* 1.2
Th-232
0.02
-0.02
0.06
0.07
0.11
0.06
-0.14
0.66
-0.04
-0.07
* 0.40
* 0.39
* 0.40
* 0.34
* 0.36
* 0.34
* 0.57
* 0.69
* 0.29
* 0.28
Th-228
0.04
0.03
0.11
0.11
0.15
0.10
-0.08
-1.2
0.04
-0.53
* 0.37
* 0.38
* 0.39
* 0.32
* 0.35
* 0.33
* 0.55
* 0.8
* 0.26
* 0.33
a) Plcocurlei (10~'2 curies) per actual cubic meter (volume measured at ambient or stack conditions)
plus or minus twice the standard deviation based on counting results only.
b) Plcocuries per dry standard cubic meter (volume of dry air sampled at 21 C. 760 mm Hg).
c) Duplicate sample.
-------
TABLE 4. RADON-222 STACK EMISSIONS
Concentration (nCi/m3)3 Annual
Source Time Date Gross Net
No. 3 Kiln
Demister
Source Average
No. 3 Kiln
Nodule Cooler
Source Average
Screening
Plant Dust
1500-1600
1335-1615
0825-1045
1050-1500
1330-1630
0820-0930
0815-1100
1050-1330
1325-1452
12/6
12/12
12/13
12/13
12/11
12/12
12/13
12/13
12/13
2.0
1.7
2.1
2.1
0.13
0.09
0.32
0.16
0.26
±
±
±
±
±
±
±
±
±
0.1
0.1
0.
0.
0.
0.
0.
0.
0.
,1
,1
06
05
07
04
06
1
1
2
1
1
0
-0
0
-0
-0
.8
.4
.0
.8
.8
.05
.51
.06
.11
.01
-0.10
0910-1200
12/10°
0.30
±
0.
04
0.15
±
±
±
±
±
±
±
±
±
±
±
±
0.1
0.1
0.1
0.1
0.3
0.07
0.09
0.09
0.08
0.09
0.24
0.07
9.6d
-0.19d
1330-1530 12/10 0.24 ± 0.05 0.08 ± 0.07
0940-1400 12/11 0.08 ±0.04 -0.01 ± Q.06
1100-1320 12/12C 0.15 ± 0.03 -0.44 ± 0.08
0830-1055 12/13 0.30 ± 0.06 0.04 ± 0.08
Source Average -0.04 ± 0.23 -0.046
No. 3 Furnace 0830-1500 12/15C 0.16 ± 0.03 0.02 ± 0.07 0.05f
Taphole Fume
Collector
a) Nanocuries (10~9 curies) per cubic meter plus or minus twice the
standard deviation based on counting statistics. Source average uncer-
tainties are calculated from the variance about the mean of the samples.
b) Calculated assuming 24 hour continuous operation for 50 weeks per year.
c) The results derived from duplicate Samples.
d) Annual emissions are for sum of three kilns.
e) Annual emission is for sum of two stacks.
f) Annual emission is for sum of six furnaces.
18
-------
are shown in Table 6. Mass emission rates measured from the three samples
were quite uniform. This uniformity is also evident in the radioactivity
emission rates of the non-volatile nuclides. Lead-210 and polonium-210
emission rates varied by factors of 3 to 4. The reason for this is unknown,
but it is probably due to the fact that lead and polonium, as vapors or fumes,
are not removed from the exhaust stream as consistently as the particulates.
The annual particulate radioactivity emission rates, calculated for the total
number of stacks from each type of source are shown in Table 7. Calculated
emissions of uranium, thorium-230, and radium-226 from the three kilns
averaged 2.2 mCi/y. The annual emission of lead-210 was 480 mCi and that for
polonium-210 was 750 mCi.
Nodule Cooler Emissions
Radioactivity concentrations in the nodule cooler exhaust were essentially
the same as for the non-volatile nuclides in the kiln demister. The over-
lapping confidence intervals for all nuclides and the mechanical nature of the
particulate generation suggest that the concentrations and emission rates for
all nuclides released from the coolers are approximately equal. The annual
emission rates of about 1 mCi/y for uranium-234 and -238 and thorium-230
probably hold for the other nuclides as well. Polonium-210 may actually be
close to the 0.6 mCi/y emission rate due to some depletion in the kiln.
Simultaneous sampling of the inlet to and outlet from the nodule cooler
scrubber showed an average removal of uranium chain nuclides of 99.5 percent.
Mass analysis of the filters showed an average mass removal efficiency of 98.5
percent.
Nodule Transfer Point Emissions
Concentrations of non-volatile nuclides averaged from about 1.0 to 5.6
during the three sampling periods (Table 3). Visible emissions
varied noticeably, with the controlling factor seeming to be the temperature
of nodules on the conveyor. At times the nodules were still glowing and
generated larger quantities of emissions at the transfer points. Non-volatile
radionuclide emissions averaged 1.5 mCi/y (Table 7). Polonium-210 was lower
most likely due to depletion in the kilns.
19
-------
TABLE 5. STACK FLOW AND PARTICIPATE EMISSION RATES
Source
No. 3 Kiln
Demister
No. 3 Nodule
Cooler
Nodule Transfer
Point Exhaust
Screening Plant
Dust Collector
South Scale Room
Dust Collector
Stocking
System Dust
Collector
Central Furnace
Stocking
System
Furnace Taphole
Fume Collector
Collected
Time Date
1340-1540
1720-1920
0952-1152
1338-1643
1012-1242
0922-1034
1208-1320
1505-1617
1057-1240
1408-1520
0933-1045
1913-1133
1522-1820C
1524-1822C
0928-1202
1040-1309
1453-1705
0905-1117
1351-1609
0858-1145
1208-1546
1355-1545°
1356-1546°
0844-1508
1525-1808
12/6
12/6
12/7
12/11
12/14
12/6
12/6
12/6
12/7
12/7
12/10
12/4
12/4
12/4
12/5
12/4
12/4
12/5
12/6
12/7
12/7
12/4
12/4
12/5
12/15
Exhaust Gas
Flow Rate
(m3/min)
3,399
3,554
3,554
1.657
1,571
1,223
1,118
1,224
1,105
1,091
1,104
605.1
606.3
622.7
610.1
394.8
389.1
386.8
578.1
536.1
573.2
823.9
787.1
887.3
840.3
Particulate
Concentration
(mg/m3)3
137. 4b
114. 4b
114. 4b
68.3
64.6
215.6
437.8
247.4
706 3
*J\J tj
1,664
176.1
189.1
* *J * 4
207.1
225.8
198.3
135.6
108.9
180.4
179.1
248.6
168.5
17.9
21.6
35.9
15.6
a) Flow rate and concentration volumes are actual cubic meters at stack
conditions.
b) No. 3 kiln volumes are dry, standard cubic meters (at 20°C, 760 mm mercury
pressure.)
c) Duplicate samples.
20
-------
TABLE 6. PARTICULATE RADIOACTIVITY ANNUAL EMISSION RATES
Radioactivity Emission Rates (pCt/s)'
ro
Time-Date
Source Collected
No. 3 Kiln 1340 - 1540
Demister 12/06
1720 - 1920
12/06
0951 - 1152
12/07
Source Average
No. 3 Nodule 1338 - 1643
Cooler 12/11
1012 - 1242
12/14
Source Average
Nodule 0922 - 1034
Transfer 12/06
Point 1208 - 1320
Exhaust 12/06
1505 - 1617
12/06
Source Average
Screening 1057 - 1240
Plant Dust 12/07
Collector 1408 - 1520
12/07
0933 - 1045
12/10
Source Average
South Scale 0913 - 1133
Room Dust 12/04
Collector 1522 - 1820"
12/04
0928 - 1202
12/05
Source Average
Stocking 1040 - 1309
System Oust 12/04
Collector 1453 - 1705
12/04
1905 - 1117
12/05
Source Average
Central 1351 - 1609
Furnace 12/06
Stocking 0858 - 1145
System 12/07
1208 - 1546
12/07
Source Average
(continued)
U-238
22 * 10
26 * 10
20 * 9
23 *3
10 * 9
11 * 10
TT^T-
39 * 9
59 * 11
19 * 7
39 * 20
63 * 7
230 * 20
25 * 9
110 * 110
11 * 4
18 * 3
20 * 5
16 * 5
5.3 * 1.9
6.2 * 2.0
4.3 * 1.8
smrra
4.9 * 2.0
8.0 * 2.4
8.9 * 2.8
7^1
U-234
24 * 12
54 * 14
24 * 12
34 * 17
5 * 11
9 * 12
-T-TT-
41 * 11
65 * 15
16 * 8
41 * 25
75 * 13
230 * 20
29 * 10
110 * 110
16 * 5
22 * 4
18 * 6
IB * 3
6.4 * 2.2
5.6 * 2.3
6.3 * 2.1
6.1 * 0.4
6.3 * 2.6
7.1 * 2.8
7.0 * 2.9
6.8 * 0.4
Th-230
21 * 29
12 * 24
13 * 23
15 * 5
2 * 24
16 * 29
9 * 10
56 * 26
100 * 50
10 * 18
55 * 45
68 * 29
280 * 90
35 * 23
130 * 130
17 * 10
21 * 8
10 * 12
TTST-
9.2 * 9.9
6.3 * 4.6
3.5 * 4.3
B^rrry
8.0 * 5.8
17 * 6
4.5 * 5.3
-nrrr-
Ra-226
23 * 16
28 * 16
16 * 13
2Z*6
-3 * 14
-1 * 14
~^rr
36 * 15
80 * 29
41 * 63
52 * 24
73 * 25
240 * 80
18 * 11
110 * 120
11 * 6
18 * 6
20 * 9
16 *5
3.8 * 2.8
5.3 * 3.0
4.3 * 2.8
4.5 * 0.8
5.7 * 3.5
7.0 * 3.8
4.5 * 3.3
5.7 * 1.3
Pb-210
6300 * 400
1900 * 200
7000 * 300
5100 * 2800
6 * 140
-40 * 140
^TT-inn-
-60 * 100
20 * 160
-20 * 98
-20 * 40
-61 * 97
160 * 100
20 * 100
40 * 110
-5 * 32
-14 * 39
-13 * 57
-11 * 5
-6 * 23
1 * 17
-5 * 28
-3.3 * 3.8
-13 * 29
5 * 29
-3 * 29
-T^TTO
Po-210
16000 * 900
3800 * 500
4000 * 500
7900 * 7000
20 * 580
-9 * 52
-mr
13 * 34
39 * 60
0 * 35
17 * JO
26 * 40
28 * 92
10 * 38
21 * 10
-3 * 17
-3 * 14
-4 * 23
^rr
-1.6 * 9.2
-4.9 * 8.4
-2.3 * 8.4
-2'9 * U/
-2.0 * 11
3.0 * 12
2.0 * 11
1.0 * 2./
Th-232
-20 * 18
1 * 15
3 * 14
"5 *13
-5 * 15
-4 * 15
I5TT-
2 * 11
-1 * 16
0 * 11
TTTT-
-1 * 10
28 * 27
2 * 12
10 * 16
-2*5
0*4
-2*6
Ti-T
0.1 * 2.6
-0.1 * 2.5
0.4 * 2.6
0-1 *°-*
0.7 * 3.3
1.0 * 3.2
0.6 * 3.2
0.8 * fl.2
Th-228
18 * 18
2 * 14
4 * 14
8i9
3 * 14
-2 * 15
^T
0 * 10
-22 * 19
-36 * 18
-19 * 18
-20 * 14
34 * 28
2 * 11
mi
-1 * 5
1 * 4
-1 * 6
T-TT
0.3 * 2.4
0.2 * 2.5
0.7 * 2.5
0.4 * 0.3
1.1 * 3.1
1.3 * 3.1
1.0 * 3.2
rmr?
-------
ro
ro
TABLE 6. (Continued)
Radioactivity Emission Bates (pCi/s)a
Time-Date
Source Collected
Furnace 1355 - 1545
Taphote 12/04
Fume 0644 - 1506
Collector 12/05
1525 - 1S08
12/05
Source Average
U-238
-2.7 * 3.2
0.0 * 2.5
-0.9 * 2.3
-I.Z *1.4
U-234
1.1
-0.5
-0.9
-0.1
* 4.0
* 3.0
* 2.8
* 1.1
Th-230
-2.5
-1.5
1.4
-U.9
« 9.2
* 6.5
* 6.5
* 2.0
Ra-226
-0.5
-1.4
0.5
-0.5
* 5.1
* 3.9
* 3.7
* 1.0
Pb-210
-40
230
44
~75"
* 55
* 50
» 43
* HO
8
0,
5
1-
Po-210
* n
.0 * 5.7
* 17
.3 * 4.0
TH-232
-C.I
-0.5
-1.0
* 5.4
* 4.2
* 3.9
* 0.6
Th-228
-0.1 * 5.2
0.6 * 3.9
-7.4 * 5.3
-?'3 * 4'4
a) Picocuries (ICr-l? curies) per second plus or minus the standard deviation based upon counting statistics. Source
average uncertainties are calculated from the variance about the mean of the samples.
b) Derived fron duplicate samples.
c) Exhaust fans were shut down several times.
-------
TABLE 7. PARTICULATE RADIOACTIVITY ANNUAL EMISSION RATES
Radioactivity Emission Rates
Source
Kiln Oemisters
Nodule Coolers
Nodule Transfer
Point Exhaust
Screening Plant
Dust Collector
South Scale Room
ro Dust Collector
U)
Stocking System
Dust Collector
Central Furnace
Stocking System
Furnace Taphole
Fume Col lector
Plant Total
U-238
2.2
1.0
1.2
6.9
0.50
0.33
0.23
-0.32
12
U-234
3.2
1.0
1.3
6.9
0.56
0.38
0.21
0.02
14
Th-230
1.4
0.9
1.7
8.2
0.50
0.40
0.32
-0.13
13
Ka-226
2.1
-0.2
1.6
6.9
-0.50
0.28
0.18
-0.15
11
Pb-210
480
-1.6
-0.6
1.9
-0.35
-0.21
-0.12
15
490
Po-210
750
0.6
0.5
1.3
-0.09
-0.18
0.032
1.4
750
Th-232
-0.5
-0.4
0
0.6
-0.03
0.006
0.025
-0.095
-0.39
Th-228
0.
0.1
0.6
0.3
0.00
0.025
0.035
-0.44
1.4
a) Mlllicuries (10~3 curies) per year. Calculate using concentrations found In Table 3 and emission rates trom Table 5.
-------
Screening Plant Dust Collector Emissions
As shown in Table 5, the TSP concentrations in emissions from the screen-
ing plant dust collector were the highest of any source, and also the most
variable. TSP and radioactivity concentrations varied by an order of magni-
tude over the three sampling periods. This was the most significant source of
non-volatile particulate radioactivity emissions from the controlled sources.
Emissions from the two stacks accounted for more than half of the plant total.
Other Emission Sources
Emissions from each of the other sources, except the furnace taphole fume
collector, had concentrations similar to the preceding sources. Stack flow
rates, however, were lower and emissions of non-volatile radionuclides were
less than 1 mCi/y for all these sources.
Lead-210 emission rates from the furnace taphole fume scrubber were highly
variable, ranging from -40 ± 55 pCi/s to 230 ± 50 pCi/s in the four samples
collected (Table 6). It had been shown in the earlier report that the primary
source of lead-210 from furnace tapping is FeP tapping. It is probable that
the highest lead-210 sample included an FeP tap. The polonium-210 annual
average emission rate from furnace tapping was 1.4 mCi.
Particle Size Analysis
Size-fractionated samples were collected from five stacks using an in-stack
cascade impactor sampler. Two samples were collected from each source.
Sources sampled were the screening plant dust collector, south scale room dust
collector, stocking system dust collector, central furnace stocking system,
and furnace taphole fume collector. Most of the impactor stages had such a
small mass of collected particulates that radiological analysis was not
attempted. Considering the sources of particulates collected it is reasonable
to assume that the size distribution of non-volatile radionuclides is similar
to the mass distribution.
Tne majority of mass from each source was found on the first impactor
stage. Cumulative mass analyses showed the following results for aerodynamic
particulate sizes.
24
-------
TABLE 8. AERODYNAMIC PARTICLE SIZE DISTRIBUTIONS
Source
Run 1
Size(nm) less than
Run 2
Size(ym) less than
Screening plant
South scale room
Stocking system
Central furnace
stocking system
Taphole fume scrubber
14.1
17.7
14.6
Invalid
12.3
8.7
34
6.8
Sample
18
16.2
17.7
14.2
12.4
12.1
8.9
27
48
6.9
28
High Volume Particulate Samples
Problems were encountered in collecting the high volume particulate
samples at the slag dump and Florida ore storage areas. Samplers were
unplugged by workers needing electrical outlets or power was accidentally cut
to the circuits on several occasions. As a result, sample volumes were
smaller than desired and analytical uncertainties were higher. The results
are shown in Table 3. When compared to the ambient station high volume
samples, the plant site samples show generally higher concentrations with the
highest being measured at the rail car dump site adjacent to the Florida ore
storage pile. While it is logical to ascribe these higher activities to the
slag dumping and ore handling activities no importance can be laid on them
because of the relatively uncontrolled sampling performed.
25
-------
SECTION 7
DISCUSSION OF RESULTS
As was expected, several sources of enhanced radioactivity emissions were
found at this elemental phosphorus plant. The gaseous and volatile radio-
nuclides - radon, polonium-210, and lead-210 - were driven off the process
materials in either the kilns or furnaces and ultimately exhausted to the
atmosphere via the kiln exhausts. These radionuclides were also those
released in greatest quantity. Annual radon emissions from the kilns were
measured at 9.6 Ci/y. Although the kiln emission control system was not
designed to remove lead and polonium fumes most of them were removed and
annual emission rates were 0.48 Ci for lead-210 and 0.75 Ci for polonium-210,
about an order of magnitude below the radon.
The screening plant dust collector emissions were found to account for
more than half of the non-volatile radioactive nuclides emitted from the
plant's controlled sources. The mass emission rates varied from 11.7 to 109
kg/h, compared to a rate of 2.9 kg/h reported by Monsanto. Mass emission
rates measured at the other sources were generally about twice as much as
reported by Monsanto 2 years earlier. The large amount of particulates from
the screening plant dust collector, and their greatly varying quantity suggest
that the emission control system was not operating properly during the survey.
If the average observed mass emission rate of 56 kg/h was reduced to 2.9 kg/h
the average non volatile radionuclide emission rates would be reduced from 7.2
mCi/y to 0.36 mCi/y. That would put it in line with the other material
handling processes following the nodule transfer point control system and
would reduce the plant emissions of the non-volatile nuclides by about one
half.
If the screening plant dust collector was not operating at design
efficiency, correcting the problem would reduce mass emissions, but would
probably not reduce the respirable fraction by the same proportion. As shown
before only 8.8 percent, on the average, of the mass emissions were below 14.1
to 16.2 urn aerodynamic diameter. Large particles would normally be removed
with more efficiency than small particles. This is shown to some degree by
the size distributions found for the other sources measured.
The two major sources of uncontrolled emissions, materials handling in the
kiln-nodule cooler area and open nodule craneway storage area, produce
primarily large particles that are deposited in the immediate area. Very
little airborne material was visibly evident at any appreciable distance from
these sources.
26
-------
REFERENCES
1. National Council on Radiation Protection and Measurements. Natural
Background Radiation in the United States, NCRP Report No. 45, Washington,
D.C., 1975.
2. Habashi, Fathi. Uranium in phosphate rock. Special Publication 52,
Montana Bureau of Mines and Geology, Montana College of Mineral Science
and Technology, Butte, Montana, December 1970.
3. Menzel, F.G. Uranium, radium, and thorium content in phosphate rocks and
their possible radiation hazards. Journal of Agriculture and Food
Chemistry, Vol. 16, No. 2, pp. 231-234, 1968.
4. Eadie, Greogry G., and David E. Bernhardt. Radiological surveys of Idaho
phosphate ore processing - the thermal process plant. U.S. Environmental
Protection Agency, Technical Note OPR/LV-77-3, Las Vegas, Nevada, November
1977.
5. Engineering-Science, Inc. Collection of airborne radon and radioactive
particulates at the Monsanto Chemical Intermediates Columbia Elemental
Phosphorus Plant Columbia, Tennessee. McLean, Virginia, April 1980.
6. Code of Federal Regulations, Title 40, Chapter 1, Part 60, Appendix A.
7. Code of Federal Regulations, Title 40, Chapter 1, Part 50, Appendix B.
27
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
EPA-520/6-82-021
4. TITLE AND SUBTITLE
2.
Emissions of Naturally Occurring Radioactivity:
Monsanto Elemental Phosphorus Plant
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
November 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Vernon E. Andrews
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Radiation Programs-Las Vegas Facility
P.O. Box 18416
Las Vegas, Nevada 89114
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
This is the fourth in a series of reports covering work performed in response to the
1977 Clean Air Act Amendments
16. ABSTRACT ~~ ' '
Naturally occurring radioactivity was measured in the atmospheric emissions and
process materials of a thermal phosphate (elemental phosphorus) plant. Representative
exhaust stack samples were collected from each process in the plant. The phosphate
ore contained 12 to 20 parts per million uranium. Processes, emission points, and
emission controls are described. Radioactivity concentrations and emission rates from
the sources sampled are given.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Natural Radioactivity
Airborne Wastes
Exhaust Gases
Technologically
enhanced
radioactivity
1808
1302
2102
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (TMiReport)
Unclassified
20. SECURITY CLASS (Tills page)
Unclassified
21. NO. OF PAGES
27
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS EDITION is OBSOLETE
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