Emissions of Naturally Occurring Radioactivity : Stauffer Elemental Phosphorus Plant

PxEPA
United St.-

Age i
Office of Radiation Pro
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EPA-520/6-82-019
November 1982
EMISSIONS OF NATURALLY XCURRING RADIOACTIVITY
STAUFFER ELEMENTAL PHOSPHORUS PLANT
Vernon E. Andrews
Office of Radiation Programs-LVF
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
and
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 PEDCo Environmental Inc. contract 68-12-2811
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, and approved for
publication. Mention of trade names or commercial products constitutes
neither endorsement nor recommendation for their use.
n
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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 the
associated radioactivity 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
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CONTENTS
Page
Forward iii
Figures vi
Tables vi

1. Background 1
2. Introduction 3
3. Summary 4
4. Plant Operations 5
Product Flow 5
Emission Points 8
5. Sample Collection and Analysis 10
Sample Collection 10
Sample Analysis 12
Data Reporting 12
6. Sample Results 13
Process Samples 13
Ambient Air Samples 13
Emission Samples 18
Radon Emanation Results 21
7. Population Distribution 25
8. Discussion of Results 26

References 28
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FIGURES

Number Page
1 Uranium and Thorium Radioactivity Decay Schemes 2
2 Stauffer Chemical Plant Location 6
3 Stauffer Chemical Plant Flow Diagram 7
4 Sampling Sites for Radon Emanation from Soil, Ore, and Slag 11
TABLES
Number Page
1 Process Materials Radioactivity Concentrations 14
2 Ambient Radon-222 Concentrations 15
3 Ambient and Stack Particulate Radioactivity Concentrations 16
4 Radon-222 Stack Emissions 19
5 Particulate Radioactivity Emission Rates 20
6 Particulate Radioactivity Annual Emission Rates 22
7 Scrubber Removal of Radionuclides 23
8 Radon-222 Emanation Rates from Soil, Ore, and Slag 24
vi
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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 approx-
imately 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. These surveys were
screening studies designed to identify important sources of airborne emissions
•of radionuclides at individual facilities.

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.
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URANIUM - 238 DECAY SERIES
THORIUM - 232 DECAY SERIES
ro
238
U
4 BxlO'yr
a
234
Th
24 da

234
Pa
6 75 hr
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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
pCi/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 the phosphate
ores. The EPA had conducted a comprehensive radiological survey of a thermal
phosphate (elemental phosphorus) plant in 1975 (4). However, problems
associated with the analyses for 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 first of
the plants surveyed was the Stauffer Chemical Company plant in Silver Bow,
Montana.

PEDCo Environmental, under contract with EPA, conducted the survey and
collected samples (5). Before the survey, representatives of PEDCo Environ-
mental and EPA visited the plant to select sampling locations. During the
period October 15-31, 1979 PEDCo Environmental, accompanied by an EPA
representative, conducted the sampling and measurement program, collecting
particulate and gas samples from plant effluents and ambient air as well as
information on plant operations. Stauffer provided meteorological data
collected by one of their meteorology stations.
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SECTION 3

SUMMARY
PEDCo Environmental collected samples of participate and gaseous emissions
from all controlled sources at the Stauffer Chemical Company plant. Ambient
particulate and gaseous samples were collected at a site 1.6 km east of the
plant. Radon-222 emanation rates were measured from soil around the plant,
from an ore storage pile, and the slag pile.

The kiln stacks emitted essentially all of the radioactivity emitted from
controlled sources. They accounted for 99 percent of the lead-210, 97 percent
of the polonium-210, and 98 percent of the radon-222. Annual emission rates
of the three radionuclides from all stacks were measured at 280 mCi for
lead-210, 200 mCi for polonium-210, and 8.2 Ci for radon-222. An additional
estimated release of 1.2 Ci/y of radon-222 is produced by ore in storage.
Annual emission rates of uranium-238 and -234, thorium-230, and radium-226
were measured at an average amount of 0.22 mCi for each radionuclide. The
estimated release of each of those radionuclides, based on measured mass
emission rates and assuming that the radioactivity concentration in the
emitted particulates was the same as in the materials handled by the process
was 4.2 mCi/year.

The radon emanation rate from the slag pile, with an average radium-226
concentration of 27 pCi/g was 3.5 ± 3.7 pCi/m^-min; much less than the soil
emanation rate of 18 * 9 pCi/m^-min. The average emanation rate from the
ore pile was 117 ± 138
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SECTION 4

PLANT OPERATIONS
PRODUCT FLOW

The Stauffer Chemical Company Silver Bow Plant is located in the community
of Silver Bow, approximately 11 km west of Butte, Montana (Figure 2). Ore is
delivered by rail from a mine in Idaho. The plant product is elemental
phosphorus. A by-product is ferrophosphorus (FeP), which is sold as a steel
alloying additive. The other solid product is slag, which can be either a
by-product or a waste product. Stauffer sold their slag for use as highway
aggregate until shortly before this survey. Pending further radiation
studies, Stauffer voluntarily withdrew their slag from the market.

Figure 3 is a schematic of the plant operation. Ore rail cars are dumped
into a pit from which ore is moved to one of two large storage piles
(Figure 4). The process of ore blending begins at this point as the ore
stockpile is built up by layers. One pile is built while ore is drawn from
the other pile. Because of the severe winter weather, ore is shipped during
the summer and stockpiled for year-round use.

The ore is further blended when it is recovered from the stockpile and
moved into a pit where it is transferred by hoppers in the kiln feed building.

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 two rotary kilns at about 1300°C. The
temperature of the ore is raised to its incipient melting point and the
tumbling action forms the ore into the desired nodular form. The hot nodules
'pass through coolers and crushers before being conveyed to storage silos.

The furnace feed consists of a mix of ore nodules, silica rock, and coke.
A proper fraction of silica is required to form slag with the necessary flow
properties to facilitate removal from the furnace. The content of silica
occurring naturally in the ore must be augmented with added silica. Coke is
added as a carbon source to reduce the calcium phosphate ore to elemental
phosphorus. The approximate reaction is:

2Ca3(P04)2 + 10 C + 6 Si02 —» P4 + 10 CO + 6 CaSi03

Nodules, coke, and silica are fed from storage silos by means of a proportion-
ing belt and skip hoist to "burden bins" which provide a continuous feed to
the furnaces.

Feed material enters the electric arc furnaces from the top and progresses
downward until reaching the molten layer on the bottom. Phosphorus and CO are
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1-90
Stauffer
Chemical
Plant
KILOMETERS
0 1
Figure 2. Stauffer Chemical Plant Location
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it Emission/Sampling Point
Figure 3. Stauffer Chemical Plant Flow Diagram
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driven off as gases and are piped off near the top of the furnace. The slag
and FeP which are continually collecting in the furnace are periodically
tapped off. FeP is tapped for about 20 minutes each 8-hour shift. Slag is
tapped (or flushed) in an 80 to 90 minute operation about seven or eight times
per 24-hour period. FeP is cooled and crushed for shipment. Slag is disposed
of on site.

The product gases through an electrostatic precipitator where particulate
contaminants are removed, and then through a spray tower where water sprays
cool the phosphorus to below the condensation point. The molten phosphorus is
filtered to remove any carry-over particulates and piped into rail tank cars
for shipment. The remainder of the gas stream, primarily CO, is used as fuel
in the kilns. Sludge resulting from the phosphorus filtering operation is
roasted to recover any residual phosphorus. Roaster residue is spread in a
6-inch layer on the stockpile prepared for winter use to prevent the damp ore
from freezing in the pile and hampering recovery.

EMISSION POINTS

Oust generated while conveying ore to the kiln feed building hoppers is
collected by a hooding system. The air is discharged through a wet scrubber.

Exhaust gases from the rotary kilns are cleaned by multiple air cleaning
devices which remove both particulates and fluorine.

Exhaust gases from the nodule coolers are treated by two sets of multiple
air cleaning devices to remove particulates.

Emissions occurring within the kiln building from materials handling and
coke drying are collected by the ventilator collector system. This system
exhausts through two sets of multiple air cleaning devices.

Emissions arising from transfer to and storage in the burden bins of
nodules, coke, and silica are collected by a hooding system and discharged
through a wet scrubber.

A small amount of phosphorus is released during slag and FeP tapping.
Upon oxidizing in air the phosphorus forms a dense white cloud of Po05
fumes. Collecting hoods intercept most of the P205 fumes and other
emissions and discharges them through the tap hole fume scrubber.

With the installation of air pollution control systems on most of the
sources of particulate emissions, the visible emissions during the period of
the survey originated from two primary sources. One is a periodic release of
some of the fumes produced during furnace tapping. The other source is the
nodule storage silo area. Material handling at the burden bins generates con-
siderable dust which exits the building through roof ridgeline ventilators.
No satisfactory method has been devised to control these dust emissons. The
point of emission is also inaccessible to sampling.
8
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Other potential sources of airborne radioactivity were the ore storage
piles and slag piles. These were considered as possible sources of gaseous
radon-222.
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SECTION 5

SAMPLE COLLECTION AND ANALYSIS
SAMPLE COLLECTION

Most samples were collected using EPA reference methods (6). Stack
sampling points were selected according to EPA Method 1. Stack gas velocity
and volumetric flow rate were determined by EPA Method 2. Gas samples for
radon analysis were collected using EPA Method 3. (Radon in this report means
radon-222). Total suspended particulates (TSP) in ducts and exhaust stacks
were determined using EPA Method 5. High volume ambient TSP samples were
collected in accordance with the Reference Method for the Determination of
Suspended Particulates in the Atmosphere (7).

PEDCo collected Method 5 TSP samples on 7.6-cm (3-inch) diameter 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.

PEDCo sampled each of the emission points described on page 8 except the
silo fugitive emissions. They collected two to four samples each of TSP and
gas samples from each point. These points are shown in Figure 3. Where more
than one exhaust of a given type existed, such as kiln exhausts, they only
sampled one. At two locations it was possible to obtain simultaneous samples
from the inlet and outlet of an emission control system.

Radon emanation rates from the surface of the ore pile and surrounding
soil areas was measured at the locations shown in Figure 4 by means of char-
coal canisters. U.S. Army M-ll gas canisters containing activated charcoal
were placed on the surface to collect radon gas emitted. The canisters were
left in position for the duration of the survey. Radon emanation rates from
the slag pile were measured using inverted tubs sealed to the surface
(Figure 4). The tubs were sealed to the slag pile using dry bentonite clay
powder moistened in place. A valve and gas cock in the bottom of the tub
permitted the collection of air samples at the time of placement and after an
elapsed time of 2 to 3 hours. The change of radon concentration in the
53-liter tub made it possible to calculate the rate of emanation from the
surface beneath the tub.

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.
10
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®
COUNTY ROAD
PLANT
ORE
ORE
SLAG
'PILE
PLANT BOUNDARY
Approximate Scale
LEGEND
(7) Soil Background
|T] Slag Pile Sample
0 0.2 0.4 0.6 0.8 1.0
Kilometers
Figure 4. Sampling Sites for Radon Emanation from Soil, Ore, and Slag
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SAMPLE ANALYSIS

PEDCo made mass determinations on TSP samples before forwarding them to
Eberline Instrument Corporation (EIC) for radiochemical analysis. Stack and
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
separating the elements of interest by chemical techniques. The separated
uranium and thorium fractions were counted on alpha spectrometers for
individual isotopic quantitation. 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
scintillation cells and counted for radon.

The EPA's project officer collected the slag pile radon samples directly
into evacuated alpha scintillation cells and counted for radon the same day.

PEDCo shipped the radon emanation canisters by air express to the EPA
Eastern Environmental Radiation Facility in Montgomery, Alabama. EPA analyzed
the canisters on a gamma spectrometer and reported the results as radon flux
(emission rate per unit area) from the surface.

DATA REPORTING

The radioactivity reported for each sample, except for charcoal canisters,
is the net radioactivity plus or minus twice the standard deviation (2s) based
on counting statistics. The net radioactivity is the gross sample radio-
activity minus counter background and (1) for filter samples, minus an average
value for the radioactivity content of a blank filter, or (2) for stack radon
samples, minus the ambient radon concentration. The counting variation, plus
the variable radioactivity content of individual blank filters, occasionally
results in a net radioactivity of less than 0. Of course, there is no
negative radioactivity. In these cases, as with all others, the net negative
results must be considered along with the 2s uncertainty.

The sample standard deviation is based only on the random variations
inherent in radioactivity counting and is propagated only in those situations
of either duplicate emission samples or samples describing process materials.
This uncertainty is not propagated when samples are collected at different
times yet are combined to describe a source average. In these cases where
multiple samples are averaged, the standard deviation is calculated from the
variance in the samples. Since there is no adequate way of describing the
variability in daily emissions for the control technology, the annual
emissions have no associated error term.
12
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SECTION 6

SAMPLE RESULTS
PROCESS SAMPLES

The average concentration in ore of radionuclides of the uranium-238
series was 32 pCi/g (Table 1). The apparent departures from secular equilib-
rium reported for the individual nuclides of the uranium series in ore samples
are due primarily to a combination of statistical variations in counting and
analytical biases. Uranium was above the normal concentration in rock by
about a factor of 50. The thorium series was at a normal concentration level.

Although a large fraction of the ore was removed as elemental phosphorus
and oxygen, the radionuclide concentrations in slag are similar to those in
ore due to the diluting effect of the added silica. The major differences
between ore and slag concentrations are for lead-210 and polonium-210, both of
which are volatilized and driven off during processing. Radionuclide concen-
trations in the nodules show that about half the lead-210 and essentially all
of the polonium-210 are lost during calcining. The rest of the lead-210 is
lost during the thermal reduction process. FeP contains significant concentra-
tions of uranium-234 and -238. However, the FeP is produced in much smaller
quantity than slag and most of the uranium is found in the slag. Radionuclide
concentrations in the four slag pile samples are in very close agreement,
reflecting the uniformity of blended feedstock and overall operations.

AMBIENT AIR SAMPLES

Radon-222 concentrations measured at the background station are shown in
Table 2. The samples collected from 1440 to 1758 hours on October 17 and on
October 18 were collected during periods when the wind direction was primarily
from the plant to the sampling site. All other samples were collected during
periods when the sampling site was either upwind or crosswind from the plant.
No effect of plant operation is apparent from the results and all samples are
considered to represent ambient concentrations. Ambient radon concentrations
vary from less than 0.1 to about 1 nCi/m3, depending on time of day, season,
and meteorology (1).

Three filters from the background high volume samplers were analyzed for
ambient particulate radioactivity concentrations. The results are in Table 3.
The measured concentrations of the uranium, thorium, lead, and radium isotopes
are comparable to those found throughout the United States (1). The polonium-
210 concentrations of 0.020 and 0.029 pCi/m3 in the October 18-21 and
October 26-28 samples are an order of magnitude higher than the normal back-

13
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TABLE 1. PRXESS MATERIALS RADIOACTIVITY CONCENTRATIONS
Radioactivity Concentrations (pC1/g)a
Material
Phosphate Ore
Phosphate Ore
Average^
Nodules
Coke 0
Silica 0
Fresh Slag
Fresh Slag
Average*3
Ferrophosphorus
Ferrophosphorus
Averageb
Slag, Drum Site 1
Slag, Drum Site 2
Slag, Drum Site 3
SI ag, Drum Site 4
Average*3
U-238
29 * 3
24 * 2
27 ± 2
26 * 2
.24 * 0.10
.14 * 0.07
26 * 2
25 ± 4
26 * 2
11 * 3
10 * 3
11 * 2
20 ± 2
26 * 2
22 ± 2
26 * 2
24 * 1
a Picocuries (10~12 curies)
U-234
29 ± 3
23 * 2
26 * 2
26 * 2
0.31 * 0
0.24 * 0
26 ± 2
25 ± 4
26 ± 2
7.6 ± 2
9.6 * 3
8.6 * 1
20 * 2
26 ± 2
22 ± 2
26 * 2
24 * 1
per gram
Th-230
54 * 11
24 * 6
39 * 6
51 * 11
.12 0.31 * 0.29
.09 0.48 * 0.31
54 * 13
46 * 14
50 * 10
.1 0.56 * 0.44
.1 0.45 ± 0.38
.9 0.51 * 0.29
37 ± 8
58 * 18
46 ± 18
39 * 8
45 * 7
plus or minus the
b Counting statistic standard deviation propagated to
Ra-226
31 * 9
21 * 6
26 * 5
21 * 6
0.11 ± 0.
0.18 * 0.
31 ± 9
28 * 8
30 ± 6
0.35 * 0.
0.39 ± 0.
0.37 * 0.
24 ± 7
29 * 9
21 * 6
Pb-210
41 *
34 *
38 *
22 *
03 0.52 *
05 0.55 *
0.53 *
-1.4 *
-0.4 *
11 0.79 *
12 0.67 *
08 0.73 *
1.3 *
1.5 *
1.7 *
34 * 10 2.6 *
27 * 4
standard
1.8 ±
deviation
2
2
1
2
0.76
0.78
0.90
1.8
1.0
0.88
1.7
0.96
0.9
0.8
1.3
1.3
0.6
based
Po-210
33
38
36
2.7
0.3
-0.3
0.0
1.8
0.9
-0.9
0.6
-0.2
6.8
1.1
1.4
0.32
2.7
± 3
* 3
± 2
* 3.9
* 2.8
* 2.7
* 2.8
* 3.1
± 2.1
* 2.5
± 2.9
* 1.9
± 4.1
* 5.5
* 5.6
* 2.1
* 2.3
on counting
Th-232
0.20 * 0.23
0.32 * 0.30
0.26 * 0.19
0.06 * 0.13
0.06 * 0.13
0.04 * 0.09
0.76 ± 0.47
1.1 * 0.6
0.93 * 0.38
0.08 * 0.16
0.07 * 0.15
0.08 * 0.11
0.21 ± 0.21
0.36 ± 0.28
0.42 * 0.28
0.57 * 0.33
0.39 ± 0.14
statistics.
Th-228
0.20
0.84
0.52
0.06
0.06
0.04
0.43
0.07
0.25
0.08
0.07
0.08
0.21
0.95
0.73
0.58
0.62

± 0.23
± 0.50
± 0.28
* 0.13
± 0.13
* 0.09
± 0.21
* 0.14
± 0.13
* 0.16
± 0.15
* 0.11
* 0.21
* 0.71
* 0.59
* 0.41
± 0.26

average result.
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ground of 0.001 to 0.003 pCi/m3. The polonium-210 concentration of 0.0043 ±
0.0028 pCi/m3 is in the range of expected background. Using the hourly
average wind speed and direction data provided by Stauffer the estimated
polonium-210 concentrations at the drive-in theater site were calculated. The
estimates were made using a Gaussian plume diffusion model and Pasquill's
diffusion categories (8). The calculated concentrations for the three sampling
periods, including an estimated background of 0.001 pCi/m3, were 0.027,
0.003, and 0.001 pCi/m3. Of the first result, 0.021 pCi/m3 was due to a
1-hour observation with an average wind speed of 0.8 km/h, and the background
site was 1.6 km from the plant. If that 1-hour observation is not used in the
calculations the predicted concentration becomes 0.006 pCi/m3. From the
calculations it is obvious that some polonium-210 above background would be
expected at the drive-in theater site under the meteorological conditions
observed on October 19-20 and 27-28. Considering the sensitivity of the
predictive model to proper selection of stability factors and precise wind
direction measurement, the measured values for polonium-210 concentration are
believed to be valid.
TABLE 2. AMBIENT RADON-222 CONCENTRATIONS
Time Concentration

Date On - Off (nCi/m3)a

10/17 0910 - 1418 0.39 ± 0.10

10/17 1440 - 1758 0.16 ±0.06

10/18 1032 - 1319 0.32 ± 0.09

10/18 1320 - 1635 0.20 ± 0.09

10/22 1058 - 1314 0.13 ± 0.06

10/22 1315 - 1605 0.12 ± 0.04b
10/22 1606 - 1859 0.17 ± 0.05
a Nanocuries (10~9 curies) per cubic meter plus or minus twice the
standard deviation based on counting results only.

b Derived from duplicate samples.
15
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TABLE 3. AMBIENT AND STACK PARTICULATE RADIOACTIVITY CONCENTRATIONS
Radioactivity Concentrations (pCt/ni3)'
Time - Date
Source Collected
Ambient Air 2355 - 10/18
0022 - 10/21
Ambient Air 0026 - 10/26
0021 - 10/28
Ambient Air 0030 - 10/28
0049 - 10/30
Kiln Feed 0852 - 1032
Conveyor 10/30/79
Kiln Feed 1305 - 1510
Conveyor 10/30/79
Kiln 1 1324 - 1627
Scrubber Exhaust 10/25/79
Kiln 1 1718 - 1943
Scrubber Exhaust 10/25/79
Kiln 1 1046 - 1701
Scrubber Exhaust 10/26/79
Nodule Cooler 0940 - 1610
10/19/79
Nodule Cooler 0941 - 1612b
10/19/79
Nodule Cooler 0956 - 1225b
U-238
0.000049
0.00016
0.00014
-0.01
-0.01
0.34
0.32
0.19
0.36
0.05
-0.07
* 0.000076
* 0.00010
* 0.00010
* 0.22
* 0.21
« 0.20
« 0.20
» 0.20
* 0.26
* 0.18
* 0,18
U-234
0.00007
0.00014
0.00013
0.12
-0.02
0.45
0.17
0.10
0.28
0.05
-0.07
* 0.00013
* 0.00014
* 0.00014
* 0.30
» 0.28
* 0.26
* 0.24
* 0.25
* 0.31
* 0.24
* 0.24
Th-230
0.00008
0.00037
0.00010
-0.02
-0.03
0.26
0.42
-0.01
0.4
0.08
-0.02
* 0.00035
* 0.00039
* 0.00034
* 0.68
* 0.66
* 0.58
* 0.67
* 0.15
* 1.2
* 0.56
* 0.55
Ra-226
-0.00013
0.00001
-0.00006
0.03
0.10
0.45
0.39
0.40
0.63
0.06
0.20
* 0.00045
* 0.00043
* 0.00045
* 0.42
* 0.42
* 0.34
* 0.34
* 0.36
* 0.45
* 0.33
* 0.35
Pb-210
0.020
0.0074
0.0074
0.7
0.3
380
420
210
0.3
0.1
0-7
* 0.002
* 0.0023
* 0:0014
* 2.9
* 2.7
* 34
* 35
4 7
* 2.8
* 2.2
* 2.4
Po-210
0.020
0.029
0.0043
1.1
0.6
190
2bO
290
11
7.4
0.8
* 0.002
* 0.005
* 0.0028
* 1.4
* 1.3
* 27
* 28
* 14
* 3
* 1.8
* 1.1
Th-232
0.00007 *
0.00009 *
0.00008 *
-0.10 *
-0.12 *
-0.07 *
-0.06 *
-0.07 *
-0.08 *
0.02 *
-0.08 *
0.00024
0.00025
0.00025
0.44
0.42
0.33
0.35
0.36
0.45
0.39
0.36
Th-228
0.00008
0,00010
0.00009
-0.05
-0.05
-0.03
-0.02
-0.03
-0.03
0.06
-0.04
* 0.00018
* 0.00018
* 0.00018
* 0.42
* 0.40
* 0.32
* 0.34
* 0.35
* 0.43
* 0.38
* 0.34
(continued)
-------
TABLE 3. (Continued)
Radioactivity Concentrations (pC1/m3)a
Source
Kiln Building
Ventilator
Kiln Building
Ventilator
Kiln Building
Ventilator
Silo System
Exhaust
51 lo System
Exhaust
Tap Hole
Fume Scrubber
Tap Hole
Fume Scrubber
Tap Hole
Fume Scrubber
Collected
1305 - 1553
10/19/70
0955 - 1225
10/24/79
1000 - 1224
10/24/79
1015 - 1221
10/29/79
1421 - 1624
10/29/79
1550 - 1805
10/16/79
0935 - 1145
10/17/79
1435 - 1637
10/17/79
I
0.37

0.36

0.29

0.23

-0.06

0.01

-0.04

-0.01

J-238
* 0.29

* 0.32

* 0.20

* 0.21

* 0.14

U-
0.37

0.51

0.29

0.32

-0.06

0.04

-0.06

-0.01

-234
* 0.32

* 0.41

* 0.23

* 0.26

* 0.18

Th-230
0.51

1.3

0.29

0.39

-0.03

-0.01

-0.02

* 0.77

* 1.1

* 0.44

* 0.68

* 0.43

* 0.41

* 0.43

Ra-226
0.57 *

0.77 *

0.42 *

0.77 *

-0.11 *

-0.10 *

-0.04 *

-0.18 *

0.37

0.51

0.29

0.39

0.26

0.25

0.26

Pb 210
1.3

0.02

0.5

1.2

0.7

0.6

7.9

4.2

* 2.2

* 3.2

* 1.7

* 2.0

* 1.8

* 1.7

* 1.1

* 0.8

Po-210
0.19 * 0.94

-0.4 * 1.4

-0.14 * 0.69

0 * 1.5

0 * 1.2

0 * 0.75

15 * 5.4

3.1 * 3.9

Th-
-0.02

-0.11

-0.06

0.05

-0.08

-0.06

-0.07

-0.06

•?32
* 0.34

* 0.49

* 0.25

* 0.35

t 0.26

* 0.26

i 0.26

* 0.27

Th-
0.01

0.06

-0.03

0.08

-0.05

-0.03

-0.04

-0.03

228
* 0.33

* 0.47

* 0.24

* 0.34

* 0.25

i 0.26

a Picocuries (10~^ curies) per cubic meter plus or minus twice the standard deviation based on counting results only.

Results derived from duplicate samples.
-------
EMISSION SAMPLES

Radon sampling results are shown in Table 4. Gross concentrations measured
in the stacks, net concentrations above the measured ambient concentrations
and average concentrations are given along with the derived annual emission
rates. Annual emission rates were calculated assuming full-time operation of
the process and annual average concentrations equal to the average obtained
from the samples.

Two sources, the kilns and the silo system exhaust, had average concentra-
tions which were significantly different from ambient. Net average radon
concentrations were 12 ± 11 and 0.12 ± 0.17 nCi/m^ respectively. The
associated annual releases were 8.2 and 0.034 curies. Thus, the kilns were
responsible for essentially all the radon emitted from the plant stacks.

Particulate radioactivity concentrations measured in stack emissions are
given in Table 3. These concentrations are calculated using the radionuclide
activity on the filter media and the sample volume corrected to stack
conditions. Using these values, the stack emission rates (pCi/sec) were
determined and summarized in Table 5. These rates are calculated from the
ratio of the stack flow rate (in standard ft^/hr, dry) to the sample volume
(standard ft^, dry). Specific stack test and sample parameters are
contained in the emission test report (5). PEDCo Environmental has calculated
and summarized these ratios or "scaling factors."

Radioanalytical results for the kiln feed conveyor exhaust samples were
not significantly different from zero. PEDCo reported an average mass
emission rate from this source of 0.98 pounds per hour (0.12 g/sec). Using
the measured radioactivity in ore, each of the uranium chain radionuclides
should have been emitted at the rate of 4 pCi/sec from the kiln feed conveyor
exhaust.

The emission rates of uranium-238 and -234, thorium-230, and radium-226 in
the kiln scrubber exhaust averaged about 3.6 pCi/sec. Emission rates of
lead-210 and polonium-210 from the kiln scrubber exhaust were 4,500 pCi/sec
and 3,200 pCi/sec, respectively.

Measured concentrations and emission rates of uranium-238 and -234,
thorium-230, radium-226, and lead-210 from the nodule cooler did not differ
significantly from zero. Based on the measured mass emission rates and radio-
activity of the nodules the best estimate of the release rates of each of
those radionuclides would be 2.7 pCi/sec. Only polonium-210 was measured at
concentrations significantly above zero. The average emission rate was
50 pCi/sec.

The kiln building ventilator is the major controlled source of particu-
lates. As a consequence it was also the major source of uranium-238 and -234,
thorium-230, and radium-226. Emissions of each of those radionuclides plus
lead-210 averaged 15 pCi/sec.
18
-------
TABLE 4. RADON-222 STACK EMISSIONS
Concentration (nCi/m3)3
Annual
Source
Kiln Feed
Conveyor

Kiln

Time
1106 -
1320 -
1041 -

0930 -
1328 -
1025 -

1320
1623
1309

1328
1555
1358

Date
10/18
10/18
10/22d
Source
10/18
10/18
10/22d
Source
Gross
0.36 ±
0.23 ±
0.22 ±
Average
14 ±
0.35 ±
22 ±
Average
0.13
0.11
0.04

1
0.14
1

Total for 2
Nodule
Cooler

1005 -

1627 -

1420

1829

10/18

10/22d
Source
0.33 ±

0.30 *
Average
0.09

0.05

Total for 2
Kiln
Building
Ventilator
1153 -
1623 -

1345
1823

10/18J
10/22d
Source
0.45 ±
0.16 ±
Average
0.13
0.04
0.
0.
0.
0.

kilns
0.

0.
0.
Net1-
04
03
09
Ob
14
15
22
12

13
07
±
±
±
±
±
±
±
±

±
±
Release (Ci)
0.16
0.14
0.07
0.03
1

0.013

0.15
1

4.1
O"
0.13

0.07
0
.08
coolers
0.
-0.
13
01
0.06
Total for 2
Silo System
Exhaust

Tap Hole
Fume
Scrubber
1400 -
1646 -

0933 -
1413 -

1643
1846

1410
1740

10/22
10/22
Source
10/17
10/17
Source
0.12 ±
0.41 ±
Average
0.28 ±
0.23 ±
Average
0.09
0.04
venti
±
±
±
0
0
0
.16
.07
.10
lators
0.00
0.24
0.12
0.10
0.08
-0.11
0.07
-0.02
a Nanocuries (10~9 curies) per cubic meter.
b Radon-222 concentration in sample as collected plus
±
±
±
±
±
±
or
0
0
0
0
0
0
.10
.06
.!/
.14
.10
.13
minus
0.020
-------
TABLE 5. PARTICIPATE RADIOACTIVITY EMISSION RATES
Radioactivity Emission Bates (pCl/sec)
Source
Kiln Feed
Conveyor
Ki In Feed

Kiln 1,
Scrubber Exhaust
Kiln 1,
Scrubber Exhaust
Kiln 1,

ro
o
Nodule Cooler

Nodule Cooler

Kiln Building
Ventilator
Ki IT Building
Venti lator

Silo System
Exhaust
Si lo System
Exhaust

Tap Hole
Fume Scrubber
Tap Hole
Fume Scrubber
Tap Hole
Fume Scrubber
Time - Date
Collected U-238
0852 - 1032 -0.13
10/30/79
1305 - 1510 -0.9
10/30/79
Average -0.11 * 1.6
1324 - 1627 4.6 * 2.7
10/25/79
1718 - 1943 4.3 « 2.7
10/25/79
1046 - 1701 2.5 * 2.6
10/26/79
Average 3.8 * 1.5

0940 - 1610b 1.9 * 1.5
10/19/79
0956 - 1225 -1.3 * 3.2
10/24/79
Source Average 0.30 * 1.8
1305 - 1553 7.6 * 5.9
10/19/79
0955 - 1225h 12 * 6.6
10/24/79
Source Average 9.8 * 4.5
1015 - 1221 2.5 * 2.2
10/29/79
1421 - 1624 -0.72 * 1.7
10/29/79
Average 0.89 * 1.4
1550 - 1305 0.2 * 2.6
10/16/79
0935 - 1145 -0.83 * 2.6
10/17/79
1435 - 1637 -0.15 * 2.5
10/17/79
U-?34 O!-230
1.2

-0.22

0.5
6.0

2.3

1.3

3.2

1.0

-1.3
-0.15
7.6

11
3.4

-0.72

1.3
0.70

-1.1

-0.15

* 3.0

* 2.8

4 2.1
* 3.5

* 3.3

* 3.2

* 1.9

* 1.8

* 4.3
* 2.3
* 6.6

* 8.6

* 5.4
* 2.8

* 2.2

* 1.8
* 3.4

* 3.4

» 3.3

-0.2R

-0.30

-0.26
3.5

5.7

-0.13

1.9

2.0

-0.33
0.84
10

19
4.1

0.41

2.3
0.25

-0.42

-0.35

* 6.7

* 6.5

* 4.7
4 7.8

4 9.0

* 1.8

* 4.0

4 5.8

4 9.9
4 5.7
4 16

4 21

4 14
4 6.1

4 5.1

4 4.0
4 7.7

4 7.9

4 7.7

Time-Weighted Averagec
Ra-226 Pb-210
0.27 * 4.2 7.2

1.0 4 4.2 2.7

0.64 4 3.0 5.0
6.0 * 4.7 5000

5.2 4 4.7 5800

5.2 4 4.5 2700

5.5 4 2.7 4500

3.0 4 2.6 1.9

3.6 4 6.2 13
3.3 4 3.4 7.5
12 » 7.6 27

21 4 n 9.0

17 * 6.7 18
8.2 4 4.1 12

1.3 4 3.2 7.9

4.8 4 2.6 10
1.9 * 4.6 12

-0.73 4 4.8 150

-3.3 4 4.7 75

43
4 28

4 27

4 19
4 470

4 480

4 100

4 230

4 17

4 43
4 23
4 44

4 63

4 38
4 22

4 22

4 16
4 32

4 21

4 15

4 13
Po-210
11 * 13

5.7 4 13

8.4 * 9.2
2500 * 14

3300 * 380

3800 4 180

3200 4 140

85 * 16

14 4 20
50 4 13
4.0 4 19

-9.0 4 28

-2.5 * 17
0 4 16

0 4 14

0 4 11
0 4 14

290 4 100

55 4 70
_
85 4 33
Th-232
-0.93 * 4.3

-1.2 4 4.2

-1.1 4 3.0
-0.97 4 4.5

-0.80 4 4.8

-0.88 4 4.7

-0.88 4 2.7

-0.24 * ?.8

-1.4 4 6.4
-0.82 4 3.5
-0.48 * 7,0

-3.1 4 9.7

-1.8 * 6.0
0.51 4 3.7

-0.96 4 3.2

-0.23 4 7.4
-1.1 4 4.g

-1.2 4 5.0

-1.2 * 4.9

rn-228
-0.45 4

-0.52 4

-0.49 4
-0.47 4

-0.28 4

-0.37 4

0.45 4

-0.66 *
-0.11 4
0.28 4

0.45 '

0.37 4
0.88

-0.58

-0.15
-0.5

-0.68

-0.61

4.2

4.0

2.9
4.3

4.7

4.5

2.6

2.7

6.1
3.3
6.7

: 9.6

5.9
4 3.6

4 3.0

4 2.3
4 4.7

4 4. a

* 4.7

a Picocuries (10-'? curies) per cubic meter.
b Results derived from duplicate sample
c Emission rates of nuclides other than Pb-210 and Po-210 were insignificant.
-------
The average emission rates of the uranium chain radionuclides, less
polonium-210, from the silo system exhaust was measured at 3.8 pCi/sec.
Assuming that the particulate material sampled was due to nodule handling and
that the radioactivity concentration of the particulates was the same as the
nodules, the average emission rate of each, based on the mass emission rate,
would be 3.1 pCi/sec, very close to the measured radioactivity emission rate.

The collection period of each tap hole fume scrubber sample included times
when a furnace was being flushed or tapped. Analysis of the data showed that
the primary source of lead-210 and polonium-210 from the source was FeP
tapping. As shown in Table 3, the concentrations of other radionuclides did
not differ significantly from zero and lead-210 and polonium-210 concentrations
varied widely between samples. The time-weighted average emission rates based
on 2-days tap and flush records and the three sample results were 43 pCi/sec
for lead-210 and 85 pCi/sec for polonium-210.

Table 6 shows the annual emission rates calculated for each operation.
These emission rates include the sum of two kiln stacks, two nodule cooler
stacks, and two kiln building ventilator stacks. Approximately 99 percent of
the lead-210 and 97 percent of polonium-210 emissions occur from the kiln
stacks. The process sample results show that essentially all of the lead-210
and polonium-210 is driven off in the kiln and furnace. The observed differ-
ence in kiln annual emissions of 280 mCi and 200 mCi, may be real, due to
different removal rates in pollution control equipment, or may be an artifact
of analysis. The kilns also emit several tenths of a curie per year of the
other uranium chain radionuclides, but most of them - about 1 Ci per year -
are released from the kiln building ventillator systems.

The removal of radionuclides by emission control systems was determined on
the number 1 kiln scrubber and the tap hole fume scrubber. As is common with
kilns, Stauffer uses an effluent control system of multiple control devices in
series. It was possible to obtain simultaneous samples on the inlet and out-
let of the final stage scrubber. Simultaneous samples were also obtained at
the inlet and outlet of the tap hole fume scrubber. The results are shown in
Table 7. The kiln scrubber removed 75 percent of the total mass entering it.
The average removal for uranium, thorium, and radium was essentially identical
at 78 percent. Both lead-210 and polonium-210 showed a 54 percent removal.
Only lead-210 and polonium-210 could be evaluated in the tap hole fume
scrubber. The fume scrubber removed an average of 86 percent of those
nuclides, compared to 91 percent of the mass. Lead and polonium, presumed to
be present as fumes after condensing from vapors, are apparently more readily
removed in the tap hole fume scrubber than in the kiln scrubber which is
designed to remove particulates.

RADON EMANATION RESULTS

Radon emanation rates from soil around the plant generally ranged from 12
to 31 pCi/m2-min with an average of 21 ± 6 (Table 8). If two low results of
2.0 and 4.2 pCi/m2-min are included the average is 18 ± 9. Radon emanation
from the top of the ore pile covered with roaster residue average 53 ± 35
pCi/m2-min. Considerable difference was found between the emanation rates

21
-------
ro
TABLE 6. PARTICIPATE RADIOACTIVITY ANNUAL EMISSION RATES
Annual Emissjon Rate (ff*C_i_/y)a
Source
Kil'i Fei'd
Conveyor
Kiln 1 plus
Ki'ln ?
Nodule Cooler 1
plus Nodule Cooler 2
Kiln Buildinq
Vent i 1 dtor
jl l;i Syilwi
F.xhaust
r,ip Hale
Fume Scrubber^
a ,, , ,3
h i •••isoruis of nuclidvs
U-2.W U-?34 Th-23U Ra-226 Pb-210
-0.003 * 0.050 0.016 » 0.066 -0.008 * 0.15 0.020 « 0.095 0.16 * 0.60
0.?4 » 0.09 U.20 * 0.12 U.12 * 0.25 0.35 * 0.17 280 * 15
0.02 « 0.11 -0.009 * 0.15 0.05 « 0.36 0.21 * 0.21 0.47 * 1.5
0.62 * 0.2(1 0.70 * 0.34 1.2 * 0.9 1.1 * 0.4 1.1 « 2.4
0.0?H « '1.04.1 U.0-11 * 0.057 0.07 » 0.13 0.!5 * 0.08 0.32 * 0.50
1.4 * 0.4

Po-210 Th-232
0.26 * 0.29 0.035 * 0.095
200 * 7 -0.06 * 0.17
3.2 * 0.8 -0.05 * 0.22
-0.16 * 1.1 -0.12 * 0,311
0 * 0.35 -0.007 t 0.076
-'.7 * l.fj

Th-22S
-0.015 * 0.091
-0.02 * tj.lfi
O.U07 i fj.21
U.02 * ll.yt
-o.uns * ''j.nn

-------
measured from the east berm of the ore pile and the west berm. The three
measurements from the east berm averaged 310 ± 140 pCi/m2-min while those
from the west berm averaged 36 ± 20 pCi/m2-min. No explanation has been
found to explain the difference between the two berms. The average radon
emanation rate from the ore pile was 110 ± 70 pCi/m2-min. The radon
emanation rate from the ore pile in use should have been about equal to the
berm average, or 170 ± 140 pCi/m2-min. Radon emanation rates measured on
the slag pile averaged 3.5 ± 3.7 pCi/m2-min.

Radon emanation rates from soil were comparable to those measured at other
locations in the United States as part of this survey, but were below the
reported National average value of 35 pCi/m2-min (9).

It is estimated that the covered ore pile emits radon at the rate of 1.2 ±
0.8 pCi/min. The uncovered ore pile is estimated to release radon at the rate
of 1.9 ± 1.5 pCi/min. The radon which would have been released from the soil
beneath the ore piles was about 0.2 uCi/min. The net radon emanation rate for
the two piles would be 1.0 ± 0.8 pCi/min or 0.53 Ci/year for the covered pile
and 1.7 ± 1.5 yCi/min or 0.89 Ci/year for the pile in use.

Radon emanated from the slag pile at the rate of 0.8 uCi/min compared to
an emission rate from the soil beneath of 0.4 uCi/min. The radon reduction
provided by the slag cover is estimated to be 0.32 yCi/min or 0.17 Ci/year.

The net radon emanation rate from the ore and slag piles during the survey
was estimated at 1.2 Ci/year. However, during part of the year only a portion
of one ore pile would be in existence and snow and ice cover during the winter
would reduce the radon emanation rate.
TABLE 7. SCRUBBER REMOVAL OF RADIONUCLIDES
Fraction Removed (Percent)

U,Th,Ra Pb,Po
Kiln 1
Kiln 1
Kiln 1
Average
71
85
69
75
59
93
87
80
76
85
100
87
59
81
69
70
66
86
81
78
37
68
57
54
58
66
38
54
48
67
48
54
75
74
76_
75
Tape Hole Fume Scrubber

Tape Hole Fume Scrubber

Average
95 100

73 75_

84 88
98

86
100
91
23
-------
TABLE 8. RADON-222 EMANATION RATES FROM SOIL, ORE, AND SLAG

Site
1
2
3
4
5
6
7
8
9
10
11
12
Average

Soil
Emanation
Rate (pCi/m2^nin
18
17
22
18
4.2
12
24
28
13
25
2.0
31
18 * 9

Ore

Pile Slag Pile
Emanation Emanation
Site Rate (pCi/m2-min Site Rate (pCi/m2-min)
Top
1
2
3
4
5
Average

East Berm
6
7
8
Average
West Berm
9
10
11
Average

75 1 1.8
100 2 8.6
22 3 3.3
30 4 0.1
35 Average 3.5 ± 3.7
53 ± 34

150
390
380
310 ± 140

13
48
47
36 ± 20
24
-------
SECTION 7

POPULATION DISTRIBUTION
The Stauffer Chemical Company plant is located in a sparsely populated
area. The processing facility is situated, as shown in Figure 4, near the
east center portion of a company-owned site about 1 mile (1.6 km) square which
is fenced to restrict access. Several ranches are located west of the plant,
with the nearest residence in that direction being about 2 km away. One
family lives at the drive-in theater 1.6 km east of the plant. Several
residences are occupied in Silver Bow about 2.5 km northeast and about 50
people live in Ramsey, about the same distance to the north-northwest.
25
-------
SECTION 8

DISCUSSION OF RESULTS
As mentioned earlier, analytical biases can result in consistent
differences in activity levels between radionuclides of a decay chain that
would normally have very nearly the same radioactivity. This can be seen in
the process sample results of Table 1 and kiln building ventilator results in
Tables 3, 5, and 6. Radionuclides of the uranium decay chain through radium-
226 in ore, modules, and slag and probably in ventilator exhaust particulates
should be at nearly equilbrium values.

Other results reported by EIC on known activity samples have shown similar
biases with thorium-230 being about twice the activity of the other samples.
Evaluation of those results has shown that thorium analyses by EIC have been
more accurate than the others. Therefore, it is believed that the thorium-230
results reported for the samples mentioned are more representative of the
uranium chain activities than the other radionuclides. However, no attempt
has been made in this report to apply any correction to the data. More
important than the specific radioactivities are the fractions of the radio-
activity in the process which are emitted from the stack. Since the biases
are probably consistent, the fractional values are considered to be valid.

A major environmental protection problem associated with thermal process-
ing of phosphate is the emission of fluorides to the atmosphere. To combat
that problem and control particulate emissions Stauffer uses multiple air
cleaning systems in series on its kilns, nodule coolers, and kiln building
ventilators. Although radioactive emissions were not a consideration when the
pollution control system was installed, it removed large fractions of the
particulate radionuclides and smaller, but still significant, fractions of the
more volatile lead-210 and polonium-210.

Each exhaust stack emits a portion of the particulate material controlled
by the exhaust system. Due to the above-average concentrations of naturally-
occurring radioactivity in the process materials the particulate emissions
result in radioactive emissions. Most of the radioactive particulate
emissions from controlled sources come from the kiln building ventilator.
Next in importance is the kiln. The kiln probably generates more airborne
particulates, but because of the more complex pollution control system
actually emits less than the ventilator.

The average measured emissions of uranium-234 and -238, thorium-230, and
radium-226 from all controlled sources were 1.3 mCi/year. A better estimate
is probably derived from the measured mass emission rates. Assuming that the
particulate material, except for the tap hole fumes, are similar to ore in
radionuclide concentration the calculated total emissions of each of the four
radionuclides is 4.2 mCi/year.
26
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The nodule cooler and tap hole fume scrubber are small sources of lead-210
and polonium-210. The kilns, however, are the major source, releasing 99 and
97 percent, respectively, of the total plant emissions of those nuclides.

As with lead-210 and polonium-210, the kilns are the major source of radon
emissions. The average measured emission rate of 8.2 Ci/year may be low since
it is based on results from four samples, one of which was extremely low. The
estimate of 1.5 Ci/year of radon from the ore pile is probably an upper limit,
considering the actual area of the ore piles averaged over the year and the
effect of winter rain, snow, and ice on reducing emanation rates.

Comparison of radioactivity removed by the kiln scrubber and tap hole fume
scrubber demonstrated that the fume scrubber removed the larger fraction of the
lead-210 and polonium-210 from the exhaust gases. Within the limits of sampling
and analytical accuracy, the kiln scrubber removes the other, nonvolatile
radionuclides in the same proportion as total suspended particulates. As would
be expected for a noble gas, no removal of radon was exhibited by the kiln
scrubber.

Although slag was found to contain about as much radium-226 as the
original ore it was found to not be a source of radon, as is the ore. The
physical form of the slag, even when somewhat frothy in appearance reduces the
rate at which radon gas is able to escape. Slag pile sites sampled included
slag which has been in place for a few days to several weeks so that at some
sites the radon would have been in equilibrium with radium-226. Gamma exposure
rates were significant on the slag pile, averaging 0.15 milliroentgen per hour
(mR/h). Ambient background gamma exposure rates were about 0.01 mR/h.
27
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REFERENCES
1. National Council on Radiation Protection and Measurements. Natural
Background Radiation in the United States, NCRP Report No. 45, 1975,
Washington, D.C.

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, 1968, pp 231-234.

4. Eadie, Gregory G., and David E. Bernhardt. Radiological Surveys of Idaho
Phosphate Ore Processing - the Thermal Process Plant. U.S. Environmental
Protection Agency, Technical Note ORP/LV-77-3, Las Vegas, Nevada,
November 1977.

5. PEOCo Environmental, Inc. Emission test report: Collection of Airborne
Radon and Radioactive Particulates at Stauffer Chemical Company,
Silver Bow, Montana. Cincinnati, Ohio, December 1979.

6. Code of Federal Regulations, Title 40, Chapter 1, Part 50, Appendix B.

7. Code of Federal Regulations, Title 40, Chapter 1, Part 60, Appendix A.

8. Slade, David H., editor. Meteorology and Atomic Energy 1968. U.S. Atomic
Energy Commission, Oak Ridge, Tennessee, July 1968.

9. Turekian, Karl K., Y. Noyaki, and Larry K. Benninger. Geochemistry of
Atmospheric Radon and Radon Products. Annual Review of Earth and
Planetary Sciences, 5:227-225, 1977. Palo Alto, California.
28
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-520/6-82-019
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Emissions of Naturally Occurring Radioactivity:
Stauffer Elemental Phosphorus Plant
5. REPORT DATE
November 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Vernon E. Andrews
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
U.S. Environmental Protection Agency
Office of Radiation Programs-Las Vegas Facility
P.O. Box 18416
Las Vegas, Nevada 89114
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Same as above
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
This is the third 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. Represent-
ative exhaust stack samples were collected from each process in the plant. The
phosphate ore contained about 120 parts per million uranium. The radioactivity
emitted in greatest quantity was radon-222 with an annual release from the plant
of 8.3 curies. Emissions of lead-210 and polonium-210 were measured at 280 and
200 mi Hi curies per year. Annual emissions of each of the other radionucl ides of
the uranium decay chain were estimated to be 4.2 millicuries. The slag pile was
determined not to be a source of radon.
7.
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 (TIlis Report)
Unclassified
21. NO. OF PAGES
28
20. SECURITY CLASS (This page)

Unclassified
22. PRICE
EPA Form 2220—1 (R«v. 4-77) PREVIOUS EDITION is OBSOLETE
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