-------
DISCUSSION OF RESULTS
Uranium Emission Rates
Table 1 shows the basic data of the study, and the uranium emission rates.
At the outset of the study, we hoped to find some correlation between the
uranium emission rate and one or more mill operating parameters. The emission
rate should logically be a function of the amount of uranium concentrate
produced by the mill per unit time, with some adjustment for the efficiency of
the stack gas cleaning equipment. Such analysis is typical in the scientific
literature and in environmental impact analyses. Specifically, the uranium
emission rate is usually estimated using the following parameters:
- Ore processing rate (usually tons per day or year)
- Average ore grade (percent UsOs)
- Efficiency of the mill process for recovering uranium
- Appropriate assumptions of operating time per year
- Efficiency of effluent cleaning equipment
An annual average emission rate, usually expressed as curies per year, is
desired for evaluating the environmental impact of the mill.
Presumably, the emission rate at any given time should be proportional to
the mill operating parameters at that time. When possible during this study,
the best estimate of mill operating parameters during the stack testing period
was obtained, including the feed rate of yellowcake slurry to the dryer and
the quantity of yellowcake packaged. However, the observed emission rates did
not correlate with these two parameters. This is likely because the stack
tests were conducted over a relatively short period (usually one to two
hours). Consequently, mill operating changes are not likely to produce
observable changes in emission rate using such short measurement periods. The
Union Carbide results of Table 6 are a good example of such inconsistency. Of
the seven test results, the second to the highest emission rate measured
22
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(0.28 Ibs UsOs/hr) corresponds to the lowest production rate (159 Ibs
UsOs/hr). Alternately, the test resulting in the lowest emission rate
(0.11 Ibs U30s/hr) corresponds to a period of identical production rate
(159 Ibs
The study demonstrated that the emission rate at a given time (the
"instantaneous" emission rate) is controlled by a complex interaction of
several factors. In addition to the mill operating parameters listed above,
these include, as a partial list, such things as:
- Drying and packaging ventilation design factors which, under
varying operational conditions, create varying yell owcake
entrainment with subsequent variations in yellowcake concentra-
tions arriving at the stack gas cleaning system.
- The adjustment and "tuning" of stack gas cleaning systems at a par-
ticular time (i.e., the "instantaneous" efficiency of the system).
- The general condition and cleanliness of the yellowcake processing
and stack gas cleaning systems, including ductwork. There may be a
considerable amount of yellowcake deposited in these systems that
may be available for resuspension.
- The nature of operating procedures for yellowcake packaging, and
how well these procedures are being followed by the particular
operator at the particular time.
Undoubtedly, the instantaneous yellowcake emission rate at the point of
the stack exhaust involves still other factors, which may be subtle, inter-
mittent, and highly variable in impact on the emission rate. These factors
are also difficult to observe, and are difficult or impossible, at least
within the context of this study, to quantify relative to the observed
emission rate.
Table 7 shows a measure of the gross variability of the test results,
expressed as a ratio of the highest to the lowest measured values for each
stack tested. (The Anaconda result is not included because only one test was
performed there.) For the UNHP and Sohio packaging stacks, an "alternate"
calculation was made to include additional tests made under operating
24
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TABLE 7. VARIABILITY OF MEASURED YELLOWCAKE EMISSION RATES
Mill
Kerr-McGee*
UC-Uravan
UN-Churchrock
UNHP*
No. Of
Stack Tests
Main
East
West
Dryer-Package
Dryer
Package
Vanadium
Roaster
Dryer
Package
2
3
3
7
3
3
5
3
3
Ratio-Highest To
Lowest Emission Rate Remarks
2.9
2.0
7.1
2.8
2.2
1.9
2.3
3.4
1.4 Yellowcake was being
Sohio
Package
(alternate)
Dryer
Package
3
2
Package 3
(alternate)
23
4.7
3.9
71
packaged.
Includes 3 tests above,
plus one when yellow-
cake was not being
packaged.
Excludes test made
when bag filter was
ruptured.
Includes test with
ruptured filter.
* The stacks at these mills were tested on two occasions at five-month
intervals.
25
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conditions that were known to be unusual or markedly different. The table
notes these conditions. Although usually the number of tests on each stack is
small, the ranges of emission rates shown in this table give an estimate of
the variability to be expected from a series of tests on a given stack.
The alternate calculation for the UNHP packaging stack shows the emission
rate range from a packaging stack that can occur depending upon whether
yellowcake is or is not being packaged at the time of the test. The Sohio
alternate calculation shows the effect of a ruptured bag filter. Certainly
more data are needed to draw definitive conclusions about the effects of such
variables. However, by just these two tests, the emission rate shows
variation by a factor of roughly 10 to 20.
Aside from these major known variables, this study shows that the emission
rates from a given stack, as measured by an individual test, can vary by
roughly a factor of two to five. Again, the relatively small number of tests
involved should be kept in mind when evaluating this data. The only exception
is the three tests on the Kerr-McGee west Microdyne stack, which vary by a
factor of seven. This may be at least partially explained by the fact that
mill operating data were not obtained during these tests. Consequently, some
unobserved factor (e.g., differences in the amount of yellowcake pack-
aged) may account for the larger range of these results.
The range of variation discussed above includes sampling and analytical
error. The Method 5 sampling procedure is estimated to have an overall prob-
able sampling error of about 7% (Shigehara et al., 1970). Analytical errors
may vary considerably, depending on the method used and the expertise of the
laboratory performing the analysis. Estimated analytical errors for routine
analyses at the uranium levels involved are as follows:
- Delayed neutron counting: 5% or less
- Radiochemistry and alpha spectroscopy: 5-20%
- Fluorimetric analysis: 25%
- Colorimetric analysis: 3%
The approximate combined sampling and analytical error could therefore range
26
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from less than 10% to about 25%. Consequently, the combined error in measur-
ing the emission rate is considerably less than the minimum variation of 100%
(factor of two) observed in the stack test results.
Estimation of Annual Average Emission Rates
Disregarding the variability and the apparent lack of correlation, we
calculated emission rates of U^OQ as a percentage of UsOa processing
rates for four of the mills where such data was available, and averaged these
percentages over the number of tests conducted. The results of these calcu-
lations, listed in Table 6, show United Nuclear Churchrock (UNC) releasing an
average of 0.118% of the 1*303 dried and packaged. Sohio releasing an
average of 0.0066% of the UaOs dried and packaged, and Union Carbide
releasing an average of 0.094% of the UsOs dried and packaged. The Union
Carbide result is notable since it corresponds to an identical release rate
calculated by Momeni et al. (1979). They were provided the Union Carbide
emission rate data from the tests reported herein, but calculated the
production rates by considering ore throughput and grade, extraction
efficiency, and mill operating time. Using Union Carbide data and that from
another mill, Momeni recommended using a value of 0.1% for estimating U^QQ
released from annual UsOs production estimates.- Note also that the UNC
data agrees with Momeni's estimation. Sohio is obviously the exception with a
total UaOs release rate of 0.0066%, and based on the data of Table 6, a
0.1% release rate applied here would over-estimate their total UaOs
release by a factor of 15.
The use of emission rates (as normally reported from stack tests viz Ib or
pCi U30a/hr) in calculating annual source terms must consider the operat-
ing periods of the several sources. Since yellowcake packaging operations are
typically intermittent with respect to yellowcake drying operations, it would
obviously be invalid to simply add the reported hourly release rates for these
two sources to arrive at a total hourly release rate in calculating annual
source terms. How intermittent packaging operations are, at least at two
mills, can be calculated based on the data of Table 6. These calculations
show the ratio of the packaging time to drying time at UNC and Sohio to be
respectively about 0.14 and 0.08. Therefore, in calculating an annual source
term, the total operating times for each source must be defined after which
27
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individual source terms may be calculated for each stack for the year. The
source term for each stack is then summed to arrive at the total annual source
term. Annual source term calculations based on the summation of drying and
packaging stack hourly release rates, without time-weighting, at UNC and Sohio
would overestimate their annual source terms by a factor of 1.5 and 2.8,
respectively.
Concentrations of Uranium Daughter Radionuclides in Yellowcake
Table 5 shows the concentrations of the three uranium nuclides (U-238,
-234, and -235) and of the daughter nuclides (thorium-230, radium-226,
lead-210, and polonium-210). This table includes results for six samples that
were analyzed by three laboratories, and for three additional samples that
were analyzed only by the EPA laboratory. Each analysis shows the percent of
each daughter nuclide's activity relative to the parent U-238 activity.
The agreement between the three laboratories is generally good. Usually
where comparable analytical results are available (between EPA and LFE), they
are within the two-sigma counting error range. (Remember that the Eberline
concentration results are not directly comparable to the EPA and LFE results,
due to reporting differences.) All the samples analyzed by EPA and Eberline
show U-238 and U-234 in equilibrium within the limits of reported counting
errors. (LFE did not report U-234 results.)
For the daughter nuclides, the results reported by all three laboratories
can be compared by referring to the calculated percentage of the daughter
nuclides relative to the parent U-238. The differences between these results
are fairly randomly distributed between the three laboratories. For thorium-
230, EPA tends to be low and Eberline high, with LFE in the middle. For
polonium-210, EPA is generally lower than LFE (Eberline did not report
polonium-210 results). While inter-laboratory agreement does not necessarily
prove accuracy, it is encouraging that there are no strong biases between the
three laboratories. Because of this, the percentage values for all analyses
of all samples from each of the four mills have been averaged to arrive at an
overall average daughter percentage in yellowcake from each mill. Table 8
shows these values.
28
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Sears (1975) reported that, for an acid leach mill, about 5% of the
thorium and 0.2% of the radium are carried over to the yellowcake product,
although these percentages may vary according to the details of the chemistry
used for uranium extraction and yellowcake purification. An alkaline leach
mill is reported to carry over 1.8% of the radium, and none of the thorium.
For both circuits, no other significant radionuclides are reported to be
present. The results in Table 8 show that thorium-230 in the yellowcake from
the three acid leach mills is considerably lower than the 5% stated above and
that the radium-226 is equal to or considerably lower than the 0.2% stated.
For the one alkaline leach mill, significant thorium-230 was found in the
yellowcake, while the radium-226 was about 17% of the value quoted by Sears.
Measurable amounts of Pb-210 and Po-210 were found in all yellowcake samples,
with that from the alkaline leach mill being higher than that from the acid
leach mills. Always, however, less than 0.09% each of lead and polonium was
carried over to the yellowcake.
Table 8. DAUGHTER RADIONUCLIDES IN YELLOWCAKE
AS PERCENT OF U-238 PARENT*
Mean ± one standard deviation (percent)
Nuclide/Mill UNHP Union Carbide Kerr-McGee
(3 samples) (3 samples) (2 samples)
Sohio
(1 sample)
Th-230 2.58 ± 0.309 0.689 ± 0.110 0.0980 ± 0.0360 0.284 ± 0.0731
(7)** (7) (3) (3)
Ra-226 0.312 ± 0.036 0.0266 ± 0.0165 0.0038 ± 0.0042 0.00033 ± 0.00006
(7) (7) (4) (3)
Pb-210 0.0876 ± 0.0117 0.0271 ± 0.0119 0.0107 ± 0.0040 0.00467 ± 0.00208
(7) (7) (3) (3)
Po-210 0.0688 ± 0.0095 0.0246 ± 0.0124 0.0080 ± 0.0000 0.0170 ± 0.00849
(5) (5) (2) (2)
* Calculated from results in Table 5.
** Number in parenthesis is the number of analyses used in calculating the
mean.
29
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SUMMARY AND RECOMMENDATIONS
The Nuclear Regulatory Commission is currently considering the monitoring
and sampling procedures that should be required at uranium mills to demon-
strate compliance with environmental radiation protection standards. In order
to estimate dose to people near the mill, a source term, or radioactivity
released per unit time, must be known or estimated. This is usually expressed
as curies per year in order to average over a suitable period. The problem
with determining uranium mill source terms in general, and yellowcake stack
source terms in particular, is in realistically estimating or calculating this
annual average emission rate.
This study shows that measured emission rates from a yellowcake processing
stack can routinely vary by a factor of two to five when tests are conducted
without any controls on the mill operating parameters. In addition, these
tests show that major anomalies (e.g., a ruptured filter in the exhaust clean-
up system) can cause variations of as much as a factor of 20 in the measured
emission rate. Based on our experience, the major operational parameter that
affects the emission rate is simply whether yellowcake is or is not being
dried or packaged during the testing period. Typically, the cleaning systems
run continuously while the operations may be performed intermittently. This
is especially true for many packaging operations and to a lesser extent for
drying operations. As discussed earlier, results from a single test at United
Nuclear-Homestake Partners show measurable amounts of yellowcake being
released from the operating packaging stack (0.02 Ib UsOs/hr) even though
yellowcake was not being packaged during the test. Later tests on this stack
show a significant increase in the emissions during periods when packaging was
under way. Consequently, an emission rate measurement (or measurements)
representing only one operating condition would bias the annual average source
term considerably.
Major events that affect the emission rate would also have to be consid-
ered for a calculation as described above. A serious malfunction of the
30
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exhaust air cleanup systems is the most obvious of these, as discussed
previously for the Sohio sample. Maintenance or repair work on the exhaust
system might also increase the emission rate significantly by dislodging
yellowcake from the system, although this would probably be short-lived.
Conversely, a complete shutdown of the yellowcake systems would reduce the
emission rate to zero during the down period.
Based on the results of this study and on other general information
obtained during the course of the study, we can recommend a general stack
testing and emission rate calculation scheme that should provide a reasonable
estimate of the annual source term from yellowcake stacks. Basically, this
scheme would consist of sampling each stack several times under various mill
operating conditions and time-weighting these various emission rates according
to the proportion of time per year during which the stack is operated under
each particular condition. Our general recommendations are as follows:
1. A number of samples would be collected from each stack over a period of
a year to establish the range of emission rates from that stack. These
tests would be made while the yellowcake processing operations are
underway with the operating conditions maintained at steady-state
conditions.
2. During this year, each stack would also be tested several times when
yellowcake operations are not underway, but with the air cleaning sys-
tems in operation, if this condition occurs normally at the mill.
This would establish the range of emission rates under this condition.
3. The tests should be conducted according to the EPA Reference Methods
using the appropriate modifications for yellowcake stack testing
described earlier in this report.
4. For each stack, a record of the operating time under each of the above
conditions would be maintained for a year, and summarized on an annual
basis.
31
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5. The total annual source term for each stack would then be calculated
by multiplying the hourly emission rate for each condition by the hours
per year the stack operates under that conditon, and summing for all
known operating conditions. The annual source term for the mill would
be obtained by summing the source terms for each stack.
6. The above calculation is intended to apply to uranium emission rates.
The uranium daughter nuclides are a small fraction of the uranium
in yellowcake, and the analyses for them are expensive and time con-
suming. Since the ratio of the daughter nuclides to uranium appears
to be fairly constant for a given mill, we suggest that they be deter-
mined once a year from a blended sample of the yellowcake produced
during the year.
7. An alternate method of estimating the source term is to relate the em-
ission rate from the various stacks to the amount of yellowcake proces-
sed (e.g., dried or packaged) in the areas served by each stack. This
technique requires an additional piece of data, the amount of yellow-
cake processed during a stack test. One can then calculate the uranium
emission (not emission rate) normalized to the yellowcake production,
expresed as pCi Ut0t/pound of yellowcake processed. Since the amount
of the yellowcake produced per year by the mill is known, the annual
source term can then be estimated by multiplying this normalized
uranium emission by the annual yellowcake production.
We feel that this calculation method would be inherently less
satisfactory than the time-weighted method discussed above because (a)
it does not account for releases which occur when yellowcake is not
being processed; (b) in some mills, the exhaust stacks do not serve a
single process area, thus complicating the relationship between yel-
lowcake processing and uranium releases; and (c) as shown previously,
there is very poor correlation between the measured emission rates and
the concurrent yellowcake processing rates. A comparison of the two
methods may be more feasible when further data and experience are
available.
32
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Technically the number and frequency of samples should be determined by a
statistical analysis of the data, and would depend primarily on the varia-
bility and the distribution of the results. These parameters would determine
the reliability of the calculated annual emission rate and the degree of
confidence associated with it. However, from a regulatory viewpoint, it may
be simpler to specify a fixed number and frequency of samples.
We think it important to remember the variability between mills and the
uniqueness of each mill. Also, changes in operating parameters can change
emission rates over a period of time. Consequently, a single, fixed sampling
regime is not necessarily always the optimum. It may not provide the most
useful technical data, and it may not be the least costly way to obtain the
data, if costs are to be considered.
Our approach in the above sampling scheme has been to outline a general
program that should provide a realistic estimate of the annual emission rate
for a mill. Logically, this would involve a larger number of samples and more
frequent sampling the first year. This will allow one to develop a feel for
the range of the results for the particular stacks and, hopefully, for the
causes of these variations. Once this range is defined and the variables are
at least partially controlled, the sampling program could be modified and used
primarily to follow trends and to confirm that no major variations are
occurring.
All the above discussions of stack sampling techniques and programs are
based on the EPA Reference Method 5 sampling technique used in this study. As
mentioned previously, the major shortcoming of this method for measuring the
annual yellowcake emission rate is the short duration of the test period (one
to two hours) compared to the time frame over which most of the variations in
the emission rate occur. As a result, a single test, or a few tests, will
likely give misleading results. As more and more tests are conducted to
average out these variables, one is, in effect, approaching continuous stack
sampling. This ideal situation would eliminate the need for, and uncertainty
involved in, averaging and manipulating the results from a number of individ-
ual tests to obtain the annual average. Such a continuous monitor should be
reliable, reasonably accurate, and inexpensive. Argonne National Laboratory
33
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(Momeni et al., 1979) has developed, but not yet tested, such a concept and
prototype. We recommend the further development of such equipment, with field
tests and evaluations of its suitability in this area.
As an aside, we feel it important to mention a dramatic reduction of the
packaging stack yellowcake release rate we observed at the United Nuclear-
Churchrock mill, after minor modifications. During the emissions tests
reported herein, the average emission rate for the packaging stack was 0.19 Ib
UaOs/hr (Table 6). Subsequently, a series of particle-sizing studies were
performed on the same stack. The emission rates calculated from these studies
averaged 0.005 Ib UsOs (Fort et al., 1980). Between these two studies,
minor modifications had been made on the packaging stack ventilation and
cleaning systems (Todd Miller, United Nuclear-Churchrock, personal communica-
tion, 1978). While emission rates determined from particle-sizing studies are
not necessarily as accurate as those determined by the Method 5 procedures,
the magnitude of the reduction indicates a definite improvement in the
efficiency of the exhaust air cleaning system. Whether cleaning systems at
other mills could be "fine-tuned" to achieve this magnitude of emission rate
reduction is unknown and was not a goal of these studies.
34
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REFERENCES
CFR (1975), Code of Federal Regulations, Title 10, Part 20. "Standards for
Protection Against Radiation."
EPA (1976), "Environmental Analysis of the Uranium Fuel Cycle, Part IV -
Supplementary Analysis-1976," EPA 520/4-76-017, July 1976.
CFR (1977), Code of Federal Regulations, Title 40. Chapter 1. Part 60,
Appendix A, "Standards of Performance for New Stationary Sources - Revision to
Reference Method 1-8."
Fort, C. W., Jr., R. Douglas, R. Gauntt, A. R. McFarland (1980), "Particle
Size Distribution of Yellowcake Emissions at the United Nuclear-Churchrock
Uranium Mill," ORP-LV-80-1, January 1980.
Gale, N. H. (1967), "Development of Delayed Neutron Technique as a Rapid and
Precise Method for Determination of Uranium and Thorium at Trace Levels in
Rocks and Minerals, with Applications to Isotope Geochronology," IAEA
Symposium Proceedings, Radioactive Dating and Methods of Low-Level Counting,
August 1967.
Glauberman, H., and A. J. Breslin (1964), "Uranium Mill Tailings Study," HASL
Technical Memorandum 64-14, Health and Safety Laboratory, U.S. AEC, New York
Operations Office, July 31, 1964.
Harward, E. David, editor (1977), "Workshop on Methods for Measuring Radia-
tion in and Around Uranium Mills," Atomic Industrial Forum, Inc. August 1977.
Johns, F. B., editor (1975), "Handbook of Radiochemical Analytical Methods,"
EPA 680/4-75-001, February 1975.
35
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Momeni, M. H., W. E. Kisieleski, D. R. Rayno, and C. S. Sabau (1979), "Radio-
isotopic Composition of Yellowcake An Estimation of Stack Release Rates,"
NUREG/CR-1216, ANL/ES-84, December 1979.
Ragland, J. W., K. M. Gushing, J. D. McCain, and W. B. Smith (October 1976),
HP-65 "Programmable Pocket Calculator Applied to Air Pollution Measurement
Studies: Stationary Sources." Ind. Env. Res. Lab., U.S. EPA, Research
Triangle Park, N.C. and Southern Research Inst., Birmingham, AL, Contract
Number EPA 68-02-2131. EPA Report Number 600/8-76-002.
Sears, M. E., R. E. Blanco, R. C. Dahlman, G. S. Hill, A. D. Ryan, and J. P.
Witherspoon (1975), "Correlation of Radioactive Waste Treatment Costs and the
Environmental Impact of Waste Effluents in the Nuclear Fuel Cycle for Use in
Establishing 'as Low as Practicable' Guides - Milling of Uranium Ores"
ORNL-TM-4903, Vol. 1, May 1975.
Shigehara, R. T., W. F. Todd, and W. S. Smith (1970), "Significance of Errors
in Stack Sampling Measurements," APCA No. 70-35, presented at the Annual
Meeting of the Air Pollution Control Association, St. Louis, Missouri,
June 14 - 19, 1970.
Sill, C. W. (1977) "Simultaneous Determination of U-238, U-234, Th-230,
Ra-226, and Pb-210 in Uranium Ores, Dusts, and Mill Tailings," Health Physics.
Vol. 33, No. 5, November 1977.
36
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APPENDIX A
HP-67/97 CALCULATOR PROGRAM FOR ESTIMATING STACK GAS MOISTURE FRACTION
The basic equation for estimating moisture fraction is: BWs = D\
Where: BWS = Moisture fraction
4a = Dew point saturation vapor pressure (in. Hg)
= a» (pabs-*")(Td-^w) (The Carrier Equation)
" 2800 - 1.3 * Tw
i" = Saturation vapor pressure at Tw (in. Hg)
pabs = Absolute stack pressure (in. Hg)
Td = Stack gas dry bulb temperature (°F)
Tw = Stack gas wet bulb temperature (°F)
The HP-67/97 program calculates i" for a given Tw using a series of
equations derived to define saturation vapor pressure (SVP) in inches of Hg as
a function of wet bulb temperature over the range 0-159°F. These equations
are given below:
for Tw = 0- 29°F, SVP = 0.03821 e°-04911 * Tw
Tw = >29- 59°F, SVP = 0.05290 e0.03840 * Tw
Tw = >59-105°F, SVP = 0.07590 eO-03250 * Tw
Tw - >105-159°F, SVP = 0.14210 e0.02651 * Tw
SVP values calculated using these equations will have a maximum error of
approximately 3%. For those interested, more precise results may be obtained
by reducing the temperature intervals and using the HP-67/97 exponential curve
fit program to define the equation of the new data group. In this same
manner, SVP equations for temperatures greater than 159°F may also be
obtained. Use the goodness of fit test (r2) in the program to determine the
appropriate grouping for the accuracy desired.
37
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The equations have been found to be more than adequate in estimating
moisture fraction for calculating isokinetic AH. The maximum difference
observed between BWs calculated using this method and Bw$ as determined by
the condensation method for the 40 tests described in this report was approxi-
mately 10%. Typically, the agreement was a few percent or less. This method
has proven sufficiently accurate for calculating AH with dew point tempera-
tures as high as 141°F.
To obtain the accuracy described, care must be taken in making the wet and
dry bulb temperature measurements. This amounts primarily to allowing the
thermometer to reach equilibrium conditions. Of course, when using separate
thermometers for the two measurements, they must be well matched.
This program is easily adapted to the HP-65 by one of two methods: (1)
Perform the SVP calculations for the range 0-1S9°F on one magnetic card,
storing SVP and Tw for use with a second magnetic card to complete the
calculation for Bws. (2) Incorporate on one magnetic card the complete
program for Tw = 0-59°F, using a second magnetic card for Tw s >60-159°F.
It should be pointed out that this method will also work to determine the
moisture fraction in ambient air.
USER INSTRUCTIONS
STEP INSTRUCTIONS . DISPLAY
1 . Input TW(°F), Touch "A" SVP,(in. Hg)
2 Input Td(°F), Touch HB" T
-------
STEP . KEY CODE
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO 2.
ORP/LV-80-3
4. TITLE AND SUBTITLE
Radioactive Emissions From Yellowcake
Stacks at Uranium Mills
7. AUTHOR(S)
C. W. Fort, Jr., R. L. Douglas and W.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Radiation Programs -Las Veqas
U.S. Environmental Protection Agency
P.O. Box 18416
Las Vegas, Nevada 89114
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Radiation Programs-Las Vegas
U.S. Environmental Protection Agency
P.O. Box 18416
Las Vegas, Nevada 89114
Processing
E. Moore
Facility
Faci 1 i ty
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
October 1980
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT AND PERIOD COVERED
14, SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
1S. ABSTRACT
A sampling program was undertaken to evaluate the releases of uranium concentrate
from uranium mills. This concentrate, known as yellowcake, is the final product of
the mill. It is routinely released to the environment through stacks which exhaust
air from both the yellowcake drying and packaging operations. During this study,
samples were taken in these stacks at six mills to evaluate the total yellowcake
emission rates. This paper describes the sampling and analytical methods used, and
presents the results obtained. Considerable variation in the emission rates was
observed, both between mills and at the same mill over time. A total of 40 emission
rate tests were made, with the measured rates ranging from 0.001 Ib U^0g (0.4 yCi
Uf t -,) oer hour to 0.9 Ib U~0p (220 yCi U. . ,) per hour. Data are also presented
oirtfie levels of uranium daughter radionucTTdis (Th-230, Ra-226, Pb-210, and Po-210)
found in the yellowcake. The implications of the results of this study for monitoring
to meet State and Federal licensing requirements are discussed. Measurements such as
these can provide specific and realistic input data to models used to estimate radia-
tion doses to people living in the vicinity of the mill. However, the variations
observed indicate the need for relatively frequent and site-specific measurements.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Uranium Isotopes
Yellowcake
1802
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS EDITION is OBSOLETE
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