DRC-2009-008032 - 0901a06880140980

UNITED STATES NUCLEAR REGULATORY COMMISSION
ENVIRONMENTAL ASSESSMENT
PREPARED BY THE
URANIUM RECOVERY FIELD OFFICE
IN CONSIDERATION OF THE RENEWAL OF
SOURCE MATERIAL LId:NSE SUA-1358
FOR
THE UMETCO MINERALS CORPORATION
WHITE MESA URANIUM MILL
Sr-:..,r.198"_.I "...l ;J
Dated:
r.
TABLE OF CONTENTS
1.0 INTRODUCTION ...............................................1
1.1 Description of and Need for the Proposed Action 1
1.2 Background Information 1
1.3 Review Scope..........................................1
2.0 ENVIROMENTAL AND RADIOLOGICAL IMPACTS 2
2.1 Land Use 2
2.2 Operating Data........................................3
2.2.1 Air Particulate Sampling 3
2.2.2 Stack Effluent Sampling........................4
2.2.3 Radon Gas Monitoring 4
2.2.4 Ground Water and Surface Water Sampling 4
2.2.5 Direct Gamma Exposure 5
2.3 Radiological Assessment 5
2.3.1 Introduction ;.......................5
2.3.2 Estimated Releases ,'; 5
2.3.3 Exposure Pathways 6
2.3.4 Radiation Dose Commitments to Individuals 6
2.3.5 Radiation Dose Commitments to Populations 6
2.3.6 Evaluation of Radiological Impacts
to the Public...............................7
2.3.7 Radionuclide Concentrations at Site
Boundaries..................................7
2.3.8 Summary 7
3.0 EFFLUENT AND ENVIRONMENTAL MONITORING PROGRAMS 8
3.1 Effl uent Monitori ng 8
3.2 Airborne Particulate Monitoring 8
3.3 Radon Gas and Direct Radiation Monitoring 8
3.4 Soil and Vegetation Sampling 9
3.5 Ground Water and Surface Water Sampling 9
3.5.1 Surface Water 9
3.5.2 Ground Water.....9
3.6 Quality Assurance for Environmental Monitoring 10
3.7 Summary ,10
4.0 TAl LINGS MANAGEMENT 11
4.1 During Operation 11
4.2 Reclamation 12
5.0 CONCLUSION 13
.,'
,.
Appendix A
Appendix B
Appendix C
Appendix 0
LIST OF APPENDICES
Page
Tab 1es and Fi gures 21
Detailed Radiological Assessment 35
Calculation of Gamma Radiation Attenuation
for Reclaimed Tailings Impoundment 53
Calculation of Thickness of Required
Cover Materi a1 55
"
1
1.0 INTRODUCTION
1.1 Description of and Need for the Proposed Action
By application dated January 30,1985,Umetco Minerals Corporation
(Umetco)requested renewal of NRC Source Material License
No.SUA-1358 authorizing uranium milling activities at their White Mesa
mill located in San Juan County,Utah.The mill is currently in a
shutdown status under a timely renewal since the previous license
expired on January 30,1985.The licensee projects resuming milling
operations by about October 1,1985.The proposed action is to issue a
renewal of the subject license authorizing operation of the facility for
maximum production of 4380 tons of U30 8 per calendar year.
The necessity for the White Mesa milling facility was discussed in
Section 10 and Appendix B of the Final Environmental Statement (FES)
for the White Mesa Project (NUREG-0556)dated May,1979.The
necessity for renewing the license is essentially the same as discussed in
the FES.
1.2 Background Information
By letter dated February 6,1978,Energy Fuels Nuclear,Inc.(EFN)
applied to the Nuclear Regulatory Commission (NRC)for a Source and
Byproduct Material License to construct and operate a uranium milling
facility located approximately 9.5 km (6 miles)south of Blanding,Utah
(see Figure 1,Appendix A).Following issuance of the FES in May,
1979 and the staff's Safety Evaluation Report (SER)in August,1979,
Source and Byproduct Material License No.SUA-1358 was issued on
August 7,1979.
The mill operated on a continual basis until February,1983 and has been
in a standby mode until the present time.Umetco purchased a
controlling interest in the mill in January,1984 and was designated
operator and licensee by Amendment No.26 issued by the NRC on
December 5,1984.
1.3 Review Scope
This environmental assessment of Umetco Minerals Corporation's request
for renewal included evaluations of the January 30,1985 renewal
application;a revised renewal application dated May,1985;additional
information submitted by letters dated May 8 and May 10,1985;and
environmental monitoring reports submitted since issuance of the original
license.
"
2
Umetco's proposed programs were evaluated against NRC regulations as
specified in 10 CFR 20 and NRC staff policy as specified in the
following:(1)Regulatory Guide 4.14,"Radiological Effluent and
Environmental Monitoring at Uranium Mills,"(2)Regulatory Guide 4.15,
"Quality Assurance for Radiological Monitoring Programs (Normal
Operations)-Effluent Streams and the Environment;"and (3)
Regulatory Guide 3 .11.1,"Operational Inspection and Surveillance of
Embankment Retention Systems For Uranium Mill Tailings."
2.0 ENVIRONMENTAL AND RADIOLOGICAL IMPACTS
2.1 Land Use
All operations to be authorized by the renewed license will be conducted
within the confines of the existing site boundary.The project site
consists of 1052 ha (2600 acres)of private land together with 726 ha
(1725 acres)of mill site claims.Surface area owned by Umetco is shown
on Figure 2 (Appendix A)and includes·most of Section 28 and portions
of Sections 21, 22, 27,32 and 33 of T.378,R.22E,and Section 16 of
T .38S,R.22E.The mill occupies 34 acres (14 ha).At the end of the
proposed period of renewal (1985 through 1991)the tailings disposal cells
will occupy another 132 acres (54 ha).
The region is characterized by an arid climate,a sparse population and
diverse topography.Primary land uses includes livestock grazing,
wildlife range,and exploration for minerals,oil and gas.The area
within 8 km (5 miles)of the project site is predominantly range land
owned by residents of Blanding,although much of the land in San Juan
County is Federally owned.The nearest resident in the prevailing wind
direction is located at the Blanding Airport approximately 5.7 km
(3.6 miles)northeast of the mill.Approximately 5.6 km (3.5 miles)
southeast of the project site is the White Mesa Reservation,a community
of 260 Ute Indians.
A historical survey was conducted in the project vicinity as part of the
initial application and six historical sites were identified.However,none
of the sites is in an area which will be affected by operations at the
White Mesa mill.
Archeological surveys of the project site conducted in 1977 and 1979
identified 121 areas which were once affiliated with the San Juan Anasazi
Indians who occupied this area of Utah approximately 686 years ago.As
a result of the archeological findings,a memorandum of agreement (MOA)
between NRC,the Utah State Historic Preservation Officer and the
Advisory Council on Historic Preservation was established to specify
requirements necessary to minimize adverse impacts to the previously
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identified archeological sites.The requirements were incorporated into
SUA-1358 as initially issued.The requirements have been subsequently
modified following amendment of the MOA.The most recent modifications
were incorporated into SUA-1358 through the issuance of an amendment
on May 11,1983.These requirements will be included in the renewed
license.
To assure continued protection of the environment,the staff will require
that the licensee conduct an annual survey of land use in the vicinity of
the mill and conduct an archeological and historical artifact survey of
areas not previously surveyed prior to their disturbance.
2.2
2.2.1
Operating Data
Air Particulate Sampling
Umetco's previous air particulate monitoring program consisted of five
continuous environmental sampling locations,Three stations were located
at the site boundary,one at the nearest residence,and one background
station 15 km upwind from the site.The samples were analyzed for
U-nat,Th-230,Ra-226,and Pb-21O.
Since the White Mesa Mill terminated operations in February of 1983,the
data reviewed for this renewal was collected during 1982 when milling
operations were continuously performed.The data indicated that
measured concentrations of U-nat,Th-230,Ra-226,and Pb-210 have
been only small fractions of the ·10 CFR 20 limits for unrestricted areas.
A summary of this data is as follows:
1.U-nat concentrations did not exceed an annual average of 0.2%
of the 10 CFR 20 limits.
2.Th-230 concentrations did not exceed an annual average of
12.1%of the 10 CFR 20 limits.
3.Ra-226 concentrations did not exceed an annual average of
0.13%of the 10 CFR 20 limits.
4.Pb-210 concentrations did not exceed an annual average of
0.8%of the 10 CFR 20 limits.
It should be noted that the concentrations measured include contributions
from natural background.
2.2.2 Stack Effluent Sampling
4
Stack sampling has been performed at least semiannually since the mill
began operation.The FES (Section 3.2)predicted a product loss from
the yellowcake drying and packaging stack of 115 kg per year of which
104 kg would be U308'This resulted in a calculated release rate of
0.029 Ci/y for U-238.Actual stack sampling measurements performed in
1982 indicated releases of 97.5 kg of U-nat from the yellowcake stack,
which corresponds to 0.027 Ci of U-238.The measured values compare
favorably with the release values predicted in the FES.
The FES also estimated that 0.0016 Ci/y of Th-230,6.2E-5 Ci/y of
Ra-226,and 6.2E-5 Ci/y of Pb-210 would be released.Based on effluent
monitoring data,the average releases during 1982 were 3.2E-5 Ci/qtr of
Th-230 (l.3E-4 Ci/y),1.0E-5 Ci/qtr of Ra-226 (4.1E-5 Ci/y),and
7.9E-5 Ci/qtr of Pb-21O (3.17E-4 Ci/y).All of the measured values
were less than the predicted releases except for Pb-210.The calculated
concentration of Pb-21O in the yellowcake stack,when flow rate was
considered,did not exceed 17.5%of the maximum permissible
concentration (MPC)for restricted areas in any quarter.
2.2.3 Radon Gas Monitoring
Radon gas monitoring was performed one week each month at the five
stations utilized to collect airborne particulate samples.During 1982,
measured radon gas concentrations did not exceed 11%of the MPC for
unrestricted areas.The background during this same collection period
measured 7.3%of the MPC.
2.2.4 Ground Water and Surface Water Sampling
Umetco previously performed quarterly sampling of nine monitoring wells,
one control well upgradient of the tailings system,one drinking water
well and two surface water sources.Samples were analyzed for five
radionuclides and various chemical and physical parameters.
A staff review of the ground water quality indicated that downgradient
monitor wells Nos.2,3,4,5,11,12 and 13 show a higher concentration
of dissolved constituents than does the background well (No.1).
Because this has been observed since the time of the preoperational
monitoring program,it probably represents normal variance in the
ground water.Based on 1982 ground water monitoring data,the highest
radionuclide concentrations measured were 0.08,10,0.09,1.8 and
0.3 percent of the applicable MPC for U-nat,Ra-226,Th-230,Pb-210
and Po-210,respectively.No ground water anomalies have been
observed.This situation is not unusual since the tailings retention
system consists of synthetically lined c,"lls.
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Surface water radionuclide concentrations have not varied appreciably.
The U-nat concentrations are higher than any other radionuclide and did
not exceed 1.1E-8 uCi/ml (0.004 %of the MPC for unrestricted areas).
2.2.5 Direct Gamma Exposure
Direct radiation exposure measurements were made quarterly at the five
air particulate monitoring stations.The highest exposure rate measured
during 1982 was 37.3 mR/qtr including background and 11.7 mR/qtr
above background.
2.3
2.3.1
Radiological Assessment
Introduction
This assessment addresses the radiological impacts from milling operations
at the White Mesa site.The licensee desires to process 2000 tons/day of
ore with an average ore grade of 0.6%,for .a yellowcake production rate
of 4,380 tons/year.This assessment presents a state-of-the-art
evaluation of impacts from the White Mesa mill at a production rate of
4,380 tons of yellowcake per year.
Components of the radiological analysis presented in this section include
estimates of the following:(1)annual releases of radioactive materials
from the mill and tailings retention system,(2)resulting dose
commitments to nearby individuals and the population within 80 km
(50 miles)of the site,and (3)concentrations of radionuclides at the
restricted area boundary.The calculated results are compared to
measured background radiation and applicable regulatory limits.Tables
and figures referenced in the text are provided in Appendix A.
2.3.2 Estimated Releases
A summary of the information and data assumptions used to calculate the
annual releases of radioactive materials from the mill and tailings
retention system is presented in Table 1.The estimated annual releases
are presented in Table 2.More detailed descriptions of release estimates
from the tailings cells and ore pad as well as descriptions of the models
and assumptions used by the staff to perform the radiological impact
assessment are provided in Appendix B.Release rates from the tailings
retention system are based on the tailings management plan discussed in
Section 4.0.
2.3.3 Exposure Pathways
6
Potential environmental pathways by which people could be exposed to
radioactive effluents from the White Mesa Mill are presented in Figure 3.
These pathways include inhalation of radioactive materials in the air,
external exposure to radioactive materials in the air or deposited on
ground surfaces,and ingestion of contaminated food products (i.e.,
vegetables,meat and milk).
2.3.4 Radiation Dose Commitments to Individuals
The nearest residence to the mill is the White Mesa Reservation,located
approximately 5.6 km southeast of the mill.The airport,the nearest
residence in the prevailing wind direction,is located approximately
5.7 km NE of the mill.In addition to calculating dose commitments to
individuals residing at the nearest residences,the staff has also
calculated dose commitments for individuals residing in Blanding,Utah,
9.95 km NE of the mill.Meat ingestion doses were calculated because
cattle are grazed in the vicinity of the mill.Table 3 presents a
summary of individual dose commitments calculated for these locations.
These doses result from releases during the final year of mill operation,
when environmental concentrations are expected to be at their highest
level.
For the purposes of this assessment,the staff has assumed that
ingestion doses at the White Mesa Reservation result from the
consumption of meat from cattle grazed within 1 km of the mill center.
There are no milk cattle in the vicinity of the mill but there is an
orchard 3.54 km north of the mill center.
Table 4 presents a comparison of the annual dose commitment resulting
from mill operations with the EPA radiation protection standard
(40 CFR Part 190).
2.3.5 Radiation Dose Commitments to Populations
Projected environmental population dose commitments are presented in
Tables 5 and 6.Table 5 presents 100 year dose commitments to the
regional population within 80 km of the White Mesa mill for the final year
of mill operation.Table 6 presents the total environmental dose
commitments to the regional population within 80 km of the mill and the
transcontinental population from operations over the renewal period of
the White Mesa mill (1985 through 1991).Transcontinental dose
commitments,as opposed to regional impacts,result entirely from the
release of radon gas.
7
Both tables discussed above also contain a comparison of total dose
commitments resulting from the White Mesa operation with dose
commitments resulting from natural background.
2.3.6 Evaluation of Radiological Impacts to the Public
A review of Table 4,which compares individual dose commitments with
the EPA 40 CFR 190 standard of 25 mrem to the whole body or any
organ,indicates that individual dose commitments are small fractions of
the standard.The highest calculated dose commitment is 4%of the EPA
standard.
A review of Tables 5 and 6 indicates that regional and transcontinental
dose commitments are only very small fractions of the dose commitments
from naturally occuring background radiation.
2.3.7 Radionuclide Concentrations at Site Boundaries
The radiological assessment also included th~calculation of projected
radionuclide locations at eight site boundary locations during the final
year of operation.A comparison of these projected concentrations with
unrestricted area concentration limits specified in Appendix B to
10 CFR Part 20 is presented in Table 7.The highest projected
concentration is 14.4%of the 10 CFR 20 limits for Th-230 and less than
1%for U-238.For the 1982 year of full operation,the highest annual
averages of quarterly concentrations measured were 12.1%for Th-230 and
0.2%for U-238 of the 10 CFR 20 limits.Therefore,the projected
highest concentrations compare favorably with the highest concentrations
actually measured at the site boundary.
2.3.8 Summary
The radiological assessment performed by the staff indicates that both
site boundary radionuclide concentrations and individual dose
commitments are small fractions of applicable standards.However,the
renewed license will require that the operator conduct an effluent and
environmental monitoring program,the results of which must be reported
to the Uranium Recovery Field Office,NRC,in accordance with
10 CFR 40.65.The licensee will also be required to conduct an annual
land use survey of the environment near the mill and report the results
of these surveys to URFO.Significant changes in regional population,
grazing or land cultivation patterns near the mill would necessitate a
revised radiological assessment,and could alter the conclusions in this
assessment.URFO will continue to review the operator's future
submittals to determine compliance with existing standards.
8
Additionally,the licensee will be required by license condition to assess
all activities not previously evaluated in this environmental assessment or
the FES for potential adverse impacts.If the evaluation indicates that
the activity could result in a significant environmental impact,the
licensEe will be required to obtain NRC approval prior to initiating the
activity.
3.0 EFFLUENT AND ENVIRONMENTAL MONITORING PROGRAMS
3.1 Effluent Monitoring
The licensee has committed to perform sampling of mill stacks utilizing
the EPA Method 5 isokinetic sampling procedure.Yellowcake stack
sampling will be performed on a quarterly basis during operation of the
facility.The particulate samples will be analyzed for U-nat on a
quarterly basis and for Th-230,Ra-226 and Pb-210 on a semiannual
basis.Ore stack sampling will be performed on a semiannual basis
during operation of the facility.The par;ticulate samples will be
analyzed for U-nat,Th-230,Ra-226 and Pb-210.The licensee has
indicated that monitored data will include ventilation system operation
levels,process feed levels,particulate emission concentrations,isokinetic
conditions and radionuclide emission concentrations.The staff will also
require that all stack sampling include a determination of flow rate.
3.2 Airborne Particulate Monitoring
Umetco proposes to perform airborne particulate sampling at the five
locations currently being monitored.The present low volume sampling
system is to be replaced with high volume particulate samplers utilizing
mass flow controllers to maintain an air flow rate of forty standard cubic
feet per minute.Samplers will be operated continuously with an
expected on-stream operating ratio exceeding ninety percent.Filters
will be changed weekly with quarterly composition for radionuclide
analysis.Samples will be analyzed for U-nat,Th-230,Ra-226 and
Pb-210.
3.3.Radon and Direct Radiation Monitoring
Umetco proposes to perform continuous radon-222 monitoring at the five
airborne particulate monitoring locations.System quality assurance will
be provided by placing a duplicate monitor at one site continuously.
The monitoring method consists of a Passive TLD system.Umetco
proposes to exchange and read the TLDs monthly.The staff feels that
quarterly readings of TLDs will minimize the relative error ass0ciated
9
with each reading.The staff will therefore require that the TLDs be
exchanged and read quarterly.
TLD badges supplied by Eberline,Inc.,or equivalent,will be utilized at
the five existing ambient particulate monitoring sites to determine
ambient external gamma exposures.Each badge consists of a minimum of
five TLD chips.Exchange of TLD badges will be on a quarterly basis.
3.4.Soil and Vegetation Sampling
Umetco's proposed programs for vegetation and soil sampling are
discussed below.Forage vegetation samples will be collected three times
per year from animal grazing areas near the mill site.The samples will
be collected near the meteorological station,to the immediate west of this
site,and by the south tailings area in the late fall,early spring and
late spring.One to two kilograms of grass are to be collected from each
site and analyzed for Ra-226 and Pb-210.
Soil Samples from the top one centimeter of surface soils will be collected
annually at each airborne particulate monitoring site.A minimum of two
kilograms of soil is to be collected per site and analyzed for U-nat and
Ra-226.
3.5
3.5.1
Ground Water and Surface Water Sampling
Surface Water
Umetco proposes to sample Westwater and Cottonwood Creeks on a
quarterly basis at locations upstream and downstream of the White Mesa
Mill and tailings disposal site.Field monitored parameters include pH,
specific conductivity and temperature.Laboratory monitored parameters
include total dissolved solids,total suspended solids,and gross alpha
concentrations.
In addition to the surface water monitoring program proposed by the
licensee,the staff will require by license condition that analyses be
performed semiannually on surface water samples for total and dissolved
concentrations of U-nat,Th-230,and Ra-226.
3.5.2 Ground Water
Umetco proposes that ground water sampling of Monitor Wells I,2,3,4,
5,11,12,13 and the culinary water well at the White Mesa facility
continue on a quarterly basis.Wells will be pumped and the water
quality monitored for pH,specific conductance and temperature during
10
pumping with sample recovery occurring when these parameters stabilize
to assure that a representative sample is obtained.The locations of the
wells are shown on the map contained in Appendix B of the renewal
application.
Umetco proposed that sample analysis be performed according to the
schedule and for the 32 parameters listed in Table 5.5-1 of the renewal
application.The proposed program consists of quarterly sampling and
analysis of samples for various constituents on quarterly,semiannual,
and annual frequencies,depending on the parameters.The staff
concludes that annual analyses will not result in a reliable data base.
The staff will therefore require that Umetco analyze for U-nat as well as
seven chemical or physical parameters quarterly and Ra-226,Th-230 and
Pb-210 as well as three additional chemical parameters semiannually.In
addition,the staff will require that the ground water sampling data for
the quarterly parameters be maintained in graphical form.
In order to assure that the requirements of the EPA 40 CFR 192
standard are met,the staff issued Amendment No.29 to SUA-8681 on
July 19,1985.The amendment required the implementation of a
detection monitoring program in accordance with 40 CFR 192.The
applicable license condition will be includ~d in the renewed license.
3.6 Quality Assurance for Environmental Monitoring
Umetco has submitted to the staff information regarding all aspects of
the quality assurance program including environmental sample collection,
handling and analysis.The staff has reviewed Umetco's quality
assurance program and concludes that the program contains all the
elements of an acceptable quality assurance program as specified in
Regulatory Guide 4.15.The proposed program will ensure that all
aspects of the environmental monitoring program are conducted in an
acceptable manner.
The licensee did not submit proposed lower limits of detection (LLD)for
the environmental monitoring program.Therefore,the staff will require
by license condition that the licensee utilize LLDs in accordance with
Section 5 of Regulatory Guide 4.14 for the analysis of samples collected
pursuant to their environmental and effluent monitoring program.
3.7 Summary
The staff concludes that the effluent and environmental monitoring and
quality assurance programs proposed by Umetco,as modified by the
staff,are acceptable and in keeping with the guidelines presented in
Regulatory Guides 4.14 and 4.15.In addition,the staff will require by
license condition that the results of all effluent and environmental
11
monitoring be reported to the Uranium Recovery Field Office,NRC,in
accordance with 10 CFR 40.65.
4.0 TAILINGS MANAGEMENT
4.1 During Operation
The design of the complete tailings management system is presented in
the report entitled,"Engineer's Report,Tailings Management System,"
June 1979 by D'Appolonia.Four cells were proposed for tailings disposal
and one cell was designed for evaporation of water.To date,three cells
have been constructed.All are synthetically lined.The initial phase of
the tailings system has been in operation since May 1980.Cell 2 began
operation in May 1980 for solids disposal and Cell 1 began operation in
July 1981 as an evaporation pond.The second phase of the Tailings
Management system consisted of Cell No.3 which is also utilized for
solids disposal.
No evidence exists that these ponds are allowing significant volumes of
tailings fluid to escape to the surrounding environment.No water has
been collected by the toe drain system in Cell No.1.The small amount
of water collected in the toe drain of Cell No.2 was demonstrated to not
be tailings liquid ("Leak Detection System Evaluation"by D'Appolonia
dated December,1981").
Through the period of renewal,only Tailings Cell Nos.1-3 will be
utilized by Umetco.No changes to the existing tailings retention system
will be necessary as no additional capacity is needed.Any changes to
the existing tailings retention system will require an amendment to
SUA-1358.
Section 5.5.7 and Section 3.0 of Appendix D to the renewal application
detail the tailings system inspection procedures.The sections describe
the daily,weekly,monthly,quarterly and yearly inspections and the
yearly technical evaluations to be performed and provide the inspection
forms to be used.The inspection program is in accordance with
Regulatory Guide 3.11.1.The licensee included a liner inspection
program with sampling and analysis of any liquids in the underdrain
system.These inspection programs will be incorporated into the
renewed license.
The licensee committed to meeting a freeboard limit of 3.5 feet for Cell 1
and 5.0 feet for Cells 2 and 3.These freeboard requirements were
approved by NRC during the initial evaluation of the tailings retention
system and will be included in the renewed license.The staff will also
12
require that mill tailings other than samples for research not be
transferred from the site without specific prior approval of the NRC.
In order to prevent blowing tailings during operation and while a cell is
being dried out,the staff will require that the licensee implement a
program to minimize blowing of tailings and verify the effectiveness of
the measures utilized by means of a weekly documented tailings area
inspection.The staff will also require that the licensee install
instrumentation on all tailings solution lines which will detect ruptures in
the lines.This will assure line breaks do not go undetected.
4.2 Reclamation
The tailings reclamation plan currently in effect for the White Mesa mill
was initially proposed by Umetco on May 14,1982.It was revised on
August 25,1982 and again on August 26,1983.The latter revision was
incorporated into Source Material License SUA-1358 on September 12,
1983.
The current plan calls for a nine foot soil cover to be placed over all
tailings.Outslopes of the pile will be flattened to 6H:IV slopes.
Erosion protection consisting of two feet of rock on the top of the pile
and four feet of rock on the outslopes will be placed on the reclaimed
pile.
A staff radon attenuation calculation was performed to show that the
cover thickness of 9 feet of soil as specified in the current reclamation
plan will be sufficient to reduce the radon emanation rate to below
20 pCi/m2-sec as specified in the EPA 40 CFR 192 standard.This
calculation is illustrated in Appendix D.The staff evaluation indicates
that approximately 7.5 feet of cover will provide the required
attenuation.As the current reclamation plan calls for two feet of rock
over the top of the cover,erosion due to sheet water flow and wind
should be minimal over a 1000 year period.Therefore,the 9 feet of
cover should provide radon attenuation over a 1000 year design life in
accordance with 40 CFR 192.
In addition to two feet of rock on the top of the pile,four feet of rock
erosion protection will be placed on outslopes of the pile,which will be
graded to a 6H:1V slope.Erosion of the outslopes should therefore be
minimal.The staff concludes that the current reclamation plan will be
effective over a 1000 year design life in accordance with 40 CFR 192.
However,the existing reclamation plan does not contain adequate detail
regarding items such as the following:
(l)dewatering of the tailings
(2)interim stabilization of exposed tailings areas during the
drying process
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(3)settlement and consolidation monitoring of the tailings to
determine when reclamation activities may be initiated
(4)timetables for and sequencing of reclamation activities.
The staff will therefore require that Umetco submit a revised reclamation
plan for USNRC review and approval in the form of a license amendment.
The revised plan will address all items listed above.
At present,the licensee maintains a parent company guarantee from
Union Carbide Corporation per letter dated November 12,1984,for
millsite decommissioning and tailings reclamation.The staff will require
that the surety arrangement in effect be updated annually and that a
detailed breakdown of costs be provided to the NRC with the annual
update.
Umetco Minerals Corporation owns the majority of the land on which the
millsite and tailings cells are located.The remainder of the land is
unpatented Bureau of Land Management land.The staff will require that
the licensee either demonstrate federal ownership or make provision for
transfer of the land to the federal government or the State of Utah prior
to termination of the license.
5.0 CONCLUSION
Impacts resulting from milling operations at the White Mesa Mill are
summarized below;
1.All activities are conducted within the existing site boundary,
where operations have been conducted since 1980.
Continuation of milling operations will not result in additional
land disturbance above that already evaluated in the FES for
the White Mesa Mill.In addition,all disturbed land will be
reclaimed following cessation of milling operations.
2.Mill emissions,for the most part,have been less than
emissions predicted in the White Mesa FES.
3.Airborne radionuclide concentrations measured at site boundary
locations have been only small fractions of 10 CFR 20
concentrations .
4.Ground water radionuclide concentrations have been only small
fractions of 10 CFR 20 values.
5.The radiological assessment performed indicates that individual
dose commitments are small ~ractions of 40 CFR 190 limits.
14
Also,estimated concentrations of radionuclides in air indicate
that even at the highest levels of expected release,the mill is
in compliance with 10 CFR 20 limits for unrestricted areas.
It is the staff's conclusion that the impacts associated with renewal of
Source Material License No.SUA-1358 are within the realm of impacts
anticipated in the FES.Recognizing these impacts,the staff has
available two alternatives with respect to the requested license renewal:
(1)Renew the license with such conditions as are considered
necessary or appropriate to protect public health and safety
and the environment;or
(2)Deny renewal of the license.
In the safety evaluation report prepared for this action,the staff has
reviewed the licensee's proposed action with respect to the criteria for
license issuance specified in 10 CFR 40,Section 40.32,and has no basis
for denial of the license.Moreover,the environmental impacts described
in this document do not warrant denial of the application.For these
reasons,license denial is considered an upacceptable alternative.
Based on the environmental assessment presented in this document,the
staff recommends that Source Material License No.SUA-1358 be renewed
subject to the following license conditions:
1.Authorized place of use:The licensee's uranium milling facilities
located in San Juan County,Utah.
2.The licensee is hereby authorized to possess byproduct material in
the form of uranium waste tailings and other uranium byproduct
waste generated by the licensee's milling operations authorized by
this license.
3.For use in accordance with statements,representations and conditions
contained in Sections 3.6.6,5.1, 5.2,5.3, 5.4,6.2 and 6.3 and
Appendix E,Section 5,of the license renewal application dated
January,1985 as revised May,1985,except where superceded by
license condition below.
Whenever the word "will"is used in the above referenced sections,
it shall denote a requirement.
4.The mill production per calendar year shall not exceed 4,380 tons of
U3D8 ·
5.The licensee shall avoid by project design,where feasible,the
archeological sites designated "contributing"in Attachment No.2 to
SUA-1358.When it is not feasible to avoid a site designated
15
"contributing"in Attachment No.2,the licensee shall institute a
data recovery program for that site based on the research design
submitted by letter from C.E.Baker of Energy Fuels Nuclear to
Mr.Melvin T.Smith,Utah State Historic Preservation Officer,
dated April 13,1981.
The licensee shall recover through archeological excavation all
"contributing"sites listed in Attachment No.2 which are located in
or within 100 feet of borrow areas,stockpile areas,construction
areas,or the perimeter of the reclaimed tailings impoundment.Data
recovery fieldwork at each site meeting these criteria shall be
completed prior to the start of any project related disturbance
within 100 feet of the site,but analysis and report preparation
need not be complete.
Additionally,the licensee shall conduct such testing as is required
to enable the Commission to determine if those sites designated as
"Undetermined"in Attachment No.2 and located within 100 feet of
present or known future construction areas are of such significance
to warrant their redesignation as "contributing."In all cases,such
testing shall be completed before any aspect of the undertaking
affects a site..
6.Archeological contractors shall be approved in writing by the
Commission.The Commission will consult with the SHPO regarding
the qualifications of all archeological contractors and the quality of
the laboratory facilities they will use.The Commission will approve
an archeological contractor who meets the minimum standards for a
principal investigator set forth in 36 CFR Part 66,Appendix C,and
whose qualifications are found acceptable by the SHPO.
7.The licensee shall conduct an annual survey of land use (private
residences,grazing areas,private and public potable water and
agricultural wells,and non-residential structures and uses)in the
area within five miles (8 km)of any portion of the restricted area
boundary and submit a report of this survey to the USNRC,
Uranium Recovery Field Office.This report shall indicate any
differences in land use from that described in the last report.
8.The results of all effluent and environmental monitoring required by
this license shall be reported in accordance with 10 CFR 40,Section
40.65 with copies of the report sent to the USNRC,Uranium
Recovery Field Office.Monitoring data shall be reported in the
format shown in the Attachment No.3 to SUA-1358,"Sample Format
for Reporting Monitoring Data."
9.Before engaging in any activity not previously assessed by the
USNRC,the licensee shall prepare and record an environmental
evaluation of suoh activity.When the evaluation indicates that such
16
activity may result in a significant adverse environmental impact
that was not previously assessed or that is greater than that
previously assessed,the licensee shall provide a written evaluation
of such activities and obtain prior approval of the USNRC in the
form of a license amendment.
10.The licensee shall maintain a USNRC approved surety arrangement
adequate to cover tailings stabilization and reclamation,mill
decommissioning,mill site reclamation,long term maintenance and
monitoring,and ground water restoration as warranted.The
licensee shall submit for USNRC review and approval a proposed
revision to the surety arrangement within six (6)months of USNRC
approval of a revised tailings area reclamation plan or approval of
or revision to any ground water protection program.The revised
surety shall be in effect within three (3)months of written USNRC
approval.Furthermore,the licensee shall submit for USNRC review
any proposed revision or update to the surety arrangement at least
two (2)months prior to the proposed effective date.Along with
each proposed revision or update and at least annually,the licensee
shall submit documentation showing a breakdown of the costs and
the cost basis for tailings stabilization and reclamation,mill
decommissioning,mill site reclamatioh.,long term maintenance and
monitoring,and ground water restoration as warranted.
If the licensee chooses to retain a corporate guarantee as the
surety arrangement,the licensee shall provide for USNRC review
and approval in the form of a license amendment the financial data
listed in ltems (a)-(d)of Attachment No.4 to SUA-1358,NRC
Self-Bonding Criteria,within four (4)months of the date of this
license and annually thereafter.
11.Prior to termination of this license,the licensee shall provide for
transfer of title to byproduct material and land,including any
interests therein (other than land owned by the United States or
the State of Utah),which is used for the disposal of such
byproduct material or is essential to ensure the long term stability
of such disposal site to the United States or the State of Utah,at
the State's option.
12.The licensee shall not make any changes to the present tailings
retention system without specific prior approval of the USNRC,
Uranium Recovery Field Office,in the form of a license amendment.
13.The license shall implement an interim stabilization program for all
tailings not covered by standing water.This program shall include
written operating procedures and shall minimize dispersal of blowing
tailings.The effectiveness of the control method used shall be
evaluated weekly by means of a documented tailings area inspection.
17
The operating procedure shall be submitted for USNRC review and
approval within three (3)months of the issuance of this license.
14.The licensee shall implement the effluent and environmental
monitoring program specified in Section 5.5 of the renewal
application as revised with the following modifications or additions:
A.Stack sampling shall include a determination of flow rate.
B.TLD chips used for radon monitoring shall be exchanged and
read quarterly.
C.Surface water samples shall also be analyzed semiannually for
total and dissolved U-nat,Ra-226,and Th-230.
D.Ground water samples from Monitor Wells 1,2,3,4,5,11,
12,13 and the culinary water well shall be analyzed quarterly
for pH,specific conductance,chlorides,sulfates,TDS,and
U-nat.Quarterly water level measurements shall also be made.
Ground water samples shall be analyzed semiannually for
arsenic,selenium,sodium,Ra-229,Th-230,and Pb-210.
E.Data for the quarterly ground water parameters shall be
maintained in graphical form and copies of the graphs included
with the environmental monitoring reports submitted in
accordance with 10 CFR 40.65.
F.The licensee shall utilize lower limits of detection in accordance
with Section 5 of Regulatory Guide 4.14,Revision 1 dated
April 1980,for analysis of effluent and environmental samples.
15.The licensee shall submit to the USNRC,Uranium Recovery Field
Office,by March 15,1986 for review and approval in the form of a
license amendment a detailed reclamation plan for the authorized
tailings disposal area which includes the following:
A.A post operations interim stabilization plan which details
methods to prevent wind and water erosion and recharge of
the tailings area.
B.A plan to determine the best methodology to dewater and/or
consolidate the tailings cells prior to placement of the final
reclamation cover.
C.Plan and cross-sectional views of a final reclamation
which details the location and elevation of tailings.
shall include details on cover thickness,physical
characteristics of cover materials,proposed testing
cover
The plan
of cover
18
materials (specifications and QA),the estimated volumes of
cover materials and their availability and location.
D.Detailed plans for placement of rock or vegetative cover on the
final reclaimed tailings pile and mill site area.
E.A proposed implementation schedule for items A through D
above which defines the sequence of events and expected time
ranges.
F.An analysis to show that the proposed type and thickness of
soil cover is adequate to provide attenuation of radon and is
adequate to assure long term stability as well as an analysis
and proposal on methodology and time required to restore
ground water in conformance to regulatory requirements.
G.The licensee shall include a detailed cost analysis of each
phase of the reclamation plan to include contractor costs,
projected costs of inflation based upon the schedule proposed
in item E,a proposed contingency cost,and the costs of long
term maintenance and monitoring.,
16.The licensee shall conduct a tailings retention system and liner
inspection program in accordance with Section 5.5.7 and
Appendix D,Section 3.0,of the renewal application.
Notwithstanding any statements to the contrary,changes in
inspection frequency shall require the approval of the USNRC in
the form of a license amendment.Further,copies of the report
documenting the annual technical evaluation shall be submitted to
the Uranium Recovery Field Office,USNRC,within one month of
completion of the report.
17.Mill tailings other than samples for research shall not be
transferred from the site without specific prior approval of the
USNRC in the form of a license amendment.The licensee shall
maintain a permanent record of all transfers made under the
provisions of this condition.
18.The licensee shall,by January 1,1986,submit to the Uranium
Recovery Field Office,USNRC,for review and approval in the form
of a license amendment a plan for instrumentation which shall detect
ruptures of the tailings discharge and solution return lines when
these lines are being utilized.Indications of a possible rupture of
these lines shall result in activation of an alarm in an occupied area
of the mill.The instrumentation shall be tested daily,and testing
documented,to ensure proper operation.The instrumentation shall
be operational within sixty (60)days of USNRC approval.
19
19.The licensee shall implement a ground water detection monitoring
program to ensure compliance to 40 CFR 192.32(a)(2)which includes
the following elements:
A.The licensee shall monitor at the point of compliance and
background wells for the following indicator parameters:
Arsenic,Selenium and pH.The licensee shall utilize analytical
techniques capable of providing lower limits of detection of
0.005 mg/l and 0.001 mg/l for arsenic and selenium,
respectively.Measurements of pH shall be reported to the
nearest 1/10 standard unit.
B.The determination of compliance shall be based on sampling
Well Nos.2 and 3.
C.The determination of background levels for the parameters
specified in subsection (A)shall be defined by sampling Well
No.1.
D.The licensee shall sample for those parameters specified in
subsection (A)above at those weUs designated in subsections
(B)and (C)on a monthly basis for a period of one (1)year
and at least twice annually thereafter.The first monthly
sample shall be taken within 30 days of the date of this Order.
All semiannual samples shall be taken at least four months
apart.
E.The licensee shall,within 60 days of collection of the last of
the twelve monthly samples,propose for USNRC review and
approval in the form of a license amendment background levels
for indicator parameters and a statistical procedure for
identifying significant changes (95%confidence level)between
data from the wells specified in subsections (B)and (C).
F.The licensee shall report the data required by subsection (D)
semiannually along with those data required by License
Condition No.18 in accordance to the reporting format,
Attachment No.5 to SUA-1358,"Sample Format for Reporting
Detection Monitoring Data."These monitoring requirements are
in addition to the requirements specified in License Condition
No.24.
20
G.The licensee shall report at least annually in accordance to
reporting requirements specified in subsection (F)the rate and
direction of ground water flow under the tailings impoundment.
!~2r~ia~~etManager
Licensing Branch 2
Uranium Recovery Field Office,RIV
Candice C.Jierree,Project Manager
Licensing Branch 2
Uranium Recovery Field Office,RIV
Approved by:
Harry J~Petten <./.
Licensing Branch 2
Uranium Recovery Field Office,RIV
21
APPENDIX A
TABLES AND FIGURES
22
Table 1 Prinicipal Parameter Values Used in the Radiological
Assessment of the Umetco White Mesa Uranium Mill
Parameter Value*
General Data
Average ore grade,%U30 8
Average secular equilibrium ore activity of U-238 and
daughters,pCi/gm
Ore processing rate,t/year
Annual operating time,days/year
Recovery rate of ore processing,%
Dust/bulk ore activity concentration ratio,
Ore Storage and Handling
'..oss of ore dust by truck dumping.lb/ton
Loss of oredust by ore pad handling machinery,lb/ton
Loss of ore dust by ore load to grizzly and hopper,lb/ton
Specific radon flux factor from ore storage,pCi/m2-sec
per pCi/gm Ra-226
Area of ore pad,acres
Reduction factor due to spraying and wetting,%
Crushing,Grinding,Screening
Uncontrolled particulate release from crushing,grinding
and screening,Ib/ton
Control efficiency for releases from crushing,grinding
and screening,%
Fraction of radon content in bulk ore released from
crushing,grinding and screening,%
See footnotes,last page of table
0.60
1196
730,000
365
96
2.5
0.002+
0.02+
0.002+
1.0
6
20
95
20
23
Table 1 (continued)
Parameter
Yellowcake Drying and Packaging
Annual yellowcake production rate,t/yr
Product purity,%U30 8
Annual U30 8 production rate,t/yr
Fraction of U30 8 production lost to atmosphere,%
Ratio of Ra-226 or Pb-210 to U-238 concentration in
yellowcake stack effluent
Ratio of Th-230 to U-238 concentration in yellowcake
stack effluent
Radon release rate from yellowcake stack
failings Management Operations
Total tailings area,m2
Dusting rate from exposed beach,gm/m2 -year
Specific radon flux from exposed beach,pCi/m2-sec
per pCi/gm Ra-226
Dust/tails activity concentration ratios
Activity in homogeneous solid tailings for:
U-238 (pCi/gm)
Th-230
Ra-226
Pb-210
Dusting reduction factor due to water cover and wetting
of exposed sands,%
See footnotes,last page of table.
Value*
4380
93
4073
0.1%#
0.001
0.005
negligible
534,200
2489
1.0
2.5
47.8
1190
1195
1195
50
24
Table 1 (continued)
*These values were selected by the NRC staff for use in its radiological assessment
of the White Mesa facility.They represent conservative selections from ranges of
potential values in instances where available data have been insufficient and/or
not specific.
+Values based on recommendations in Colorado Department of Health,Fugitive
Emission Factors Worksheet (draft)of Air Pollution Control Division.
#The rationale for this figure is presented on page G-6 of the "Final Generic
Environmental Impact Statement on Uranium Milling"(NUREG-0706).
25.
Table 2 Estimated Annual Airborne Releases of Radioactive
Materials from the Umetco White Mesa Uranium
Mill in the Final Year of Operation under the Renewal*
Estimated Releases (Curies/Year)+
Source Description U-238 Th-230 Ra-226 Pb~210 Rn-222
Ore Delivery 1.30E-3 1.30E-3 1.30E-3 1.30E-3 7.93E+l
Crushing 7.00E-4 7.00E-4 7.00E-4 7.00E-4 3.26E-l
Blowing Ore 7.00E-4 7.00E-4 7.00E-4 7.00E-4 5.15E+2
Grizzly 7.00E-4 7.00E-5 7.00E-4 7.00E-4 7.93E+l
Yellowcake Stack 4.00E-2 2.00E-4 4.00E-5 4.00E-5 0
Evaporation Pond 1.10E-3 2.65E-2 2.66E-2 2.66E-2 6.72E+l
'ailings Cell 2 1.80E-3 4.20E-2 4.20E-2 4'.20E-2 2.42E+3
Tailings Cell 3 1.80E-3 4.20E-2 4.20E-2 4.20E-2 2.42E+3
*Releases of all other radionuclides in the U-238 decay series are also included
in the radiological impact analysis.These releases are assumed to be identical
to those presented here for parent nuclides.For instance,the release rate
of U-234 is taken to be identical to that for U-238.Release rates of Pb-210
and Po-210 are assumed equal to that given for Ra-226.
+Releases are estimated on the basis of parameters as displayed in Table 1.
#Releases from the tailings impoundment reflect the configuration as proposed
for the final year of operations.
26
Table 3 Annual Dose Commitments to Individuals in the Vicinity
of the Umetco White Mesa Uranium Mill
Annual Dose Commitment,*mrem/year
Exposure Whole Bronchial
Location Pathway Body Bone Lung Epithelium
White Mesa Inhalation+1.69E-2#4.57E-1 6.63E-1 2.47E+1
Reservation External ground 5.11E-2 5.11E-2 5.11E-2
5.6 kIn SE External cloud 3.22E-1 3.22E-1 3.22E-1
Nearest Resident Meat &Vegetable
ingestion§5.57E-2 6.86E-1 5.57E-2
Total 4.46E-1 1.52E+0 1.09E+0 2.47E+1
Airport Inhalation 1.57E-2 4.17E-1 6.44£-1 1.09E+1
5.7 kIn NE External ground 5.73E-2 5.73E-2 5.73E-2
Nearest resident External cloud 1.37E-1 1.37E-1 1.37E-1
in prevailing
wind direction
Total 2.lOE-1 6.11E-1 8.38E-1 1.09E+1
Blanding Inhalation 7.86E-3 2.12E-1 3.03E-1
9.95 kIn NE External ground 2.59E-2 2.59E-2 2.59E-2
External cloud 9.08E-2 9.08E-2 9.08E-2
Meat &Vegetable
ingestion 3.02E-2 3.73E-1 3.02E-2
Total 1.55E-1 7.02E-1 4.50E-1 1.09E+1
*Dose commitments are integrated over a 50-year period from one year of exposure.
+Doses to the whole body,lungs,and bone are those resulting from the inhalation
of particulates of U-238, U-234,Th-230,Ra-226,Pb-210 and Po-210.Doses to the
bronchial epithelium are those resulting from the inhalation of radon daughters.
-2#Read as 1.69 x 10 or 0.0169.
§lngestion impacts result from the assumed consumption of meat from ctttle grazed
within 1 kIn of the mill center.
27
Table 4 Comparison .of Annual Dose Commitments to Individuals
with EPA Radiation Protection Standards (40 CFR 190)*
Annual Dose Commitment,*mrem/year
Average
Location Exposure Pathway Body Bone Lung
EPA limits 25.0 25.0 25.0
(40 CFR 190)
1.White Mesa Reserv.Inhalation 1.60E-2 4.30E-l 6.56E-l
5.6 km SE External 1.13E-3 1.13E-3 1.13E-3
Nearest resident Meat ~Veg~ta,ple 5.47E-2 6.61E-l 5.47E-2
mgestlon
Total 7.18E-2 1.092E+0 7.12E-l
Fraction of limit 2.90E-3 4.37E-2 2.85E-2
2.Airport Inhalation 1.53E-2 4.03E-l 6.40E-l
5.7 km NE External .1.'36E-3 1.~6E-3 1.36E-3
Nearest resident in
prevailing wind
Total 1.67E-2 4.04E-l 6.41E-l
Fraction of limit 7.00E-4 1.62E-2 2.57E-2
3.Blanding Inhalation 7.28E-3 1.94E-l 2.98E-l
9.95 km NE External 5.95E-4 5.98E-4 5.98E-4
Meat &Vegeta,ple
2.95E-2 5.50E-l 3.28E-lingestion
Total 3.73E-2 5.50E-l 3.28E-l
Fraction of limit 1.50E-3 2.20E-2 1.31E-2
*40 CFR Part 190 specifically excludes any dose commitments arising from the
release of radon and its daughters.
+Meat ingestion impacts result from the assumed consumption of meat from cattle
grazed within 1 km of the mill center.
28
Table 5 Annual 100-year EnvironJjlen:.al Dose Commitments to Regional
Population Within BO-kID Radius of the Umetco White Mesa
Uranium Mill
Exposure Pathway
Inhalation
External ground
External cloud
Vegetable ingestion
Meat ingestion
Milk ingestion
TOTAL
~stimated population
.ose from natural
background§
Annual Environmental Dose Commitments (EDC),person-rem *
Year
Whole Body Bone Lung
Bronchial +
Epithelium
4.62E-2#1.25E+0 1.715E+0 4.272E+I
1.236E+0 1.236E+0 1.236E+0
6.33E-I 6.335E-I 6.335E-I
2.04IE-I 2.970E+0 2.04IE-I
9.985E-3 1.526E-I 9.985E-3
1.794E-2 1.951E-I 1.794E-2
2.148E+0 6.443E+0 3.817E+0 4.272E+I
1
1.325E+3 .1.659E+3 1.33E+3 5.048E+3
Ratio of total EDC
to background
population dose
0.0016 0.0039 0.0029 0.0085
*Doses to the whole body,lung,and bone are those resulting from the releases
of particulates of U-238,U-234,Th-230,Ra-226,and Pb-210.
+Inhalation doses to the bronchial epithelium are those resulting from the
inhalation of radon daughters.
#Read as 4.62 x 10-2 or 0.0462
§Background doses are based on the regional population size of 9,015 and
natural background organ doses as follows:
Whole body -147 mrem/yr
Bone -184 mrem/yr
Lung -148 mrem/yr
Bronchial epithelium -560 mrem/yr
Source:G.L.Montet et al.,"Description of United States Uranium Resource
Areas,a Supplement to the Generic Environmental Impact Statement on
Uranium Milling,"Report NUREG/CR-0597,ANL/ES-75,prepared by Argonne
National Laboratory for the U.S.Nuclear Regulatory Commission,June
1979.The staff assumes the population dose due to background is
equivalent to the general background dose for the Wyoming Basin.
29
Table 6 Total Environmental Dose Commitments (EDC)through
the Renewal Period of the Umetco White Mesa Uranium Mill
EDC to each organ,person-rem
Bronchial
Whole Body Bone Lung Epithelium
EDCs received by population 2.148E+0 6.443E+0 3.817E+0 4.272E+1+
within 80 Km of mill
EDCs received by population 5.169E+3 6.944E+4 1.100E+3 3.134E+4
beyond 80 Km of mill
Total EDCs received by 5.172E+3 6.945E+4 1.104E+3 3.138E+4
continental population
Fraction of background#2.100E-4 2.820E-3 4.500E-5 2.560E-4
I
"'Total EDCs shown are the combined result of operational releases for the entire
duration of 6.0 years (1985-1991).
+The notation 4.272E+1 denotes 4.272 x 101 or 42.72.
#Background values estimated on the basis of year 1991,a continental population
of 245.5 million persons,each person receiving 100 millirem/year to the whole
body,bone,and lung and 500 millirem/year to the bronchial epithelium.
Table 7 Cumparison o.Predicted 'Air Concem,..atJon Uuru.g the 1'mal leal'01 i'lU.
Operation with 10 CFR 20 Limits fa ~elected Unrestricted Areas
Predicted Air Concentrations,pCi/m3
U-238 U-234 Th-230 Ra-226 RN-222(WL)*Pb-210 Bi-210 Po-210
NORTH SITE BOUNDARY
3.S9E-02#3.S9E-02CONC.,PCI/M3 S.29E-03 S.16E-03 1.39E-03 S.16E-03 S.14E-03 S.14E-03
MPC,PCI/M3 S.OOE+OO 4.00E+00 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+00
FRACTION OF MPC 7.18E-03 8.98E-03 6.62E-02 2.S8E-03 4.19E-02 1.29E-03 2.S7E-OS 7.3SE-04
Sum of fractions equals 1.29E-01
SOUTH SITE BOUNDARY
CONC.,PCI/M3 1.36E-02 1.36E-02 1.1SE-02 1.1SE-02 3.SSE-03 1.1SE-02 1.1SE-02 1.1SE-02
MPC,PCI/M3 S.OOE+OO 4.00E+OO 8.00E-02 2.00E+OO 3.33E-02 4.00E+00 2.00E+02 7.00E+00
FRACTION OF MPC 2.71E-03 3.39E-03 1.44E-01 5.75E-03 1.07E-01 2.87E-03 S.73E-OS 1.64E-03
Sum of fractions equals 2.67E-01
EAST SITE BOUNDARY
C(lNC.,PCI/M3 8.61E-03 8.61E-03 3.12E-03 3.09E-03 1.04E-03 3.09E-03 3.08E-03 3.08E-03
w
0
MPC,PCI/M3 S.OOE+OO 4.00E+00 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+OO
FRACTION OF MPC 1.72E-03 2.1SE-03 3.90E-02 1.S4E-03 3.12E-02 7.73E-04 1.S4E-OS 4.40E-04
Sum of fractions equals 7.69-02
WEST SITE BOUNDARY
CONC.,PCI/M3 6.13E-04 6.13E-04 1.08E-03 1.08E-03 4.9SE-04 1.09E-03 1.08E-03 1.08E-03
MPC,PCI/M3 5.00E+00 4.00E+00 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+00
FRACTION OF MPC 1.23E-04 1.S3E-04 1.35E-04 5.41E-04 1.49E-02 2.72E-04 5.40E-06 1.S4E-04
Sum of fractions equals 2.97E-02
NORTHEAST SITE BOUNDARY
CONC.,PCI/M3 7.34E-03 7.34E-03 2.64E-03 2.62E-03 9.6SE-04 2.62E-03 2.61E-03 2.61E-03
MPC,PCI/M3 S.OOE+OO 4.00E+OO 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+OO
FRACTION OF MPC 1.47E-03 1.83E-03 3.30E-02 1.31 E-03 2.90E-02 6.S6E-04 1.31E-OS 3.73E-04
Sum of fractions equals 6.77E-02
See footnotes,last page of table
Table 7 (Cont'~ued)
Predicted Air Concentrations,pCi/m3
U-238 U-234 Th-230 Ra-226 RN-222(WL)*Pb-210 Bi-210 Po-210
SOUTHWEST SITE BOUNDARY
CONC.,PCI/M3 9.44E-04 9.44E-04 2.09E-03 2.09E-03 7.73E-04 2.10E-03 2.09E-03 2.09E-03
MPC,PCI/M3 5.00E+00 4.00E+00 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+00
FRACTION OF MPC 1.89E-04 2.36E-04 2.62E-02 1.05E-03 2.32E-02 5.24E-04 1.04E-05 2.98E-04
Sum of fractions equals 5.17E-02
SOUTHEAST SITE BOUNDARY
CONC.,PCI/M3 3.88E-03 3.88E-03 2.38E-03 2.37E-03 1.31 E-03 2.38E-03 2.36E-03 2.36E-03
MPC,PCI/M3 5.00E+00 4.00E+00 8.00E-02 2.00E+00 3.33E-02 4.00E+00 2.00E+02 7.00E+OO
FRACTION OF MPC 7.77E-04 9.71E-04 2.97E-02 1.18E-03 3.94E-02 5.94E-04 1.18E-05 3.37E-04
Sum of fractions equals 7.30E-02
NORTHWEST SITE BOUNDARY
CONC.,PCI/M3 2.69E-02 2.69E-03 6.59E-03 6.49E~03 1.45E-03 6.49E-03 6.48E-03 6.48E-03
MPC,PCI/M3 5.00E+00 4.00E+00 8.00E-02 2.00E+60 3.33E-02 4.00E+00 2.00E+02 7.00E+OO w
FRACTION OF MPC 5.38E-03 6.73E-03 8.24E-02 3.25E-03 4.36E-02 1.62E-03 3.24E-05 9.25E-04 .....
Sum of fractions equals 1.44E-01
,.
*WL denotes "working level."A one-WL concentration is defined to be any combination of air concentrations
of the short lived Rn-2~daughters Po-218,Pb-214,Bi-214,and Po-214 that,in one liter of air,will
yield a total of 1.3 x 10 Mev of alpha particle energy in their complete decay to Pb-210.Predicted
values given for outdoor air are those calculated on the basis'of actual ingrowth from released Rn-222.
+ .Values given are from 10 CFR Part 20,Appendix B,Table II,Col.1.
#-2Thenotation3.59E-02 denotes 3.59 x 10 or 0.0359
§Compliance with 10 CFR Part 20 is not aChieved if the sum of the fractions is greater than 1.That is,if
radionuclides A,B,and C are present in concentrations C , CB' C and if the applicable maximum
permissible concentrations (MPCs)are MPC A'MPC B,and iiPCC'res~ectively,then the concentrations shall
be limited so that the following relationship exists:. .
(CA/MPCA) +(CB/MPCB ) +(Cc/MPCC)
.:.=1
32
T"•
T,.•
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t·o,
Location of the .ite of the White Me.a Uranium Project [OBS •ore buying
station].Source:Plateau Resources.Ltd.,Application for a Sourc~.~teriQt License
for the BLandi"-J Ore Buyi""Statio"-.Grand.Junction,Colo.,Apr,3,197B,Fig,2.1.2,
FIGURE 1
.,
•I,
I
I'
33-----,--~------~------_._-------.
,PROJECT SITE MAP
(TOWNSHIP 37 SOUTH PANGE 22 EAST)
onE FROM MINES
INHALATION
w
-'"
MAN
MAN
MAN --esClI---
~IBEEFR
CATTLE
INGESTION
DIRECT EXTERNAL
RADIOACTIVITY
IN SOIL
RADON AND PARTICULATES
ZoE
'"olLWo
RADIOACTIVITY
IN -1•.1:..
VEGETATION.X.
AIRBORNE
RADIOACTIVITY Z EXPOSURE
Q,I UJ~i ...Z
W
lL'"a·wa:
PRODUCT TO
MARKET
YELLOWCAKE DRYING
AND PACKAGING
ORE PAD.FEED
AND GRINDING
LEACHING AND
EXTRACTION
..
..,
~
G>
C
;0
fT1
W
Figure 3 Sources of Rlldiollctlve Effluents from the EXX_C?_~Hlghlond MlIIll_nd Exposure PathwllYS to Man
~
,,,....c·.J,•I ..,'-'"~"ep _.""--b I .---.-I
• I t _
.1_,.;")1 'j_r(,;.':...:.:.~...;~.rem
35
APPENDIX B
DETAILED RADIOLOGICAL ASSESSMENT
(B-1)
36
Appendix B
DETAILED RADIOLOGICAL ASSESSMENT
This assessment describes the models,data,.and assumption~used by the staff
to perform its radiological impact assessment of the Umetco White Mesa
Uranium Mill.The primary calculational tool employed is MILDOS,l an NRC-modified
version of the UDAD (Uranium Dispersion and Dosimetry)computer code originated
at Argonne National Laboratory.2
B.1 ANNUAL RADIOACTIVE MATERIAL RELEASES
Table 2 lists estimated annual activity releases for the Umetco White Mesa Uranium
Mill.All data except for the annual average dusting rate for exposed tailings
sands are based on the data and assumptions given in Table 1.This dusting
rate is calculated in accordance with the following equation:
M=3.156 X 10'o 5 I RsFs '. s
where
F =annual average frequency of occurrence of wind speed group s,
5 dimensionless;
Rs =dusting rate for tailings sands at the avera~e wind speed for wind
speed group s for particles ~20 ~m diam,glm os;
M =annual dust loss per unit area,g/m2 -year;
3.156 x 10'=number of seconds per year;
0.5 =fraction of total dust loss constituted by particles·
~20 ~m diameter,dimension1ess.1
The values of Rs and Fs used by the staff are as given in Table B.1.
The calculated value of the annual dusting rate,M,is 2489 g/m 2 -year.Annual
curie releases from the tailings pile are then given by the following
relationship:
(B-2)
where
A=assumed beach area of the pile,m2 ;
f =fraction of dusting rate con~ro11~d by mitigating actions,cd'. 1linens10n"ss;
37
Table 8.1 Parameter values for calculation of annual dusting
rate for exposed tailings 5ands~
Wind speed Average wind Dusting rate Annual frequency
group (knots)speed (mph)rate (g/m2 ·s)occurrence
0-3 1.5 0 0
4-6 5.5 0 0
7-10 lOA)3.92E-7t 0.1219
11-16 15.5 9.68E-6 0.0195
17-21 21.5 5.71E-5 0.0035
>21 28.0 2.08E-4 0.1879
-Dusting rate as a function of wind speed is computed by the
MIlDOS code.1 Wind speed frequencies obtained from annual
joint frequency data presented in Table B.2.
tRead as 3.92 x 10-7 ,or .000000392.
f
I UU II",;U.,
i~~CN.WHtT~MESA MtLL COOEEMtLOOS.REVO (7/79)
ETSET'ONSITE METOATA
,'JOINT FREOUENCY IN PERCENT.DIRECTION INDICATES WH ERE WINO IS FROM FREOWS'.37367.
PH'N NNE NE ENE E ESE SE SSE S SSW SW WSW
OATE=85/05/31.
PAGE NO.2
.29282•.12185 ••01950••00353•.18785
W WNW NW NNW TOTALS
,~----------------------------------------------------------------------------------------------------------------------------------:::'TAiHLITV CLASS 1
1.5 .4478 .2171 .3329 .2595 .3329 .3322 .7119 .6999 1.0312 ••212 .9393 ••661 .5690 .2195 .3793 .2321 7 .•779
~.5 .1555 .0990 .1555 .0565 .1555 • 1131 .4948 .9047 1.5833 1.1733 1.2016 .3958 .4806 .1838 .2969 .1414 7.5913
0.<1 .1131 .0990 .0990 0.0000 0.0000 .0141 .0424 .1212 .3817 .6503 .7775 .2120 .2403 .1414 .1919 .1131 3.2090
5.5 .0424 .0141 0.0000 0.0000 .0141 .0141 0.0000 0.0000 0.0000 .0565 .0990 .0424 .0707 .0283 .0141 .0141 .•098
1.50.00000.00000.00000.00000.00000.00000.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
R.O .129..0430 .1710 .1429 .1996 .1574 .2583 .3734 .3329 .2609 .2157 .1009 .0565 .1431 .onl .1002 2.7271
L"".8872 .•722 .758...598 .7021 .6309 1.5074 2.0951 3.3291 2.5622 3.1321 1.217I 1 ••1/11 .7151 .9303 ./1009 2 I .•150
STABILITY CLASS 2
1.5".0565 .0565 .0565 .0990 .0648 •1555 .3817 .5937 .9471 .8058 .3917 •1979 •1131 .1414 .0707 .0990 •.2.09
5.5 .0848 .0484 .0424 .0141 .0283 .0848 .0990 •1414 .4906 1.1309 .9058 .3393 .1696 .0565 .1696 .2120 3.9075
0.0 .0282 0.0000 0.0000 .0141 .0141 0.0000 0.0000 .0424 .1555 .2403 .3817 .3 110 .1 131 .0565 .0707 .0948 1.51 24
5.5 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 .0282 .0141 0.0000 0.0000 0.0000 0.0000 0.0000 .0283 .0706
1.50.00000.00000.00000.0000 0 0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
8.0 .0990 .0424 .15550.0000 .0424 .0282 .0565 .0848 .11 31 .1272 .0565 .0283 .0565 .0141 0.0000 .0141 .9186
LL .2685 .1473 .2544 .1212 .1696 .2685 .5372 .8623 1.7245 2.3193 1.6257 .8765 .4523 .2685 .3110 .4382 '0.6500-----------------------------------------------------------------------------------------------------------------------------------STAftlLJTV CLASS 3
1.5 .1555 .1414 .0565 .0263 .0990 .00.8 .2262 .3251 .6644 .3958 .1555 .0424 .1131 .0707 .•938 .0848 2.8273
5.5 .0565 .0141 .0141 .0141 .0141 .0707 .0948 .2262 .4524 .5230 .2262 .1272 .1272 .0565 .0990 .0565 2.1626
0.0 .0848 0.0000 0.0000 0.0000 0.0000 .0141 .0141 0.0000 .113I .1979 .2545 .1272 .2545 .0565 .1839 .0849 1.3953
5.5 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 .0141 .0424 .0283 .0283 .0141 0.0000 0.0000 .0282 .1554
1.50.00000.00000.00000.00000.00000.00000.00000.0000 .0141 0.0000 0.0000 0.0000 .0141 0.0000 0.0000 0.0000 .0282~.0 .•665 .7775 .4948 .1272 .1 131 .0283 .0565 .113 I •113 I .0849 .1272 .0424 .0849 .0283 .0848 .0707 2.8131
I.L .7633 .9330 .5654 .1696 .2262 ·1979 .3816 .6644 1.37'2 1.2439 .7911 .3675 .6078 .2120 .5514 .3250 9.3119._---------------------------------------------------------------------------------------------------------------------------------STABILITY CLASS 4
1.5 1.5126 1.7246 1.0319 .1696 .1939 .0707 .2262 .3534 .4949 ••392 .3534 .2696 .2262 .2403 .39.7 .5513 8.2273 w
3.5 1.1592 .6079 .6361 .0848 .2120 .0848 .2686 .1979 .5513 .4806 .6220 .4100 .3251 .5372 .6785 .9330 7.7890 00
o.'il .1555 .1414 .0282 .0848 .0141 .0283 ••979 .0424 .2120 .3958 .2545 .3675 .3110 .0565 .3817 .3393 3.0109
5.5 .0565 0.0000 .0141 0.0000 0.0000 0.0000 .0141 0.0000 .0565 .0848 •1131 .0707 .12720.0000 .0565 .0707 .6642
1.5 .01.1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 .0283 .0424 .0849 .0283 0.0000 0.0000 0.0000 0.0000 •1979
~.o .7257 .7107 .5811 .0567 .0142 .0142 .1135 .0428 .1276 .0143 .0710 .0284 .1559 .0709 .14'8 .1420 3.0108
LL 3.62363.1846 2.291..3959 .424'.1980 .8203 .6365 1.•705 1.4561 1.4999 I •1735 I.1454 .9049 1.6402 2.0363 22.900.-----------------------------------------------------------------------------------------------------------------------------------\TABILITY CLASS 5
1.5 3.8309 2.9545 .9047 .1 131 .0424 .0.2..2686 .3534 .25.5 .1272 .2686 .0990 .2'20 .1839 .3110 .5089 10.H50
~.5 2.1487 1.3571 .2969 .0424 .0283 .09.8 .2969 .0565 .6079 .2969 ••353..2969 .2403 .2686 .6503 .7069 7.7327
3.0 •1,~72 .1696 .2545 .0283 0.0000 .014'.0283 .0283 .1979 .4100 .3817 .1555 .0990 .0990 .6079 ."'665 3.0678I50.0000 .0.2..08.80.0000 0.0000 0.0000 .0141 0.0000 .0141 .0848 •0990 .042•.0565 0.0000 .1272 .08·8 .650'
1.50.00000.00000.00000.00000.00000.00000.0000 0.0000 0.0000 .0707 .0283 .0141 .0141 0.0000 0.0000 0.0000 .1272
I.;)1 ••1.7 .9.25 1.0996 .5712 ••985 .2923 .3960 .2070 .3976 .2652 .3685 .1921 .5272 .3261 .9751 .8423 9.3159.L 7.5215 5 .•661 2.6405 .7550 .5692 ••336 1.0039 .6452 1.4720 1.2548 1.4995 .8000 '.1491 .8775 2.6715 2.6093 31.3687--._------------------------------------------------------------------------------------------------------------------------------.TASIlITV CLASS 6
1.5 .6927 .•382 .3393 .1555 .1555 .0565 .1272 .1272 .1836 .1272 .1938 .113 I .1313 .2272 .5655 .4948 •.1188
•.5 .0990 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 .0990
1.0 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
•.5 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
1.5 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
1.0 O.COOO 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
.L .7917 .•382 .3393 .1555 .1555 .0565 .1272 .1272 .1838 .1272 .•1838 .1131 .1313 .2272 .5655 .4948 •.2178._---------------------------------------------------------------------------------------------------------------------------------.L 13.855810.6.1.6.8.94 2.0620 2.2.67 1.785•••3778 5.0307 9.5511 8.9625 9.73164.5477 ••90203.2052 6.6699 6.50.5 99.9235
39
ft =fraction of ore content of particular nuclide present in the
tailings;
S =annual release for the particular beach area,Ci/year;
C =assumed raw ore activity,pCi/g;
2.5 =dust-to-tails activity ratio;
10-12 =Ci/pCi.
The staff considered one evaporative pond and four tailings impoundments
increasing in beach area from startup in 1985.8.The total impoundment
is estimated to have a maximum capacity of 534,200 m2 •However,during
the operational phase of the mill's life,80%of the total area is
assumed to be available for dusting.In the final year of the renewal,
427,360 m2 are assumed to be available for dusting;the remainder of the
tailings are assumed to be covered by tailings liquid or controlled by
water spraying.
I
Dust losses from the ore storage piles were estimated by assuming that
they would be about 10%of those from an equivalent area of tailings
beach.
8.2 ATMOSPHERIC TRANSPORT
The staff analysis of offsite air concentrations of radioactive materials
has been based on two years of meteorological data collected at the White
Mesa uranium mill site from June 1981 to June 1982.The collected
meteorological data are entered into the MILDOS code as input in the form
of a joint frequency distribution by stability class,wind speed group,
and direction.The joint frequency data employed by the staff for this
analysis are presented in Table 8.2.
The dispersion model employed by the MILDOS code is the basic
straight-line Gaussian plume model.Ground-level,sector-average
concentrations are computed using this model and are corrected for decay
and ingrowth in transit (for radon-222 and daughters)and for depletion
caused by deposition losses (for particulate matter).Area sources are
treated using a virtual point source technique.Resuspension into the
air of particulate material initially deposited on ground surfaces is
computed using a resuspension factor that depends on the age of the
deposited material and its particle size.For the isotopes of concern
here,the total air concentration including resuspension is about
1.6 times the ordinary air concentration.
The assumed particle size distribution,particle density,and deposition
velocities for each source are presented in Table 8.3.
..
40
Table 8.3.Physical characteristics assumed for particulate
~ateria1 releases
Deposition
Diameter .Density Velocity AMAD'"
Activity source (IJm)(g/cm3 )(cm/s)(IJm)
Crusher dusts 1.0 2.4 1.0 1.55
Yellowcake dusts 1.0 8.9 1.0 2.98
Tailings,ore pile dusts
30%5.0 2.4 1.0 7.75
70%35.0 2.4 8.8 54.2
Ingrown radon daughters 0 1.0 0.3 0.3
-Aerodynamic equivalent diameter,used in calculating inhalation
doses.1
8.3 CONCENTRATION IN ENVIRONMENTAL MEDIA
Information prOvided below describes the methods and data used by the staff to
determine the concentrations of radioactive materials in the environmental
~edia of concern in the vicinity of the site.These include concentrations in
the air (for inhalation and direct external exposure),on the ground (for
direct external exposure),and in ~eat and vegetables (for ingestion exposure).
Concentration values are computed explicitly by the MIlDOS code for U-238,
Th-230,Ra-226,Rn-222 (air only),and Pb-210.Concentrations of Th-234,
Pa-234,and U-234 are assumed to equal that of U-238.Concentrations of
8i-210 and Po-210 are assumed to equal that of Pb-210._
8.3.1 Air concentrations
Ordinary,direct air concentrations are computed by the MIlDOS code for each
receptor location from each activity source by particle size (for particulates).
Direct air concentrations computed by MIlDOS include depletion by deposition
(particulates)or the effects of ingrowth and decay in transit (radon and
daughters).To compute inhalation doses,the total air concentration of each
isotope at each location,as a function of particle size,is computed as the
sum of the direct air concentration and the resuspended air concentration:
(B-3)
where
=total air concentration of isotope i,particle size p.at time
t,pCi/1I 3 ;
41
Caipd =direct air concentration of isotope i,particle size p,for
the time constant,pCi/m3 ;
Caipr(t)=resuspended air concentration of isotope i,particle size p,
at time t,pCi/m3 •
The resuspended air concentration is computed using a time-dependent
resuspension factor,Rp(t),defined by
Rp(t)=(l/V )lO-S e-ARt for t <1.82 yearp-
=(1/Vp)10-9 for t >1.83 year,(B-4)
where
R (t)=ratio of the resuspended air concentration to the ground
p concentration,for a ground concentration of age t years,of
particle size p,m-1 ;
Vp =deposition velocity of particle size p,cm/s;
1
AR =assumed decay constant of the resuspension factor (equivalent to
a 50-d half-life),5.06 years;
10-s =initial value of the resuspension factor (for particles with a
deposition velocity of 1 cmls),m-1 ;.
10-9 =terminal value of the resuspension factor (for particles with a
deposition velocity of 1 cm/s),m-1 ;
1.82 =time required to reach the terminal resuspension factor,years.
The basic formulation of the above expression for t~e resuspension factor,the
initial and final values,and the assigned decay constant derive from experi-
~ental observations.4 The inverse.relationship to deposition velocity
eliminates mass balance problems involving resuspension of more than 100%of
the initial ground deposition for the 35-~m particle size (see Table B.3).
Based on this formulation,the resuspended air concentration is given by
Caipr(t)=0.01 Caipd x 10-5
1 -exp[-(Ai *+AR)(t -a)]
(Ai*+AR)
exp[-A.-(t -a)]-exp(-A.*t)
+10-4 o(t)1 A.*1 (3.156 x 107 ),
1
(B-5)
where
a =(t -1.82)if t <1.82,years;
6(t)=O·if t <1.82 and is unity otherwise,dimensionless;
~~=effective decay constant for isotope i on soil,year _1;1
0.01 =deposition velocity for the particle size for which the
initial resuspension factor value is 10-s per meter,m/s;
3.156 X 107 =s/year.
Total air concentrations are computed using Eqs.B-3 and 8-5 for all
particulate effluents.Radon daughters that grow in from released radon are
not depleted because of deposition losses and are therefore not assumed to
resuspend.
8.3.2 Ground concentrations
Radionuclide ground concentrations are computed from the ~alculated airborne '
particulate concentrations arising directly from onsite sources (not including
air concentrations resulting from resuspension).Resuspended particulate
concentrations are not considered for evaluating ground concentrations.The
direct deposition rate of radionuclide i is calculated using the following
relationship:
(B-6)
(B-7)
where
C d'=direct air concentration of radionuclide i,particle size p,
a 1p pCi/m3 j
Ddi =resulting direct deposition rate of radionuclide i,pCi/m2 ·sj
V =deposition velocity of particle size P.m/s (see ref.4).p
The concentration of radionuclide i on a ground surface resulting from
constant deposition at the rate Ddi over time interval t is obtained from
1 -exp(-Ai +~e)t
C .(t)=Dd·gl 1
where
ground surface concentration of radionuclide i at time t,
pCi/m2 ;
43
t =time interval over which deposition has occurred,s;
A =assumed rate constant for environmental loss,,_I;e
A.=radioactive decay constant&for radionuclide i.S·I.1
The environmental loss constant Ae corresponds to an assumed half-time for
loss of environmental availability of 50 years.4 This parameter accounts for
downward migration in soil and loss of availability caused by chemical
binding.It is assumed to apply to all radionuclides deposited on the ground.
Gr9und concentrations are explicitly computed only for U-238,·Th-230,Ra-226,
and Pb-210.For all other radionuclides,the ground concentration is assumed
equal to that of the first parent radionuclide for which the ground
concentration is explicitly calculated.For 1ead-210,ingrowth from deposited
radium-226 can be significant.The concentration of lead-210 on the ground
caused by radium-226 deposition is calculated by the staff using the standard
Bateman formulation and assuming that radium-226 decays directly to 1ead-210.
If i =6 for radium-226 and i =12 for lead-210 (ref.1),the following
equation is obtained:
where
I
1 -exp(-A*t)exp(-A6*t)-exp(-A*12t)____...:1~2:..-+__~:.:.._
Ai2 A6-AU ,(8-8)
incremental lead-210 ground concentration resulting from
radium-226 deposition,pCi/m2 ;
)..1<=n effective rate constant for loss by radioactive decay
migration of a ground-deposited radionuclide and=A +A S·I.n e'
8.3.3 Vegetation concentrations
Vegetation concentrations are derived from ground concentrations and total
deposition rates.Total deposition rates are given by the following
sUlMlation:
and
(8-9)
where D.is the total deposition rate,inclUding deposition of resuspended
activity,of radionuclide i,pCi/m2 ·s.
Concentrations of released particulate materials can be environmentally
transferred to the edible portions of vegetables or to hay or pasture grass
consumed by animals by two mechanisms -direct foliar retention and root
44
uptake.Five categories of vegetation are treated by the staff:edible above
ground vegetables,potatoes,other edible below ground vegetables,pasture
grass,and hay.Vegetation concentrations are computed using the following
equation:
(8-10)
where
=soil-to-p1ant transfer factor for isotope i,vegetation type v,
dimensionless;
=resulting concentration of isotope i,in vegetation v,pei/kg;
Ev =fraction of foliar deposition reaching edible portions of
vegetation v,dimensionless;
E =fraction of total deposition retained on plant surfaces,0.2,
r dimensionless;•
P =assumed areal soil density for surface mixing,240 kg/m2 ;
tv =assumed duration of exposure while growing for vegetation v,s;
y =v
A =w
assumed yield density of vegetation v,kg/m2 ; .
decay constant accounting for weathering losses
14-d half-life),5.73 x 10-7 per second.
{equivalent to a
The value of Ev is assumed to be 1.0 for all above ground vegetation and 0.1
for all below ground vegetab1es.6 The value of t is taken to be 60 d,except
for pasture grass,where a value of 30 d is assum~d.The yield density,Y ,
is taken to be 2.0 kg/m2 ,except for pasture grass,where a value of v
0.75 kg/m2 is applied.Values of the soil to plant transfer coefficients,
8 "are provided in Table 8.4.Vl
8.3.4 Heat and milk concentrations
Radioactive ~ateria1s can be deposited on grasses,hay,or silage,which are
eaten by meat animals,which are,in turn,eaten by man.It has been assumed
that meat animals obtain 75%of their feed requirements by open grazing and by
eating non10ca11y grown stored feed for the remaining portion of their feed
requirement.The equation used to estimate meat concentrations is
(8-11)
where
45
Table 8.4 Environmental transfer coefficients
Material U Th Ra Pb
Plant/soil,Bvi
Edible above ground 2.5E-3·4.2E-3 1.4E-2 4.0E-3
Potatoes 2.5E-3 4.2E-3 3.0E-3 4.0E-3
Other below ground 2.5E-3 4.2E-3 1.4E-2 4.0E-3
Pasture grass 2.5E-3 4.2E-3 1.8E-2 2.8E-2
Stored feed (hay)2.5E-3 4.2E-3 8.2E-2 3.6E-2
Beef/feed.Fbi'pCi/kg 3.4E-4 2.0E-4 5.1E-4 7.1E-4
per pCi/d
"'Read as 2.5 x 10-s.or .0025.
Source:U.S.Nuclear Regulatory Commission."Calculational
Models for Estimating Radiation Doses to Man from
Airborne Radioactive"Materia1s Resulting from
Uranium Operations."R~port Task RH 802-4 •.
Washington.D.C .•May 1979.
Cpgi
Chi
Cbi
Fbi
=concentration of isotope i in pasture grass.pCi/kg;
=concentration of isotope i in hay (or other stored feed),pCi/kg;
=resulting concentration of isotope i in meat.pCi/kg;
=feed-to-meat transfer factor for iso~ope i.pCi/kg per pCi/d
(see Table B.4);
Q =assumed feed ingestion rate,50 kg/d;
0.25 =fraction of total annual feed requirement assumed to be satisfied
by pasture grass;
0.75 =fraction of the total annual feed requirement assumed to be
satisfied by locally grown stored feed (hay).
The above grazing assumptions are also reflected in the following equation for
_ilk concentrations:
C .=QF •(0.80C ."o.OCt .)•ml III pgl 11 (8-12)
46
where
=average concentration of isotope i in ~ilk,pCi/l;
=feed-to-milk activity transfer far.tor for isotope i,pCi/l per
pCi/d ingested (see Table B.4).
B.4 DOSES TO INDIVIDUALS
Doses to individuals have been calculated fer inhalation;external exposure to
air and ground concentrations;and ingestion of vegetables,meat,and milk.
Internal doses are calculated by the staff,using dose conversion factors that
yield the SO-year dose commitment;that is,the entire dose insult received
over a period of SO years following either inhalation or ingestion.2 '7 Annual
doses given are the SO-year dose commitments resulting from a one-year
exposure period.The one-year exposure period was taken to be the final year
of mill operation,when environmental concentrations resulting from plant
operations are expected to be near their highest level.
B.4.1 Inhalation doses
Inhalation doses have been computed using air concentrations.obtained by
Eq.B-3 (resuspended air concentrations are included)for particulate
materials and the dose conversion factors presented in Table B.S.
Dose to the bronchial epithelium from radon-222 and short-lived daughters were
computed based on the assumption of indoor exposure at 100%occupancy.The
dose conversion factor for bronchial epithelium exposure from radon-222
derives as follows:
1.1 pCi/m3 radon-222 =5 x 10-6 working levels (Wl).*
2.Continuous exposure to 1 Wl =25 cumulative working level months (WLM)
per year.
3.1 WLM =5000 mrem.8
Therefore,
(1 pCi/m3 radon-222)x 5 x 10-6 Wl
pCi/m 3
x 25 WLM x
WL
5000 mi 11 i rem =
WLM
0.625 mi11irem,
and the radon-222 bronchial epithelium dose conversion factor is taken to be
0.625 millirem per year per pCi/m 3 •
~One WL concentration is defined as any combination of short-lived radioactive
decay products of radon-222 in 1 L of air .hat will release 1.3 x lOS MeV of
alpha rarticle e~ergy during radioactiv~decay to lead-?lO.
47
Table 8.5 Inhalation dose conversion factor,'.Values
are given in millirem per year per pCi/m3
Particle size =0.3 ~m
Organ U-238 U-234 U-230 Ra-226 Pb-210 Po-210
4.36E+0
1.35E+2
1.13E+2
·3.45E+l
7.72E+3
Whole body
Bone
Kidney
liver
Hass average lung
Whole body
Bone
Kidney
Liver
Hass average lung
Whole body
Bone
Kidney
liver
Hass average lung
7.46E+0'"
2.32E+2
1.93E+2
5.91E+l
6.27E+l
Particle size =1.0 pm,density =8.9 g/cm3
9.82E+0 1.12E+1 1.37E+2 3.58E+1 4.66E+0
1.66E+2 1.81E+2 4.90E+3 3.58E+2 1.45E+2
3.78E+1 4.30E+1 1.37E+3 1.26E+0 1.21E+2
O.O.2.82E+2 4.47E-23.69E+l
1.07E+3 1.21E+3 2'.37E+3 4.88E+3 5.69E+2
Particle size =1.0~m,density =2.4 g/cm 3
4.32E+0 4.92E+0 1.66E+2 3.09E+l
7.92E+1 7.95E+l 5.95E+3 3.09E+2
1.66E+1 1.89E+1 1.67E+3 1.09E+0
O.O.3.43E+2 3.87E-2·
1.58E+2 1.80E+2 3.22E+3 6.61E+3
Particle size =5.0 pm
1.29E+0
5.24E+0
3.87E+l
1.15E+l
2.66E+2
5.95E+l
2.43E+0
1.79E+l
5.34E+0
3.13E+2
4.71E-l
1.92E+0
1.42E+l
4.22E+0
4.20E+2
Whole body
Bone
Kidney
Liver
Hass average lung
Whole body
Bone
Kidney
Liver
Hass average lung
1.16E+0
1.96E+1
4.47E+0
O._.
1.24E+3
7.92E-l
1.34E+l
3.05E+0
O.
3.33E+2
1.32E+0 1.01E+2 4.00E+l
2.14E+l 3.60E+3 4.00E+2
5.10E+0 1.00E+3 1.41E+0
O.2.07E+2 4.97E-2
1.42E+3 1.38E+3 2.84E+3
Particle size =35.0 pm
9.02E-l 5.77E+l 3.90E+l
1.46E+l 2.07E+3 3.90E+2
3.47E+0 5.73E+2 1.38E+0
O.1.19E+2 4.85E-2
3.80E+2 3.71E+2 7.64E+2
4.84E+0
1.50E+2
1.25E+2
3.83E+l
3.30E+2
4.43E+0
1.38E+2
1.15E+2
3.51E+l
8.70E+l
7.10E-l
2.89E+0
2.13E+l
6.36E+0
1.88E+2
7.28E-l
2.96E+0
2.19E+l
6.52E+0
5.75E+l
"'Read as 7.46 x 100 ,or 7.46.
Sources:H.Homeni et·al.,"Uranium Dispersion and Dosimetry (UDAD)Code,"Report
ANLlES-72,NUREG/CR-0553,Argonne National laboratory,Chicago,Hay
1979 and D.R.Kallcwarf,"Solubility ClaHification of Airborne Pro-
ducts from Uranium Ores and Tailings Pile""ReportPNl-2830,
NUREG/CR-0530,Pacific North....est Laboratory.Richland,Wash.,January
1979.
48
B.4.2 External doses
External doses from air and ground concentrations are computed using the dose
conversion factors provided in Table B.6.1 Doses are computed based on 100%
occupancy at the particular location.Indoor exposure is assumed to occur
14 hid at a dose rate of 70%of the outdoor,dose rate.
B.4.3 Ingestion doses
Ingestion doses are computed for vegetables and meat (beef and lamb)on the
basis of concentrations obtained using Eqs.B-9 through 8-12.ingestion rates
given in Table B.7.and dose conversion factors given in Table B.8.1 '4
Vegetable ingestion doses were computed assuming an average 50%activity
reduction caused by food preparation.4 Ingestion doses to children and teen-
agers were computed but were found to be equal to or less than doses to adults.
49
Table B.6 Dose conversion factors for external exposure
Isotope
U-238
Th-234
Pa(m)-234
U-234
Th-230
Ra-226
Rn-222
Po-218
Pb-214
Bi-214
Po-214
Pb-210
U-238
Th-234
Pa(m)-234
U-234
Th-230
Ra-226
Rn-222
Po-21S
Pb-214
Bi-214
Po-214
Pb-210
Skin
For air concentration doses,
mi11irem per year per pCi/m3
1.05E-S*
6.63E-5
8.57E-S
1.36E-S
1.29E-9
6.00E-S
3.46E-0
8.18E-7
2.06E-3
1.36E-2
9.89E-7
4.17E-S
For ground concentration doses,
mi11irem per year per pCi/m2
2.13E-6
2.10E-6
1.60E-6
2.60E-6
2.20E-6
1.16E-6
6.1SE-8
1.42E-8
3.89E-S
2.18E-4
1.72E-8
6.65E-6
Whole body
1.S7E-6
5.24E-5
6.64E-5
2.49E-6
3.S9E-6
4.90E-5
2.83E-6
6.34E-7
1.67E-3
1.16E-2
7.66E-7
1.43E-3
3.17E-7
1.66E-6
1.24E-6
4.78E-7
6.12E-7
9.47E-7
S.03E-8
1.10E-8-
3.16E-5
1.85E-4
1.33E-S
2.27E-6
*Read as 1.05 x 10-s,or .0000105.
Source:U.S.Nuclear Regulatory Commission,"Calculational Models
for Estimating Radiation Doses to Man from Airborne
Radioactive Materials Resulting from Uranium Hilling
Operations,"Report Task RH 802-4,Washington.D.C.,May
1979.
50
Table B.7 Assumed food ingestion rates-
Infant Child Teen Adult..
Vegetables,kg/year 48 76 105
Edible above ground 17 29 40
Potatoes 27 42 60
Other below ground 3.4 5.0 5.0
Meat (beef,fresh pork,28 45 78
and lamb),kg/year
Milk,L/year 208 208 246 130
-Ingestion rates are averages for typical rural farm
households.No allowance is credited for portions of
year when locally or homegrown food may not be
available.f
Source:J.F.Fletcher and W.L.Dotson,"HERMES - A
Digital Computer Code for Estimating Regional
Radiological Effects from the Nuclear Power
Industry,"Report HEOL-TME-71-168,Hanford
Engineering Development Laboratory,Hanford,
Wash.,December 1971.
Table B.8 Ingestion dose coversion factors,values are in millirem/pCi ingested
Isotope
Age Group Organ U-238 U-234 Th-234 Th-230 Ra-226 .Pb-210 8i-210 Po-210
Infant Whole body 3.33E-4*3.80E-4 2.00E-8 1.06E-4 1.07E-2 2.38E-3 3.58E-7 7.41E-4
Bone 4.47E-3 4.88E-3 6.92E-7 3.80E-3 9.44E-2 5.28E-2 4.16E-6 3.10E-3 .
Liver O.O.3.77E-8 1.90E-4 4.76E-5 1.42E-2 2.68E-5 5.93E-3
Kidney 9.28E-4 1.06E-3 1.39E-7 9.12E-4 8.72E-4 4.33E-2 2.08E-4 1.26£-2
Child Whole body 1.94E-4 2.21E-4 9.88E-9 9.91E-5 9.87E-3 2.09E-3 1.69E-7 3.67E-4Bone3.27E-3 3.57E-3 3.42E-7 3.55E-3 8.76E-2 4.75E-2 1.97E-6 1.52E-3liverO.O.1.51E-8 1.78E-4 1.84E-5 1.22E-2 1.02E-5 2.43E-3Kidney5.24E-4 5.98E-4 8.01E-8 8.67E-8 4.88E-4 3.67E-2 1.15E-4 7.56E-3.-<.n
Teenager ~Whole body 6.49E-5 7.39E-5 3.31E-9 6.00E-5 5.00E-3 7.01E-4 5.66E-8 1.23E-4Bone1.09E-3 1.l9E-3 1.14E-7 2.16E-3 4.09E-2 1.81E-2 6.59E-7 5.09E-4LiverO.O.6.68E-9 1.23E-4 8.13£-6 5.44E-3 4.51E-6 1.07E-3Kidney2.50E-4 2.85E-4 3.81E-8 5.99E-4 2.32E-4 1.72E-2 5.48E-5 3.60E-3
Adult Whole body 4.54E-5 5.17E-5 2.13E-9 5.70E-5 4.60E-3 5.44E-4 3.96£-8 8.59E-5
Bone 7.67E-4 8.36E-4 8.01E-8 2.06E-3 4.60E-2 1.53E-2 4.61E-7 3.56E-4
Liver O.O.4.71E-9 1.17E-4 5.74E-6 4.37E-3 3.18E-6 .7.56E-4
Kidney 1.75E-4 1.99E-4·2.67E-8 5.65E-4 1.63E-4 1.23E-2 3.83E-5 2.52E-3
*Read as 3.33 x 10-4 or .000333.
Sources:U.S.Nuclear Regulatory Commission,"Calculational Models for Estimating Radiation Doses to
Man from Airborne Radioactive Materials Resulting from Uranium Milling Operations,"Report
Task RH 802-4,Washington,D.C.,May 1979 and G.R.Hoenes and J.K.So1dat,"Age-specific
Radiation Dose Conversion Factors for a One-Year Chronic Intake,"Report NUREG-172,
Battelle Pacific Northwest Laboratories,Richland,Washington,November 1977.
·52
REFERENCES FOR APPENDIX 8
1.U.S.Nuclear Regulatory Commission,"Calculational Hodels for Estimating
Radiation Doses to Han from Airborne Radioactive Materials Resulting from
Uranium Hilling Operations,"Report Task RH 802-4,Washington,D.C.,
Hay 1979.
2.M.Momeni et al.,"Uranium Dispersion and Dosimetry (UOAD)Code,"Report
ANL/ES-72,NUREGI CR-OS53,Argonne National Laboratory,Chicago,
May 1979.'"
3.Umetcc Minerals Corporation,Radiation Dose Information Schedule.
May 8,1985.
4.U.S.Nuclear Regulatory Commission,"Final Generic Environmental Impact
Statement on Urani um Hi 11 i ng ,"Report NUREG-0706,Washi ngton,D.C.,
September 1980.~
S.D.C.Kocher,"Nuclear Decay Data for Radionuclides Occurring in Routine
Releases from Nuclear Fuel Cycle Facilities,"Report ORNL/NUREGITM-102,
Oak Ridge National Laboratory,Oak Rtdge,Tenn.,AUQust 1977.
6.J.F.Fletcher and W.L.Dotson,"HERMES - A Digital Computer Code for
Estimating Regional Radiological Effects from the Nuclear Power Industry,"
Report HEDL-TME-71-l68,Hanford Engineering Development Laboratory,
Hanford,Wash.,December 1971.
7.D.R.Kalkwarf,"Solubility Classification of Airborne hoducts from
Uranium Ores and Tailings Piles,"Report NUREG/CR-0530j PNL-2830,Pacific
Northwest Laboratory,January 1979.~
8.National Academy of Sciences -National Research Council,"The Effects on
Populations of Exposure to Low Levels of Ionizing Radiation,Report on
the Advisory Committee on Biological Effects of Ionizing Radiation,"U.S.
Government Printing Office,Washington,D.C.;1972.
9.G.R.Hoenes and J.K.Soldat,"Age-Specific Radiation Dose Conversion
Factors for a One-Year Chronic Intake,"Battelle Pacific Northwest
Laboratories,U.S.Nuclear Regulatory Commission Report NUREG-0172,
November 1977.t
-Available for purchase from the NRC/GPO Sales Program,U.S.Nuclear
Regulatory Commission,Washington,D.C.20555,and the National Technical
Information Service,Springfield,Virginia 22161.
tAvailable for purchase from the Nationall Technical Information Service.
53
APPENDIX C
CALCULATION OF GAMMA RADIATION ATTENUATION FOR
RECLAIMED TAILINGS IMPOUNDMENT,
54
APPENDIX C
CALCULATION OF GAMMA RADIATION ATTENUATION FOR RECLAIMED TAILINGS IMPOUNDMENT
Assuming soil to be composed mainly of $i02 the ~ass attenuation coefficient
for a 1 to 2 MeV gamma ray is 0.0518 cm2/~.i (Most of the dose rate from a
typical natural emitter is ;n this range.)Assuming that the tailings Ra-226
activity of the slimes is 1196 pCi/Q,as indicated in Table 2;and the con-
version facto.s of 2.5 uR/hr per pC,/g Ra-226;then the esti.ated gamma
radiation should not exceed 26.2 R/year.If the bulk density of the soil is.
assumed to be 1.6 g/cm3 ,then the effect of the proposed 2.7~m(9 ft)of soi 1~aterial would reduce the gamma radiation to about 3.60 x 10-9 R/year.The
calculation is as follows:
1/10 =exp[-(IJen /p)px)=exp[-(O.0518 cm2/g)(1.6 g/cm3)(274cm))=1.37 x 10-10;
I =<1.37 x 10-10)(26.2 R/year}=3.60 x 10-9 R/year =3.60 x 10-6 mR/year
f •
The area's background radiation dose from all sources of radioactivity,including
the contribution from fallout,is about 147 ~R/year.4 Thus,the gamma radiation
from the deposited tailings after reclamation would be insignificant compared
to the natural background radiation.
REFERENCES FOR APPENDIX C
1.U.S.Department of Health,Education,and Welfare,"Radiological Health
Handbook,"U.S.Government Printing Office,Washington,D.C.,January 1970,
p.139.
2.H.May and L.D.Marinelli,"Cosmic Ray Contribution to the Background of
Low Level Sci ntillation Spectrometry,The Natural Radiation Environment,"
J.A.S.Adams and W.M.Lowder,Eds.,University of Chicago Press,
Chicago,1964.
3.Schiager,K.J.,"Analysis of Radiation Exposures On or Near Uranium Mill
Tailings Piles."Rad.Data and Reports 15:411-425.(1974)
4.G.L.Montet et al,"Descriptions of United States Uranium Resource Areas,
a Supple~ent to the Generic Environmental Impact Statement on Uranium
Milling,"Report NUREG/CR-0597,Report ANL/ES-75,prepared by Argonne
National Laboratory for the U.S.Nuclear/Regulatory.Commission,June 1979,
pp.16-1 and 16-2.Available for purchase from the NRC/GPO Sales Program,
U.S.Nuclear Regulatory Commission,Washington,D.C.20555,and the
National Information Service,Springfield,VA 22161.
55
APPENDIX D
CALCULATION OF THICKNESS OF REQUIRED COVER MATERIAL,
56
Appendix D
CALCULATION OF THICKNESS OF REQUIRED COVER MATERIAL
D.1 INTRODUCTION
The thickness of cover material required for uranium mill tailings
reclamation is usually determined by a radon flux or concentration
criterion which must be satisfied.The general approach used in
estimating the required thickness of a cover can be divided into two
phases.First,the characteristic parameters of the tailings and cover
must be measured or estimated.These include the radon diffusion
coefficients,porosities and moistures of t~e tailings and cover,and the,
radium content and emanating power of the tailings.Second,the
thickness of cover needed to achieve a prescribed radon flux is
determined by iteratively calculating radon fluxes for various cover
thicknesses until the thickness giving the prescribed flux is found.
Alternatively,an approximate expression can be used to calculate the
cover thickness directly.
In the following equations,the diffusion coefficient for radon in the total
pore space of the soil is designated by the symbol D,consistent with
recent reports on radon movement.A second parameter,the effective
bulk diffusion coefficient of the soil,is often designated D ,and hase
sometimes been confused with D due to varying symbols and nomenclature
used in the literature.The two are related by D =De/p,where p is
the total soil porosity.
57
2.1 RADON DIFFUSION EQUATION
The one-dimensional steady-state radon diffusion equation is:
where
C =radon concentration in the total pore space (pCi cm -3)
D =diffusion coefficient for radon in the total pore space
(cm2s-1)
1\=decay constant of radon (2.1 x 10-6 s-I)
R =specific activity of radium in the soil (pCi g-I)
f =dry bulk density of the soU (g cm-3 )
E =radon emanation coefficient (dimensionless)
p =total porosity of the soil (dimensionless)
The radon flux from the bulk soil material is related to the radon
(1)
concentration in its pore space by Fick's Law:
J =_104 Dp dCdx '
where
(2)
J =bulk radon flux (pCi m-2 s-I)
104 =factor to convert units from pCi cm-2s-1 to pCi m-2s-1
Verification of Umetco's proposed tailings cover will be performed using
the RAECOM computer program since the necessary iterative calculations
are best performed by a computer.
58
The licensee proposed to reclaim the White Mesa tailings impoundments
using 9.0 feet of soil and 2 to 4 feet of rock cover to prevent erosion of
the soil cover.Estimated input parameters are conservative and no
credit was given for radon attenuation by the top layer of rock.
The attached table lists the input parameters utilized for the RAECOM
computer program.Results of the RAE COM computer run indicate that
approximately 7.5 feet of cover will attenuate radon to 20 pCi/m2 -sec.
Therefore,the cover proposed by Umetco for the existing tailings
impoundments should attenuate radon to less than 20 pCi/m2-sec in
accordance with the 40 CFR 192 standard.Should the impoundment's
size or constituents change from that described in Appendix A of the'.
licensee's renewal application dated May,1985,a new cover evaluation
should be performed.
59
Table D.1
Parameters Used in URFO RAECOM Run
For Umetco White Mesa Mill
Thickness
(em)
Porosity3
(fraction)
Diffusion
Coefficient
(cm2/s)
Radon Source4
Term (pCi/cm3/s)
Moisture4
(%)
Tailings
5002
0.40
0.030
0.0012
8.0
Soil
274
0.39
0.012
o
9.0
1 Since the licensee will scatter sands and slimes.the
tailings are considered to be a homogeneous mixture of
sands and slimes.
2 A maximum depth of tailings is assumed.
3 Conservative estimates.
4 From Q =Rp E~/P where R =specific activity.p =bulk
density,E =emanation fraction,i\=2.1E-6/s decay
constant and P =porosity.
60
:TCO WHITE MESA MILL
•••••••I N PUT PAR A MET E R S ••••••••••
pCi/m2/SEC
pCi/LITER
!BER OF LAYERS :
~N FLUX INTO LAYER 1 :
lFACE RADON CONCENTRATION :
:ER 2 ADJUSTED TO MEET JCRIT :
2
.000
.000
20.0 +/-.100E-02 pCi/m2/sec
lE SOURCE FLUX (JO)FROM LAYER 1:573.4 pCi/m2/sec
,ER
!
THICKNESS
(cm)
500.
274.
OIFF COEFF
(cm2/sec)
3.00000-02
1.20000-02
POROSITY
.4000
.3900
SOURCE
(pCi/cm3/sec)
1.20000-03
.00000+00
MOISTURE
(DRY WT.PERCENT)
8.00
9.00
Ise.
!ase press <return>to continue.
iULTS OF RADON DIFFUSION CALCULATION
LAYER THICKNESS EXIT FLUX EXIT CONC.MIC
(cm)(pCi/m2/sec)(pCl/liter)
1 500.2.11850+02 3.60320+05 .7602
2 231.1.99880+01 .00000+00 .7187
>p -Program terminated.