ML20039B420

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Forwards Draft NRC Radiological Assessment of Dawn Mining Co U Mill Renewal for Comment
ML20039B420
Person / Time
Issue date: 11/16/1981
From: Scarano R
NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To: Strong T
WASHINGTON, STATE OF
References
REF-WM-33 NUDOCS 8112230013
Download: ML20039B420 (41)
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{{#Wiki_filter:M m b w n ue. w -55 WM-33 y ty~ .y y-G PDR. DISTRIBUTION: WMUR w/f WMUR:DMG NN \\ b UOl WMUR r/f WM-33 WM r/f NMSS PDR OGillen Mr. T.R. Sttong, DEMartin l Department of Social and Health Services RScarano DNussbaumer j State of Washington BFisher We( r Olympia, Washington 98504 JLinehan l Dear Mr. Strong ~, HPettengill REBrowning JBMartin In response to your technical assistance request and in accordance with agreements made during my conversations with Ms. Nancy Kirner of your staff, enclosed for your consents is a draft of our staff radiological assessment of' the Dawn Mining Company Uranium Mill renewal. If you should have any questions regarding this matter, please contact Mr. Daniel M. Gillen of my staff at (301) 427-4115. I Sincerely, lh Ross A. Scarano, Chief Uranium Recovery Licensing Branch Division of Waste Management / af % c3 '/ /)N fu) 3,p S[n / 2 Oi DEC3 1981 - ~1 s;. u.s.mau.no w a co -iu m s /S 6*,/h W I [T g \\ 0'f(\\ ase uc.,ed : 3wm 33om PDR WASTE 8112230013 811116 WM-33 PDR. "'c'>.....F.Vgy,( " %..... W

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f-DRAFT. i DRAFT RADIOLCGICAL ASSESSMENT OF THE DAWN MINING COMPANY URANIUM MILL FORD, WASHINGTON NOVEMBER,1981 PROJECT WM-33 PREPARED BY THE C.S. NUCLEAR REGULATORY COMMISSION WASHINGTQN,.D.C. i FOR THE DEPARTMENT OF SOCIAL AND HEALTH SERVICES r f STATE OF WASHINGTON ~' TO DOCUMENT TECHNICAL' ASSISTANCE BEING PROVIDED IN CONNECTION WITH THE LICENSE RENEWAL i i i c O

f-DEFT 4. RADIOLOGICAL ASSESSMENT

4.1 INTRODUCTION

This section presents the NRC staff's assessment of the radiological impacts of the Dawn Uranium Mill for license renewal of the facility. An assessment was recently performed to evaluate the impacts of the new below grade tailings impoundment. Since the completion of that assessment, more information has become available relating to the operational plan of the mill (Ref. 1, 2). For this reason, the values presented here in the various tables are different from those in the previous assessment of the new tailings impoundment. Major components of the staff's evaluation documented here have included detailed assessments of the following: (1) annual releases of airborne radio-active materials from the mill and all tailings storage areas; (2) resulting incremental radioactivity concentrations in air and in other environmental media; and (3) resulting incremental radiation dose commitments to individuals and populations. he calculated results are compared to natural background radiation exposurt and applicable.reguldtory limits. All potential airborne exposure pathways likely to contribute a significant fraction of total exposures have been included in the analysis. Dose commitments resulting from all releases are presented and discussed. The values presented for the annual emission-rates and annut.1 dose commitments represent the worst year of operation. The NRC staff understands that Dawn Mining Company is-planning to cover greater portions of the inactive tailings areas, thus reducing impacts from annual emissions. As a predictive calculational analysis, the results of this evaluation are dependent upon, and sensitive to, values chosen for the many necessary input parameters. Changer in input parameter values used in this assessment would necessarily result in changes to the calculated results. Significant modifi-cations to the Dawn facility's design or mode of operation, which would affect the assumptions made here concerning effluent relenses, would necessitate a ' revised analysis to confirm or qualify the conclusions drawn here. Additionally, the results of the complex predictive mathematical analysis presented shere have inherent levels of uncertainty which are difficult to quantify. Such 3 results must be adequately supported by empirical data obtained through site-specific effluent and environmental monitoring programs before a high degree of confidence can be established. 4.2 ESTIMATED RADIOACTIVITY RELEASES This assessment is based on an evaluation of radioactivity-releases from the various components of the entire Dawn facility during the year of highest radioactive emission from the operation. Incremental annual dose commitments due to releases"are predicted to be highest during this year. The basit information, data, and assumptions used to estimate radioactivity releases,are summarized in Table 4.1. The estimated release rates contributed by each

's 4-2 Table 4.1 Principal Parameter Values Used in the Radiological Assessment of the Dawn Mining Company Uranium Project _ Parameter Value(s)* A. General Data Average ore grade, % Ua0e 0.153 Ore concentration, pCi/g U-238 and daughters 432.0 Ore processing rate, MT/d 430.0 Days /yr_ operational ' 346 ~ B. Ore Storage: Pile (s) ,,7 . Actual 'irea, : acres 13.6 /mnual aversie dustjloss rate, g/m yr 2 .Du'st/ ore. activity rhtio ~ 42.0

2. 5 "lReductionifa'ctor for chemical spraying

- and wetting'. % 50.0 , Release. rate for tr0ck dumping a.nd ore pad .[. Specific Rn-222. flu)x, fromj ore piles, pCi/g Ra-226 'Nactivities, % pCi/m -sec 2 4.5 x 10 3 1.0 i \\ w. t C. Hoppers.and,Faeders. .m "'.. b8 Release rate for ore feeding, % 4.0 x 10 3 s Dust / ore activity ratio 2.5 Reduction factor fet dust control, % 50% Fraction 'of Rn-222 e' uilibrium ore content c q s 'C,', s -released,J. ,s, x-20.0 1 qq w ~ s. 'D. ' Crushing and'Grir. ding v.m ,.e,", i s N,- N < Release 4 rate Torjerushing-and geinding, % 4.0 x 10 3 ' - a O Efficiency of particuliite loss control, % 99.0 ~ 0 6 2 ust/ ore activity ratio. ' 2.5 s ^ Fraction of Rn-7.22 equilibrium ore content releasep, %.9 s,' 'd 20.0 v e y -,c' s n s r ~ ' E.c Fine Or'e ' Storage's D' - ~. f s;- ~v e, s s . NRelease-rate for-fiiieiore :cti.yf ties, % 4.0 x 10 3 Efficiency.2f particulate loss control, % 80.0 ~ D0st/ ore activity; ratio 2.5 ' l ffactich;sf Rri-222'dquilibrium ore content . renal 6d,% \\ 5'; E 20.0 e, s. s s see fottnites last ppgeTof t'ible. ; J

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Y 'o 4-3 Table 4.1 (Continued) Parameter Value(s)* F. Yellowcake Drying and Packaging Yellowcake production rate, MT/ year 214.0 Release rate of yellowcake product to atmosphere, MT/ year 8.33 x 10 3 Activity ratio of Th-230 to U-238 in yellowcake 0.5 Activity ratio of Ra-226 to U-238 in yellowcake 0.1 Activity ratio of Pb-210 to U-238 in yellowcake G.1 Yellowcake purity, % 79.0 E. Tailings Impoundment System General parameters Fraction Th to tailings, % 99.5 Fraction Ra and Pb to tailing's, % 99.9 Annual average cust loss rate, g/m yr 420.0 2 Dust / tails activity ratio 2.5 Dusting reduction factor for water cover, moisture, and chemical agents,, % 80.0 Specific Rn-222 flux from exposed beach, 2 pCi/m -sec 1.0 pCi/g Ra-226 Abandoned tailings impoundment Total area, acres 59.2 Area exposed to dusting, % 1.0-3.0 Fraction U to tailings, % 9.2 Tailings activities, pCi/g U-238 62.1 . Th-230 671.5 Ra-226 674.2 Pb-210 674.2 Inactiva tailings impoundment Tot; ea, acres 47.0 Area exposed to dusting, % 90.0 Fraction U to tailings, % 6.0 Reduction factor of dust loss by chemical stabilization and wetting, % 80.0 Tailings activities, pCi/g U-238 40.5 Th-230 671.5 Ra-226 674.2 Pb-210 674.2 See footno'tes last page of table. t

44 Table 4.1 (Continued) Parameter Value(s)* - Below grade tailings impoundment Total area, acres 27.2 Fraction of U to tailings, % 6.0 Reduction factor of dust loss by water cover, chemical stabilization, % 80.0 Tailings activities, pCi/g U-238 25.9 Th-230 429.8 Ra-226 431.6 Pb-210 431.6

  • Paramt er values presented here are those selected by the NRC staff for use in its radiological impact assessment of the Dawn Mining Company uranium mill project.

In. instances where available data have been insufficient and/or not specific, reasonably con-servative estimates have been made. 4 r< m ~ +-, - e --, -,, r- ,-we. e---, w y w s-

DRAFT 4-5 facility component are presented in Table 4.2.' This table is based on the assump-tion that the new below grade tailings impoundment will continue to be controlled by water cover, chemical stabilization, or other means, such that 80 percent of potential release: will be abated. More detailed information pertaining to the evaluation of radioactivity releases is provided in Appendices A and B. 4.3 EXPOSURE PATHWAYS Potential environmental pathways by which people could be exposed to radioactive materials resulting from the project are presented schematically in Figure 4.1. The pathways of concern for the airborne effluents include inhalation of radioactive materials in the air, external exposure to radioactive materials in the air or deposited on the ground, and i g estion of centaminated food products (vegetables, meat and milk). 4.4 RADIATION DOSE COMMITMENTS TO INDIVIDUALS The estimated radiation dose at each individual receptor depends on the distance and direction of the receptor with respect to each of the sources, as well as the wind directional frequency toward the receptor from each of the sources. The dose decreases with distance as the radioactive particulates are dispersed and depleted by deposition, and their concentration decreases. The direction of the reference point with respect to the mill is important because the average concentration of particulates is higher downwind. Prevailing winds in the site vicinity are out of the SSW and SW sectors (see Appendix B Table B.2). ~' The most critical nearby receptor is incated 0.41 miles (0.66 km) NNW of the mill, and the nearest residence in the prevailing wind direction is 0.53 miles (0.86 km) NE of the mill. There is a' closer residence to the mill, however impacts at this location were found to be lower than those presented here, because the location is not in the prevailing wind direction from the sources. In addition, the licensee has reported the location of a residence in the prevailing wind direction 0.62 ciles (1.0 km) ENE of the mill. This location was also assessed and impacts are presented. The nearest population center is Ford, Washington 1.43 miles.(2.30 km) E of the mill. ' Table 4.3 presents the calculated annual dose commitments received by people living at these locations. For each of these locations, it was assumed that individuals would have access to, and consume as part of their normi diet, vegetables grown locally at the residence and beef fed by grazing in an area approximately 0.4 km N of the mill. Due to the scarcity of information on consumpt. ion of locally produced milk, it was conservatively assumed that a local milk ingestion pathway existed at each nearby location. Figures in parenthesis in Table 4.3 reflect reduction in the extent of consumption of locally produced food. These reductions were based on information available from the Stephen's County Agricultural Agent. 4.5 RADIATION DOSE COMMITMENTS TO POPULATIONS The annual 100 year environmental dose commitments received by the (regional) nopulation within 50 miles (80 km) of the site are presented in Table 4.4.

4-6 Table 4.2 Estimated Annual Releases of Radioactive Materials Resulting from the Dawn Mining Company Uranium Project

  • Annual releases, Curie / year **

Release source U-238 Th-230 Ra-226 Pb-210 Rn-222 Ore storage 4.86E-03t

4. 86E-03 4.86E-03 4.86E-03 7.48E+02 Hopper and feeders 3.21E-03 3.21E-03 3.21E-03 3.21E-03 1.29E+01 Grinding and crushing 6.43E-05
6. 43E-05 6.43E-05 6.43E-05 1.29E+01 Fine ore storage 1.29E-03 1.29E-03 1.29E-03 1.29E-03 1.29E+01 Yellowcake stacks
1. 86E-03
9. 31E-06 1.86E-06 1.86E-06 0.0 Tailings impoundments Abandoned pile 1.56E-04 1.69E-03 1.69E-03 1.69E-03 5.llE+03 Inactive pile 1.61E-03
2. 66E-02 2.68E-02 2.68E-02 4.04E+03 Below grade pile 5.93E-04 9.92E-p3 9.96E-03 9.96E-03 1.50E+03

^ Releases are based on estimates for the most critical year of mill operation (1981). nw Releases of all other isotopes 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 isotopes. 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. tThe notation 4.86E-03 is read as 4.86 x 10 3 or 0.00486. l V l 1 l -~

O ORE FROM MINES I Y ORE PAD, FEED AND GRINDING A \\ 4,'O 4 (, y o,o ## INil ALATION MAN LEACHING AND T 3D-f RADON AND PARTICULATES EXTRACTION \\ AlHUORNE DIRECT EXTERNAL RADIOACTIVITY g EXPOSURE MAN i ci. got.b ?b o@ J k- [ ] OO g TAILINGS gp l y y STORAGE 2 O RADIOACTIVITY q g IN SOIL Y o YELLOWCAKE DRYING - -{;>. MILK f )f . CATTLE AND PACKAGING kADIOACTIVITY INGESTION MAN 4 IN' VEGETATIO DEEF PRODUCT TO 9 MARKET CATTLE _. _ _.l. -m Fig. 4.1 Sources of Radioactive Effluents from the Mill and Exposure Pathways to Man H

Table 4.3 Annual Dose Commitments to Individuals in the Vicinity of the Dawn Mining Company Uranium Mill (mrem / years) Exposure Whole Bronchial Location Pathway

  • Body iBone Lung Epithelium Nearest resident Inhalation *^

0.27 7.74 10.9 305. in prevailing External ground 3.74 3.74 3.74 3.74 wind direction External cloud 0.61 0.61 0.61 0.61 0.9 Im NE Ingestion Vegetablet 1.56 (0.78) 18.6 ( 9.3) 1.56 ( 0.78) 1.56 ( 0.78) Meat #,5 0.46 (0.05) 5.78 ( 0.05) 0.46 ( 0.05) 0.46 ( 0.05) Milk 0.38 4.00 0.38 0.38 Total 7.02 (5.83) 40.47 (25.44) 17.05 ~ 6.46) 311,75 (310.56) Nearby resident Inhalation ** 0.34 9.58 13.9 454. s2 0.7 km NNW External ground 3.89 3.89 3.89 3.89 External cloud 0.68 0.68 0.68 0.68 Ingestion Vegetablet 1.80 (0.90) 21.6 (10.80) 1.80 ( 0.90) 1.80 ( 0.90) Meat #,9 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) 0.46 ( 0.05) Milk 0.44 4.63 0.44 0.44 Total 7.61 (6.30) 46.16 (30.16) 21.17 (19.86) 461.27 (459.96) Nearby resident Inhalation ** 0.19 5.41 7.58 265. 1.0 km ENE External ground 2.80 2.80 2.80 2.80 External cloud 0.62 0.62 0.62 0.62 Ingestion Vegetablet 1.12 (0.56) 13.40 ( 6.70) 1.12 ( 0.56) 1.12 ( 0.56) Meat #,9 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) 0.46 ( 0.05) Milk 0.28 2.89 0.28 0.28 IEEE Z Total 5.47 (4.50) 30.90 (19.00) 12.86 (11.89) 270.28 (269.31)

g=,

r See footnotes last page of table

Table 4.3 (Continued) Exposure Whole Bronchial Location Pathway

  • Body Bone

' Lung Epithelium Nearest town, Inhalation ** 0.02 0.55 0.69 72.4 Ford, Washington External ground 0.28 0.28 0.28 0.28 2.3 km E External cloud 0.45 0.45 0.45 0.45 Ingestion .Vegetablet-0.13 (0.07) 1.56 ( 0.78) 0.13 ( 0.07) 0.13 (. 0.07) Meat #,9 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) 0.46 ( 0.05) Milk 0.03 0.33 0.03 0.03 Total 1.37 (0.89) '8.95 ( 2.97) 2.04 ( 1.56) 73.75 ( 73.27) 4-

  • Doses are irtegrated over a 50 year period from one year of inh.a.lation or ingestion.

da Q* 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.. tValues in parentheses represent a.50% reduction based on a growing season of 6 months per year.

  1. Ingestion doses result from the consumption of the meat of cattle grazing 0.4 km N of the mill.

SValues in parentheses represent a 90% reduction due to the exportation of locally grazed cattle. Cll23 3:= M

4-10 Table 4.4 Annual Ensironmental Dose Commitments to the Regional Population Within a 50 mile Radius Resulting from the Dawn M bing Company Uranium Mill Annual Environmental Dose Commitments (EDC), person-rem / year

  • Exposure Pathway Whole Body Bone Lung Bronchial Epithelium **

Inhalation 0.20 6.03 2.54 352.8 External from ground 1.13 1.13 1.13 1.13 External from : loud 5.49 5.49 5.49 5.49 Vegetable ingestion 6.35 103.7 6.35 6.35 Heat ingestion 0.21 3.84 0.21 0.21 Milk ingestion 0.40 '4.82 0.40 0.40 Total 13.78 125.0 is 12 366.4 Estimated population dose from natural backgroulid 53,849 70 650 ' 54,280 241,242 Ratio of total annual regional population dose to that from natural backgroundt 0.0003 0.0018 0.0003 0.0015

  • 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.

C* Inhalation doses' to the bronchial epithelium are those resulting from the inhalation of radon daughters. tBackground doses are based on the regional population size of 430,790 and background radiation doses presented in Reference 3.

4 11 The population distribution data (Table 4.5),' projected to the year 1990, were used to do the estimation. Releases of radon gas yield radiological impacts which occur over a range of thousands of miles from a release source. Annual impacts of radon releases from the facility that octer within 50 miles (80 km) of the site are listed in Table 4.4. Impacts resulting from the entire life of the mill for both regional and extra-regional populations are given in Table 4.6. Also listed in Table 4.6 are total impacts received by the continental population. 4.0 EVALUATION OF COMPLIANCE WITH REGULATORY LIMITS Dese commitments to individuals at the locations noted in Section 4.4 were calculated for the purpose of evaluating compliance with the limits specified by the U.S. Environmental Protection Agency's (EPA) 40 CFR Part 190, "Radiatica Protection Standards for Normal Operations of the Uranium Fuel Cycle." Under 40 CFR Part 190, total doses to any organ of an offsite individual are limited to 25 millirems / year, excluding contributiens from radon-222 and its radioactive daughters. Table 4.7 provides a comparison of the calculated dose commitments to individuals with the 40 CFR Part 190 limits. Doses in this table are lower than total doses (Table 4.3) because contributions from radon-222 and its daughters have been omitted. As indicated in Table 4.7, individual doses to the bone at the nearby residences are above the 25 mrem per. year limit. However, it should be noted that ever 75% of the calcu]ated impacts at these locations is attributable to the inges-tion pathway, and that these calculations are based on the assumption that 100% of the meat, vegetables, and milk consumed by the nearby population is locally produced..A more realistic assumption, based on information provided by the agricultural agent for Stephens County, Washington, is that not more than 10% of the meat and 50% of the vegetables that are grown locally are consumed by the local population. Appropriate adjustments to the estimates were made (see parenthetical values in Tables 4.3 and 4.7). With the adjust-ments, doses to the bone at the nearest residence are-slightly above EPA standards. No adjustment was made for the milk ingestion pathway because scant information on the extent of consumption of locally produced dairy ' products was.available. However, should the assumption on the extent of consumption of locally produced milk be overestimated, it is likely that total doses would be within EPA standards. Under 10 CFR Part 20, air concentrations in unrestricted areas are limited to maximum permissible concentrations (MPCs). Table 4.8 presents the results of the staff's evaluation of compliance with 10 CFR Part 20 for calculated annual average air concentrations for selected restricted area boundary locations. As indicated by the results presented in Table 4.8, there does not appear to be any problem in meeting the MPC limits specified in 10 CFR Part 20. In addition to the locations evaluated in Table 4.8, other locations along the restricted area boundary were evaluated but were found to have lower computed average air concentrations.

y 10/28/81 4-12 2PANTL/A Table 4.5 Projected 1990 Population Distribution Mile Radius of the Dawn Mining Company Uranium Mill J l H titIE ter E s#E E Ear SE .SSE 3 33W 3a "W H kNW Nw NNw EtLONETE43 I n.0 22.5 a5.0 67.5 90.0 112.5 135.0 157.5 1e0.0 202.5 225.0 2s7.5 270.0 29f,5 315.0 137.5 J .........................................................................................................a.......................... 1 1.0 2.0 l 3 3 10 to 3 6 5 5 to 5 5 0 0 5 to lo J l 2.0 3.0 1 5 3 16 th 5 to 10 to 10 to 5 5 to 5 to 5 l J 3.0 4.0 1 5 10 .th 21 5 26 _16 16 21 to 5 5 to 5 5 1 8 a.O. 5.0 1 5 16 16 16-5 31 21 21 21 to 5 5 16 to 10 5 ] 1 5.0 10.0 1 52 S2 31 26 52 52 31 31 21 52 16 16 21 10 to 10 I J 10.0 20.0 1 52 105 52 210 105 92 52 31 52 52 21 52 441 52 21 21 1 20.0 30.0 1 105 274 52 970 970 1259 210 52 540;, 52 al 52 52 - 21 37 to 7 ) I N 30.0 44.0 1 53 53 53 319 6482 9664 15193 14084 159 *,159 53 21 53 32 159 11 I 3 10.0 50.0 1 2242 11 It 319 3299 36614 187655 '8050 159 159 1699 53 27 ' 21 11 11 i 50.0 60.0 I in6 11 11 319 319 93360 10407 7551 159 53 212 382 27 11 11 11 2 1 60.0 70.0 1 106 11 377 2273 106 3186 1062 262 159 32 552 159 106 11 .31 11 I ) 10.0-ro.O l 5236 11 11 198.9 2210' 29n9 658 212 58s 32 53 1179 212 11 11 1 l', t l 13561 f 7P53 215320 302n5 1895 626 2647 1929 975 19s 306 121 h 1 0 80.0 1 7970 564 656,6a68 t) 3 c e \\ P

4-13 Table 4.6 Environmental Dose Commitments (100 year) to Continental Populations from the Operation of the Dawn Mining Company Uranium Mill Total Environmental, Dose Commitments (EDC), Person-Rem Whole Body Bone Lung Bronchial epithelium EDCs received by the population within 80 km of the mill 226.5 2,677 356.5 8,863 EDCs received by the population beyond 80 km of the mill 2,758 37,180 605.2 12,780 Total EDCs received by the continental population 3,054 39,8f:i0 961.8 21,650 Fraction of background *

2. 53 E-06 * *
3. 30E-05 7.95E-07
3. 58E-06
  • Background values _.estiaated on the basis of year 1990 continental population of 366.4 million people, each person receiving 100 millirem / year to the whole body, bone, and lung and 500 millirem / year to the bronchial epithelium.
    • The notation 2.53E-06 denotes 2.53 x 10 8 or 0.00000253.

e

4-14 Table 4.7 Comparison of Annual Dose Comnitments to Individuals with EPA Radiation Protection Standards (40 CFR 190)* Calculated annual dose commitment (mrem / year) location Exposure Pathway Whole body Bone Lung Nearest resident Inhalation 0.27 7.74 10.90 in prevailing External exposure 0.10 0.10 0.10 wind direction Ingestion 0.9 km NE Vegetable ** 1.56 (0.78) 18.60 ( 9.30) 1.56-( 0.78) Maatt,# 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) Milk 0.38 4.00 0.38 Total 2.77 (1.58) 36.22 (21.72) 13.40 (12.21) EPA limit 25.0 25.0 25.0 Fraction of limit 0.11 (0.06) 1.45 ( 0.97) 0.54 ( 0.49) Nearby resident Inhalation 0.33 9.57 13.90 0.7 km NNW External exposure 0.10 0.10 0.10 Ingestion Vegetable ** 1.80 (0.90) 21.60 (10.80) 1.80 ( 0.90) Meatt,# 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) l Mi l k O.44 4.63 0.44 Total 3.13 (1.82) 41.68 (25.68) '16.70 (15.39) { EPA limit 25.0 25.0 25.0 Fraction of limit 0.13 (0.07) 1.67 ( 1.03) 0.67 ( 0.62) Nearby resident Inhalation 0.19 5.40 7.57 1.0 km ENE External exposure 0.07 0.07 0.07 Ingestion Vegetable ** 1.12 (0.56) 13.4 ( 6.70) 1.12 ( 0.56) Meatt,# 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) Milk 0.28 2.89 0.28 Total 2.12 (1.15) 27.54 (15.64) 9.50 ( 8.53) EPA limit 25.0 25.0 25.0 Fraction of limit 0.08 (0.05) 1.10 ( 0.63) 0.38 ( 0.34) SGe footnotes last page of table.

4-15 = Table 4.7 (Continued) Calculated annual dose commitment (mrcm/ year) location Exposure Pathway-Whole body ' Bone Lung Hearest town, Inhalation 0.02 0.54 0.68 Ford, Washington External exposure 0.01 0.01 0.01 2.3 km E Ingestion Vegetable ** 0.13 (0.07) 1.54 ( 0.77) 0.13 ( 0.07) Meatt,# 0.46 (0.05) 5.78 ( 0.58) 0.46 ( 0.05) Milk 0.03 0.33 0.03 Total 0.65 (0.18) 8.20 -( 2.23) 1.31 ( 0.84) EPA limit 25.0 25.0 25.0 Fraction of Limit 0.03 (0.01) 0.33 ( 0.09) 0.05. ( 0.03) R40 CFR Part 190 excludes any contributions resuTting from the releases of radon and its daughters. DRValues in parentheses represent a 50% reduction based on a growing season of 6 months per year. tMeat ingestion doses result from' consumption of mea.t from cattle grazed 0.4 km N of the mill site.

  1. Values in parentheses represent a 90% rec' action due to the exportation of' locally grazed cattle.

f 1 4 e

~ DRAFT 4-16 Table 4.8 Comparisons of Air Concentrations During Mill Operation i witt 10 CFR Part 20 Limits for Unrestricted Areas Total air concentrations, pCi/m, of radionuclides, 3 U-238 U-234 TH-230 Ra-226 Pb-210 WL* concentration 10 CFR Part 20 limits ** 3.00E+00 4.00E+00

3. 00E-01 2.00E+00 4.00E+00 3.33E-02 Restricted area boundary (0.3 km NE) 1.37E-02t
1. 37E-02
1. 49E-02 1.49E-02 1.48E-02 1.52E-03 Fraction of limit 4.57E-03 3.42E-03
4. 95E-02 7.43E-03 S.71E-03 4.55E-02 Restricted area boundary (0.1 km N) 9.35E-03 9.35E-03
1. i3E-02 1.13E-02 1.12E-02 1.60E-03 Fraction of limit 3.12E-03 2.34E-03
3. 75E-02 5.63E-03
2. 81E-03 4.80E-02 Restricted area boundary (0.2 km W) 6.S9E-03 6.09E-03
8. 77E-03 8.78E-03 8.77E-03 1.89E-03 fraction of limit 2.03E-03 1.52E-03
2. 92E-02 4.39E-03 2.19E-03 5.67E-02 Station 2 (0.4 km NE) 6.50E-03
6. 50E-03
7. 43E-03 7.43E-03 7.44E-03 1.68E-03 Fraction of limit 2.17E-03 1.63E-03
2. 48E-02 3.72E-03 1.86E-03
5. 05E-02
  • WL denotes " working level. " A one-WL concentration is defined to be any combination of air concentrations of the short lived Rn-222 daughters Po-218, Pb-214, Bi-214, and Po-214 that, in one liter of air, will yield a total of 1.3 x 105 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. nn Values given are from 10 CFR Part 20, Appendix B, Table II, Column 1. TThe notation 1.37E-02 denotes 1.37 x 10 2, or 0.0137.

~ 4-17 4.7 OCCUPATIONAL RADIATION EXPOSURE the mill workers and the general public to radiation. Uran for workers are required to be monitored and kept below regulatory lim addition, protection measures to reduce occupational exposure In reviewed and revised in accordance with the requirement to make s as low as is reasonably achievable. The scope of this NRC staff review has not included a review of the radiological safety program proposed for the mill. However, occupational exposures can be characterized in general terms. mills have shown that the exposures of mill workers to airborne r are normally below 25 percent of the maximum permissible concentratio in Appendix B of 10 CFR Part 20 and that external exposures are n than 25 percent of 10 CFR Part 20 limits (Refs. 4 and 5). uranium mill employees may have exceeded, over A recent review w sible exposure to yellowcake, or 10 percent of the radon concentrations. an average worker to these radioactive components over probably does not exceed 25 percent of the total permissible exposure. 4.8 RADIOLOGICAL IMPACT ON BIOTA OTHER THAN MAN f ~ Although no guidelines concerning acceptable limits of radiation exposu

{

been established for the protection of species other than man, it is g t agreed that the limits for humans are also conservative for those species (Refs. 6-13). Doses from gaseous effluents to terrestrial biota (such as birds and mammals) are quite similar to those calculated for man and arise from the same dispersion pathways and considerations. of the mill will be monitored and maintained within safe radiologicalBecause t protection limits for man, no adverse radiological impact is expected for resident biota. ~4. 9

SUMMARY

.0F RADIOLOGICAL IMPACTS AND CONCLUSIONS This predictive analysis is based on reasonably conservative assumptions a for the annual estimated impacts, on the worst year of operation for release Using information provided by the operator (Refs. 1, 2), local land and ag cultural information, and NRC staff estimates, the assessuents predict imp which are slightly above 40 CFR 190 EPA Radiation Protection Standards. Calculated impacts to the regional and continental popultffen prove to be small fractions of the contribution from natural backgrouno radiation. estimated annual ambient air concentrations of radionuclides indi Also compliance with:10 CFR Part 20 NRC Radiation Protection unrestricted areas. i

4-18 monitoring data collected by the operator.Theresultsofthepr e that the operator conduct a comprehensive effluent monitoring prog results of which must be reported to the State of Washington, Departm , the Social and Health Services at six-month intervals. environment. -These surveys are reported to the Moreover the operator is annual basis. patterns near the mill would be included in revised a the conclusions in this assessment. As an Agreement State, the State of Washington (Department of Social and Health Services) will review submittals to determine whether they are in compliance with existing s rs .i 4 l l we J I o O C

DRAFT 4-19 References 1. " Principal Parameters for Radiological Assessment " Dawn M May 1980.

ompany, 2.

Uranium Mill," Newmont Services, Ltd., March" Input y 13, 1981. 3. the Draft GEIS, Argonne National Laboratory, N ent to June 1979. , ANL/ES-75, 4. B. R. Metzger, " Nuclear Regulatory Commission Occupational Ex Experience at Uranium Plants," Conference on Occupational He -] with Uranium, Report ERDA-93, Washington, DC, 1975. ence 5. Presentation to the Environmental Subcommit on, pn Reactor Safecuards, Occupational Radiation Exposure Control a mmittee Cycle Facilities, January 26, 1978. 6. Long-Term Biota Effects Problem," Nucl. Saf.S. I. Auerb The 2 12:25-35 (1971). l 7: Los Alamos. Scientific Laboratory, Los, Alamos, N J[ Proposed Interim Standard for Plutonium, Report LA-5483-MS , and A Scientific Laboratory, Los Alamos, N. Mex.,1974. , Los ATamos 8. Office, Las Vegas, Nevada, 1973.Enewetak Radiolooical Surv i 9. a Carcinogenic Hazard," Rad. Res.N. A. Frigerio, K. F. Eckerm 62:599 (1975). 10. A. H. Sparrow et al., " Chromosomes and Cellular Radiosensitivity " _ Rad. Res. 32:015 (1967). 11. Oceanography, National Academy of Science-Na Washington, DC, 1971. 12. Environment to Animals and Man," Environ. ControlR. J. 2:337-85, 1971. 13. Aquatic Organisms, USAEC Report UCRL-50564, ~ v. ew

O A-1 APPENDIX A CALCULATION OF SOURCE TERM Introduction The radiological assessment for the operation of the Dawn Mining Company Uranium Mill was performed using the MILDOS computer code. The input to the computer code consists of site-specific data and staff estimates of the radio-active effluents from the mill and tailings management systems. These source term calculations for the tailings impoundment are described in Appendix B. Source terms are defined as the estimated quantity of radioactivity released in a specific period of time. The mill sources e.ddressed in this appendix are: 1. The ore pad and its related activities. 2. Mill hoppers and feeders. 3. Grinders and crushers. 4. Fine ore storage and transfer of fin'e ore. 5. Yellowcake drying and packaging. Some general parameter values which are necessary to these calculations are: 1. The annual o're processing rate is 148,780 MT/ year. ~ ~ 2. The ratio of radioactivity in the ore dust to that of the bulk ore is 2.5. 3. The bulk ore activity for U-238, Th-230, Ra-226, and Pb-210 is 432 pCi/g. Ore Pad Activities Particulate emissions from the ore pad are the result of: I 1. Truck delivery of ore. 2. Ore pad handling by front-end loaders and other equipment. 3. Windblown emission. Radon gas emissions are estimated on a specific Rn-222 flux (Ref. A.1) of p m sec Rn-222 1* 0 pCi/g Ra-226 1. Truck Unloading The release rate is estimated by the staff to be (Ref. A.2): 0.04 lb/ ton = 0.04/2000 = 2 x 10 s release fraction t

A-2 The particulate release is then: 148,780 MT/ year x 108 g/MT x 2.5 x 10 12 Ci/pci x 2 x 10~5 ~ x 432 pCi/g = 3.21 x 10 3 Ci/ year 2. Handling The release rate is estimated to be (Ref. A.2): ~ 0.05 lb/ ton = 0.05/2000 = 2.5 x 10 5 release fraction. [ The particulate release is then: 148,780 MT/ year x 10s g/MT x 2.5 x 10 12 Ci/pCi ~ ~ x 2.5 x 10 5 x 432 pCi/g =.4.02 x 10 3 Ci/ year 3. Windblown Emission The dusting rate for the ore pad is'.42 g/m year (Ref. A.1) 2 The particulate release is then: 2 2 42 g/m year x.432 pCi/g x 2.5 x 5.5 x 104 m x 10 1I Ci/pCi = 2.49 x 10 3 Ci/ year ~ 4. Radon-222 Release from Ore Pad The staff estimates radon release to be 1.0 pC -s x 432 pCi/g x 3.156 x 107 sec/ year g -226 ~ x 10 12 Ci/pCi x 5.5 x 104 m'- = 748 Ci/ year Total o'e pad emissions for U-238, Th-230, Ra-226, Pb-210 (secular r equilibrium): ~ 3.21 x 10 3 Ci/ year ~ 4.02 x 10 3 Ci/ year ~ 2.49 x 10 3 Ci/ year ~ 9.72 x 10 8 Ci/ year x 50 percent reduction (Ref. A.3)' ~ = 4.86,x 10 3 Ci/ year Total ore pad radon emission is 748 Ci/ year.

A-3 Hoopers and Feeders The release rate is estimated to be (Ref. A.2): 0.08 lb/ ton = 0.08/2000 = 4 x 10 5 release fraction. The particulate release is then: 148,780 MT/ year x 108 g/MT x 2.5 x 432 pCi/g x 4 x 10 5 ~ ~ x 10 12 Ci/pCi = 6.43 x 10 3 Ci/ year. Dust suppression techniques such as chemical spraying and wet'.ing on the ore pad would reduce dust in the transfer of ore to the grinding stage..Thus, the particulate release for U-238, Th-230, Ra-226, and Pb-210 is estimated to be: 6.43 x 10 3 Ci/ year x 50% (Ref. A.3) = 3.21 x 10 3 Ci/ year. The radon release in based on a staff estimate that 20 percent of the secular equilibrium content of radon escapes at this stage cf the ore processing. This estimate also accounts for radon. released from other sources such as the leaching, CCD, and other circuits in the hill, which are not specifically addressed. The radon release is computed as: 148,780 MT/ year x 108 g/MT x 10 22 Ci/p'Ci x 20% x 432 pCi/g = 12.9 Ci/ year Grinding and Crushing The release rate is estimated to be (Ref. A.2): 0.08 lb/ ton = 0.08/2000 = 4 x 10 5 release fraction. The particulate release is then: 148,780,MT/ year x 108 g/MT x 432 pCi/g x 2.5 x 4 x 10 5 x 10 12 Ci/pCi = 6.43 x 10 3 Ci/ year. This emission point has an emission control device (bag house), which the applicant estimates (Ref. A.4) at 99.5 percent efficiency. The staff selected a 99 percent efficiency to account for downtime and other routine losses of efficiency. Thus, the particulate souce term is then: 6.43 x 10 3 Ci/ year x 1% = 6.43 x 10 5 Ci/ year.

A-4 The staff estimates that the radon source terin will be approximately the same as that for the hopper and feeder: 12.9 Ci/ year for the same reasons as mentioned before. Fine Ore Storace The staff estimates loss from loading in, loading out, and transfers of ore to and from the fine ore storage area. The release rate for each of these four activities is estimated (Ref. A.2) to be 0.02 lb/ ton each.

Thus,

~ 4 x 0.02 lb/ ton = 0.08/2000 = 4.0 x 10 5 release fraction. The particulate source term for U-238, Th-230, Ra-226, and Pb-210 is estimated to be: 148,780 MT/ year x 108 g/MT x 2.5 x t x 10 s.x 432 pCi/g x 10 12 Ci/pCi = 6.43 x 10 3 Ci/ year. The applicant estimates (Ref. A.4) efficiency of emission control to be 80 percent, so the particulate source term reduces to: ~~ ~ 6.43 x 10 3 Ci/ year x 20% = 1.29 x 10 3 Ci/ year. Again, the radon source term is estimated to be 12.9 Ci/ year. Yellowcake Drying and Packaging The yellowcake production rate is reported by the applicant to be 214 MT/ year. (F.ef. A.5) The applicant reports the y'early emission rates-of 4.86 x 10 3 MT/ year for the dryer and of.3.47 x 10 3 MT/ year for pack -ing. The total release rate is then 8.33 x 10 3 MT/ year. The U-238 particulate source term is: 8.33 x 10 3 MT/ year x 108 g/MT x 3.33 x 10 7 Ci/g U-238 x 0.85 ~ x 0.79 = 1.86 x 10 3 Ci/ year, where 0.85 is the percent of uranium in Us03 and 0.79 is the reported purity of yellowcake. The Generic Environmental Impact Statement on Uranium Milling (Ref. A.6) reports that the activity of Th-230 in yellowcake is 0.5 percent that of U-238 and that activity of Ra-226 and Pb-210 are each 0.1 percent that of U-238.

A-S The Th-230 source term is: 1.86 x 10 3 Ci/ year x 0.5% = 9.31 x 10 6 Ci/ year. The Pb-210 and Ra-226 source terms are: 1.86 x 10 3 Ci/ytar x 0.1% = 1.86 x 10 8 Ci/ year. Radon release from yellowcake operations is assumed to be negligible. Summary Except for the yellowcake source terms, the U-23E, U-234, Th-230, Ra-226, and Pb-210 quantities are considered to be in secular equilibrium. In general, radioactive emissions which are not explicitly calculated are assumed to be equal to the next higher-up parent in the decay chain. The MILDOS code also accounts for mechanisms such as ingrowth of radon daughters, resuspension, and deposition, all of which are further explained in Appendix B. REFERENCES FOR APPENDIX A A.1. Table 4.1, Section 4. A.2. " Fugitive Dust Emission Factors," Colorado Department of Health, Air Pollution Control Jivision, Stationary Sources Section. ~ A.3. U.S. Environmental Protection Agency, " Technical Guidance for Control of Industrial Process Fugitive Particulate Emissions," Report EPA-45013-010, March 1977. A.4. " Principal Parameters for Rarfiological Assessment." Dawn Mining Company Uranium Mill, May 1980. A.5 " Input Data for the Radiological Assessment of the Dawn Mining Company." Newmont Services, Ltd., March 13, 1981. ~A.6. " Generic Environmental Impact Statement on Uranium Milling," NUREG-0706, U.S. Nuclear Regulatory Commission, September 1980.

B-1 APPENDIX B ' DETAILED RADIOLOGICAL ASSESSMENT Supplemental information is provided below which describes the models, data, and assumptions utilized by the' staff in performing its radiological impact assessment of the Dawn Mining Company Uranium Project. The primary calcula-tional tool employed by the staff in performing this assessment is MILD 05 (Ref. B.1), an NRC modified version of the UDAD (Uranium Dispersion and Dosimetry) computer code originated at Argo.ce National Laboratory (Ref. B.2). B.1 ANNUAL RADI0 ACTIVE MATERIAL RELEASES Estimated annual activity releases for the Dawn Mining Company Uranium Project are provided in Table 4.2. They are based on the data and assumptions given in Table 4.1 and described elsewhere in Section 4, with the exception of the annual average dusting rate for exposed tailings sands. This dusting rate is calculated in accordance with the following equation: M = 3.15 107 RF (B-1) s3 s where F is the annual average frequency of occurrence of wind speed s group s', dimensionless; R is the dusting rate for tailings sands at the average wind s speed for wind speed group s, for particles 5 20 pm diameter, 2 g/m sec; M is the annual dust icss per unit area, g/m.yp; 2 3.156 x 107 is the number of seconds per. year; and t O.5 is the fraction of the total dust loss constituted by particles 5 20 pm diameter, dimensionless. The values of R, and F utilized by the staff are as given in Table B.1. s l l e i i ( h, .e.,. e...nm ep ro.M

  • .. e

._m.-m --h =

f* B-2 Table B.1 Parameter values for calculation of annual dusting rate for exposed tailings sands Wind Speed Average Wind Dusting Rate Frequency of Group, knots Speed, mph (R,), g/m -sec* Occurrence (F )** 2 3 0-3 1.5 0 0 4-6 5.5 0 0 7-10 10.0 3.92 x 10'7 0.38011 11-16 15.5 9.68 x 10 6 0.18314 17-21 21.5 5.71 x 10 5 0.04671' ~ >21 28.0 2.08 x 10 4 0.00993 A Dusting rate as a function of wind speed is computed by the MILDOS code (Ref. B.1).

  • 'nd speed frequencies obtained from annual joint frequency Wi data presented in Table B.2.

d f e O s

c. EH m I .e i e e e e e e e t i j g 3 e a e e .e 8

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  • Fde 8 CdMCCCC 0 eeCCCC> Be

_ q -NCOOCe 8 43=CComt meNONod e E meCeCh e CeNCOCh e OOOC CC= S e e

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== 4 0 C CCC=9 CCCC=9C 5 6 8 8 8 8 9 0 0 ceCCCCe 8 COdOCC= 0 me=dtect eOemeace CPeOCCC 6 eeCCCocam V 9 MCCCCCO 8 cDC000t 9 Nt CC ece 8 MOOme*=8 COfCCC4 e NCCCCC= t-8 CNCOCCN G CCeCC CC 8 m+meCome eCedeemi C=NCOGM e CeCC CCC BC Q 0 CC CCCCC O CN=CC.CC C O P e k O. C. 8 CONCCOd 9 5 C=4 =CCO 8 0 'O M d C C C.C.C Sm e e e e e e o e s O e o e e e e e o e o e e e s ce e o e e e e e e e e s e e e o e e e f 3 OCCC CCO O = O' NC= C 8 C -CCC=3 OCCC= 0 W O 'B '9 ~ ' 'O " O NOCCCCN CemCCCh k hedeCN 4 ededC CC 0 CwmCCC= 0

  1. eCCCCC N

I CCCCCCC 4 meeCCCN S 4Nmed Cr G kadam4h 9 CtWCCCa t m>CCCC= te O e CCCCCCC a O=NOCoe s =cmOCCC e ed-Noame CoeCCCe 8 eNCCCCN eo O 3 0 C CCCCCO S C==JCON S C=>= Cop I C F- @ m = = C 8 CN>CCCC 0 NOCCCCC ic 4 W. 0 e e e o e e e e e e e e e o e 8 e o e e e e e B e e o e e o e t e o e e e e o g e e e e e e e g e c ee CCCCC 4 OCO 8 0 8 Nc= ce C OCC-8 CCCC O N E ' ' 'e '0

  • =

I C=CCCC= 0 C&=OCCC kmmeCCN S Meeme=> Ce=CCCC S =WCCCCmem 8 d=CCCCM S dNCCCCe 5 CCe>CCe t eeACC-A t CerCCCC S C=CC CCe t= b I =eGCOCmt CmmCCCd 8 Ne@cCCe e m e e. d e c N 8 CCOOCCm9 -h CCCCE 8 e U 0 CCCCCCC 8 =N=CCCc B CN@ OOCe9 Neemmce e O@cCCC= 0 P-CCCC4 DN C 9 e e e e e e e e e e e e e e e 5

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Q M 8 0000 0 CCO e CC e MN > 4 O -COCN S =OOOC=0m 3 0 B 9 4 8 9 e= 8 d>OCCCmB NeeCCCe 8 PeCCCot t OCNemCC 8 COOCCCp t ME CCCC= l e 7 8 g NMCCCC4 8 dm>CCC4 8 NcnCCCO 3 mm>=MdC 8 CeCCCCc 0 emCCCCM tw 0 C=CCCC= 8 ONACCCe e MC =CCCP I meNmNCA B C CMCCCm8 meCC CCC sh b wI CCCCCCC 8 C=CCCC= 8 Q=eCCCd t =Ome=Cmt 04tCCCN 0 McCCCCC em F. 8 o e e e e e e e e e e e o e o e o e e o e o e e e e o e e e e t e e e o e e e t e e e e o e e g e m8 CCCC 8 CCC 0 CCC 8 N e 5 C =CCCN S CCCC 8e C 6 8 6 5 9 D 0 5 erCOCCe 8 rCNCCCh 0 me=CCCC 8 kNMPC Ce 9 CN=CCCM 8 eeCCCCC se 9 MOCCCOS O ke# CCCC 8 =chCOCN E Mmm=d Oe O Cm4CCCm8 eC OCCom oC 0 CNCCCCN O camCCC= 0 =ddCCCO 8 4C NNOca 8 GemCCCO 9 erCCCCelm y e CCCCCCC 8 CCCCCCN S C=NOCOc t apCMOC=0 CmmCCCM f NG CCCOk am O W D e o e o e e e 3 e e e e e e e t 'e o e o e e e g e e e o e e o g e o e e e e e 8 e o e e e e e ge "C C 8 OCCO e OOC 0 COC s ON S C OCC B OOOC S e e e S a e e e b 8 e(COCCW D PE =COOE I ameCocos mm@mCC=a omeCCCN S S eOOCCC em 8 MC CCCCM B CM-CCCO S Ced4CCd 4 dd =NCCM S Ce>CCCm 8 WNCOCC> tc y B CNCOCON S decOCOc t NOW CComa MC4CCCce OecCCCF G 4W COCCC le W e C CCCCCCC 8 C=CCCCN e C=NGCCet wen-CCN s CmCCCCmo NMOCCCese f. 8 e e e e e e e g e o e o e o e g e e e e e e o g . e o e e e o g e o e e e o e e e e e e e e o g e W8 OOOC e - CCC 6 OC 8 CCa t C CCC 8 0C00 SN O s 3 3 e a t a 7 5 EN CCoCrt NCmCCCN S m=COCCes meeCPCd e CemCCCC f CeCCCCC Se 8 OmOCOCU B CdE CCCm t cck CCCC I C=d =CC= 8 CCCCC C C I N4CCCCC se 8

==CCCCN s eNtCCCP 8 MC=NCCC 4 CNmeNCh e CmdCCCE O

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DRAFT ~ B-4 The calculated value of the annual dusting rate, M is 420 g/m yr. Annual 2 curie releases from the tailings piles are then given by the following relationship: S MA (1-f ) I.t (C) (2.5 x 10 12) (B-2) = c where A is the assumed beach area of the pile, m ; 2 f is the fraction of the dusting rate controlled by mitigating c actions, dimensionless; f is the fraction of the ore content of the particular nuclide t present in the tails; S is the annual release for the particular beach area, Ci/yr; C is the assumed raw ore activity, pCi/g;

2. 5 is the dust to tails activity ratio; and 10 12 is Ci/pCi.

The tailings impoundments consist of three areas: (1) the abandoned tailings area (59.2 acres); (2) the inactive tailings area (47 acres); and (3) the below grade tailings area (27 acres). The abandoned tailings area is no longer in use and consists of old tailings from processing ore with an estimated average activity of 675 pCi/g. At present only 3 percent of this area is not covered by wood chips or other cover material, and it is estimated that it will be 99 percent covered by 1985. The inactive tailings area is being stabilized by a soil cover. At present approximately 10 acres is exposed, and as drying progresses, more cover will be applied to exposed areas. The staff has estimated an 80 percent reduction factor of dusting for the present assessment. As the interim stabilization cover is apph ed to the rest of t2's area, particulate emissions would effectively be eliminated. The present below grade tailings disposal area is in operation, and the staff has assumed an 80 percent reduction factor for dusting because of water cover and other dust mitigation measures which are utilized in below grade impoundments. Dust losses from the ore storage piles were estimated by assuming they would be about 10 percer2 of those from an equivalent area of tailings beach. Calculated dust losses were reduced by 50 percent to account for dust loss control measures agreed to by the operator. k

B-5 B.2 ATMOSPHERIC TRANSPORT The staff analysis of offsite air concentrations of radioactive materials was based on five years of meteorological data collected at Spokane, Washington, over the period 1967 through 1971 (Ref. B.3). The collected meteorological data were entered into the MILD 05 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 3.2. The dispersion model employed by the MILDOS cede is the basic straight-line Gaussian plume model (Ref. B.1). Ground-level, sector-average concentrations _ are computed using this model and are corrected for decay and ingrowth in transit (for Rn-222 and daughters) and for depletion due to deposition losses (for particulate material). Area sources are treated using a virtual point source technique. deposited on ground surfaces is treated using a resuspension factor depends on the age of the deposited material and its particle size (Ref. B.1). 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 B.3. lable B.3 Physical characteristics assumed for ~ particulate material releases c Deposition Diameter Density Velocity' AMAD* Activity Source pm g/cm3 cm/sec pm Activity Source Crusher dusts 1.0 2.4 1.0 1.55 Yellowcake dusts 1.0 8.9 1.0 2.98 Tailings, ore pile dusts 5.0 (30%)

2. 4 1.0 7.75 Tailings, ore pile dusts 35.0 (70%)
2. 4 8.8 54.2 Ingrown Rn daughters
0. 3 1.0 0.3 0.3
  • Aprodynamic equivalent diameter, used in calculating inhalation doses (Ref. B.4).

B.3 CONCENTRATIONS 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' media of concern in the vicinity of the site. 1.'ese' include concentrations in the air (for inhalation and direct external exposure),7on the ground (for direct external exposure), and in meat, milk and vegetables (for ingestion. k N 'l s

un n %,3 7

( q, #

4 n 3 3,. w' a - %l: p .s , t 7 1 <,, u y. c s s. ^"~eyosure). Concentrati,ca v5]IJe( are c'omputed' explicitly by the MILDOS code for %238, Th-230, Ra-226, Rn-222'(fjr only); and Pb-210. Concentrations of - ~ - ~ ' -QTh-234, Pa-234, and U-234, are usugnea to be equal to that of U-238. Concentra-q jicions of Bi-210 and Po-210 arc (numed -to be equal to that of Pb-210. 3 ~ cB.3.1 Air Concentrations N ^ C0rtinary, direct air concentrations are computed by the MILDOS code for each ~~ receptor location, from eacr. activity source, by particle si:>e (for particu- ~ ~ '_ i.lates). Direct air concentr$tions computed by MILDOS include depletion by -deposition (particulates) or the-effects of ingrowth and decay in transit (radcrF and daughters). In order to compute-inhalation doses, the total air V concentration of each isot~ ope at each location, as a function of particle ~~ size, is computed as the Yum of the direct air concentration and the resuspended ~ cir concentfation: ~ C. (t) C. d+ C.a1pr(t)> (B-3) = alp alp where C"IE(t) is the total air co.ncentration of isotope i, particle size p, at time t, pCi/m., a - C. ~d - is the direct air co centration of isotope i, particle alp size p, for the time constant, pCi/m ; and 3 1-C'.a1pr(,) is the resuspended air concentration of isotope i, particle t ~ s size p_, at time't, pC.i/m, ' 'iThe resuspended air conce i is~ computed using a time-dependent resuspension factor, R (t), defined by p '= -(1/V )10 5 ~eN t (for t 51.82 yr) (B-4a) R R (t) p p s (DV)108 (f'or t > 1.83 yr) (B-4b) R (t) = p p ~ .where R (t) is the raf.io of the resuspended air concentration to the p-ground co.ncentration, for a ground _ concentration of age-t years, o_f particle size p, m 2; V is the deposition' velocity of particle size p, cm/sec; p A is the assumed decay constant of the resuspension factor R (equivalent to a 50-day half-life), 5.06 yr; 10 5 is the initial value of'the resuspension factor (for particles with a deposition velocity of 1 cm/sec), m 1; 10'8, _i.s the'~ terminal value of the resuspension factor (for particles with a deposition velocity of 1 cm/sec), m_1; and 4 'b

B-7 h 1.82 is the time required to reach the terminal resuspension factor, years. The basic formulation of the above expression for the resuspension factor, the initial and final values, and the assigned decay constant were derived from experimental observations (Ref. B.5). The inverse relationship to depositior. velocity eliminates mass balance problems involving resuspension of more than 100 percent of the initial ground deposition for the 35 pm particle size (see Table B.3). Based on this formulation, the resuspended air concentration is given by: 1 - exp [-(A * + A )(t - a)] g R aipr(t) = 0.01 Caipd (gx,g) (B-5) C 10 5 j p i -exp [-A *(t - a)) - exp (-A *t)" g g + 10 46(t) (3.156 x 107) xx i is equal to (t - 1.82) if t < 1.82 and is equal to zero where a otherwise, years; 6(t) is zero if t < 1.82 and is unity otherwise, dimensionless; A* is the effective decay constant for isotope i on soil, year 1; g 0.01 is the deposition velocity for the particle size for which the initial resuspension factor value is 10 5 per meter, m/sec; 3.156 x 107 is sec/ year. Total air concentrations are computed using equations B-5 and B-3 for all particulate effluents. Radon daughters which grow in from released radon are not depleted duc to deposition losses and are therefore not assumed to resuspend. i B.3.2 Ground Concentrations Radionuclide ground concentrations are computed from the calculated 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: Ddi = C Y (B-6a) adip p, p

B-8 a w ere C is the direct air concentration of radionuclide i, adip 3 particle size p, pCi/m ; D is the resulting direct deposition rate of radionuclide i, pCi/m -sec; 2 di V is the deposition velocity of particle size p, m/sec (see Ref. B.1). p ~ The concentration of radionuclide i on a ground surface due to constant deposition at the rate D ver time interval t is catained from d,i 1 - exp [-(A. + A )t] Cg$(t) = Ddi A +A (B-6b) i e ~ 9g(t) is the ground surface concentration of radionuclide i at time t,- where C 2 pCi/m ; t is the time interval over which deposition has occurred, sec; A, is the assumed rate constant for environmental loss, set 1; A, is the radioactive decay constant for radionuclide i, sec 1 (Ref. B.6). Thb environmental loss constant, A, corresponds to an assumed half-time for loss of environmental availability *of 50 year.s, (Ref. B.5). This parameter accounts for downward migration in soil and loss of availability due to ' chemical binding. It is assumed to apply to all radionuclides deposited on the grounc. Ground concentrations are explicitly computed only for uranium-238, thorium-230, radium-226, and lead-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 lead-210, ingrowth from deposited radium-226 can be significant. The concentration of lead-210 on the ground due to radium-226 deposition is calculated by the staff, using the standard Bateman formulation End assuming that radium-226 decays directly to lead-210. If i = 6 for radium-226 and i = 12 for lead-210 (Ref. B.1), the following equation is obtained: ~ I ~ **P("A$2 ) + exp(-A*6 ) - **E(~ A52 t) t t A 0 12 d6 (B-7) g12(Pb+Ra) = C xx 3x xx 3x 6 12. 6 12 where C'12(Pb+Ra) is the incremental lead-210 ground concentration resulting 9 from radium-226 deposition, pCi/m ; 2 e

B-9 A* is the effective rate constant for loss by radioactive decay and migration of a ground-deposited radionuclide and is equal to A

  • A, sec 2, n

e B.3.3 Vegetation Concentrations Vegetation concentrations are derived from ground concentrations and total deposition rates. Total deposition r;ates are given by the following summation: D$= C,9p p, (B-8a) V P where D is the total deposition rate, including deposition of resuspended g activity, of radionuclide i, pCi/m:-sec. 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 uptake. Five categories of vegetation are treated by the staff. They are edible above ground vegetables, potatoes, other edible below grouno vegetables, pasture grass, and hay. Vegetation concehtrations are computed using the following equation: 4 1 - exp(-A t ) yy Cyg=DEE;,' +C $r gg(By$/P) (B-8b) where B is the soil-to plant transfer factor for isotope i, vegetation type v, y$ dimensionless; C is the resulting concentration of isotope i in vegetation v, pCi/kg; yg E is the fraction of the foliar deposition reaching edible portions of y vegetation v, dimensionless; F is the fraction of the total deposition retained on plant surfaces, r 0.2, dimensionless; P is the assumed areal soil density for surface mixing, 240 kg/m ; 2 t is the assumed duration of exposure while growing for vegstation vi y sec; 2 Y is the assumed yield density of vegetation v, kg/m ; y A is the decay constant accounting for weathering losses (equivalent g to a 14-day half-life), 5.73 x 10 7 per second.

B-10 The value of E is assumed to be 1.0 for all 'above ground vegetation, and 0.1 y for all below ground vegetables (Ref. B.7). Th9 value of t is taken to be 60 days, except for pasture grass, where a value of 30 days is assumed. The y yield density, Y, is taken to be 2.0 kg/m except for pasture grass, where a 2 y value of 0.75 kg/m2 is applied. Values of the soil to plant transfer coefficients, Byg, are provided in Table B.4. Table B.4 Environmental transfer coefficients Uranium Thorium Radium Lead Soil to plant (Byj) Edible above ground 2.5E-03 4.2E-03 1.4E-02 4.0E-03 Potatoes 2.5E-03 4.2E-03 3.0E-03 4.0E-03 Other below ground 2.5E-03 4.2E-03 1.4E-02

4. 0E-03 Pasture grass 2.5E-03 4.2E-03 1.8E-02 2.8E-02 Stored feed (hay) 2.5E-03 4.2E-03 8.2E-02 3.6E-02 Feed to beef (Fbi),pCi/kg 3.4E-04 2.0E-04 5.1E-04 7.1E-04 per pCi/ day Feed to milk (F,5), pCi/L 6.1E-04 5.0E-06 5.9E-04 l'. 2E-04 per pCi/isy Source:

U.S. Nuclear Regulatory Commission, Calculational Models for Estimating Radiation Ooses to Man from Airborne Radio-active Materials Resulting from Uranium Operations, Task RH 802-4, May 1979. B.3.4 Meat and Milk Concen'trations Radioactive inaterials can be deposited on grasses, hay, or silage which is eaten by meat animals, which are in turn eaten by man. It has been assumed that meat animals obtain their entire feed require:ent by grazing eight months per year, and by eating nonlocally grown stored feed for approximately 10 weeks. The equation used to estimate meat concentrations is: Cbi = Q Fbi (0.67 Cpgj + 0.20 Chi) (B-9a) where C is the concentration of isotope i in pasture grass, pCi/kg; pgg C is the concentration of isotope i in hay (or other stored feed), hi pCi/kg; C is the resulting concentration of isotope i in meat, pCi/kg; bi F is the feed to meat transfer factor for isotope i, pCi/kg per pCi/ day bi (see Table B.4);

B-11 Q is the assumed feed ingestion rate, 50 kg/ day; 0.67 is the fraction of the total annual feed requirement assumed to be satisfied by pasture grsss; and 0.20 is the 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 milk concentrations: C,4 = Q F,9 (0.67 Cpgg + 0.20 Chi) (B-9b) where C,9 is the average concentration of iostope i in milk, pCi/1; and F. is the feed to milk activity trsnsfer factor for isotope i, pCi/1 "I per pCi/ day ingested (see Taole B.4). B.4 DOSES TO INDIVIDUALS Doses to individuals have been calcula'ted for inhalation; external exposure to air and ground concentrations; and ingestion of vegetables, raeat, and milk. Internal doses are calculated by the staff, using dose conversion factors that yield the 50 year dose commitment, that is, the entire dose insult received over a period of 50 years following either inhalation or ingestion. Annual doses given are ~t'he 50 year dose commitments resulting from a one year exposure period. The one year exposure period was taken to be the worst year for mill operation releases, 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 obtair.ed by Eq. B-3 (resuspended air concentrations are included) for particulate materials and the dose conversion factors presented in Table B.S. (Ref. B.1, B.8). Doses to the bronchial epithelium from Rn-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 Rn-222 derives as follows: ~ 3 1) 1 pCi/m Rn-222 = 5 x 10 S Working Level (WL).* 2) Continuous exposure to 1 WL = 25 cumulative working level months (WLM) per year. 3) 1 WLM.= 5000 mrem (Ref. B.9).

8-12 Table B.5 Inhalation dose conversion factors (mrem / year /pci/m ) 8 Organ U-238 U-234 U-230 Ra-226 Pb-210 Po-210 Particle Size = 0.3 pm Whole body 7.46E+00 1.29E+00 Bone 2.32E+02 5.24E+00 Kidney 1.93E+02 3.87E+01 Liver 5.91E+01 1.15E+01 Mass average lung 6.27E+01 2.66E+02 Particle Size = 1.0 pm Density = 8.9 g/cm3 Whole body 9.82E+00 1.12E+01 1.37E+02 3.58E+01 4.66E+00

5. 95E-01 Bone 1.66E+02 1.81Es02 4.90E+03 3.58E+02 1.45E+02 2.43E+00 Kidney 3.78E+01 4.30E+01 1.37E+03 1.26E+00 1.21E+02 1.79E+01 Liver 0.

O. 2.82E+02 4.47E-02 3.69E+01 5.34E+00 Mass average lung 1.07E+03 1.21E+03 ',2.37E+03 4.88E+03 5.69E+02 3.13E+02 Particle Size = 1.0 pm Density = 2.4 g/cm3 Whole body 4.32E+00 4.92E+00 1.66E+02 3.09E+01 4.36E+00 4.71E-01 Bone 7.92E+01 7.95E+01 5.95E+03 3.09E+02 1.35E+02 1.92E+03 Kidney 1.66E+01 1.89E+01 1.67E+03 1.09E+00 1.13E+02 1.42E+01 Liver 0. O. 3.43E+02 3.87E-02 3.45E+01 4.22E+00 Mass average lung 1.58E+02 1.80E+02 3.22E+03 6.61E+03 7.72E+02 4.20E+02 Particle Size = 5.0 pm Density = 2.4 g/cm3 Whole body 1.16E+00 1.32E+00 1.01E+02 4.00E+01 4.84E+00 7.10E-01 Bone 1.96E+01 2.14E+01 3.60E+03 4.00E+02-1.50E+02 2.89E+00 Kidney 4.47E+00 5.10E+00 1.00E+03 1.41E+00 1.25E+02 2.13Et01 Liver 0. O. 2.07E+02

4. 97 E-02 3.83E+01 6.36E*00 Mass average lung 1.24E+03 1.42E+03 1.38E+03 2.84E+03 3.30E+02 1.83E+02 Particle Size = 35.0 pm 3

Density = 2.4 g/cm l Whole body

7. 92E-01 9.02E-01 5.77E+01 3.90E+01 4.43E+00 7.28E-01 Bone 1.34E+01 1.46E+01 2.07E+03 3.90E+02 1.38E+02 2.96E+00 Kidney 3.05E+00 3.47E+00 5.73E+02 1.38E+00 1.15E+02 2.19E+01 Liver 0.

O. 1.19E+02 4.85E-02 3.51E+01 6.52E+00 Mass average lung 3.33E+02 3.80E+02 3.71E+02 7.64E+02 8.70E+01 5.75E+01 i 1 I

B-13 Therefore: (1 pCi/m8 Rn-222) x (5 x 10 8 m3) x (25 )x(5000"{**)=0.625 mrem C and the Rn-222 bronchial epithelium dose conversion factorais taken to be 0.625 mrem /yr per pCi/m. 3 B.4.2 External Doses External doses from air and ground concentrations are computed using the dose conversion factors provided in Table B.6 (Ref. B.1). Doses are computed based on 100 percent occupancy at the particular location. Indoor exposure is assumed to occur 14 hrs / day at a dose rate of 70% of the outdoor dose rate. Table B.6 Dose convers'en factors for ext'ernal exposure Dose factors for doses from air Dose factors for doses from ground 3 concentrations, mrem /yr per pCi/m f. concentrations, mrem /yr per pCi/m2 Isotope Skin Whole Body Isotope Skin Whole Body . U-228 1.05 E-05 1.57 E-06 U-238 2.13 E-06 3.17 E-07 Th-234 6.63 E-05 5.24 E-05 Th-234 2.10 E-06 1.66 E-06 Pa(m)-234 8757 E-05 6.64 E-05 Pa(m)-234 1.60 E-06 1.24 E-06 U-234 1.36 E-05 2.49 E-06 U-234 2.60 E-06 4.78 E-07 Th-230 1.29 E-09 3.59 E-06 Th-230 2.20 E-06 6.12 E-07 Ra-226 6.00 E-05 4.90 E-05 Ra-226 1.16 E-06 9.47 E-07 Rn-222 3.46 E-10 2.83 E-06 Rn-222 6.15 E-08 5.03 E-08 Po-218 8.18 E-07 6.34 E-07 Po-218 1.42 E-08 1.10 E-08 Pb-214 2.06 E-03 1.67 E-03 Pb-214 3.89 E-05 3.16 E-05 Bi-214 1.36 E-02 1.16 E-02 Bi-214 2.18 E-04 1.85 E-04 Po-214 9.89 E-07 7.66 E-07 Po-214 1.72 E-08 1.33 E-08 Pb-210 4.17 E-05 1.43 E-05 Pb-210 6.65 E-06 2.27 E-06

  • 0ne WL conce t ation is defi ed as any combination of short-lived radio-nr n

active decay products on Rn-222 in one liter of air that will release 1.3 x 10s MeV of alpha particle energy during radioactive decay to Pb-210. B.4.3 Ingestion Doses. Ingestion doses are computed for vegetables, milk and meat (beef and lamb) on the basis of concentrations obtained using Equations B-8 and B-9, ingestion rates given in Table B.7, and dose conversion factors given in Table B.8 (Refs. 3.1, B.10). Vegetable ingestion doses were computed assuming an average 50 percent activity reduction due to focd preparation (Ref. B.5). Ingestion doses to children and teenagers were computed but found to be equivalent to or less than doses to edults. ,m m e -+q e +c y y -g--- - - -s

O ~ B-14 Table B.7 Assumed food ingestion rates,* kg/yr Infant Child Teen Adult I. Vegetables (total): 48 76 105 a) Edible above ground 17 29 40 b) Potatoes 27 42 60 c) Other below ground

3. 4 5.0 5.0 II.

Meat (beef, fresh pork, and lamb) 28 45 78 III. Milk (liters /yr) 208 208 246 130

  • All data taken from Reference B.7.

Ingestion rates are averages for typical rural farrg households. No allowance is credited for portions of year when locally or homegrown food may not be available. 9 e E i I L i

.~ . =. -. j L 1 4 Table B.8 Ingestion dose conversion factors (mrem /pCi ingested) Isotope t Age Group Organ U-238 U-234 Th-234 Th-230 Ra-226 Pb-210 B1-210 Po-210 f' Infant Whole body 3.33 E-04 3.80 E-04 2.00 E-08 1.06 E-04 1.07 E-02 2.38 E-03 3.58 E-07 7.41 E-04 Bone 4.47 E-03 '4.88 E-03 6.92 E-07 3.80 E-03 9.44 E-02 5.28 E-02 4.16 E-06 3.10 E-03 i Liver 0 0 3.77 E-08 1.90 E-04 4.76 E-05 1.42 E-02 2.68 E-05 5.93 E-03 Kidney 9.28 E-04 1.06 E-03 1.39.E-07 9.12 E-04 8.71 E-04 4.33 E-02 2.08 E-04 1.26 E-02 Child Whole body 1.94 E 2.21 E-04 9.88 E-09 9.91.E-05 9.87 E-03 2.09 E-03 1.69 E-07 3.67 E-04 Bone 3.27 E-03 3.57 E-03 3.42 E-07 3.55.E-03. 8.76 E-02 4.75 E-02 1.97 E-06 1.52 E-03 4 Liver 0 0 1.51 E-08 1.78 E-04 1.84 E-05 1;22 E-02 1.02 E-05 2.43 E-03 Kidney 5.24 E-04 5.98 E-04 8.01 E-08 8.67'E-08 4.88 E-04 3.67 E-02 1.15 E-04 7.56 E-03 Teenager Whole body 6.49 E-05 7.39 E-05 3.31 E G.00 E-05 5.00 E-03 7.01 E-04 5.66 E-08 ' 1.23 E-04 i-Bone 1.09 E-03 1.19 E-03 1.14 E-07 2.16 E-03 4.09 E-02 1.81 E-02 6.59 E-07 5 09 E-04 Liver 0 0 6.68 E-09 1.23'E-04 8.13 E-06 5.44 E-03 4.51 E-06 1.07 E-03 Kidney 2.50 E-04 2.85 E-04 3.81 E-08 5.99 E-04 2.32 E-04 1.72 E-02 5.48 E-05 3.60 E-03 s g e g E 4 3 - l 7; Z Kidney 1.75 E-04 1.99 E-04 2l67E 5$65E-E i i a t

F B-16 ~ References for Appendix B B.1 U.S. Nuclear Regulatory Commission, "MILDOS - A Computer Program for Calculating Environmental Radiation Doses from Uranium Recovery Operations," NUREG/CR-2011, April 1981. B.2 M. Momeni, et al., " Uranium Dispersion and Dosimetry (UDAD) Code," Argonne National Laboratory Report, ANL/ES-72, NUREG/CR-0553, May 1979. B.3 " Wind Distribution of Pasquill Stability Classes - Spokane, Washington, 1967-1971," National Climatic Center, Asheville, North Carolina. B.4 U.S. Nuclear Regulatory Commission, " Calculational Models for Estimating Radiation Doses to Man from Airborne Radioactive Materials Resulting from Uranium Milling Operations," Task RH 802-4, May 1979. ~ B.5 " Final Generic Environmental Impact. Statement on Uraniu'm Milling," U.S. Nuclear Regulatory Commission, NUREG-0706, September 1980. B.6 D. C. Kocher, " Nuclear Decay Data for Radionuclides Occurring in Routine Releases from Nuclear Fuel Cycic.Faqilities," Report ORNL/NUREG/TM-102, Oak Ridge National Laboratory, August 1977. B.7 J. F. Fletcher and W. L. Dotson (compilers), " HERMES - A Digital Computer Code for Estimating Regional Radiological Effects from the Nuclear Power Industry," Jianford Engineering Development Laboratory, HEDL-TME-71-168, December 1971. B.8 D. R. Kalkwarf, " Solubility Classification of Airborne Products from Uranium Ores and Tailings Piles," Report NUREG/CR-0530; PNL-2830, Pacific Northwest Laboratory, January 1979. B.9 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 (BEIR), U.S. Government Printing Office,'1972. B.10 G. R. Hoenes and J. K. Soldat, " Age-Specific Radiation Dose Conversion Factors for a One-Year Chror.ic Intake," Battelle Pacific Northwest Laboratories, U.S. Nuclear Regulatory Commission Report NUREG-0172, November 1977. i t}}

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