P.1 6

TECHNICAL BACKGROUN D SUPPLEMENT I NSUPPORT O F RULEMAKINGADJUSTMENT ACTIVITIE S FORREPORTABL E QUANTITIE S (RQ )

O F RADIONUCLIDE S

Marc h198 9

U.S . Environmenta l Protectio nAgenc y Offic e o f Radiatio nProgram s

Washington , D CP.1 7

i . r J
EXECUTIV E SUMMARY
The purpos e o f Chi s sCud ywa s Co esCimaC e the poCenCia l dose s an d risk s associate d wic henvironmenca l release s o f radionuclide s fro mcoa l an

d coa l as h pile s a c utilit yan d indusCria l facilicie s wic hcoal-fire d boilers . Suc h release s mayoccur during o r following Che deliveryo f coa l an d Che disposa l o f coa l ash . The dumping o f coa l an d ash , a s wel l a s subsequenC release s o f radionuclide s fro

mcoa l and as hpiles , coul d b e subjec c C o Che noCificatio n requirement s unde r Che Comprehensive Environmenca l Response , CompensaCion , an d LiabiliC

yAc t (CERCLA ) o f 1980 , a s amended , becaus e suc hrelease s mayequa l o r excee d the radionuclid e reportabl e quantit y(RQ) . The R Q I s a reporting trigge r fo r notifying Che Naciona l Respons e Cence r o f a releas e s o tha t the nee d fo r a respons e ca nb e evaluate d i na timel ymanner . Conservative model s wer e use d t o estimat e the potentia l radiatio ndose s an d resulting healt hrisk s t o nearb yresident s and t o worker s a s a resul t o f radionuclid e release s fro mcoa l an

d coa l as hpiles . I nparticula r fo r nearb y resident s assume d t o resid e 10 0 meter s fro mthe piles , dose s and risk s wer e .estimated vi a th

e following potentia l exposur e pathways : (1 ) direc t radiation ; (2 ) variou s pathway s o f exposur e t o particulate s release d t o the air , including inhalaCion , immersio ni na nairborn e plume , direc c radiaCio n from parciculace s deposite d o nthe ground , an d ingestio no f crop s contaminate d b y airborn e deposition ; (3 ) inhalatio no f radon ; (4 ) ingestio no f contaminate d groun d water , a s wel l a s ingestio no f crop s and livestoc k assume d C o b e contaminate d b

ythe groun

d water ; an

d (5 ) ingestio no f contaminate d surfac e water , a s well : a s ingestio no f crop s and livestoc k assume d t o b e contaminate d b ythe surfac e water . Th e result s o f thes e ris k analyse s ar e presente d i n Tabl e ES-1 . A s show ni nthe Table , the critica l exposur e pathwayt o nearb y resident s (i.e. , the on e yielding the highes t dos e and ris k estimates ) wa s foun d t o b e the inhalatio no f rado nfro mas hpiles , wit hthe lifetime ris k o f fata l cance r cause d b ythi s exposur e estimate d t o b e 1. 8 xIO" 5

. Fo r workers , radiatio n dose s an d resulting healt hrisk s wer e estimate d vi a four potentia l exposur e pathways : (1 ) direc t radiatio nwhe nstanding nex t t o (i.e. , 1 0 meter s from ) a coa l o r as hpile ; (2 ) direc t radiatio nwhe n standing o n a coa l o r as hpile ; (3 ) variou s pathway s o f exposur e t o airborn e particulaces , including inhalaCion , immersio ni na nairborn e plume , an d direc c radiaCio nfro

mparciculace s deposiCe d o nche ground ; and (4 ) inhalaCio no f radon . A s show

ni nTabl e ES-2 , Che cricica l exposur e paChwayfo r worker s wa s foun d C o b e direc c radiaCion , especiall ywhe nscanding o na coa l o r coa l as h pile . The maximu

mlifecime ris k o f faca l cance r cause d b ydirec t radiatio n. whe nstanding o nanas hpil e fo r eigh t hour s a day , five day s pe r week , 5 0 week s pe r yea r fo r 4 7 year s wa s estimate d t o b e 4. 3 x10"* ; the maximu m lifetime ris k caused b ydirec t radiatio nfro mstanding nex t t o the as hpil e during the same perio d wa s estimate d t o b e 1. 8 x10"* . Th e lifetime cance r risk s t o worker s due t o exposure s vi a the othe r pathway s wer e estimate d t o be 5 xIO" 6 o r less . The estimate d healt hrisk s t o nearb yresident s ar e wel l withi nthe genera l rang e o f healt hrisks , 10" * t o IO" 7 , routinel yconsidere d t o b e acceptabl e withi nth e Superfund program . The estimate d healt hrisk s t o worker s throug

hal l bu t the direc t radiatio npathway s ar e als o withi nthi s

il lP.1 8

• ,S accepCabl e range . Th e poCenCia l ris k fro mdirec c radiaCio nC o worker s sCanding o no r nea r a coa l as hpil e fo r eigh c hour s a da yfo r 4 7 year s i s slighcl yabove che uppe r bound o f generall yaccepte d risk s i nthe Superfun d program . I t i s clear , however , tha t suchpotentia l exposure s do no t requir e anemergencyresponse , bu t rathe r mor e appropriatel yshoul d b e evaluate d i n the contexC o f genera l worke r safecyan d regulacor

yconcrols . Furcher , i n discussion s wic hinduscr yexperc s an

d afCe r a furche r evaluacio n o f worke r praccices , i c became clea r tha t worker s generall yar e shielde d mor e full ytha n i s reflecte d i nthe mode l analyze d i nChi s reporc . Taking inC o accounC chi s addiciona l shielding , risk s woul d b e close r Co 2. 6 x10" * raChe r Chan4. 3 x 10"* . T o pu C Ches e occupaCiona l risk s inC o concexc , a lifecime ris k o f 4. 3 x 10" * correspond s Co a nannua l dos e o f 3 3 mreman d anannua l ris k o f 9. 2 xIO" 6 fo r faca l cancers . Thi s annua l ris k leve l i s lowe r ChanChe observe d annua l risk s o f job-relate d accidenta l death s fo r al l othe r industries . Fo r example , the U.S . averag e fo r al l industrie s wa s 1 1 pe r 100,00 0 o r 1. 1 x10' * i n1985 . Fo r industrie s wit hthe safes t record , wholesal e and retai l trades , the annua l accidenta l deat hrac e average d abou t 5 pe r 10,00 0 o r 5. 0 x10" ' fro m198 0 t o 1984 . Finally , whe ncomparing the yearl ydos e rat e fro ma nas hpil e t o naturall yoccurring backgroun d radiatio nlevels , the dos e t o the worke r fall s o nthe lowe r end o f the rang e o f radiatio nexposure s normall yassociate d wit h naCura l background radioactivity . Th e rang e o f reporte d exposur e race s from natura l background radiaCio nvarie s fro ma lowo f 3 5 mrem/yr C o a higho f 18 0 mrem/yr .

i vP.1 9

TABLE ES- 1 ESTIMATE

DDOSE S AN

DRISK S T

ONEARB YRESIDEN

T

Parameters * Coa l As h

• Direc t Radiatio n (a t 10 0 meters ) Dos e (mrem/yr ) Lifetime risk : 1. 7 x10" 1 4. 5 xIO" 6 6. 1 x10" 1

1. 6 xIO" 5

• Particulat e Emission s (a t 10 0 meters ) Dos e (mrem/yr) : Lifetime risk : 3. 4 xIO' 2 4. 1 xIO" 7 2. 7 xIO" 2

3. 9 xIO" 7

• Rado n Emission s (a t 10 0 meters ) Concentratio n(pCi/L) : Lifetime risk :

• Ground Water b (a t 3 0 meters ) Concentratio n(pCi/L) : Dos e (mrem/y) : Lifecime risk : 9. 0 x10" * 4. 8 xIO" 6

0. 0 0. 0 0. 0 3. 3 xIO" 3

1. 8 xIO" 5

0. 0 0. 0 0. 0

• Surfac e WaCe r (a c 60 0 meters )

- - Concentratio n(pCi/L) c : 1. 2 xIO" 3 Dos e (mrem/y) : 4. 4 xIO" 3

- - Lifetime risk : 2. 9 xIO" 8 2. 0 xIO" 1 7. 3 xIO" 1 4. 6 xIO" 6

a Risk s ar e fo r fata l cancer s base d o na 7 0 yea r lif e span . bTher e i s n o radionuclid e migratio nt o nearb ywell .

c Wate r concentration s ar e reporte d onl yfo r Ra-226 , bu t dose s and risk s reflec t al l radionuclides .

vP.2 0

TABLE ES- 2 ESTIMATE

DDOSE S AN

DRISK S T

OWORKE R

Parameters 8 Coa l As h

• Standing NexC C o Pil e (a C 1 0 meters ) Yearl ydos e (mrem) : 1. 5 1 4

- - Lifetime risk : 2. 0 xIO" 5 1. 8 x10" *

• Standing o nPil e ( 1 mete r height )

- - Yearl ydos e (mrem) : Lifetime risk :

• Particulat e Emission s (a t 1 0 meters )

- - Yearl ydos e (mrem) : Lifetime risk : 3. 3 4. 3 xIO" 5

1. 5 xIO" 2 1. 9 x10' 7 3 3

4. 3 x10" *

8. 2 xIO" 3 1. 3 xIO" 7

• Rado nEmission s (a t 1 0 meters )

- - Concentratio n(pCi/L) : 2. 6 xIO" 3 5. 7 xIO" 3

- - Lifetime risk : 2. 2 xIO" 6 5. 1 xIO" 6

" Risk s ar e fo r fata l cancer s base d o nexposure s starting a t ag e 1 8 an

d ending a t 6 5 year s o f age .

v iP.2 1

. .

TABL E O F CONTENT S Pag e 1. 0 Introductio n1 2. 0 Coa l an

d Coa l Quantitie s an d Sourc e Term s 1 2. 1 Coa l 2 2. 2 As h6 3. 0 Direc t Radiatio n 8 3. 1 Standing Nea r Coa l an d As hpile s 8 3.1. 1 Dos e t o Worke r 1 0 3.1. 2 Dos e t o Residen t 1 0 3. 2 Standing o nCoa l an d As hPile s 1 3 3.2. 1 Dos e t o Worke r 1 3 4. 0 Fugitiv e Dus t Emission s 1 3 4. 1 Radioactiv e Sourc e Term s an d Releas e Rate s 1 4 4. 2 Particulat e Dose s an d Risk s 1 5 4.2. 1 Dos e t o Worke r 1 5 4.2. 2 Dos e t o Residen t 1 6 5. 0 Rado n 1 7 5. 1 Rado nEmanatio nan d Releas e Rate s 1 7 5. 2 Rado nConcentration s an d Risk s 1 9 5.2. 1 Exposur e t o Worke r 1 9 5.2. 2 Exposur e t o Nearb yResiden t 1 9 6. 0 Ground an

d Surface-Wate r 2 0 6. 1 Ground-Wate r Mode l 2 4 6. 2 Surface-Wate r Mode l 2 4 6. 3 Radioactiv e Sourc e term2 5 6. 4 Ingestio nMode l 2 6 6. 5 Wate r Concentration s an d Dose s 2 7 7. 0 Industria l Boiler s 2 8 7. 1 Quantitie s o f Coa l an d As h2 8 7. 2 Distanc e t o Surfac e Strea m3 1 7. 3 Surface-Wate r Us e 3 1 7. 4 Direc t Radiatio n3 1 7. 5 Conclusio n3 2 Reference s 3 3 Appendi x3 8

V i lP.2 2

LIS T O F TABLE S No . Pag e 1 Coa l an

d Coa l As hPil e Characteristic s an d Sourc e Term s 3 2 Majo r Assumption s an d Parameter s 4 3 Dose s an

d Risk s t o Worke r 1 1 4 Dose s an

d Risk s t o Nearb

yResiden t 1 2 5 Qualitativ e an d Comparativ e Evaluatio n o f Utilit yan

d Industria l Boiler s 2 9

LIS T O F FIGURE S No . Pag e 1 Hypothetica l Coa l an d Coa l As hSit e 2 1 2 Coa l Pil e Configuratio n2 2 3 As hPil e Configuratio n2 3

Vll lP.2 3

1. 0 INTRODUCTIO N Th e purpos e o f thi s stud yi s t o estimat e th e potentia l dose s and risk s associate d wit henvironmenta l release s fro mcoa l an d coa l as hpile s a t utilit yan d industria l facilitie s wit hcoal-fire d boilers . Suc hrelease s ma yoccu r durin g o r followin g th e deliver y o f coa l an d th e disposa l o f coa l ash . Th e result s o f thi s study wil l b e use d t o provid e backgroun d informatio nt o conside r exemptin g coa l an d coa l as hpile s fro mth e CERCL Anotificatio n requirements . Th e dumpin g o f coa l an d ash , a s wel l a s release s fro mcoa l an d as hpiles , coul d b e subjec t t o CERCL Anotificatio n requirement s becaus e suc hrelease s ma yequa l o r excee d th e radionuclid e reportabl e quantit y(RQ) . Th e R Q i s a reportin g trigge r fo r notifyin g th e Nationa l Respons e Cente r o f a releas e s o tha t governmen t official s ca nevaluat e th e nee d fo r a response . Th e followin g exposur e scenario s ar e evaluate d i nthi s report : (1 ) Direc t radiatio nexposure , (2 ) Airborn e release s o f rado nan d fugitiv e dusts , (3 ) Pil e leachat e migratio nt o ground-water , an d (4 ) Pil e surface-wate r runof f t o a nearb ystream . Fo r direc t radiatio nan d airborn e exposures , th e potentia l dose s an d risk s ar e evaluate d fo r bot ha nonsit e worke r an d a nearby resident . Potentia l dose s an d risk s fro mexposur e t o contaminate d ground-wate r an d surface-wate r runoff , however , ar e onl yanalyze d fo r th e nearb yresident ; worker s ar e assume d drin k wate r fro m othe r source s (bottle d wate r o r fro ma communit ysuppl ysystem) . 2. 0 COA L AN D COA L AS H OUANTITIE S AN D SOURC E TERM S Th e quantitie s o f coa l hel d i nstorag e an d as hdispose d by utilit yboiler s ar e know nt o var ysignificantly . Th e actua l siz e o f suc hpile s an d thei r configuration s vary , dependin g upo n th e typ e an d siz e o f th e boile r a t th e facility . Sectio n7 addresse s th e applicabilit yo f thi s assessmen t t o industria l boilers . Th e geometr yo f eac hpil e an d th e tota l amoun t store d a t an yon e sit e als o chang e a s a functio n o f tim e sinc e materia l i s alway s bein g added , removed , an d subjecte d t o storag e o r wast e managemen t procedures . Becaus e o f thi s dynami c process , ther e is , i n fact , n o "model " pil e tha t i s trul yrepresentativ e o f a specifi c site . Furthermore , storag e an d wast e disposa l managemen t practice s var y wit heac hsite . Thes e practice s coul d incorporat e procedure s o r engineere d feature s tha t provid e greate r confinemen t o f th e coa l o r coa l ash . Thes e practices , take ntogether , ten d t o minimiz e release s an d exposures .P.2 4

I nvie wo f thes e uncertainties , severa l simplifying assumption s wer e mad e i n modelin g eac hpil e an d exposur e scenario . Withi nth e contex t o f thi s evaluation , th e concep t o f th e referenc e pil e an d exposur e model s i s employe d onl yt o evaluat e th e magnitud e o f potentia l dose s an d risks , rathe r tha nt o characteriz e industry practices . Tabl e 1 present s th e characteristic s o f th e referenc e coa l an d coa l as hpile s use d i nthi s analysis . Th e assumption s an d parameter s use d i nthi s analysi s ar e show ni nTabl e 2 . 2. 1 COAL Coa l i s typicall ystore d i nlarg e piles . Th e practic e i s t o stockpil e a 60

- t o 90-daysupply , whic hmayrepresen t a s muc ha s tw o millio nmetri c ton s (Mt ) o f coa l fo r a 1,00 0 megawat t (MW ) powe r plan t (EPR84 , EPA88 , EPA79) . Thes e larg e pile s ar e kep t inactive , wit hth e coa l maintaine d i nope nstorage , whil e th e dail yplan t requirement s (u p t o abou t 7 days ) ar e me t b yusing smalle r activ e piles . Th e amoun t o f coa l store d i nactiv e pile s i s typicall ya smal l fractio n(les s tha n1 0 percent ) o f tha t store d i ninactiv e pile s (EPR84 , EPA78) . Depending upo n environmenta l conditions , costs , climate , an d geography , th e activ e and inactiv e storag e pile s maybot hb e enclose d i n structures . Enclose d storag e i s no t considere d i nthi s analysi s sinc e an

yassociate d release s fro mthes e facilities , othe r than rado nan

d it s decayproducts , woul d b e negligible . I naddition , th e impac t from

rado nan

d rado ndaughter s a t enclose d facilitie s i s analogou s t o th e potentia l effect s estimate d fo r ope npile s becaus e rado ni s no t retaine d b yth e storag e facility . Ther e i s n o need , therefore , t o analyz e coa l storag e facilitie s separately . Coa l i s store d primaril yi ntw o basi c type s o f geometry ; con e an d rectangular . Coa l pile s ar e usuall y2 5 t o 4 5 fee t highan d ca n cove r a nare a o f up t o 7 5 acres . Othe r type s o f configuration s includ e kidne yan

d wedg e shape s (EPR84) . Fo r th e purpos e o f thi s study , i t i s assume d tha t fift ypercen t o f th e pile s ar e con e shape d an

d fift ypercen t ar e o f rectangula r configuration . Base d o nth e result s o f a 197 8 EPAstudy , i t i s als o assume d tha t th e typica l inactiv e storag e pil e contain s 95,00 0 M t o f coa l (EPA78) . Thi s quantit yi s though t t o b e representativ e o f overal l practice s o f electri c utilit ystations , cok e plants , an d industria l boilers ; an d maycharacteriz e abou t 7 0 percen t o f facilitie s wit hcoal-fire d plants . Althoug hth e demand fo r electricit yha s bee nincreasing a t 1. 7 percen t pe r yea r fo r th e las t decade , th e amoun t o f coa l store d a t an yon e sit e ha s no t necessaril yincrease d a t thi s rat e (NER87 ) . Fo r th e purpos e o f thi s study , i t i s assume d that , a s ne wfacilitie s ar e buil t an d operated , th e distributio nan d siz eTabl e 1 : Coa l an d coa l as hpil e characteristic s an d sourc e term s PARAMETERS( a ) COAL AS H o PHYSICAL/RADIOLOGICAL -Quantit y(Mt) : 9.5(E+4)(b ) 1.5(E+6 )

- Depth/Heigh t(m) : 1 1 5

- Pile/Are aRadiu s (m) : 8 027 0

- Tota l Are a (m 2 ) : 2.0(E+4 ) 2.3(E+5 )

- Direc t Radiatio n Effectiv e Radiu s (m) : 4 5 1 8

- Edg e o f Pil e t o Recepto r Distanc e (m ) Worker : 1 0 1 0 Public : 10 0 10 0

- Concentratio n(pCi/g ) U-238 : 0.4 3 4. 3 Th-232 : 0.3 5 3. 5 o SOURC E TERM S

- Particulat e Emissio n Rat e (kg/yr) : 61 0 34 0

- Radionuclid e Releas e Rat e (Ci/yr ) Radon : 2.3(E-1 ) 4.0(E+0 ) U-238 : 6.6(E-7 ) 1.7(E-6 ) Th-232 : 5.3(E-7 ) 1.4(E-6 )

- Ground/Surface-Wate r Tota l Inventory(Ci ) U-238 : 4.1(E-2 ) 6.3(E+0 ) Th-232 : 3.3(E-2 ) 5.1(E+0 ) ( a ) Se e tex t fo r details , l ) ( b ) Denote s exponentia l notation : 9.5(E+4 ) = 9. 5 x10 + 4P.2 6

Tabl e 2 : Majo r assumption s an d parameter s (a ) PARAMETER S o STANDIN GNEX T T O PIL E WORKE R RESIDEN T

- Distanc e (m) :

- Dos e Rat e (urem/h )

Coal : As h:

- Occupanc y

Hours : Fractio n(%) : Indoo r (%) : Outdoor s (%) :

- Shieldin g Facto r (%) : Fractio n(%) : 1 0 0. 9 8. 1 2,00 0 10 0 NA 10 0 7 0 5 0 10 0 3.3(E-2)( b ) 1.2(E-1 ) 8,76 6 6 7 6 7 3 3 8 0 6 7 o STANDIN GO NPIL E

- Heigh t (m ) :

- Dos e rat e (urem/h )

Coa l : As h:

- Occupanc y

Hours : Fractio n(%) : Outdoor s (% ) :

- Shieldin g Facto r (%) : Fractio n(%) : 1. 0 2, 0 2 0 2,00 0 10 0 10 0 7 0 5 0 N A NA NA N A NA NA NA NA O AIRBORN E EMISSION S Downwin d distanc e (m) : 1 0 10 0 o GROUND/SURFACE-WATE R

- Distanc e t o wel l (m) :

- Distanc e t o strea m(m )

- Strea mflo w(cu.ft/s ) NA N A N A (a ) se e tex t fo r details . ( b ) Denote s exponentia l notation : 3.3(E-2 ) 3 0 60 0 1 0

= 3. 3 x1 0 - 2P.2 7

o f coa l pile s remai nunchanged ; onl yth e tota l numbe r o f plant s an d tota l amoun t o f coa l consume d hav e increased . I f i nfact , ther e wer e a proportiona l relationshi p betwee nrising electrica l demand an

d coa l storage , the nth e assume d amoun t (95,00 0 Mt ) o f coa l woul d hav e t o b e increase d b ya facto r o f 1.18 , t o 112,00 0 Mt . Withi nth e contex t o f thi s study , thi s uncertaint yi s assume d t o b e insignificant . Th e radioactivit yconten t o f coa l i s know nt o varyove r two order s o f magnitud e (UNS82) . Th e concentratio no f uranium-23 8 (U-238 ) and thorium-23 2 (Th-232 ) i ncoa l ca nrang e from0.0 8 t o 1 4 pCi/ g and 0.0 8 t o 9 pCi/g , respectivel y(UNS82 ) . I na revie w o f 80 0 coa l sample s characterizing U-23 8 concentrations , Wagne r an d Greine r note d tha t onl y0. 5 percen t o f th e sample s excee d an activit yo f 1 0 pCi/ g (WAG82) . Bec k conducte d a nevaluatio no f nearl y1,00 0 U.S . coa l sample s an d reporte d averag e (arithmetic ) U-23 8 an

d Th-23 2 concentration s o f 0. 6 an d 0. 5 pCi/g , respectivel y(BEC80) . Th e frequencydistributio no f measure d U an d T hcontent s i ncoal , however , indicate s tha t concentration s (based o ngeometri c mean ) ar e i nfac t predominantl ylower . Fo r example , th e reporte d mea ngeometri c concentration s o f U-23 8 an d Th-23 2 ar e 0.3 4 pCi/ g an d 0.2 6 pCi/g , respectivel y(BEC80) . I nthi s analysis , th e presenc e o f uranium-23 5 (U-235 ) i ncoa l i s ignore d becaus e o f it s lowe r concentratio nwhe ncompare d t o U-238 . Becaus e o f it s shorte r half-life , U-23 5 ha s decaye d mor e rapidl ytha n U-238 . Fo r eac hpC i o f U-23 8 i ncoa l ther e i s les s tha n0.007 3 pC i o f U-235 , o r abou t les s tha n1 percen t (NCR87) . Fo r th e purpos e o f thi s analysis , th e adopte d coa l concentration s ar e thos e use d i nsuppor t o f th e preparatio no f th e 198 9 radionuclid e Nationa l Emissio nStandard s fo r Hazardou s Ai r Pollutant s (NESHAP ) (EPA89) . Thes e concentration s ar e 0.4 3 an d 0. 3 5 pCi/ g fo r U-23 8 and . Th-232 , respectively . A s ca nb e noted , th e selecte d concentration s fal l withi nth e rang e bounde d b yth e geometri c mea n(o nth e lowend ) an d arithmeti c averag e (o nth e uppe r end ) a s reporte d b yBeck . I nspit e o f th e larg e variation s note d i nradionuclid e concentrations , i t i s anticipate d tha t ove r th e operationa l lif e o f mos t boilers , thes e variation s woul d b e expecte d t o averag e ou t an d fal l withi nth e rang e characterize d b yth e arithmeti c an d geometri c means . Finally , i t i s als o very unlikel ytha t a singl e min e producin g coa l wit helevate d radioactivit ywoul d b e th e sol e supplie r t o an yparticula r facilit ythroughou t it s entir e operationa l life .P.2 8

2. 2 AS H Coa l as hi s generate d whe ncoa l i s burned . Th e amoun t o f as h produce d depend s upo n th e minera l conten t o f th e coa l an d typ e o f boiler . During th e combustio nprocess , som e o f th e ashe s ar e entraine d wit hho t flu e gase s t o for mfl yas hwhil e some , to o larg e o r heav

yt o b e entrained , settl e t o th e bottom o f th e boile r t o for

m bottomash . Fo r example , pulverize d coa l boiler s generat e mor e fl yas htha nstoke r boiler s becaus e th e combustio n proces s take s plac e i na stat e o f suspension , rathe r tha ni na be d (EPA88 , EPR88 , EEI88) . Liqui d sla g i s forme d whe nth e as h melt s unde r th e intens e hea t and drain s t o th e bottomo f th e boiler . I nconsiderin g th e tota l quantit yo f as hgenerated , th e relativ e amount s o f fl yash , bottomash , an d sla g ar e dependen t upo nth e typ e o f coa l use d an d th e configuratio no f th e boiler . I nth e aggregate , th e distributio no f fl yas hmayconstitut e abou t 7 0 t o 8 0 percen t o f th e tota l as hproduced , wit hth e balanc e comprise d o f bottomas hand solidifie d sla g materia l (EPA79) . Th e minera l conten t o f coa l varie s fro m 3 t o 3 0 percen t depending upo nth e minin g regio nfrom whic hth e coa l originate s (EPA88 , ACA86) . Utilitie s ar e als o selecting coal s wit hlowe r as hconten t t o facilitat e complianc e wit hparticulat e emissio nstandards . Coa l i s ofte nwashe d t o remov e exces s minerals . Washin g can reduc e th e minera l conten t b ya s muc ha s 5 0 t o 7 0 percent . Th e averag e as hconten t o f coa l use d i n198 5 b yelectri c utilitie s range d from5. 9 t o 29. 4 percent , wit ha nationa l averag e o f 10. 1 percent . Th e averag e as hconten t o f coa l burne d sinc e 197 5 ha s als o decrease d steadily , fro mabou t 1 4 percen t t o th e curren t valu e o f 10. 1 percen t (EPA88 , ACA86) . Th e as hconten t o f coa l i s expecte d t o remai na t abou t 1 0 percen t unti l th e en d o f th e century . Fo r thi s analysis , i t i s assume d tha t th e typica l as h conten t i s 1 0 percent . Th e majorit y(7 0 t o 8 0 percent ) o f th e coa l as hproduce d i s dispose d i n wast e facilitie s (EPA88) . Th e balanc e i s bein g use d o r recycle d i na variet yo f commercia l applications , suc ha s a cemen t substitute , structura l fill , materia l fille r o r additive , lan d management , an

d soi l conditione r (ACA86) . Ashe s ar e typicall ydispose d int o drylandfill s o r as hponds . Sluice d ashe s and flu e ga s desulfurizatio nsludge s ar e store d temporaril yi n pond s fo r dewaterin g an d ar e late r remove d an d transporte d t o a drylandfill . Eventually , mos t o f th e as hi s place d i na drylandfill . Atypica l as hdisposa l landfil l mayb e anywher e from7 5 t o 15 0 acre s i nsiz e (EEI88 , EPA88) . A n as hpil e o f thi s siz e i s presume d t o suppor t th e disposa l need s o f aP.2 9

moder npowe r plan t wit ha capacit ytha t range s fro mabou t 50 0 M

W t o 1,00 0 MW . As hi s dispose d i nlandfill s o f varyin g dimensions . Fo r example , th e siz e o f disposa l area s ca nrang e anywher e fro m 1 0 t o 6 0 acre s whil e some facilitie s us e disposa l area s a s larg e a s 20 0 acres . O n th e extreme , a sit e wa s reporte d t o hav e a landfil l facilit yo f 43 8 acre s (EPA88) . I norde r t o mee t particulat e emissio nstandards , ashe s generall yar e dispose d i n smalle r area s o r cells . Smalle r activ e disposa l area s mayus e a s muc ha s 2 0 acre s an d o nth e averag e compris e abou t 5 t o 1 0 acre s (N0V89) . Th e dept ho f th e as hbe d upo nclosur e mayb e a s thic k a s 3 0 fee t (EPA88) . Fo r th e purpos e o f estimating airborn e an d waterborn e releases , i t i s assume d tha t th e tota l are a o f th e landfil l i s 6 0 acres , wit ha n averag e dept ho f 1 5 feet . Give nth e disparit yo f informatio nabou t suc hsites , 6 0 acre s i s assume d t o b e a conservativ e estimat e and , therefore , wil l tend t o overestimat e releases . Thi s acreag e i s als o assume d t o includ e al l area s wher e as hi s bein g handle d a s par t o f th e overal l wast e managemen t activitie s (including disposal , grading , capping , etc. ) an d wher e ther e exist s th e possibilit yfo r offsit e releases . N o credi t i s take nfo r feature s o r practice s whic hwoul d tend t o reduc e suc h releases . Fo r example , some utilitie s trea t coa l pile s wit ha ta r an d wate r mixtur e t o reduc e fugitiv e dus t emissions . Similarly , durin g as hdisposa l activities , th e expose d disposa l cell s ar e periodicall ycovere d wit hsoi l cap s t o reduc e wind erosion . Th e tota l quantit yo f as hi s assume d t o b e 1. 5 millio nM t base d o na disposa l dept ho f 1 5 feet . Depending upo nth e siz e o f a powe r plan t and th e as hcontent , thi s volum e mayi n fac t represen t mor e tha non e year' s wort ho f as hgeneration . Th e radionuclid e distributio nan d concentration s i nas har e als o knownt o var ysignificantly . Fo r example , U-23 8 and Th- 2 3 2 concentration s hav e bee nnote d t o rang e fro m1. 5 t o 8. 6 pCi/ g an d 0. 4 t o 7. 5 pCi/g , respectivel y(BEC89 , BEC80) . Th e averag e concentratio no f U-23 8 an d Th-23 2 i nfl yas har e reporte d t o b e abou t 5. 4 and 1. 9 pCi/g , respectivel y(UNS82) . Th e radioactivit y o f fl yas hi s typicall yhighe r tha ncoal . Thi s enrichmen t i s dependen t upo nth e typ e o f coa l used , it s as hcontent , an d th e typ e o f boile r (UNS82) . Th e enrichmen t rati o als o varie s dependin g upo nth e elementa l for mo f th e radionuclide . Fo r example , enrichmen t ratio s o f abou t 1. 3 an d 1. 4 ar e reporte d fo r U-23 8 an

d Th-232 , respectivel y(UNS82) . Th e presenc e o f U-23 5 i n coa l as hi s no t considere d i nthi s analysi s becaus e o f th e low concentratio no f U-23 5 i nash . Fo r othe r radionuclides , muc h highe r enrichmen t ratio s hav e bee nobserved ; enrichmen t ratio s o f u p t o 2 hav e bee nobserve d fo r radium-22 6 an d a s higha s 1 1 fo r polonium-210 .P.3 0

Becaus e o f th e disparat e informatio nan d dat a regarding th e presenc e o f radionuclide s an d thei r amount s i nas hmaterials , a simplifie d approac hi s use d her e t o estimat e th e "typical " U-23 8 an d Th-23 2 concentration s o f fl yash , bottomash , an d slags . I t i s assume d tha t radionuclid e mas s balanc e i s maintaine d betwee n th e coa l tha t i s introduce d i nth e boile r an d wha t i s eventuall y recovere d i nth e as han d sla g contents . Th e smal l amoun t (les s tha n5 percent ) whic hpasse s throughparticulat e emissio ncontro l system s and become s airborn e i s ignore d i nthi s analysis . I t i s als o assume d tha t th e radioactivit ytypicall ycontaine d i n sludge s i s eventuall ytake nt o th e landfil l and combine d wit hth e ashe s and slag s fo r disposal . Finally , th e uncertaint yassociate d wit hth e mechanism s o f fl yas henrichmen t and radionuclid e concentration s i nfl yash , bottomash , and slag s i s addresse d b y assumin g tha t th e concentration s o f U-23 8 an d Th-23 2 i nth e as h i s a norde r o f magnitud e greate r tha nthei r respectiv e concentration s i ncoal . Thi s approac hyield s U-23 8 an d Th-23 2 concentration s o f 4. 3 an d 3. 5 pCi/g , respectively . Thes e value s fal l wel l withi nth e observe d rang e o f concentrations . 3. 0 DIREC T RADIATION Thi s sectio npresent s modelin g assumption s t o estimat e dose s an d risk s fromdirec t radiatio nexposure s t o a worke r near , o r standin g on , a coa l o r as hpile , and fo r a nearb yresiden t situate d jus t of f th e sit e boundary . Th e worke r i s assume d t o b e a t a distanc e o f 1 0 meter s fro meithe r pile . Similarly , th e exposur e associate d whil e standing directl yo nth e coa l o r coa l as hpil e i s estimate d assuming a nexposur e heigh t o f 1 meter . Th e dos e t o th e nearb

yresiden t i s calculate d fo r a distanc e o f 10 0 meter s fromth e fac e o f th e coa l an d as hpiles . Th e majo r assumption s an

d parameter s ar e liste d i nTable s 1 an d 2 . Thi s evaluatio nexclude s th e contributio nfromth e ambien t background exposur e rate . Th e exposur e rate s ar e expresse d i nmicro-Roentge n pe r hou r (uR/h ) an d dos e rate s ar e note d a s micro-re mpe r hou r (urem/h) . 3. 1 STANDINGNEA

RCOAL AND AS H PILE S Radiatio nexposure s fro mth e coa l pil e ar e estimate d assuming tha t th e individua l i s standing nea r th e pil e a t a distanc e o f 1 0 meter s (m) . Give nth e volum e an d physica l dimensions , th e pil e i s modele d a s a finit e slab(SCH74 , MOR73 , CEM69) . Th e effectiv e are a an d radiu s o f th e coa l pile , t o whic hth e worke r o r nearb y residen t ar e exposed , ar e assume d t o b e 6,40 0 m 2 an d 4 5 m , respectively . Thi s surfac e are a represent s a naverag e storag e configuratio nbetwee n th e rectangula r an d con e geometries . I t i s assume d tha t th e radiatio nfluxoriginate s onl yfromon e sid e o f th e four-side d rectangula r slab . Fo r th e con e configuration , th eP.3 1

flu xi s assume d t o b e du e t o hal f o f th e tota l latera l surfac e area . I neithe r case , i t i s assume d tha t ther e ar e n o obstruction s tha t woul d shiel d o r bloc k exposure s fro m th e pil e t o th e receptor . Fo r th e as hpile , th e effectiv e are a an d radius , fro

m whic hth e exposur e originates , ar e assume d t o b e 1,00 0 m 2 an d 1 8 m , respectively . Thi s are a represent s th e fronta l are a o f a nactiv e as hpile . I t i s assume d tha t th e activ e fac e o f th e landfil l i s abov e grad e and tha t ther e ar e n o obstruction s betwee nth e pil e an d th e receptor . I nestimatin g dose s an d risks , exposur e duratio ni s base d o n 2,00 0 hour s pe r yea r wit h10 0 percen t occupancy . Shielding may , however , reduc e th e exposur e an d dose . Fo r example , i f th e individua l wer e operating a vehicl e o r machinerywhil e nea r th e pile , th e exposur e coul d b e reduce d b ya facto r ranging anywher e from0.1 5 t o 0. 7 (NCR85a ) . Fo r thi s analysis , i t i s assume d tha t th e worke r spend s hal f o f hi s tim e operating a vehicl e o r machinerywhic hprovide s some shielding . Ashielding protectio n facto r o f 0. 7 i s applie d fo r 5 0 percen t o f th e tim e (i.e. , whil e operatin g equipment ) an d non e fo r th e balanc e o f th e time . I nth e aggregate , thi s mode l assume s tha t th e worke r i s expose d effectivel yt o a tota l o f 1,70 0 hour s pe r yea r (or 8 5 percen t o f th e time ) t o eithe r th e coa l o r as hpile . Radiatio n exposur e rates , fo r th e U-23 8 decaychain , ar e calculate d assumin g equilibriu mwit hit s decayproduct s (dow nt o lead-21 0 an

d a neffectiv e gamma ra yenerg

yo f 1. 6 MeV

pe r disintegratio n(NCR76) . Similarly , a neffectiv e gamma ra yenerg y o f 2. 3 Me V

i s use d fo r th e Th-23 2 decayserie s (dow nt o thallium-201 . Becaus e th e exposur e i s i npar t du e t o scattere d gamma rays , a buil d up facto r o f 2.7 2 i s applie d becaus e o f th e dept ho r thicknes s o f th e coa l o r coa l as hpiles . Typicall yabou t 9 0 percen t o f th e ambien t radiatio nexposur e rat e i s du e t o gamma ray s originatin g onl yfro mth e top 2 t o 3 fee t o f material s (NCR87) . Th e exposur e rate s fo r th e worker , a t 1 0 meters , ar e 0. 9 an d 8. 1 uR/ hfo r coa l and ash , respectively . I nassessing th e effec t o f varyin g distance s o nexposur e rates , thi s calculatio nwa s repeate d fo r tw o additiona l locations , 3 an d 2 0 meter s fro

mth e edg e o f th e pile . Thes e change s d o no t yiel d a significan t reductio no r increase , les s tha n1 5 percent , i nth e exposur e rate . Withi nth e contex t o f thi s analysis , i t i s assume d tha t thi s variatio ni s insignificant .3.1. 1 Dos e t o Worke r

Usin g th e assumption s liste d above , estimate d exposur e rates , doses , and risk s fo r coa l an d coa l as har e shownfo r th e worke r i nTabl e 3 . Th e annua l dos e assuming 10 0 percen t occupanc yi s 1. 5 an d 1 4 mrem/yr fo r coa l an d coa l ash , respectively . Th e risk s associate d wit hsuc hexposure s ar e estimate d usin g a ris k facto r o f 2. 8 x10~ 4 pe r rad fo r a nadult . Thi s individua l i s assume d t o star t workin g a t ag e 1 8 an d wor k unti l ag e 65 . Combinin g thes e factors , th e equivalen t lifetime ris k facto r fo r fata l cancer s i s 1. 3 x10~ 5 pe r mrem/yr , assuming a one-to-on e relationshi p betwee nabsorbe d dos e an d dos e equivalen t an d a facto r o f 1.1 1 a s th e averag e rati o o f tissu e t o ai r energyabsorptio n coefficients . Th e lifetime risk s du e t o direc t radiatio n exposure s ar e 2. 0 x10~ 5 fo r coa l an d 1. 8 xIO" 4 fo r coa l ash . 3.1. 2 Dos e t o Residen t Th e sam e methodologyi s applie d t o determin e dose s and fata l cance r risk s t o th e nearb yresident , however , th e distanc e an d occupanc yfactor s wer e changed . Fo r th e nearb yresident , th e recepto r poin t i s assume d t o b e locate d a t 10 0 meters . Th e occupanc yfacto r assume s tha t tw o third s o f th e individual' s tim e i s spen t o nth e property . O f th e tim e spen t o nth e property , tw o third s i s spen t indoor s an d on e thir d i s spen t outdoor s (NCR85a) . Fo r th e tim e whic hi s spen t indoors , a facto r o f 0. 8 i s applie d t o accoun t fo r th e shielding afforde d b yth e structur e (NCR85a) . I nth e aggregate , thi s mode l assume s tha t th e nearb yresiden t i s effectivel yexpose d t o a tota l o f 5,10 0 h/yr (o r 5 8 percen t o f th e time ) t o eithe r th e coa l o r as hpile . Othe r ris k assessmen t studie s hav e assume d simila r exposur e scenarios , durations , an d shielding protectio nfactor s ranging fro m5 8 t o 6 7 percen t (NRC80 , NIE87 , RAD88 , NCR85a) . Th e derive d exposur e rate s are , respectively , 0.03 3 an d 0.1 2 urem/ hfo r th e coa l an d as hpile s (se e Tabl e 2) . Th e yearl ydose s an d risk s (fo r fata l cancers ) ar e show ni nTabl e 4 fo r th e nearb y resident . Th e dos e du e t o th e coa l pil e i s estimate d t o b e 0.1 7 mrem/y r wit ha corresponding ris k o f 4. 5 xIO"" 6

. Fo r th e as h pile , th e dos e and ris k ar e estimate d t o b e 0.6 1 mrem/yr an d 1. 6 xIO" 5 , respectively . I t i s instructiv e t o plac e thes e dose s i nperspectiv e b y comparin g themt o exposure s from naturall yoccurring radioactivity . NCR P Repor t No . 9 4 summarize s surve yresult s whic hencompas s varie d geographica l location s (NCR87) .

1 0P.33 _

Tabl e 3 : Dose s an d risk s t o worker( a )

PARAMETER S ( b ) o STANDIN GNEX T T O PIL E (a t 1 0 meters ) -Yearl ydos e (mrem) : -Lifetim e risk : O STANDIN GO NPIL E (l-mete r height ) -Yearl ydos e (mrem) :

, -Lifetim e risk : o PARTICULAT E EMISSION S (a t 1 0 meters ) -Yearl ydos e (mrem) : -Lifetim e risk : o RADO NEMISSION S (a t 1 0 meters ) -Concentratio n(pCi/L ) -Lifetim e risk : COA L

1. 5 2.0(E-5)( c )

3. 3 4.3(E-5 )

1.3(E-2 ) 1.6(E-7 )

2.2(E-3 ) 1.8(E-6 ) AS H

1 4 1.8(E-4 )

3 3 4.3(E-4 )

7.3(E-3 ) l.l(E-7 )

5.2(E-3 ) 4.3(E-6 ) (a ) Se e tex t fo r technica l detail s an d assumption s fo r eac h exposur e pathway . (b ) Risk s ar e fo r fata l cancer s base d o nexposure s startin g a t ag e 1 8 an d endin g a t 6 5 year s o f age . ( c ) Denote s exponentia l notation : 2.0(E-5 ) = 2. 0 xIO" 5

.

1 1P.3 4

Tabl e 4 : Dose s an d risk s t o nearb yresident(a )

PARAMETER S ( b ) COA L AS H O DIREC T RADIATIO N (a t 10 0 meters )

- Dos e (mrem/yr) : 1.7(E-1)(« ) 6.1(E-1 )

- Lifetim e risk : 4.5(E-6 ) 1.6(E-5 ) o PARTICULAT E EMISSION S (a t 10 0 meters ) -Dos e (mrem/yr) : 2.7(E-2 ) 2.2(E-2 ) -Lifetim e risk : 3.4(E-7 ) 3.4(E-7 ) O RADO NEMISSION S (a t 10 0 meters ) -Concentratio n(pCi/L) : 7.0(E-4 ) 2.8(E-3 ) -Lifetim e risk : 3.9(E-6 ) 1.6(E-5 ) o GROUND-WATE R( c ) (a t 3 0 meters ) -Concentratio n(pCi/L) : 0. 0 0. 0 -Dos e (mrem/yr) : 0. 0 0. 0 -Lifetim e risk : 0. 0 0. 0 o SURFACE-WATE R (a t 60 0 meters ) -Concentratio n(pCi/L ) (<* ) : 1.2(E-3 ) 2.0(E-1 ) -Dos e (mrem/yr) : 4.4(E-3 ) 7.3(E-1 ) -Lifetim e risk : 2.9(E-8 ) 4.6(E-6 ) (a ) se e tex t fo r technica l detail s fo r eac hexposur e pathway . (b ) Risk s ar e fo r fata l cancer s base d o na 7 0 yea r lif e span . ( c ) Ther e i s n o radionuclid e migratio nt o nearb ywell , se e text . ( d ) Wate r concentration s ar e reporte d onl yfo r Ra-226 , bu t dose s an d risk s reflec t al l radionuclides . ( e ) Denote s exponentia l notation : 1.7(E-1 ) = 1. 7 x10" 1 = 0.17 .

1 2P.3 5

Th e rang e o f reporte d exposur e rate s associate d wit hnatura l background radiatio n varyfro m3 5 t o 18 0 mrem/yr . A s ca nb e noted , th e incrementa l dos e t o th e worke r i s stil l belo wthe lowe r rang e o f radiatio nexposure s normall yassociate d wit h natura l background radioactivity . B ycomparison , th e dos e t o th e nearb yresiden t i s insignificant . 3. 2 STANDINGONCOAL AND COAL AS H PILE S Radiatio ndose s attribute d t o standing o na coa l o r coa l as hpil e ar e modele d a s a ninfinit e slabsource . Radiatio nexposur e rate s a t on e mete r abov e th e surfac e ar e calculate d assuming tha t Uan d Thdecaychain s ar e i nequilibriu mwit hthei r decayproducts . Th e exposur e rate s ar e base d o nconversio nfactor s o f 1. 8 an d 2. 8 uR/ hpe r pCi/ g fo r Uan d Th , respectively . Thes e conversio n factor s represen t actua l environmenta l exposur e rate s o f typica l soils , including gamma ra yscatter , buildup , and sel f absorptio n (NCR76) . 3.2. 1 Dos e t o Worke r Usin g th e assumption s note d earlier , th e exposur e rates , doses , and risk s ar e estimate d fo r a worke r standing o na coa l o r as h pil e (se e Tabl e 2 ) . Th e tota l yearl ydos e assuming 10 0 percen t occupanc yi s estimate d t o b e 3. 3 and 3 3 mrem/y r fo r coa l an d coa l ash , respectivel y(se e Tabl e 3 ) . Th e lifetime risk s fo r fata l cancer s du e t o suc hdirec t radiatio nexposure s ar e estimate d t o b e 4. 3 x10~ 5 fo r coa l an d 4. 3 x10~ 4 fo r coa l ash . A s state d earlier , onl yth e incrementa l exposur e du e t o coa l as happroache s th e lowe r rang e o f radiatio nexposur e rate s normall yassociate d wit hnatura l background radioactivity . (Se e Appendi

xfo r additional informatio

nreflectin

g industr

ypractices. ) Whe nthes e ris k estimate s ar e pu t i nperspectiv e wit hothe r occupationa l hazards , the yar e comparabl e t o th e observe d ris k o f jo brelate d accidenta l death s fo r al l industries . Fo r example , th e Unite d State s averag e fo r al l industrie s wa s 1 1 pe r 100,00 0 o r 1. 1 x10~ 4 i n198 4 an d 198 5 (EPA87a) . Fo r industrie s wit hth e safes t record , wholesal e an d retai l trades , th e annua l accidenta l deat hrat e average d abou t 5 pe r 100,00 0 o r 5. 0 x10~ 5 from198 0 t o 1984 . Fo r th e worke r standing o nth e as hpil e fo r on e yea r an d receivin g a dos e o f 3 3 mrem , th e ris k o f fata l cancer s i s abou t 9. 2 x10~ 6

. Thi s ris k i s i nfac t a nincrementa l ris k abov e th e jo brelate d accidenta l deat hrat e fo r thi s secto r o f th e industry . 4. 0 FUGITIVE DUS T EMISSION S Airborn e fugitiv e dus t emission s ca nresul t i ndownwind exposure s t o a worke r locate d onsit e an d t o th e genera l public .

1 3P.3 6

Th e exposur e pathway s o f concer nar e inhalatio no f airborn e particulate s and direc t radiatio nfrom plum e deposition . I n addition , ingestio no f crop s an d vegetable s contaminate d fro m plum e deposite d radioactivit yi s als o addresse d a s anothe r potentia l exposur e pathway . I t shoul d b e note d tha t th e particulat e releas e rate s d o no t tak e credi t fo r th e applicatio no f dus t emissio ncontrols . Fo r example , dus t contro l measure s whic hinclud e th e placemen t o f to p soi l covers , applicatio no f wate r and chemica l mixture s o n expose d areas , and minimizin g th e activ e portio no f th e disposa l are a woul d tend t o reduc e suc hfugitiv e emissions . 4. 1 RADIOACTIVE SOURC E TERM S AND RELEAS E RATE S Th e •particulat e emissio nrate s presente d i nTabl e 1 wer e estimate d usin g EP Aand NR C model s fo r resuspende d particulate s whic har e typicall yles s tha n10 0 micro-mete r (um ) (EPA89 , NRC80) . Large r particle s whic hmayb e transporte d b ysurfac e cree p and saltatio nprocesse s d o no t contribut e t o airborn e resuspensio n (HIN82 , NRC80) . Thes e processe s involv e larg e particl e size s whic har e no t resuspende d o r respirable . Surfac e cree p involve s particle s (50 0 t o 1,00 0 umi nsize ) tha t ar e rolle d along th e surfac e and collid e wit hothe r particles . Saltatio ninvolve s particle s (ranging from 10 0 t o 50 0 um ) whic h lurc hint o th e ai r withi na fewcentimeter s o f th e surfac e an d ar e rapidl ybrough t bac k downb ygravity . Fo r thi s analysis , i t i s als o assume d tha t smalle r size d particle s hav e elevate d specifi c activitie s du e t o highe r surfac e area-to-volum e ratio s (KAL85 , NRC80) . An activit yenrichmen t facto r (rati o o f airborn e particulat e t o nonresuspendabl e material ) o f 2. 5 i s applie d t o al l dus t emissions . Th e dus t releas e rate s depend upo neac hpile' s expose d surfac e area . Fo r th e coa l pile , th e surfac e are a i s assume d t o b e 24,00 0 m 2

. Th e emissio nrat e fo r coa l dus t i s derive d fromdat a presente d i na 197 8 stud ywhic hmeasure d downwind dus t emissio n rate s nea r a 110,000-M t coa l pil e (EPA78 ) . Th e stud yreveale d tha t fo r particle s withi nth e respirabl e rang e (les s tha n7 um) , th e emissio nrat e wa s 70 6 kg/yr . Assuming a proportiona l relationshi p fo r a 95,000-M t coa l pile , th e revise d yearl y emissio nrat e i s 61 0 kg . Th e resulting U-23 8 and Th-23 2 yearl y emissio nrate s ar e 6. 6 xIO" 7 and 5. 3 xIO" 7 Ci/yr , respectively . Fo r eac hdecaychain , i t i s assume d tha t th e following decay product s ar e i nequilibriu mwit hthei r respectiv e paren t radionuclides : U-234 , Th-230 , Ra-226 , lead-21 0 (Pb-210) , polonium-21 0 (Po-210) , Ra-228 , Th-228 , Ra-224 , Pb-212 , an d bismuth-21 2 (Bi-212) .

1 4P.3 7

A s wa s note d earlier , th e as hpil e i s muc hlarge r tha n th e coa l pile ; i t i s assume d t o hav e a nexpose d are a o f 6 0 acre s o r 230.00 0 m 2

. Th e dus t emissio nrate s reflec t erosio ndu e t o win d an d vehicula r traffic . Th e tota l estimate d as hparticulat e emissio nrat e i s 34 0 kg/yr . Th e estimate d fugitiv e emissio nrate s an d sourc e term s ar e show ni nTabl e 1 . Becaus e thi s particulat e emissio nrat e characterize s tota l wind blown material , th e amoun t whic hi s respirabl e i s i nfac t les s tha nth e amoun t showni n Tabl e 1 . I t i s estimate d tha t th e respirabl e fractio ni s abou t 1 5 percen t o f th e tota l emissio nrat e (TEK79 , ACA86) . Th e resulting U-23 8 and Th-23 2 yearl yemissio nrate s ar e 1. 7 x10~ 6 and 1. 4 x 10~ 6 Ci/yr , respectively . 4. 2 PARTICULAT E DOSE S AND RISK S Atmospheri c dispersio nt o downwind location s i s determine d using th e AIRDOS-EP Amodel . Th e model , a s revised , i s describe d elsewher e (EPA79 , PAR89) . Radionuclid e concentration s ar e estimate d fo r downwind location s o f 1 0 and 10 0 meter s fromth e edg e o f eac hpile . 4.2. 1 Dos e t o Worke r I nevaluatin g th e dos e an d ris k t o th e hypothetica l worker , i t i s assume d tha t th e worke r i s locate d 1 0 meter s fromth e edg e o f eithe r pil e an

d i s subjecte d t o th e following exposur e pathways : inhalation , immersion , and ground deposition . Th e result s reflec t occupationa l exposure s associate d wit h2,00 0 wor k hour s pe r year . N o othe r modifyin g factor s (e.g. , shielding , filtration , o r additiona l dilution ) ar e applie d t o th e estimate d concentration s o r associate d doses . Th e associate d downwind dose s an d risk s (fo r fata l cancers ) ar e showni nTabl e 3 . Th e dos e an d lifetime ris k t o th e hypothetica l worke r ar e 7. 3 x10" 3 mrem/yr an d 1. 1 xIO" 7 , respectively , fo r coa l as hemissions . Th e corresponding dos e an d ris k fo r th e coa l dus t emission s ar e 1. 3 x10~ 2 mrem/yr an d 1. 6 x10~ 7 , respectively . I t i s interestin g t o not e tha t th e dos e attributabl e t o coa l dust s i s highe r (jus t unde r a facto r o f 2 ) tha ntha t o f fl yas h emissions . A s wa s note d earlier , th e radionuclid e concentration s fo r coa l dust s wer e a facto r o f 1 0 lowe r tha nthos e fo r coa l ash . Accordingly , lowe r radionuclid e concentration s woul d ten d t o decreas e th e dose . Th e coa l dus t emissio nrat e is , however , highe r tha nth e on e derive d fo r th e as hpile . Fo r th e sak e o f comparison , th e respectiv e emissio nrate s (inunit s o f g/cm 2 -s ) ar e a s follows : coa l dust , 8. 1 x10" 1 1 ; coa l as hdu e t o wind

1 5P.3 8

erosion , 4. 3 x10~ 1 3 ; an d coa l as hdu e t o vehicula r traffic , 1. 8 xIO" 12

. Finally , th e atmospheri c dispersio nfactor s ar e als o slightl ydifferen t betwee nth e coa l an d as hpile s becaus e th e are a o f th e as hpil e i s greate r tha ntha t o f th e coa l pile . 4.2. 2 Dos e t o Residen t Fo r th e membe r o f th e genera l public , th e dos e an d ris k ar e estimate d fo r a locatio nnea r th e sit e boundary . I t i s assume d tha t th e residen t i s expose d t o al l possibl e pathways , including thos e describe d fo r th e worke r wit hth e additio no f ingestio n o f locall ygrownvegetable s an d crop s tha t hav e becom e contaminate d fromplum e deposite d radioactivity . I t i s assume d tha t onl ya narro wstri p o f lan d an d servic e road separat e th e edg e o f eithe r pil e t o th e propert yfenc e an d tha t a narro wbuffe r zon e exist s beyond th e fenc e lin e an d th e neares t residence . Give nthi s configuration , th e hypothetica l residen t i s place d a t abou t 10 0 meter s from th e edg e o f eac hpile . I t shoul d b e note d tha t th e selectio no f th e 10 0 mete r distanc e i s no t withou t basis . Base d o nth e result s o f a revie wo f U.S . Geologica l Surve ymap s fo r 9 9 utilit ysite s locate d i n3 3 States , i t wa s note d that , a t th e 94t hpercentile , occupiabl e structure s wer e locate d a t distance s greate r tha n10 0 meter s (EPA88 , ICF89) . A t th e 50t hpercentile , th e neares t structure s wer e note d a t distance s greate r tha n35 0 meters . Th e majorit y(6 0 percent ) o f thi s informatio n i s base d o nmap s tha t ar e les s tha n1 0 year s old . Fo r th e remaining maps , 3 6 percen t o f th e dat a wer e obtaine d fro mmap s datin g fro

mI96 0 t o 1978 . Th e balance , o r 4 percent , o f th e map s ar e a t leas t 2 8 year s old . I norde r t o supplemen t thi s informatio nwit hmor e recen t data , th e EPA' s Pollutio nAssessmen t Branc h(Offic e o f Ai r Qualit y Plannin g and Standards ) wa s contacted . Th e Pollutio nAssessmen t Branc hnote d tha t i t i s no t uncommo nfo r residentia l o r commercia l structure s t o b e locate d withi n10 0 t o 20 0 meter s fro m utilit ysite s (PET89 , STE89) . Arevie wo f Tabl e 4 indicate s tha t th e dos e t o th e nearb y residen t fromas hemission s i s estimate d t o b e 2. 2 x10~ 2 mrem/yr an d th e lifetime ris k fo r fata l cancer s i s estimate d t o b e abou t 3. 4 xIO" 7

. Th e correspondin g dos e an d ris k fromcoa l dus t emission s ar e 2. 7 x10~ 2 mrem/y r an d 3. 4 x10~ 7 , respectively . Th e earlie r discussio nan d compariso naddressin g th e difference s betwee ncoa l an

d coa l as hsourc e term s an d dose s ar e als o vali d here .

1 65. 0 RADON

Rado nemanatio n ca nresul t i ndownwind exposure s t o worker s an d member s o f th e genera l public . Th e worke r i s assume d t o b e onsit e a t abou t 1 0 meter s fro meithe r pile . Member s o f th e genera l publi c ar e assume d t o b e locate d a t 10 0 meter s fromth e edg e o f eac hpile . Rado ni s release d onl yfromth e expose d area s o f th e pile s and n o credi t i s take nfo r feature s o r measure s whic hmay reduc e th e emanatio nrates . Fo r example , coa l as hmayb e dispose d o f i na dewatere d form . Th e presenc e o f residua l wate r may significantl yreduc e rado nemanatio nrates . Furthermore , whe n coa l as hi s dispose d i nlandfills , eac hdisposa l cel l i s eventuall ycappe d wit ha soi l cover . Suc hmeasure s als o reduc e rado nreleas e rates . 5. 1 RADONEMANATIONAND RELEAS E RATE S Th e estimate d radon-22 2 (Rn-222 ) emanatio nrate s ar e base d o n th e relationshi p o f Ra-22 6 concentration s i nsoil s (pCi/g ) t o th e area l exhalatio nrate s (pCi/m 2 -s) . Give nth e varie d natur e o f coa l and coa l ash , some simplifying assumption s hav e bee n made . Th e assume d Ra-22 6 concentrations , releas e rate s an d expose d pil e area s ar e liste d i nTable s 1 an d 2 fo r bot hcoa l an d as hpiles . Severa l importan t factor s gover nth e exhalatio nrat e o f radon , including minera l form , materia l densit yan d porosity , particl e siz e distribution , an d moistur e content . Changing meteorologica l conditions , suc ha s atmospheri c pressure , surfac e wind velocity , and difference s betwee nsoi l and ai r temperatures , ar e knownt o hav e pronounce d effect s o nrado nemanatio nrate s (NCR85 , NCR87) . I nthi s analysis , th e rado nsourc e term s ar e estimate d usin g a relationshi p (soi l concentratio nt o exhalatio nrate ) whic h reflect s empirica l data . Fo r example , th e NCR P note s tha t fo r typica l soils , a naverag e rado nemanatio nrat e i s abou t 0. 5 pCi/m 2

- s pe r pCi/ g (NCR85) . Th e U.S . Nuclea r Regulatory Commissio ncite s rado n emanatio nrate s fo r tailing s an d soil s wit hvaryin g moistur e content s base d o nwor k conducte d b yTanne r and Schiage r (NRC80) . Th e reporte d rate s fo r wet , moist , and dry material s ar e 0.35 , 0.65 , an d 1. 2 pCi/m 2

- s pe r pCi/g , respectively . Schiage r suggests , fo r drytailings , a rado n emanatio nrat e o f 1. 6 pCi/m^- s pe r pCi/ g (SCH74) . Thi s conversio n facto r assume s a ninfinitel ythic k an d drytailing s bed . Typically , abou t 9 0 percen t o f th e rado nsourc e termoriginate s fro mth e firs t 7 fee t o f material . Th e emanatio nrate s fro mcoa l i s believe d t o b e withi nth e rang e o f rate s typicall yobserve d i nsoils . Beck , however , note s tha t fo r som e type s o f coals , th e emanatio nrat e coul d b e highe r tha n

1 7P.4 0

tha t o f soi l (BEC89 ) . Fo r example , bituminou s coa l wa s reporte d t o b e abou t 1. 3 time s highe r an d lignit e coa l wa s nearl y3 time s higher . Fo r thi s analysis , th e coa l rado nexhalatio nrat e i s assume d t o b e 0. 7 pCi/m 2

- s pe r pCi/g , a rat e typicall yreporte d fo r soils . Thi s averag e rat e i s base d o nth e thre e value s give n above , excludin g th e rat e fo r drytailings . Thi s rat e i s slightl y highe r (facto r o f 1.4 ) thanth e previousl ynote d valu e fo r averag e soils . Give ntha t coa l as hdisposa l facilitie s mayinclud e suc hfeature s a s settling pond s o r wate r saturate d areas , th e rado nexhalatio n rat e mayi nfac t b e muc hlower . I naddition , coa l as hi s generall ybelieve d t o hav e a lowe r exhalatio nrat e tha nsoil s sinc e th e as hi s vitrified . Rado ni s though t t o b e generate d an d t o decaywithi nth e particl e i nwhic hRa-22 6 i s trapped . Bec k report s tha t fl yas htypicall yha s a lowe r exhalatio nrat e tha n tha t o f soil . Fo r example , i t i s note d tha t th e rati o o f th e productio nrat e t o tha t o f th e emanatio n rat e i s abou t 1 5 percen t fo r soi l and abou t 2 percen t fo r fl yan d botto mas h(BEC89 ) . I t i s als o note d tha t weathering mayincreas e th e exhalatio nrate . I f th e as hparticle s wer e subjecte d t o weathering , conceivabl y th e rado nexhalatio nrat e coul d increas e ove r tim e and reac h level s tha t ma yb e typica l t o thos e observe d fromnatura l soils . Kalkwar f report s emanatio ncoefficient s ranging fro m0. 7 t o 9. 8 percen t fo r 3 set s o f as hsample s (1 5 measurements ) an d 1. 8 percen t fo r a n as hsampl e fromth e U.S . Nationa l Burea u o f Standard s (KAL85) . Th e result s revea l tha t smalle r particle s releas e rado na t a greate r rat e tha nlarge r ones . Fo r example , th e emanatio ncoefficien t fo r particle s les s tha n0. 5 micro-mete r (um ) wa s abou t tw o time s highe r tha ntha t o f particle s withi nth e rang e o f 11-1 5 um . I f th e 11-1 5 u mparticl e siz e wer e use d a s th e cu t of f poin t fo r characterizing rado nemanatio nrate s betwee n larg e an

d smal l particles , th e rado nemanatio n coefficien t mayb e assume d t o b e abou t 3 percen t fo r particle s greate r tha ni l u m and 4. 3 percen t fo r particle s les s tha n1 1 um . Ratioin g thes e value s t o th e soi l rado nemanatio ncoefficien t rat e o f 1 5 percen t an d soi l exhalatio nrat e o f 0. 5 pCi/m 2 -s , a nexhalatio nrat e o f 0.1 3 pCi/m 2

- s pe r pCi/ g i s derive d fo r coa l ash . Thi s exhalatio n rat e i s weighte d t o reflec t th e partitionin g facto r betwee nfl y as h(8 0 percent ) and bottomas han d sla g material s (2 0 percent ) (EPA79 ) . Th e yearl yrado nreleas e rat e i s calculate d using th e U-23 8 concentratio n assuming secula r equilibriu mwit hRa-226 , surfac e are a o f eac hpile , an d th e derive d rado nexhalatio nrate s o f 0. 7 an d 0.1 3 pCi/m 2

- s pe r pCi/ g fo r coa l an d ash , respectively . Th e estimate d rado nreleas e rate s ar e 0.2 3 Ci/yr an d 4. 0 Ci/yr , respectively , fo r coa l an d as hpiles . Radon-22 0 (Rn-220 )

1 8P.4 1

emission s fromth e Th-23 2 decaychai nar e ignore d becaus e th e dos e associate d wit hthi s nobl e ga s i s on e orde r o f magnitud e les s tha nth e dos e du e t o Rn-22 2 (PAR89) . 5. 2 RADONCONCENTRATION S AND RISK S Atmospheri c dispersio nt o downwind location s wer e determine d using th e AIRDOS-EP Amodel . Th e model , a s revised , i s describe d elsewher e (EPA79) . Th e downwind rado nconcentration s ar e estimate d fo r tw o distance s fro mth e edg e o f th e coa l an d as h piles . Thes e distance s ar e 1 0 meter s fo r th e worke r an d 10 0 meter s fo r th e nearb yresident . Fo r th e worker , th e result s reflec t exposure s associate d wit h2,00 0 wor k hour s pe r year . Fo r th e genera l public , th e risk s ar e base d o n10 0 percen t occupanc y (8,76 6 hour s pe r year ) an d 70-yea r lif e span . 5.2. 1 Exposur e t o Worke r Th e associate d downwind concentration s an d risk s estimate d fo r th e worke r ar e showni nTabl e 3 . Fo r th e coa l as hpile , th e rado n concentratio ni s estimate d t o b e 5. 2 x10" 3 pCi/ L wit han associate d lifetime ris k (fo r fata l cancers ) o f 4. 3 xIO" 6

. Th e correspondin g rado n concentratio nfo r th e coa l pil e i s estimate d t o b e 2. 2 x10" 3 pCi/ L wit ha nestimate d ris k o f 1. 8 xIO" 6

. A s i nth e previou s analysi s fo r particulat e emissions , n o othe r modifyin g factor s wer e applie d t o thes e results . 5.2. 2 Exposur e t o Nearb yResiden t Fo r th e genera l public , th e downwind rado nconcentration s an d risk s ar e estimate d fo r a locatio njus t outsid e th e sit e boundary . I t i s assume d tha t onl ya narro wstri p o f lan d an d servic e roa d separat e th e edg e o f eithe r pil e t o th e propert y fenc e an

d tha t a narro wbuffe r zon e exist s beyond th e fenc e lin e an d th e residence . Give nthi s configuration , th e hypothetica l residen t i s place d a t abou t 10 0 meter s from th e edg e o f eac h pile . Fo r th e as hpile , th e rado nconcentratio ni s estimate d t o b e 2. 8 x10" 3 pCi/ L an d th e associate d lifetime ris k (fo r fata l cancers ) i s 1. 6 x10~ 5 (se e Tabl e 4) . Th e corresponding rado n concentratio nan

d ris k fo r th e coa l pil e ar e estimate d t o b e 7. 0 xIO" 4 pCi/ L an d 3. 9 xIO" 6 , respectively . I t i s interesting t o not e tha t th e rado nconcentratio nfo r the coa l pil e i s somewha t lowe r ( 4 times ) whe ncompare d t o tha t o f th e fl yash . A s wa s note d earlier , th e radionuclid e concentration s fo r coa l wer e assume d t o b e 1 0 time s lowe r than thos e fo r coa l ash . Accordingly , lowe r radionuclid e

1 9P.4 2

concentration s woul d tend t o decreas e th e sourc e term . O n th e othe r hand , th e rado nemanatio nrat e i s highe r fo r coa l whe n compare d t o coa l ash , b ya facto r o f abou t 5 . Finally , th e atmospheri c dispersio nan d dilutio n factor s ar e als o slightl y differen t betwee n th e coa l and as hpile s becaus e th e surfac e are a o f th e as hpil e i s greate r tha ntha t o f th e coa l pile . 6. 0 GROUND AND SURFACE-WATE R Th e ingestio nexposur e pathway s evaluate d i nthi s repor t includ e th e consumptio no f contaminate d ground an d surface-wate r an d foodstuffs , suc ha s vegetables , milk , an d meat . Th e mechanism s whereb yfoodstuff s maybecom e contaminate d includ e th e us e o f contaminate d irrigatio nwater , watering livestocks , an d growing crops . Th e ingestio ndose s ar e estimate d using th e Environmenta l Protectio n Agenc yPRESTO-EPA-CP Gmodel . Th e risk s fo r fata l cancer s ar e base d o n a lifetime exposur e o f 7 0 years . Th e PREST O model , a s revised , i s describe d elsewher e (EPA87) . Give nth e differen t type s o f facilitie s and varyin g sit e characteristics , th e developmen t o f a typica l o r mode l coal-fire d plan t i s beyond th e scop e o f thi s evaluation . Becaus e suc h facilitie s ar e locate d i nsevera l differen t geographica l area s wit hdifferen t geochemica l an d geohydrologica l characteristics , i t i s no t uncommo nfo r man ymode l parameter s t o varyb ysevera l order s o f magnitud e (FRE79 , NCR85 , NRC83 , HEA84 , EPR84) . Fo r example , ground-wate r velocity , surfac e strea mflowrate , an

d hydrauli c conductivit yca nvaryove r si xorder s o f magnitude . Wit hthes e consideration s i nmind , th e ground an d surface-wate r mode l parameter s wer e selecte d t o represen t conservativ e conditions . Th e ground and surface-wate r mode l take s int o accoun t suc h parameter s a s th e aquifer' s bul k density , effectiv e porosity , thickness , por e wate r velocity , dispersivities , radionuclid e distributio ncoefficient , etc . Se e th e PREST O Cod e fo r mor e detail s o n th e require d mode l inpu t (EPA87) . Th e selectio no f thes e parameter s reflec t th e dat a provide d i nth e PREST O mode l and conservativ e assumption s fo r a humi d site . Conceptually , th e ground and surface-wate r model s ar e illustrate d i nFigure s 1 , 2 , and 3 .

2 0P.4 3

Figur e 1

. Hypothetica l coa l an d coa l as h sit e

2 1P.4 4

HUMI D PERMEABL E SIT E - GROUNDWATE R PATHWA Y

R = 1.11m/y r

150 m

_____ _ 30 m

—•< %

,-l.t.m/y r

HUMI D IMPERMEABL E SIT E - SURFAC E WATE R PATHWA Y

R = 1.11m/y r

150 m / 600 m 0.6 4 m/y r

Figur e 2

. Coa l pil e configuratio n

2 2P.4 5

HUMI D PERMEABL E SIT E - GROUNDWATE R PATHWA Y

R = 1.11m/y r

- - r 500 m / E

• \

• • •30 m



## „ -^._fl

_

-

HUMI D IMPERMEABL E SIT E - SURFAC E WATE R PATHWA Y

I R = 1.1 1 m/y r

500 m 600 m

•0.3 5 m/y r

0.00 1 m/y r 

# Hy

Figur e 3 . As h pil e configuratio n

2 3P.4 6

6. 1 GROUND-WATE RMODE L Th e analysi s i s modele d fo r tw o cases : on e fo r th e coa l pil e an d th e othe r fo r th e as hpile . Th e mode l assume s tha t ground-wate r contaminatio noccur s whe nU-23 8 an d Th-232 , and thei r deca y products , infiltrat e a naquifer . Eac hpil e i s modele d a s a volume sourc e ove r a naquife r o f constan t dept h(se e Table s 1 and 2 an d Figure s 2 an

d 3) . Ground wate r i s the n withdrawnfro ma down-gradien t wel l locate d nea r eac hpile . Al l o f th e wate r need s ar e supplie d fro

mthi s well , including domesti c supplies , crop and pastur e irrigation , an d waterin g o f livestock . Th e ground-wate r mode l assume s tha t th e unsaturate d zon e i s permeabl e an

d i s subjecte d t o a highrainfal l rate , 1. 1 m/yr . Th e wel l i s assume d t o b e locate d 3 0 mfro mth e edg e o f th e pile . Th e wate r tabl e i s assume d t o b e locate d 1 mbelo wth e bottomo f eithe r pil e and th e aquife r thicknes s i s assume d t o b e 2 0 m . Th e ground-wate r velocit yi s assume d t o b e 2. 0 m/y r an d th e permeabilit yo f th e unsaturate d zon e belo wth e pile s i s assume d t o b e 1 0 m/yr . ^ 6. 2 SURFACE-WATE RMODE L I nmodelin g th e surface-wate r scenario , conservativ e assumption s ar e use d t o estimat e drinking wate r concentrations . Th e surface-wate r mode l assume s tha t th e sit e i s locate d i na humi d are a wit himpermeabl e soil s t o maximiz e surfac e runoff . Th e surface-wate r runof f fro mth e surrounding are a i s assume d t o drai nint o th e creek . Th e coa l storag e an d as hdisposa l site s ar e locate d nea r th e creek . Th e powe r plan t an d facilit ywate r needs , however , ar e assume d t o b e me t fro ma rive r an

d no t fromth e creek . Th e leachate s frombot hpile s ar e assume d t o flow down-gradien t an

d int o th e nearb

ycree k (se e Figure s 1 , 2 , an d 3 ) . Afarme r i s assume d t o dra wal l o f hi s wate r need s fro mth e cree k fo r drinkin g an d irrigatio npurposes . Th e cree k i s assume d t o b e als o use d t o wate r livestocks . N o ground o r wel l wate r i s available . Th e mode l assume s tha t th e cree k i s locate d 60 0 meter s awayand tha t 3 0 percen t o f th e rainfal l become s surface-wate r runoff . Th e selectio n o f th e creek' s flowrat e wa s base d o na revie wo f rive r an

d streamflowrate s whic har e characteristi c o f utilit y coal-fire d plants . Th e sourc e o f th e dat a i s a nEPAstud ywhic h identifie s condition s an d parameter s neede d t o asses s th e potentia l huma n healt han d th e environmenta l effect s fromcoa l combustio nwastes . Th e repor t compile s flowrate s fo r 10 0 randoml yselecte d coa l powe r plan t site s locate d i n3 3 State s (EPA88) . Th e reporte d flowrate s wer e show nt o vary significantly ; i nsome cases , flowrate s var yove r si xorder s o f

2 4P.4 7

magnitude . Th e overal l averag e flowrat e i s abou t 18,00 0 ft 3 /s . Si xsite s reporte d flowrate s lowe r tha n1 0 ft 3 /s . I nthi s analysis , a flowrat e 1 0 ft 3 / s i s use d a s a cut-of f poin t t o mode l a conservativ e scenario . I t shoul d b e note d tha t i f th e averag e flowrat e o f 18,00 0 ft 3 / s wer e use d instead , a highe r degre e o f dilutio nwoul d b e obtained , consequentl yresulting i nlowe r surface-wate r concentration s an d doses . 6. 3 RADIOACTIVE SOURC E TER M Th e tota l radionuclid e inventoryo f eac hpil e i s derive d b y multiplyin g th e U-23 8 an d Th-23 2 concentration s b yth e respectiv e quantit yo f material s i neac hpil e (se e Tabl e 1 ) . Th e coa l pil e radionuclid e inventoryi s 0.04 1 C i fo r U-23 8 an d 0.03 3 C i fo r Th-232 . Th e radionuclid e inventoryfo r th e as hpil e i s 6. 3 C i an d 5. 1 Ci , respectively , fo r U-23 8 an d Th-232 . Th e radioactiv e sourc e termi s derive d usin g th e distributio n coefficien t (Kd ; expresse d i nmillilite r pe r gram , mL/g ) an d effectiv e porosit yt o determin e th e amoun t o f radioactivit y assume d t o b e availabl e fo r movemen t ou t o f th e coa l an d as h piles . Th e distributio n coefficien t (Kd ) i s als o use d t o mode l th e movemen t and retardatio no f U-23 8 and Th-23 2 i nth e aquife r an d surfac e runoff . A s wit hothe r ground-wate r parameters , th e K d value s ar e als o knownt o varywidely . Uraniu mand Thoriu

mar e ubiquitou s i nsoils . Th e adsorptio no f U-23 8 an d Th-23 2 an

d thei r decayproduct s i nsoil s and sediment s i s a reversibl e process . Th e rang e o f K

d value s i s als o dependen t o nth e ion-exchang e capacit yo f th e soi l a s wel l a s soi l materials . Fo r example , radiu mbehave s lik e Sr2 + an d Ba2 + (NCR85 , EPR84 ) . Th e Ra-22 6 K d ha s bee nreporte d t o varyfro m lowvalue s (200-50 0 mL/g ) t o highe r value s (1,000-6,00 0 mL/g ) fo r a variet yo f soils . I n some instances , Kd s a s higha s 20,00 0 t o 30,00 0 mL/ g hav e bee n observe d o r reporte d (NJD87) . Generally , K d value s fo r soil s o f ari d region s ar e lowe r tha nthos e observe d i nsoi l o f humi d regions . Simila r case s ca nb e mad e t o illustrat e th e behavio r o f th e othe r decayproduct s considere d i nthi s analysis . I nthi s analysis , tw o set s o f K d value s ar e applied : on e t o characteriz e th e leaching an d movemen t o f th e radionuclide s withi nth e coa l an d as hmaterial s an d th e othe r t o mode l th e natural.environmen t beyond th e edg e o f eithe r pile . Th e movemen t o f thes e radionuclide s i s modele d using K d value s generall y accepte d b

yEPAfo r modeling simila r situation s (EPA87) .

2 5P.4 8

Fo r th e coa l an

d as hmaterials , th e selecte d K d value s ar e assume d t o b e lowe r tha nthos e fo r soi l becaus e i t i s als o assume d tha t coa l o r coa l as hdoe s no t hav e th e sam e ion-exchang e capacit ya s tha t o f natura l soil s (EPR84 , EEI88 , GIL83 , NCR85a) . Th e selecte d K

d value s fo r th e coa l an d ash , expresse d i nmL/g , ar e a s follows : Po-210 , 100 ; Pb-210 , 100 ; Ra-226 , 75 ; Th-228 , 3,000 ; Ra-228 , 75 ; Th-230 , 3,000 ; Th-232 , 3,000 ; U-234 , 50 ; an d U-238 , 50 . I nth e contex t o f ground an d surface-wate r modeling , highe r K

d value s yiel d lowe r wate r concentrations . Th e area s beyond th e edg e o f th e pil e includ e th e unsaturate d zone , aquifer , an

d surfac e soil . Fo r thes e areas , th e selecte d K d value s ar e a s follows : Po-210 , 220 ; Pb-210 , 220 ; Ra-226 , 220 ; Th-228 , 60,000 ; Ra-228 , 220 ; Th-230 , 60,000 ; Th-232 , 60,000 ; U-234 , 750 ; and U-238 , 750 . A s before , thes e unit s ar e expresse d i nmL/g . I t shoul d b e pointe d ou t tha t coa l as hi s generall ybelieve d t o b e insolubl e becaus e th e activit yi s containe d i na glas s matrix . Weatherin g ari

d chemica l action , however , mayleac hth e activit y hel d o nth e oute r surfac e laye r o f th e as hparticle . I na stud y t o asses s th e leaching propertie s o f coa l an d coa l as hsamples , Wagne r and Greine r indicate d tha t radionuclide s ar e no t readil y leache d fromcoa l o r as hsample s (WAG82) . Th e stud yals o support s th e assumptio nthat , i nmos t cases , leachate s d o no t appea r t o excee d th e EP Aguid e (les s tha no r equa l t o 5 pCi/ L fo r Ra-226 ) fo r drinkin g water . Base d o nth e Wagne r an d Greine r study , i t wa s deduce d tha t th e K d value s use d i nthi s analysi s ar e conservative . Fo r example , th e Ra-22 6 K d derive d fromWagne r an d Greine r dat a is , o nth e average , 50 0 mL/ g fo r coa l and 2,00 0 mL/ g fo r ash . Thi s analysis , o nth e othe r hand , use s a Ra-22 6 K d o f 7 5 mL/ g fo r bot hcoa l and coa l ash . I nvaryin g degrees , thi s genera l relationshi p i s als o tru e fo r th e othe r radionuclides . 6. 4 INGESTIONMODE L Th e dose s associate d wit hth e ingestio no f contaminate d wate r an d foodstuff s ar e estimate d using th e PRESTO-EPA-CP Gmode l (EPA87) . Th e ingestio n pathwayaddresse s th e consumptio no f contaminate d wate r an

d foodstuffs , suc ha s vegetables , milk , an d meat . Wate r i s assume d t o b e withdrawnfroma down-gradien t wel l o r nearb y creek . Al l o f th e wate r need s ar e supplie d fromthi s wel l o r creek , including domesti c uses , irrigatio no f crop s an d pastures , an d waterin g o f livestocks . Th e food an d wate r consumptio nrate s an d environmenta l transpor t parameter s reflec t generall yaccepte d assumption s an

d parameter s use d i nth e PREST O mode l (EPA87) .

2 6P.4 9

6. 5 WATE RCONCENTRATION S AND DOSE S Th e ground and surface-wate r concentrations , doses , an d risk s ar e give ni n Tabl e 4 . Fo r th e ground-wate r pathway , base d o n th e result s o f th e PREST O code , th e leachate s ar e no t expecte d t o reac hth e well . Radionuclid e migration , unde r th e coa l o r as h pil e and withi nth e aquife r itself , i s primaril ydependen t upo n th e distributio ncoefficient s (Kds ) an d aquife r flowrate . Fo r example , th e movemen t o f Ra-22 6 i s typicall yo nth e orde r o f abou t 0. 2 cmpe r yea r base d o na retardatio nfacto r o f 90 0 an d ground-wate r velocit yo f 2. 0 m/yr . Give nthi s rat e o f travel , Ra-22 6 doe s no t reac hth e wel l withi na 1,000-yea r time period . Asimila r se t o f example s ca nb e mad e t o illustrat e thi s characteristi c (immobility ) fo r th e remaining radionuclides . Accordingly , th e dos e an d risk s fro

mthi s exposur e pathwayar e assume d t o b e nil . Give nth e assumption s o f th e surface-wate r model , leachate s ar e assume d t o b e release d int o th e nearb ycreek . Th e Ra-22 6 concentration s i n th e cree k ar e estimate d t o b e 0.001 2 an d 0. 2 pCi/L , respectively , fo r th e coa l an d as hpiles . Wate r concentration s ar e reporte d onl yfo r Ra-226 . Dose s an d risks , however , reflec t al l radionuclides . Th e yearl ydose s ar e estimate d t o b e 0.004 4 mre mfo r th e coa l pil e and 0.7 3 mre mfo r th e coa l ash . Typically , 8 0 percen t o f th e dos e i s du e t o th e drinkin g o f contaminate d water . Th e corresponding lifetime risk s fo r fata l cancer s ar e estimate d t o b e 2. 9 x10~ 8 fo r th e coa l pil e and 4. 6 x10~ 6 fo r th e as hpile . I nvie wo f th e presenc e o f Ra-226 , radon-22 2 ( a decayproduc t o f Ra-226 ) mayals o b e presen t i nwater . Radon-22 2 i nsurface-wate r is , however , no t a problembecaus e thi s nobl e ga s i s rapidl y aerate d ou t o f th e wate r (HES85 , EPA89a) . I t ha s bee nshow ntha t th e presenc e o f rado ni nsurface-wate r suppl ysystem s i s generall ynondetectabl e an d occur s onl ya t verylow concentrations , les s tha n10 0 pCi/ L (HES85) . Th e overal l averag e fo r th e Unite d State s i s 1 pCi/L . Typically , suc hconcentration s ar e wel l belo wth e rang e o f th e propose d U.S . EPAdrinking wate r rado nconcentratio nlimi t o f 20 0 t o 2,00 0 pCi/ L (EPA89a) . Comparin g th e as hpil e Ra-22 6 concentratio nresul t t o naturall y occurrin g radiu

mi nsurface-wate r reveal s tha t it s presenc e i s withi nth e rang e o f natura l environmenta l levels . Fo r example , surfac e Ra-22 6 concentration s typicall yrang e fro m0. 1 t o 0. 5 pCi/ L (HES85 , COT84) . Th e Ra-22 6 concentratio ndu e t o coa l pil e runof f is , however , significantl ylower , b yabou t tw o order s o f magnitude .

2 7P.5 0

7. 0 INDUSTRIAL BOILER S Industria l boiler s ar e use d mainl yt o produc e proces s steam , generat e electricit y(typically , fo r th e facility' s ow nneeds) , an d fo r spac e heating . Industria l boiler s ar e use d virtuall yi n everyindustryfrom smal l manufacturing t o larg e productio n facilities . A s wit hutilit ycoal-fire d plants , th e consumptio no f coa l i s proportiona l t o th e siz e o r capacit yo f th e industria l boiler . Typically , ove r 9 9 percen t o f th e industria l boiler s hav e a capacit yo f les s tha n7 5 MW(thermal ) (EPA84) . Give nth e varie d distributio nan

d applicatio no f industria l boilers , thre e industrie s typicall ydominat e th e consumptio no f coal . Thes e ar e th e chemical , paper , an d meta l fabricatio nindustrie s (stee l an d aluminum) . Fo r example , thes e thre e industrie s consume d nearl y9 0 percen t o f th e tota l coa l use d b yindustria l boiler s i n197 4 (EPA84) . A s wa s note d i nSectio n2 o f thi s report , th e quantit yo f stockpile d coa l an d as hdispose d onsit e wer e assume d t o b e representativ e o f overal l practice s a t utilit ycoal-fire d plants . I t wa s als o assume d tha t b yevaluating utilities , th e result s woul d envelo p industria l facilitie s whic har e typicall ymuc h smalle r i ncapacit yo r size . Th e us e o f coa l withi nth e industria l sector , t o a certai nextent , i s als o assume d t o b e implicitl yaddresse d becaus e th e quantit yo f coa l use d i n thi s analysi s als o reflect s operating practice s o f industria l boilers . I norde r t o asses s whethe r ther e ar e othe r significan t difference s betwee n utilit yan d industria l boilers , a qualitativ e compariso nwa s performe d fo r thes e tw o type s o f facilities . Th e result s o f thi s comparativ e evaluatio nar e show ni nTabl e 5 . Becaus e ther e ar e some similaritie s betwee nthes e tw o type s o f facilities , thi s discussio nfocuse s onl yo nparameter s tha t ar e different . Th e relativ e likelihoo d o f a nassumptio no r a paramete r applicabl e t o utilit yo r industria l boiler s ar e als o give ni n Tabl e 5 . Th e objectiv e o f thi s qualitativ e evaluatio ni s t o determin e t o wha t exten t th e utilit yris k assessmen t result s als o appl yt o industria l facilities . 7. 1 OUANTITIE S O F COAL AND AS H Typically , industria l boiler s us e les s coa l and , consequently , generat e smalle r quantitie s o f ash . Th e majorit yo f industria l boiler s als o d o no t stor e larg e quantitie s o f coa l o nsit e (STE89 , EPA84) . A t industria l facilities , coa l i s als o store d i n silo s rathe r tha ni nexpose d piles . Similarly , ashe s ar e no t alway s dispose d o nsite ; rather , theyar e ofte ndispose d elsewher e o r shippe d t o cemen t o r aggregat e plants . Give n thes e practices , i t ma yb e conclude d tha t th e amoun t o f coa l use d an d

2 8TABLE 5 QUALITATIV

E ODMPARATIV

E EVALUATIO

N OF UTILIT YAN DINDUSTRIA

L BOILEB S

Ke yInpu t Paramete r Assumption / Valu e Used It o f Case s Represente d UtilityBoiler s a / Rational e _o f Case s Represente d Industria l Boiler s b / Rational e Quantityo f Coa l 9 . i. x 1 0 metri c ton s 70X Based on dat a i nth e literatur e <70 X Base d on dat a l n the literatur e an

d the fac t tha t industria l boiler s ar e o f smalle r capacity

I.IJJ.II. I l I v

-J ! A_I I 1 . x1 0 metri c ton s 50 1 Roughl ya naverag e figur e based on literatur e an d persona l communication s <1X Base d on as hgeneration rate s calculate d usin g dat a i n '8 4 NESHAP s BI O I.i.l.lt.lLtl l U l AM I IJlSJ.-Su i Onsit e -100 * Based on literature , i t appear s tha t mos t utility boiler s dispos e o f thei r as honsit e <100 X Industria l boiler s ar e probabl ylocated on smalle r sites , whic h don' t allowfo r onsit e disposa l Distanc e Lo Surfac e Wate r 60 0 meter s 50X A n averag e figur e base d o n dat a i n198 8 Repor t t o Congres s <50 X Industria l boiler s les s likel yt o b e nea r surfac e wate r than utilities , whic hrequir e surfac e wate r for cooling Strea mflowRat e 1 0 CF S -5 X Based on strea mflowdat a i n198 8 Repor t t o Congres s >5 X Industria l boiler s ar e probabl ymor e likel yt o b e nea r smalle r streams (again , theydon' t nee d t o b e nea r larg e bodie s o f wate r tha t serve I s a sourc e o f cooling water ) Surfac e Wate r Us e Individua l use s strea m a s sol e sourc e o f drinking water , wate r fo r watering livestock (whichi s hi s sol e sourc e o f meat) , an d wate r for watering a garden(whichi s hi s sol e sourc e o f vegetables ) Unlikel yt o occur (-101 ) Based on the genera l recognitiontha t i t woul d b e unlikel yfo r a farme r t o b e located i nsucha positionrelative t o a powe r plant , an

d t o us e sucha smal l strea

ma s a sol e sourc e o f wate r Ver yunlikel yt o occur (0-1X ) Based on dat a in '8 4 NESHAP s BID , industria l boiler s ten

d t o be

located i n generall y urban/suburban areas ; sucha surfac e wate r us e pattern i n an urban / suburban setting i s ver y unlikel y

2 9TABLE 5 (continued ) QUALITATIV

E COMPARATIV

E EVALUATIO

N OF UTILIT YAHDINDUSTRIA

L BOILEB S

Ke yInpu t Paramete r Assumption / Valu e Used II o f Case s Represente d UtilityBoiler s a / Rational e t o f Case s Represente d Industria l Boiler s b / Rational e Distanc e t o Neares t Residen t 10 0 meter s -5 X Based on a reviewo f USG S topographica l map s o f almos t 10 0 utilityboile r site s ~95 X Industria l boiler s ar e mor e likel yt o b e located i n generall y urban/suburban setting , wit hclose r nearb

y resident s (o

n the orde r o f 30-5 0 meter s away )

Overal l conclusion : 1X-10 X Overal l conclusion : <1 X

a / Based onthe 198 8 Repor t t o Congres s o nCoa l Combustio n Waste s (EPA , Offic e o f Soli d Waste . EPA/530-SW-88-002 , Februar y1988) , ther e ar e approximatel y1,37 8 utility boiler s i

n th e U.S . Thes e boiler s wer e located at roughl y50 0 differen t sites . b / Based ondat a i

nthe 198 4 NESHAP s BI D (EPA , Offic e o f Radiatio n Programs , "Radionuclides : Backgroun d Information Documen t fo r Fina l Rules , Volume II, " EP A520/1

- 8< J -022-2 , Octobe r 1984) , ther e wer e approximatel y51,18 7 industria l boiler s aroun d 1981 .

3 0P.5 3

as hgenerate d b

yutilit yboiler s represen t a nuppe r bound o f th e siz e o f coa l an

d as hpile s a t industria l sites . Accordingly , i t i s anticipate d tha t th e potentia l rang e o f exposure s an d risk s a t industria l facilitie s i s lowe r tha nthos e estimate d fo r utilit y sites . 7. 2 DISTANC E T O SURFAC E STREA M Anaverag e distanc e o f 60 0 meter s t o th e neares t surface-wate r bod ywa s use d t o characteriz e th e utilit ysite . Give n tha t industria l boiler s ar e smalle r facilities , the yar e les s likel y t o rel yo n a surface-wate r strea mfo r cooling purposes . Th e presenc e o f a smal l strea mmay , however , b e sufficien t t o suppl y th e need s o f a nindustria l boiler , bu t woul d no t b e adequat e fo r coal-fire d powe r plants . O nth e othe r hand , industria l boiler s mayop t t o us e wel l wate r o r depend o na communit ywate r suppl y systempurel yt o b e assure d o f a reliabl e sourc e o f water . Accordingly , industria l boiler s ar e les s likel ytha nutilit y plant s t o rel ysolel yo na surfac e stream . Th e risk s associate d wit hth e surface-wate r exposur e pathwayis , therefore , assume d t o b e no t muc hdifferen t tha ntha t o f risk s estimate d fo r utilit y powe r plants . Give n thes e considerations , i t i s assume d tha t th e result s obtaine d fo r utilit ysite s represen t a nuppe r bound i n term s o f potentia l dose s an d risk s associate d wit hindustria l facilities . 7. 3 SURFACE-WATE RUS E Th e exposur e scenari o assume s tha t a smal l farme r meet s al l o f hi s wate r need s from a smal l surfac e stream . Surfac e wate r runof f an d leachate s fromth e coa l an d as hpile s wer e assume d t o flow int o th e stream . Thi s wate r i s use d fo r drinkin g purpose s a s wel l a s fo r cro p irrigatio nand waterin g o f livestocks . Industria l boiler s ar e mor e likel yt o b e locate d i nurba no r suburba nareas . I f a nindustria l boile r wer e locate d i na n urba nsetting and nex t t o a surfac e stream , th e depicte d patter no f wate r usag e i nsuc h a nurba nsettin g woul d b e a nunlikel yscenario . I f th e wate r wer e use d t o suppl ya communit ywate r system , th e wate r woul d b e treate d (a t leas t filtered ) prio r t o bein g distributed . Accordingly , th e potentia l ris k o f bein g expose d t o leachat e discharge s i na n urba nsetting i s unlikely . I nan ycase , th e dose s and risk s estimate d fo r utilit yboiler s ar e expecte d t o represen t a n uppe r bound fo r thos e a t industria l facilities . 7. 4 DIREC T RADIATION Th e nearb

yresiden t wa s assume d t o b e locate d 10 0 meter s away fro mth e utilit ycoa l an d as hpiles . Recognizin g tha t industria l boiler s ar e mor e likel yt o b e locate d i nurba nareas , ther e i s a

3 1P.5 4

possibilit ytha t th e nearb yresiden t mayi nfac t b e close r t o suc hpiles . Fo r industria l boilers , th e distance s mayb e o nth e orde r o f 3 0 t o 5 0 meter s (STE89) . Shorte r distance s betwee n th e sourc e o f radiatio nan d recepto r increas e th e dose . O nth e othe r hand , smalle r coa l an d as hpile s reduc e th e exposur e rate s becaus e o f th e smalle r sourc e terman d differen t physica l configurations . Accordingly , thes e competing factor s tend t o negat e eac hother . I nvie wo f thes e considerations , i t i s assume d tha t dose s an

d risk s fo r industria l boiler s ar e bound b ythos e estimate d fo r utilit yboilers . Finally , give ntha t th e majorit y o f industria l boiler s ar e muc hsmaller , th e possibilit yo f radiatio n exposur e level s approaching thos e calculate d fo r utilit yboiler s i s unlikely . 7. 5 CONCLUSION I noveral l terms , onl ya fewse t o f parameter s o r assumption s diffe r betwee nutilit yan d industria l boiler s (se e Tabl e 5 ) . Generally , i t mayb e conclude d tha t th e dose s an d risk s estimate d fo r utilit yboiler s ma yb e applicabl e onl yt o a smal l fractio no f th e tota l numbe r o f industria l boilers . I nsom e instances , i t wa s als o note d tha t competin g factor s tha t tend t o increas e dose s an d risk s ar e negate d b yothers . I nsuc hinstances , th e ne t risk s ar e n o highe r tha nthos e estimate d fo r utilit yboiler s an d i n some case s ar e possibl ylower . Give nth e scop e o f thi s comparativ e evaluation , i t i s estimate d tha t a smal l numbe r (les s tha n1 percent ) o f th e industria l boiler s mayproduc e dose s and risk s o f th e same magnitud e a s thos e estimate d fo r utilit yboilers .

3 2P.5 5

REFERENCE S ACA8 6 Coa l As hBoo k - Technica l Summary , America nCoa l As h Association , Washingto nD.C , 1986 . BEC8 9 Lette r Transmitta l - Pape r titled : Som e Radiologica l Aspect s o f Coa l Combustion , Harol d L . Bec k an d Kevi n M . Miller , Jan . 13 , 1989 . BEC8 0 Beck , H.L. , e t al. , Perturbation s o nth e Natura l Radiatio n Environmen t Du e t o th e Utilizatio no f Coa l a s a nEnergy Source , Natura l Radiatio nEnvironment , CONF-780422 , Vol . 2 , pp . 1521-1558 , 1980 . CEM6 9 Cember , H. , Introductio nt o Healt hPhysics , Pergamo n Press , Ne wYork , 1969 . CLI8 3 Cline , W. , et.al. , Radiu man d Uraniu

mConcentration s i n Georgi a Communit yWate r Systems , Healt hPhysics , Vol . 44 , Jan . 1983 , pp . 1-12 . COT8 4 Cothren , C.R. , Lappenbusch , W.L. , Complianc e Dat a fo r th e Occurrenc e o f Radiu man d Gros s Alpha-Particl e Activit yi n Drinkin g Wate r Supplie s i nth e Unite d States , Healt h Physics , Vol . 46 , Mar . 1984 , pp . 503-510 . EEI8 8 Ediso nElectri c Institute , Ashe s an d Scrubbe r Sludges-Fossi l Fue l Combustio nBy-Products : Origin , Properties , Us e and Disposal , Publicatio nNo . 48-88-05 , Ma y1988 . EPA8 9 U.S . Environmenta l Protectio nAgency , Draf t Environmenta l

Impac t Statemen t fo r Propose d NESHAP S fo r Radionuclide s - Background Informatio nDocument , Vol . II , EPA 520/1-89-006 , Feb . 1989 . EPA89 a U.S . Environmenta l Protectio nAgency , Draf t Briefing Pape r - Rado ni nDrinking Wate r - Option s fo r th e MCL , Offic e o f Drinking Water , Feb . 1 , 1989 . EPA8 8 U.S . Environmenta l Protectio nAgency , Waste s fro m th e Combustio no f Coa l b yElectri c Utilit yPowe r Plants , Repor t t o Congress , EPA/530-SW-88-002 , Feb . 1988 .

3 3P.5 6

REFERENCE S EPA8 7 Rogers , V . an d Hung , C. , Low-Leve l and NARMRadioactiv e Waste s - Mode l Documentatio nPRESTO-EPA-CP G- Methodology and User s Manual , U.S . Environmenta l Protectio nAgency , EPA520/1-87-026 , Dec . 1987 , a s revised . EPA87 a Radiatio n Protectio nGuidanc e t o Federa l Agencie s fo r Occupationa l Exposure , Federa l Registe r Vol . 52 , No . 17 , pp . 2822-2834 , Jan . 27 , 1987 . EPA8 4 U.S . Environmenta l Protectio nAgency , Radionuclide s - Background Informatio nDocumen t Fo r Fina l Rule s NESHAPS , Vol . II , EPA520/1-84-022-2 , Oct . 1984 . EPA7 9 Moore , R.E. , e t al. , AIRDOS-EPA : AComputerize d Methodologyfo r Estimating Environmenta l Concentration s an d Dos e t o Ma nfro

mAirborn e Release s o f Radionuclides , U.S . Environmenta l Protectio nAgency , EPA520/1-79-009 , Dec . 1979 , a s revised . EPA79 a U.S . Environmenta l Protectio nAgency , Radiologica l Impac t Cause d b

yEmission s o f Radionuclide s int o th e Ai r i nth e Unite d States , U.S . Environmenta l Protectio nAgency , EPA520/7-79-006 , Aug . 1979 . EPA7 8 U.S . Environmenta l Protectio nAgency , Sourc e Assessment : Coa l Storag e Piles , EPA-600/-78-0041 , May1978 . EPR8 8 Electri c Powe r Researc hInstitute , Classificatio n o f Fl y As hfo r Us e i nCemen t an d Concrete , EPR I CS-5116 , Fina l Report , Apr . 1987 . EPR8 4 Kincaid , C.T. , e t al. , Geohydrochemica l Model s fo r Solut e Migration , Electri c Powe r Researc hInstitute , Battell e Pacifi c Northwes t Laboratories , EPR I EA-3417 , Vol.1 , Fina l Report , Feb . 1984 . FRE7 9 Freeze , R.A . an d Cherry , J.A. , Groundwater , Prentice-Hall , Inc. , Englewood s Cliffs , NJ , 1979 . GIL8 3 Gilbert , T.L. , e t al. , Pathway s Analysi s an d Radiation-Dos e Estimate s fo r Radioactiv e Residue s a t Formerl yUtilize d MED/AE C Sites , U.S . Departmen t o f Energy , ORO-8 3 2 , Mar . 1983 .

3 4P.57 _

REFERENCE S HEA8 4 Heath , R.C , Basi c Ground-Wate r Hydrology , U.S . Geologica l Surve yWate r - Suppl yPape r 2220 , Thir d Printing , 1984 . HES8 5 Hess , CT. , et . al. , Th e Occurrenc e o f Radioactivit yi n Publi c Wate r Supplie s i nth e Unite d States , Healt h Physics , Vol.48 , Ma y1985 , pp . 553-586 . HIN8 2 Hinds , W.C , Aeroso l Technology , JohnWile y& Son s Publications , 1982 . ICF8 9 Telephon e communicatio nwit hMr . Stev e Wyngarden , ICF , Inc. , Jan . 26 , 1989 . KAL8 5 Kalkwarf , D.R. , Emanatio nCoefficien t fo r Rni nSize d Coa l Fl yAsh , Healt hPhysics , Vol . 48 , Apr . 1985 , pp . 429-43 6 MOR7 3 Morgan , K.Z. , Turner , J.E. , Principle s o f Radiatio n

Protection , R.E. , Kriege r Publishing Company , 1973 . NER8 7 Electricit ySuppl yan d Demand fo r 1987-1996 , Nort h America nElectri c Reliabilit yCouncil , Nov . 1987 . NIE8 7 Niemczyk , S.J. , e t al. , User' s Manua l fo r REUSIT : A Compute r Cod e fo r Estimating th e Ris k fro mResidua l Radioactivity , Draf t Fina l Report , U.S . Environmenta l Protectio nAgency , Nov . 1987 . NJD8 7 NJDEP , Technica l Background Informatio nRepor t fo r th e

Soi l Blendin g Program , Ne wJerse yDepartmen t o f Environmenta l Protection , Baker/TSA , Inc. , Jun . 1987 . NCR8 7 NCRP , Exposur e o f th e Populatio ni nth e Unite d State s an d Canad a fromNatura l Background Radiation , Nationa l Counci l o nRadiatio nProtectio nan d Measurements , NCR P Repor t No . 94 , Dec . 1987 . NCR8 5 NCRP , Evaluatio no f Occupationa l an d Environmenta l Exposure s t o Rado nan d Rado nDaughter s i nth e Unite d States , Nationa l Counci l o nRadiatio nProtectio nan d Measurements , NCR P Repor t No . 78 , May1985 . NCR85 a NCRP , Radiologica l Assessment : Predicting th e Transport ,

Bioaccumulation , an d Uptak e b

yMa no f Radionuclide s Release d t o th e Environment , Nationa l Counci l o nRadiatio n Protectio nan

d Measurements , NCR P Repor t No . 76 , May1985 .

3 5P.5 8

REFERENCE S NCR7 6 NCRP , Environmenta l Radiatio nMeasurements , Nationa l Counci l o nRadiatio nProtectio nan d Measurements , NCR P Repor t No . 50 , Dec . 1976 . NCR7 5 NCRP , Natura l Background Radiatio ni nth e Unite d States , Nationa l Counci l o nRadiatio nProtectio nan d Measurements , NCR P Repor t No . 45 , Nov . 1975 . NOV8 9 Telephon e communicatio nwit hMr . JohnNovak , Ediso n Electri c Institute , Washington , D.C , Jan . 2 5 ,1989 . NRC8 3 Till , J.E. , Meyer , H.R. , Radiologica l Assessmen t - A Textboo k o n Environmenta l Dos e Analysis , U.S . Nuclea r RegulatoryCommission , NUREG/CR-3332 , Sept . 1983 . NRC8 0 U.S . NRC , Fina l Generi c Environmenta l Impac t Statemen t o n Uraniu m Millin g (Projec t M-25) , U.S . Nuclea r Regulatory Commission , NUREG-0706 , Vol . Ill , Sept . 1980 . PAR8 9 Telephon e communicatio nwit hMr . BarryParks , U.S . EPA , ORP/La s Vegas , Jan . 20 , 1989 . PET8 9 Telephon e communicatio nwit hMr . Warre nPeters , U.S . EPA , Offic e o f Ai r Qualit yPlanning an d Standard s (08QPS ) - Pollutio nAssessmen t Branch , Researc hTriangl e Park , N.C , Jan . 26 , 1989 . RAD8 8 Stricket , R.G. , Lowe , J. , Assessmen t o f NORM

Concentration s i nCoa l As han d Exposur e t o Worker s an d Member s o f th e Public , Radia nCorporatio nRepor t t o th e Utilit yWast e Activitie s Grou p an d Ediso nElectri c Institute , Jun . 1988 . SCH7 4 Schiager , K.J. , Analysi s o f Radiatio nExposure s o no r Nea r Uraniu mMil l Tailing s Piles , U.S . Environmenta l Protectio n Agency , Radiatio nDat a an d Reports , Vol . 15 , No . 7 , pp . 411-425 , Jul . 1974 . STE8 9 Telephon e communicatio nwit hMr . Wal t Stevenson , U.S . EPA , Offic e o f Ai r Qualit yPlanning an d Standard s (08QPS ) - Pollutio nAssessmen t Branch , Researc hTriangl e Park , N.C , Feb . 2 , 1989 .

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REFERENCE S TEK7 9 Informatio n Bas e (Including Source s and Emissio nRates )

fo r th e Evaluatio nan d Contro l o f Radioactiv e Material s t o Ambien t Ai r - Tas k 2 , Repor t Prepare d b yTeknekro n Research , Inc . fo r th e U.S . EPAOffic e o f Radiatio n Programs , Jul . 1979 . UNS8 2 Unite d Nation s Scientifi c Committe e o nth e Effect s o f Atomi c Radiation, , Source s an d Effect s o f Ionizing Radiation , Anne xB an d C , 1982 . WAG8 2 Wagner , P. , Greiner , N.,R. , Thir d Annua l Repor t - Radioactiv e Emission s fromCoa l Productio nan d Utilization , Octobe r 1 , 198 0 - Septembe r 30 , 1981 , Lo s Alamo s Nationa l Laboratory , LA-9359-PR , Jun . 1982 .

3 7P.6 0 Appendi x

ADDITIONAL INFORMATIONONWORKE REXPOSUR E REFLECTINGINDUSTR YPRACTICE S Th e radiatio nexposur e t o a worke r wa s calculate d assuming tha t anindividua l i s assigne d t o as hmanagemen t activitie s wit hn o othe r periphera l functions . Thes e activitie s ar e assume d t o occu r o na full-time basis . Th e worke r i s assume d t o spen d 8 hour s pe r day , 5 day s pe r week , an d 5 0 week s pe r yea r performin g suc h activities . Th e individua l i s assume d t o b e employe d starting a t ag e 1 8 an

d retiring a t ag e 65 , fo r a caree r spanning 4 7 years . Th e exposur e mode l als o containe d th e assumptio n tha t th e worke r spen t 50 % o f hi s time seate d on e mete r abov e th e surfac e o f th e as hpil e operatin g machineryo r equipmen t t o manag e th e pile . Th e equipmen t o r machineryprovide s shielding an d protectio nfro

m ambien t exposures . I nth e contex t o f radiatio n protection , shielding protectio nfactor s ca nrang e from0 t o 1 ; wit h1 indicating n o protectio nan d 0 indicating maximu mprotection . Protectio n factor s ranging fro m0.1 5 t o 0. 7 hav e bee n cite d i n th e literatur e fo r simila r type s o f analyse s (1 , 2) . I nthi s analysis , a conservativ e protectio nfacto r o f 0. 7 wa s assumed . Give nthes e assumptions , a yearl ydos e o f 3 3 mremwa s calculate d fo r th e hypothetica l worker . Th e associate d life-time ris k fo r fata l cancer s wa s estimate d t o b e 4. 3 x10" 4

. Additiona l dat a and informatio nwhic hreflec t industrypractice s wer e obtaine d fro

mOSHA , trad e organizations , an d firm s involve d i nth e as hdisposa l busines s i norde r t o asses s th e reasonable

nes s o f thes e assumptions . OSH Aindicate d tha t fo r th e purpos e o f conductin g ris k assessmen t analyses , anoccupationa l lif e spa n o f 4 5 year s i s normall yuse d (3) . Thi s valu e compare s closel y wit hth e occupationa l lif e spano f 4 7 year s use d i nth e ris k assessment . Th e Ediso nElectri c Institut e an d th e America nCoa l As h Associatio nwer e contacte d fo r informatio nan d bot horganization s referre d u s t o companie s whic hprovid e as hdisposa l managemen t service s t o utilitie s (4 , 5) . Thes e tw o firm s ar e JT Mindustries , locate d i nAtlanta , Georgi a an d th e America nFly . As hCompany , locate d i nDe s Plaines , Illinois . Representative s from bot horganization s indicate d tha t typicall y some individual s ar e full yassigne d t o as hdisposa l an d manage men t activitie s fo r a s muc ha s 8 hour s pe r day , 5 day s pe r week , an d 5 0 week s pe r yea r (6,7) . However , i t wa s note d tha t littl e time i s spen t i ndirec t contact , i.e. , walkin g o r standing , o n th e as hpil e itself .

3 8P.6 1

Th e as his ' dispose d o r emplace d usin g truck s o r othe r vehicles . Th e as hi s grade d an d compacte d using bulldozer s and graders . Th e worke r ride s o r operate s th e equipmen t whil e seate d 3- 4 meter s abov e th e as hpile . Some as hmanagemen t personnel , othe r tha nequipmen t operators , performQ Aan d testing function s whic h requir e direc t acces s t o th e as hpile . Typically , suc h individual s spend 8-1 0 hour s pe r wee k o nth e as hpil e withou t th e benefi t o f an

yshielding tha t a vehicl e mayprovide . Th e balanc e o f th e tim e i s spen t i n a laboratoryo r o nsome relate d technica l o r administrativ e tasks . Comparin g thi s informatio nwit hth e assumption s use d i nmodelin g th e exposure , dose , an d risk s t o th e worker , indicate s tha t th e mode l i s i n agreemen t wit hOSH Aan d industrypractices . Th e occupationa l duratio n i s essentiall yidentica l and th e assumptio n tha t suc hactivitie s ar e conducte d o na full-time basi s b y designate d individual s i s als o realistic . I naddition , whil e th e ris k assessmen t mode l too k credi t fo r shielding fo r hal f o f th e time , i t appear s fro m th e abov e informatio ntha t shielding i s virtuall yalway s presen t and therefor e th e shielding protectio nfacto r coul d b e applie d fo r 10 0 percen t o f th e time . I t wa s als o note d tha t th e vehicle s bein g operate d ar e heav yequipment , suc ha s bulldozers , graders , an d trucks . Th e siz e an d mas s o f thi s typ e o f heav yequipmen t provide s mor e shielding , an d therefor e a mor e protectiv e shielding factor , tha n wa s include d i nth e ris k assessment . Th e operato r als o ride s o r operate s th e equipmen t a t a greate r heigh t o r distanc e fromth e as hpile , whic hresult s i na lowe r dos e fro m direc t radiation . Thes e factor s provid e additiona l protectio n tha t ca nb e factore d int o th e model . Th e shieldin g tha t th e equipmen t provide s ma yb e reassesse d t o obtai na mor e realisti c protectio nfactor . Give nth e varyin g an d comple xphysica l configuration s o f suc hheav yequipment , i t i s beyond th e scop e o f thi s analysi s t o provid e a detaile d mode l o f suc ha nexposur e scenario . Suc hanalyse s ar e bes t performe d usin g compute r codes . Instead , a revise d shielding protectio nfacto r ha s bee n obtaine d froma Nuclea r RegulatoryCommissio n(NRC ) stud ywhic haddresse d th e topi c a s par t o f a ris k assessmen t stud y(2) . Shieldin g protectio nfactor s ranging fro m0. 4 t o abou t 0. 7 ar e cite d b yth e NR C fo r variou s type s o f equipment . Th e factor s als o inherentl yreflec t varyin g distance s abov e a plan e sinc e th e heigh t varie s betwee ndifferen t type s o f equipment . Th e factor s als o incorporate , t o varying degrees , a rang e o f physica l configuration s betwee nth e sourc e o f exposur e an d th e receptor . Fo r example , a noperato r locate d i nth e cabwoul d benefi t from littl e o r n o shielding , whil e anoperato r locate d abov e heavie r

3 9component s (e.g. , engine , transmission , chassis ) woul d b e expose d

t o a lesse r radiatio nfield . Give nthes e considerations , a mor e protectiv e shielding facto r o f 0. 6 i s assumed . Applying thes e revise d distance , exposur e duration , an d shielding factor s t o th e previou s calculations , reveal s tha t th e dos e an d risk s fo r th e worke r hav e bee nreduce d b ya facto r o f abou t 1.6 . Th e revise d annua l exposur e rat e i s estimate d t o b e 2 1 mrem/yr versu s 3 3 mrem/yr , a s previousl yestimated . Th e corresponding life-time risk s fo r fata l cancer s i s no w2. 6 x10" 4 versu s th e previou s estimat e o f 4. 3 x10' 4

. References/Source s 1 . NCRP , Radiologica l Assessment : Predicting th e Transport , Bioaccumulation , an d Uptak e b

yMa no f Radionuclide s Release d t o th e Environment , Nationa l Counci l o nRadiatio nProtectio n an d Measurements , NCR P Repor t No.76 , Ma y1985 . 2 . U.S . Nuclea r RegulatoryCommission , Reacto r Safet yStudy : An Assessmen t o f Acciden t Risk s i nU.S . Commercia l Nuclea r Powe r Plants , WASH-1400 , Oct . 1975 . 3 . Teleco n wit hMs . Sandr a Lee , U.S . EPA , fo r OSHAdata , Feb . 24 , an d 28 , 1989 . 4 . Teleco n wit hMr . JohnNovak , Ediso nElectri c Institute , Washington , DC , Feb . 21 , 27 , an d Mar . 1 , 1989 . 5 . Teleco nwit hMr . Eras t Borissoff , America nCoa l As h Association , Washington , DC , Feb . 2 4 an d 28 , 1989 . 6 . Teleco nwit hMr . Gre g Cain , America nFl yAs hCompany , De s Plaines , IL , Mar . 1 , 1989 . 7 . Teleco nwit hMr . GerryHeavilon , JT MIndustries , Atlanta , GA , Mar . 1 , 1989 .

4 0