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# 42 ) 102RQ-RN-5- 4 44 ) 102RQ-RN-5- 6 46 ) 102RQ-RN-5- 8 48 ) 102RQ-RN-5-1 0 50 ) 102RQ-RN-5-1 2 52 ) 102RQ-RN-5-1 4 54 ) 102RQ-RN-5-3 1 56 ) 102RQ-RN-2-5- 1 58 ) 60 ) 62 ) 64 ) 66 ) 68 ) 70 ) 72 ) 74 ) 76 ) 78 ) 80 )

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### COMBUSTION^ENGINEERIN G

Augus t 18 , 198 6

MEMORANDU

M TO : Barbar a Hostage , EP A FROM : Patrici a Scofield , EMS I SUBJECT : Advantage s an d Disadvantage s o f Method s fo r Estimating Releas e Fraction s fo r the Ingestio n Pathwa y

A s yo u requested , Tabl e 1 ha s bee n develope d t o identif ythe advantage s an d disadvantage s fo r using eithe r solubilitie s o r retardatio n factor s fo r estimating ingestio n pathwayreleas e fractions . Tabl e 1 summarize s thes e results ; however , shoul d no t b e considere d complet e sinc e additiona l informatio n i s forth

coming fro

mthe Battell e Pacifi c Northwes t Laborator yan d the Nuclea r Regulator y Commission . I f yo u hav e an ycomment s o r questions , pleas e do no t hesitat e t o call . 

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"/'/'>- , Patrici a Scofiel d Combustio n Engineering , EMS I Enclosur e

Environmenta l Monitorin g &Services , Inc . Combustio n Engineering , Inc
. 242 1 WestHillcres tDriv e NewburyPark , Californi a 9132 0 (805 ) 498-677 1METHO D - SOLUBILITIE S TABL E 1 RELEAS E FRACTION S FOR INGESTIO N METHO D - RETARDATIONFACTOR (Kd ) ADVANTAGE S DISADVANTAGE S ADVANTAGE S DISADVANTAGE S K(d )

2 . Doe s no t hav e t o tak e int o accoun t specifi c scenarios . Les s inheren t uncertainitie s a s compare d t o the K ^ valu e l.Th e amoun t o f materia l tha t woul d be solubl e in pur e wate r woul d almos t alway s b e greate r tha

n th e amoun t require d t o delive r the AL I 2 . Parameter s tha t woul d nee d assesse d —

• Dissolutio n rate s • Precipitatio n • Particl e siz e • pH 3 . Ther e ar e no curren t accepte d value s used , e.g. , Regulatory Guides . 1 . Numerou s reference s fo r K ^ value s fo r a variet yo f media . The san d aquife r repre sent s a conservativ e scenario , especiall y i f pur e water(distilled ) i s assumed . , 1 . Inheren t uncertaintie s associ

ated wit hK ^ estimation : a . Laboratorytes t method s yiel d differen t results , e.g. , colum

n versu s batc h b . K d i s a rati o o f tw

o concentrations ; a smal l o f erro r i n soi l o r wate r can produc e a larg e amoun t o f error . 2 . Variatio n i n soi l typ e —pH , soi l composition , particl e siz e distributions , etc . 3 . Time factor s — a . Th e Batc htes t require s onl y a fewhours , i f equilibriu m i s no t achieve d the n erro r i s introduced . b . Ther e ar e problem s assoc i ated wit husing shor t ter m test s t o simulat e leaching ove r lon

g time period s 4 . Th e NR C (Mike Bell ) i s no t for i fon d o f K d values .

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