ML20070G057

Chemical Toxicity of Uranium Hexafluoride Compared to Acute Effects of Radiation.Final Report

ML20070G057
Person / Time
Issue date:	02/28/1991
From:	Mcguire S NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:
References
NUREG-1391, NUDOCS 9103110209
Download: ML20070G057 (17)

Text

.

a NUR EG-1391 Chemical Toxicity of Uranium Hexafluoride Comaarec to Acute E'fects of Raciation Final Report U.S. Nuclear Regulatory Commission Of0cc of Nuclear Regulatory Research Stephen A. McGuire 5

'E t.,**.+/

o$314@lll91022e 1391 R PDR

~.-

. ~. -.

.. ~

)

AVAILABILITY NOTICE Avallabihty of Reference Materials Cited in NRC Publications Most' documents cited in NRC publications will be available from one of the following sources 1.

The NRC Pubic Document Room 2120 L Street. HW. Lower Level, Washington DC 20555-

2..The Superintendent of Documents, U.S. Government Printing Office, P.O. Box 37082, Washington DC 20013 7082-3.

The National Technical information Service, Springfield, VA 22161 Although the listing that follows represents the majority of documents cited in NRC publica-tions, it is not intended to be exhaustive.

Referenced documents available for inspection and copying for a fee from the NRC Public Documeat Room include NRC correspondence and internal NRC memorandat NRC Office of Inspection and Enforcement bulletins, circulars, information noticos, inspection and investi-i gation notices;. Licensee Event Reports; vendor reports and correspondence; Commission papers; and applicant and licensee documents and correspondence.

The following documents in the NUREG series are available for purchase from the GPO Sales Program; formal NRC staff and contractor reports, NRC sponsored conference proceed-Ings, an6 NRC booklets and brochures. Also evaltaue are Regulatory Guides, NRC regula-

tions in the Code of Federal Regulations, and Nuclear Regulatory Commission issuances.

Documents available from the National Technical information Service include NUREG series reports and technical reports prepared by other federal agencies and reports prepared by I

the Atomic Energy Commission, forerunner agency to the Nuclear Regulatory Commission.

Documents available from public and special technical librarios include all open literature

. items, such as books, Journal and periodical articles, and transactions. Federal Register notices, federal and. state legislation, and congressional reports can usually be obtained from these' libraries.

Documents such as theses dissertations, foreign reports and translations, and non NRC -

conference proceedings are available for purchase from the organization sporssoring the publication cited.

~Singte copies of NRC draft reports are available free, to the extent of supply, upon written -

request-to the Office of Information Resources Management. Distribution Section, U.S.

Nuclear Regulatory Commission. Washington.-DC 20555.

Copies of industry codes and standards used in a substantive manner in the NRC regulatory process are maintuned at the NRC Library,7920 Norfolk Avenue, Bethesda, Maryland, and -

are available there for reference use by the public. Codes and standards are usually copy-righted and may be purchased from the orig;nating organization or, if they are American National Standards, from the American National Standards institute,1430 Broadway, New York. NY 10018.

NUREG-1391 C:1emical Toxicity of RE Uranium Hexafluoric e Compared to Acute Effects of Radiation Final Report Manuscript Completed: January 1991 Date Published: February 1991 Stephen A. McGuire Division of Regulatory Applications Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission Washington, DC 20555

,p" "%,,

[

+,

i ABSTRACT The chemical effects from acute exposures to uranium For times t other than 30 minutes, the concentration C of hexafluoride are compared to the nonstochastic effects hydrogen fluoride considered to have the same effect can from acute radiation doses of 25 rems to the whole body be calculated using a quadratic equation: C - 25 mg/m3 and 300 rems to the thyroid. 'Ihe analysis concludes that (30 min /t)" The purpose of these analyses is to pro-an intake of about 10 mg of uranium in soluble form is vide information for developing design c.m! siting guide-roughly comparable, in terms of early effects, to an acute lines based on chemical toxicity for enrichm 'nt plants us-4 whole body dose of 25 rems because both are just below ing uranium hexafluoride, These guidelints are to be the threshold for significant nonstochastic effects. Simi-similar, in terms of stochastic health effects. to enteria in l

larly, an exposure to hydrogen fluoride nt a concentration NRC regulations for nuclear power plants, which are of 25 mg/m3 for 30 minutes is roughly comparab!c be-based on radiation doses.

cause there would be no significant nonstochastic effects.

l t

l l

iii NURI!G-1391

Contents Page Abstract...

iii Acknowledgments.........................

sii

-l

1. Purpose of This Report......

1

2. Effects of the Radiation Doses in 10 CFR Part 100.........................

t

3. Chemical Toxicity of Uranium Hexafluoride and its Products.

2 3.1 U ra n i u m Toxici ty.....................................

2 3 2. Radiation Dose from Uranium.....

4 3.3 Hydrogen Flu orid e Toxicity.....................................................

4 3.4 Fl u orid e Toxici ty....................................................................

7

4. Comparison of the Chemical Toxicity of Uranium Hexafluoride With Radiation Doses....

7 References.............

9 Figure 1

Effects of &posure of Animals to Hydrofluoric Acid '. Air.....

6 Tables 1

Relative Weights of Uranium Hexafluoride and Its Products.

2 2

Health Effects from Intake of Soluble Uranium............

3 l

l-l 3-Intakes of Uranium of Various Enrichments To Produce 25. rem Effective Dose Equivalent...........

4 4

Effects of inhalation of Hydrogen Flouride on Animals (from Patty,1962) 5 5

Concentrations of an Exposure to Hydrogen Fluoride Equivalent in Effect to NIOSH IDLH Level...

7 l

l i

l l

l l

l l

l I

v NUR EG-1391

e ACKNOWLEDGMENTS The contributions of the following people are gratefuHy 1990. 'the author would like to thank The people who acknowledged: Dr. Shlomo Yaniv of the NRC for infor-took the time and effort to resiew and cu:omet.t on the raation and discussions on the health risks of radiatien; report.

llarbara Brooks, formerly of the NRC, for information on uranium metabolism and bioassay; Dr. Aflhomas Clark, formerly ef the NRC for many helpfulideas and sugges-

'the people who corataented are (in oider of receipt): Dr, tions Gary Comfort of the NRC for help with uranium Pael li. Marrow, Univetrity of Rochester t.tedical C enter; hexafluoride atmospheric dispersion calculations; Peter Dr, Darre0 R. Fisher 11attelle Pecific Norttwest I abora-laysen and Charles Nilsen of the NRC for many help (al tmles; Mr. Jack li, lioney, Athet Signal Inc.; Ms. Je ssie i

I comments and suggestions; Dr. Kathleen Thiessen of CectinWater, Native Ameticans for a Clean linviron-Oak Ridge National Laboratory for information on hy.

ment: Mr. Marvin LeWs, Philadelphia: Mr. l.cc R. Iz ccy, drogen fluoride; Howard Ludwig of NIOSil for informa-Sequoyah FuelsCorporation: Dr. Kathleen M.Thicswn, tion on the NIOS!! IDLil for hydrogen fluoride; Oak Ridge,TN; Mr. Michael Mariot te Nuclear tr. forma-Dr. Vlasta Molak of NIOSil for information on the toxic-tion and liesource Service; Mr Robert A. Just, Martin ity of hydrogen fluoride; and Dr. EdwardStein of OSil A MxiettA Energy Sp. cms, ine.; Mr. Pcter LeRoy, Duke for discussions on the OSHA limits on exposure to sol.

Ergineering nod Se: vices, Inc.; Mr. W. Reid Wilhum.

.ible uranium.

Martin Marietta Energy Systems, int.; Mr. 7. M. Selby, llattelle.Pacitie Northwest labwatories Mr. Richard !!.

{

A draft of this report was published for public comment Sanderson, l'.S. linvironmental Protection Agency; and irt April 1990, with comments requested try July 15, Mr.1%1ip G. Stwell, U.S. Department of linergy.

)

{

i i

b I

vii N('RI E l39!

I

1 l

1. Purpose of This Pp t exposure a npwen fluo._, at a peak concentration of X mil %w as per cubic meter.

The purpose T.Gg moe;my. the early chemi.

cal effects frer' acvts expot irtn to utnd ' hexafluoride O&ty f,19U8, th. NRC's Office of Nuclear Materia,.

wnh the efkis from rue iaktion de f 25 rems to Safety and Safeguards (NMSS) requested techmcal sup-the whole tx dy ed 30f' cem. to the thyrg py, from the Office of Nuclear Regulatory Research with regard to appropriate values. NMSS requested the determination of values for chemical exposures that,like On April 72, M the NRC pubIwhc.t in the Federal a 25-rem whole body dose or 300 rem thyroid dose, would Register an Advance Notice of ProposedWhmaking on n t cause signtficant nonstochastic effects.

the regulation of uranium enrichment plants (53 FR 13276).The aotice said the NRC was considering adding Since the time of the oripad rt quest, the Commission b

to its regulations a new 10 CFR Part 76 dealing with has decided not to proceed with a Part 76 rulemaking at uran'um enrichment plants.

this time (Chilk,1989) nis report provides the support reques'ed tot adetermmation of the equivalency between The notice pointed out thti the release of uranium the chemical t0xicity of uranium hexafluoride and adia-i bexafluoride in an accident muld be primarily a toxic tio. dose needed for the revie'v of 'icense applications chemical hazard rather than a adiological hazard.The for uranium enrichment facilities using uranium potential toxic chemical effects to a person exposed to hexafluoride, p

uranium hexafitoride would tw more severe than the 4/

radiological effects, because umnium is only o.Wy ra-

/

dioactive and because uranium hexafluoride tonns com.

2. Effecte of the Radiation Dows m, pounds that are readily soluble in the body so they can be 10 CFR Part 100 transported quickly tosesitive ' issues.

The radiation dose 6410 CM Part 100 are 25 tura Re advance notice therefore stated thu i would be to the whole body fro s external radiation and 300 rems to appopriate to 'stablish design and siung guidelines the thyroid from radioa%e iodires. Dese values were based on chemical expmire frast are roughly equivalent fixed at a dose at which it was bee.m t i at no sh f. cant to the radiological guidelines in 10 CFR Part 100,"Reac-obsIrvable early effects would occur.

tor Site Criteria " Those guidelines are matained in 10 The immediate effects of larp neute doses of nidiation 1

CFR 100.11. "Determhation of Exclusion Area, Low arc nausea, loss of appetite, fatigue, vomiting, diarrhea, lbplation Zone, and Popd. tion Centt t Distance._ T and changes in the counts of diff crent types of okiod ceP.s.

establish the minimum size of an excius.on trea and bw

%~p cifects would occur only if a threshold dose were population ronedh applicant must show that a specific excevded. Nene of these cffects would be expected in a pashlated release, pven the containment capabil9y of personexposed to a 25 rem acute dose. A 25 rem whole the plant, would not cause doser to in&iduals in 1 hose body do'r.otdd cause a !cmporary reduction in sperm areas exceuling certain Wes. Speafically, the exclusion count in maics and an elevation in chromosome abnor-

~

area must be large enough that "an individual located at malities in bhwl. However, in establishing the dose val-nny point o1 its boundary kr two hours immediately fol-ues in 10 CFR Part 100, these effects w ere not considcred lowing onset of the povo.ated finion pmduct telease significant in compruan with the acute radtatron syn-i yvould not receive a total radat on dose to the whole body drome eIfects.

in excess of 25 rem or a total radiation dose m excess of 300 reto o the thy roid fromiodine exposurL" A fo3, note Be principai effects of a w hole body radiation dose of 25 to 10 cpl! 100.]tstates, "The whole body dose of 25 re m tems are belised to be stochastic effects (delayed onset, referred to above rmresponds numerically to the onceim mJomly occtrring effects), specifically an increased risk a lifetime accideMal or emeri;ency dose for radiathan of cancer it, groups of exposed people and potentially workers which, actmling to NCRP { National Cou nd on tarmfr.1 gentic effeas in the offspring of people who Ra '.iation Protecnon and Measurements) recommenda' were irradis(cJ prior to conception of the offspring.

tions, may be disteptded in the determiranon of citir radiation exposurr r4htus.. "

The esiderton mat an acute dose of 25 rems to the whole oody would result m an increased likelihood of cance' is W1 f.otice stattd "The staff thus propeses using reasonably substantial.The most up to-date and authori-q nntities or corcentration values which are et th7 lower Latise estimates of the risks of cancer death are consid.

rrnge e average thteshold level fcr chemically toxk cred to be those in UNSCEAR 1988 and I!EIR V,1990.

c 'fec.s which, if exceededseould caus.c transient or peo ne data in UNSQAR 1988 yield a risk from acute n2nent injury " The ne, lice suggested that the corte-radiation doses in the range of 4 to 11 cancer deaths per spondi ig va(ues for a uranium nanfluoride release migh 10d person-rems.The 13fil d V estimate is 5.5 to 12 cancer he an -n;ake c( cranium between 4 and 40 rnilhp ams and deaths per 104 persomrems, quite close to the i

NUREG-1391 I

j UNSCE AR 1988 estimate.'lhese estimates apply specifi.

Table 1. Rtlative Weight 5 of Uranium 11eiafluoride j

cally to acute doses between 50 and 600 rems and to the and lis Products s

Japanese population specifically. Ilowever, the risk Mit-mates for a U.S. population exposed to acute doses of 25 Uranium hexafluoride 1.00 rems should not be greatly different from the UNSCl!AR Uranium OM or llEIR risk estimates. Iherefore, the risk of cancer HF 0.23 death for an m erage person exposed to 25 rems is consid-cred to be in the range of about 0.01 to 0.03 per person i.looride ions 0.32 exposed.

~-

4 For genetic effects, UNSCEAR 1988 estiraakd 1.2 ef-3.1 Uranium Toxicity iccts in all successive generations per W person tem received before or during the reproductive pe riod 'lhere.

fore, the average risk of a radiation-induced genetic disor-The most important toxic effect of uranium is t'amage to der in a descendent of an average person exposed to a the kidneys. liigh doses of uranium cause tissue damage 2Ocm dose is estimated to be about 0.003' n the kidneys, leading to functional loss as indicated by failure to resorb urinary protein, glucose, catalase, phosi A 300-rem dose to the thyroid from radioactive iodines is phate, citrate, and crcminine. Iligh doses of uranium also not believed to have any acute effects. Hypothyroidism affect the blood vasculature throughout the body. Capil-from radioiodines is considered to have a threshold of lary permeability, blood pressure, and edema may in-1000 rems (Abrahamson,1989). The likelihood of death crease, and clotting ability may decrease. Uranium may damage capillary membranes, and it it also known to from thyroid c?ncer is estimated to be m the vicinity of induce some damage to liver and muscle tissue..is effects 0.002 (Abrahams<m,1989); in addition, some nonmalig-nant thyroid nodules could be caused. Based on the avail-on the nervous system may be similar to those Wm pol-able evidence, a 300-rem thyroid dose is considered to soning Sy other heavy metals (Fisher 10S8).

have less risk than a whole body dose of 25 rems.

1 The toxic effects of uranium were reviewed by a panel of

~

While a whole body dose of 25 rems or a thyroid dose of four prominent uranium toxicologists in 19S4 (Just,1984, 300 rems have a potential for significant long.ttem ef.

and Just and limler,1984). The toxicologists were fects, they do not produce significant nonstochastic Dr. John 11. Ilursh, Dr. lxonard J. Irach, Dr. Paul E.

(deterministic) cifects.

Morrow, all from the University of Rochester, and Dr.

Mcdonald 11. Wrenn from the University of Utah. 'the

[.anel arrived at a consensus on the toxic effects of ura-

3. ChelHICal Toxicity of Uranluin nium.'the results presented in Just and limler are shown IICXaIhloride and ItS Products in Table 2. In addition, the toxic effects M uranium were reviewed at a meeting sponsored by the NRC in Decem-Whch aranium hexafluoride is scleased in air, it reacts ber 1985 (Kathren,1988). The information by Kathren is rapidly with water vapor and forms uranium oxyfluoride consistent with that presented by Just and Emler.

and hydrogen fluoride:

A word of explanation is necessary to explain the mean-UFe + 2110 - UO Fr + 411F + heat ings :.f the row labeled "'lhreshold for transient renal 2

3 injury or effect" and the row labeled "No effect." The The reaction occurs very rapidly The chemical reaction "No effect" row gives levels of uranium at which the releases heat, which may make a plume of these chemical expert panel was confident that there would be no observ-products buoyant and cause it to rise. The chemicals aNe cRects M any type 'lhe row labeled Threshold for formed by the reaction have three toxic effects: (1) the transient renalinjuy or effect is the paners estimate of uranium in the uranyl complex acts as a hemy metal the level at which effec;s start to be observed.

poison that can affect the kidneys; (2) the hydrogen fluo-ride is an acid that can cause acid burns on the skin or The renal injury or effect threshold of 0.058 mg-U/kg is lungs if it is concentrated and (3) the fluorides (uranium the level at which one or more of the chemical compo-oxyfluoride and hydrogen fluoride) can cause fluoride nents of the urine indicates that there has been some poisoning if intakes are large. Ilach of these effects will be change to some structure within the kidney. 'the chemical discussed separately below, changes at the threshold level have been found to be in '.sient, wh the chemical composition of the urine One kilogram of UFe contains 0.68 kg of uranium and soon returning to normal. Microscopic cxamination of the 0.32 kg of fluoride ions.'the reaction with water in the air kidney would detect no damage several weeks after the produces 0.23 kg of IIF, as shown in Table 1.

exposure.

NURl!G-1391 2

Tabla 2. liculth Effeo fin,i Intake of Soluble Uranlum Uranium Uranium Uranium intake per Lg body wt (mg) in (mg) by llcalth effect (mg.U/kgP 70 kg person 70 kg person" 50% lethality 1.63 114 230 1hreshold for permanent renal damage 0.3"'

21 40 1hreshold for transient renal injury or effect 0.058 4.06 8.3 No effect 0.03 2.1 4.3

'llated on Just and Emler,19M,cacept where noted The number of significant figures result from avernpng and do not imply that much ptremon

" Intake is defined as tlx total arnount of materialinhaled into the txuty,f the intake mH be excreted through the kid t uncludes tnaterialimmediately ethaled en addition to matenal abvirbed by the buc!v. I or 1-mteron uramum (triurd.1987, pge D-163).prncies in soluble form, about 49% o

"*Dased on the conclusions of Wann in Just.19M.

At the transient renal injury threshold, the initial loss of been subjected to intakes equivalent to a 40-mg intake by reserve capacity, if any, would be small; and that loss a 70 kg hurnan, nor have long term biochemical function would subsequently be reduced by repair Thus, the long-changet been detected.

term consequences to a person subjected to a single in.

take of uranium at the injury threshold should be mini.

Medical examinations of two workers involved in a ura, mal.

nium hexafluoride accident in 1944 revealed no physical findings attributable to uranium intake (Kathren,1986).

An intake above 8 or 9 mg produces evidence of transient The workers were estimated to have had ir,itial lung depo-cffects but no evidence of long term effects. If there are sitions of 40 to 50 mg of uranium (equivMent to total any long term effects, the effects are too small to be intakes of 80 to 100 mg of uranium). Thirty eight years detected.

after the accident, no effects of the uranium were found.

'this surgests that accidental intakes of 80 to 100 mg can NRC regulations (10 CFR 20.103(a)(2)) limit acute in-occur without sign'ricant long-term effects. and therefore takes of soluble uranium by workers on a weekly basis suggests that the pennanent damage threshold may be because of its chemical toxicity. The limit for weekly in-higher than the values in Table 2' take is 9.6 mg.1his limit also applies to a single short-duration intake. NRC believes this intake would cause no Similarly, Fisher et al. (1990) studied the effects of ura-harmful effects.*lhe NRC limit was based on the ACGill nium on 31 workers involved in an accident in 1986. None TLV (threshold limit values) of 0.2 mg/m3 (ACGill, of the workers has sustained nr.y observable health cf fects 1986) inhaled for 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> at a breathing rate of 1.2 m3/hr.

from exposure to uranium.1hc highest intake was esti.

Ilased on the above information, this level is still appro-mated at 24 mg, and eight of the intakes were in the sange priate.

. of 11 to 24 mg. These observed effects do not appear to support a threshold for transient effects as low as 8 mg as A recent NRC final r71e on emergency preparedness for shown in Tab!c 2.

fuel cycle and other n,dioactive material licensees (54 FR 14051, April 7,1989)sclected 2 mg of soluble uranium as The results of two cases of accidental exposure to large i

a potential intake by a penion offsite for which ernergency amounts of uranium that occurred in China were recently plans would have to be prepared. The 2-mg value was reported (Sulu,1990). In one case, a wor ker was exposed selected to be well below the threshold at which effects to a cloud of UF4 powder. UF is generally considered a 4

could be expected to be observed and to have a large moderately soluble (Cire.s W) compound. The total uri-margin of safety. Thus, the 2-mg value specified in the nary excretion through day 1065 was cakulated to oc rule contains a larger safety margin than appropriate for about 87 n,g. Kidney function started to show abnormali-the comparison in this report.

ties on day 78.ollowing the accident, Kidney function gradually returned to norn...I during the course of a j

Of the panel of experts whose views are presented in Just seven-year medical followup. The amount of soluble and Emler, 1984, only Wrenn identified a level of ura-Class W 1-micron urar.ium particles that would have to l

nium expected to cause permanent injury. That level was be inhaled to prom a arinary excretion of 87 mg is equivalent to a uranium intake of 40 mg. However, micro.

about 600 mg (Lessard,1987, page 11-340). The reported

(

scopic examinations of the kidneys of animals have not health effects associated with the uranium urinary excre.

l found evidence of long-term injury when the animais haa tion of 87 mg are fairly consistent with those in Table 2, 3

NUREG-1391 1

nlthough the lack of any observed permanent kidney dam-2.535 rems per rnicrocune, calculatcJ f rom the value of age suggests that permanent kidney damage may require 6.85 x 10> Sv:lig pren m 1.ckerman (19%) for more uranium intake than indicated m the table when uranium-235, solubility Class it The cuct values for uranium enters the kidneys gradually.

uranium-234 and uramum-238 are shghtly different, but exact values would not af fect the results.

In the second Chinese case, a man was exposed through the skin to uranyl nitrate and uranium oxide. 'Ihe uramum Table 3 shows taat, even for the highest ennehments, the oxide would be relatively inert, but the uranyl nitrate uranium intake needed to produce a dose of 25 rems is would bc highly soluble (Class D). Urmary excretion was well over 100 mg. This compares to an intake of 10 mg of 130 mg (equivalent to 260-mg intake by inhalation). The uranium derived as the intake of soluble uranium that patient became ill and showed signs of kidney damage, would not result m acute effects from chermcal toxicity.

The signs of kidney damage disappeared by one month Therefore, uranium mtake for soluble uranium com-after the accident. 'Ihese results also suggest that the pounds will be limited on the basis of chemical toxicity values in Table 2 for permanent Lidney damage may be rather than raianon dose, regardless of ennchment, too low.

Ilased on the discussion above, it is concluded that the 3.3 II drogett Fluoride Toxicity 3

NRC's limit of 9.6 mg of soluble uranium for a smgle ecute intake is an intake that would produce in humans Moderate exposures to hydrogen fluoride in air can cause either minimal or nondetectable effects, either short.

s nartingof the skin,tespiratoryirntauon. irritation of the term or long-term.Thus, an intake of soluble uranium of conjunctiva (the mucous membrane that lines the inner 9.6 mg, rounded off to 10 mg, is selected in this report as surface of the cyclids), and pronounced taste. Massive being comparable to a radiation exposure of 25 rems since exposurc to hydrogen fluonde m air can cause progtessive neither of these exposure conditions have significant destruction of the bronchial mucous membrane and swel-acute effects to the exposed individual.

ling of lung tissue, which can be fatal.

The toxicity of hydrogen fluoride has been reviewed in 3.2 Padiation Dose from Uranium industriul ugiene und Tom olog (Patty,1962). in J ust and Emler (1934), in "Cntena for a llecommended Stan-

,Ihe quantity of uranium ip soluble form and at vanous dard-Occq <tional Exposure to llydrogen 171uonJe" ennchments that must be mhaled to deliver an effective dose equivalent of 25 rems is shown in 'lable 3. Ihe (NIOSil,1976). and in " Summary Review of llealth Ef-specific ac;ivities m rable 3 were calculated using the fects Associated with Ilydrogen l'luoride and Related Compoands: Health issue Assessment"(EPA,198S).

following equation (from 10 Cl R Part 20, Appcodix 11, fo tnote 3h

.lhe effects of inhalation of hydropen fluoride as de:cr-S A = 0.4 + 0.38E + 0.0034F2 mined by expenments on animals are summarized "a.

ble 4.

where: SA = spccific activity in microcuries/p, and E = enrichment it. percent uranium-235.

I"! *""7.togc substanm, thm wuld be concern about senous mjunes at sublethal levels. llowever, in the case The effective dose equivalent in rems per gram of ura-of acute exposures to hydrogen fluoride,if fatality from nium intake was calculated by using a conversion factor of suffocation caused by edema (swelling)in the lungs does

'Ir.ble 3, Intakes of Uranium of Yario'as Enrichments To Produce 25 rem EITecthe Dose Equhalent Effecth e intake to produce Uranh.s ichment Speelfic aethity dose equivalent 25-rem effecti e

(% (NE (pCilg) per gram U (rcr')

dose equivalent (milligrams)

O./1 0.67 1.7 14.700 4

1,97 5.0 5,000 20 9.36 23.7 1,000 50 27.40 70.7 353 93 65.2 165.0 151 NURIE 1391 4

~~

i 3

Table 4. IJiects of inhalal!an of Ilydrogen I'luoride on Animals (from Patty,1962) lif' concentration (mg/m3)

Lficct 1500 Some animals died from a 5 minute exposure.

1000 No animals died from exposures of 30 minutes or less, but there was damage to tissue, 500 All animals exposed for 15 minutes or more showed signs of weakness and ill heahh.

100 Could be tolerated for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> without causing death, but was a severe irritant.

$0 Rabbits and guinea pigs showed signs of mild irritation,

. such as coughir; and sneezing, which appeared to lessen after 5 to 15 minutes.

24 Was tolerated for a total of 41 hours4.74537e-4 days <br />0.0114 hours <br />6.779101e-5 weeks <br />1.56005e-5 months <br /> without a fatality, although animals subsequently lost weight.

not occur, the swelling will subside and recovery should rnortality response relationship of irritant and systemi-be complete. Thus, acute sublethal inhalation of hydro-cally acting vapors and gases in which the respmse is gen fluoride is not expected to have long term effects, proportional to C"t, where the exp(ment n is greater than NIOSH (1985) designates a hydrogen fluoride concentra.

tion of 30 ppm (25.4 mg/m3)as immediately dangerous to The best experimental data on the ccmcentration-timo.

life or health (1D111). IDill is defired as "a maximum effect relationship appear to be thoe of Machle (1934) concentration from which one cotdJ escape within 30 and Rosenholtz (1963). Figure 1 is reproduced direc.ly minutes without any escape impairing symptoms or any from M.ichte (1934). He authors have drawn two lir es irreversible health effects(NIOSH,198$).

which they considered to represent cqual effects. T.ie Documentatism on the basis of the NIOSH IDIJi(Lud-wig,1990) states that the IDLH is based on the statement at.3 C

of Patty (1962) that 24 mg/m3 (30 ppm)was tolerated by animals for a total of 41 hours4.74537e-4 days <br />0.0114 hours <br />6.779101e-5 weeks <br />1.56005e-5 months <br /> without a fatahty.

Where C

concentration of IIF

=

A more recent study of the acute toxicity of hydrogen a

a constant fluoride estimated the LCa (lethal concentration to 50 t

time exposed to HF

=

percent of exposed subjects) to be 1670 mg/m3 for a b

exponent

=

30-minute exposure and 1070.ng/m3 for a 60-minuta l

exposure (Rosenholtz,1963). lixposures of rats to 6% 0f This equation is algebraically equivalent to ter llerge's the LCw (80 mg/m3 for 60 minutes) caused only very mild equation. From the slope of the lic in Figuce 1, transient effects-occasional blinking of the eyes and b = 0'58' pawing of the nose, but no other signs of toxicity.There.

fore, the NIOSH IDLil seems reasonably protective.

If one wanted to adopt a more conservat ep* oach and l

select a value of b that would yield a flader c'.rve (lower The NIOSH IDLH suggests a concentration of hydrogen fluoride that can be tolerated for 30 minutes without concentrations for shorter exposure times), t;ie value of b could be rounded down to b = 0.5. He equation would escape impatrmg symptoms or any irreversible health ef' fects, but it does not tell what concentration could be then express a quadratic relationship in which response is pmoortional to concentration squared times time of ex-tolerated for shorter times with the same lack of effect.

posure.Thus, for times t (in min) shorter than 30 minutes, f or substances like uranium that act slowly compared t the concentration C equivalent to the IDLil value of 25 hydrogen fluoride, the tox,c effect is proportional to the i

mg/m3 is given by this relationship:

total intake, which is the product of concentration times time of exposure (Haber% rule). Iloweser, for acute tuic-ity, ten llerge (1%6) found a concentration (C)-time (t)

C - 25 mg/m3 (30 min /t) /2 5

NURI!G-1391 1

i.

Y

%).--g l

l cj ]g

~

I h

?

f i

g

- Aq

-- 7 \\_

-y_._

[y o

q N

N o

s s

6,

\\*

'N

.1 g

.E Q----

g E

w%

K

1. 1 2 il 10 to No too 180 MM to Dd lhLLIC3Ne3sde)

ITIC Figure 1. Effects of exposure of animals to hydrofluoric acid in air. 9 - Death all animals. S - Proportional deaths in group. O - No deaths in group. From Machle,1934. Lines were drawn by authors to show equal effects.

Table 5 shows concentrations calculated from this equa-I!RPG-3 'Ihe maximum airborne concentration below tion.

which it is believed that nearly allindividuals could be exposed for up to one hour without The values in Table 5 are in reasonable agreement with experiencing or developing life threatening the observations of Machle (1934)that a concentration of health effects.

100 mg/m3 could be tolerated by human volunteers for only a little more than a minute.

The ERPG-1 value for ilF is 4.1 mg/m3, the ERPG-2

'the values are also n reasonable agreement with the value is 16.4 rng/m3, and the ERPG-3 value is 41 mg/m3 emergency response plannit.g guidelines for 60-minute exposures to hydrogen fluoride developed by the Ameri.

The ERPG-2 level appears to correspond most closely to can Industrial Hygiene Association (AlllA,1988). The the NIOSil IDill. It corresponds to a level that would AlH A Emergency Response Planning Guidelines are de-cause irritation and have an objectionable odor but no fined as:

serious transient effects and no permanent effects, The ERPG-2 level of 16.4 mg/m3 for 60 minutes is in good ERPG-1 The maximum airborne concentration below agreement with Table 5.

which it is believed that nearly all individuals could bc exposed for up to (me hour without expencncmg other than mdd, transient ad-The concentration-time-response relationship for hydro-verse health effects or without perceiving a gen fluoride has also been studied by ten llerge (1986),

clearly defined objectionable odor, based primarily on the data of Machte (1934)and using a sophisticated statistical technique. Ten Berge also con-ERPG-2 The maximum airborne concentration below cluded that for hydrogen fluoride exposure the effect is which it is believed that nearly all individuals proportmnal to M could be exposed for up to one hour without experiencing or developing irreversible cr The same quadratic relationship has been derived by other serious health effects or symptoms Turner and Fairhurst (1990) based largely on the experi-which could impair an individuars ability to ments of Rosenholtz (1963). Turner and Fairhurst devel-take protective action.

oped the concept of " toxic load" as a measure of the i

NUREG-1391 6

l l

1 Table 5.6ncentrations of an Exposure to flydrogen I'luodde Equivalent in Effect to NIOSil IDLil Level Exposure time Concentration equivalent Exposure (mini to IDLil (mg/m3)

(mg-min /m3) 1 137 137 2

97 194 5

61 306 10 43 433 15 35 530 30 25 750 60 17.7 1060 impact of hydrogen fluoride.They also found a quadratic sium ions. llowever, subjects who have died of massihe relationship:

hydrogen fluoride inhalation do not seem to die of meta-Duonde ion cUccN M of th consequenas of toxie load - C2t severe acid burns to the respiratory tract (Braun,1984).

They then determined a " dangerous toxic load" (ITIL),

A lethal dose from acute fluoride poisoning is estimated which it a pl below the threshold for human fatahty.

to be an absorption of 32 to 64 mgof fluoride per kilogram Fn a expertmental data, they determmed that the mouse of body weight (!!PA,1988). A safe or no cifeet absorp-was the animal most susceptihte to damage from hydro-tion is considered to bc 8 to 16 mg per hilogram of luly gen fluoride. I or the mouse, they determined that a toxic weight. In a 70-kg person, the no effect absorption would load of 2,400.000 ppm 2-min [1,720,000 (mg/m3)2-min]

be about 500 to 1000 mg. Intakcs of this magnitude would would be below the threshold of lethality. Thus, for exam-be associated with lethal quantitics of both uranium and plc, a concentration of 240 mg!m3 for 30 minutes would hydrogen fluoride. 'Ihus, for all practical purposes, acute produce a dangerous toxic load.

effects of fluoride toxicity from a uranium hexafluouJe release can be ignored. There has been some resemh Turner and Fairhurst's ITIL is a factor of 8 higher than that indicates that fluorides may be carcir.openic. A re-the NIOSil 1D1.11. 'Ihc difference occurs because they cent animal study found more cancers in rats given fluo-are based on different criteria (fatality 'hreshold vs. no rides than in controls. No effcct was observed in mice, but escape-impairing symptoms). Ilowever, I urner and Fair-in another study, animal and human tissues maintained in hurst support the usc of a quadratie rclationship between test tubes and treated with fluoride were subjested to concentration and effect.

genetic tests to indicate possible cancer risks. All tests To surnmarize, in selecting a level for no significant ef-Icet, short term or long term, it was decided to use as a Overall, there is not yet a scientific consensus on whether basis the NIOSil IDI.IIlevel of 25 mg/m3 for 30 minutes.

fluorides are carcinogenic. This issue, however, is not If the exposure time t has a duration other than 30 min-directly relevant to this report, because the basis for com-utes, the concentration C can be calculated by the equa-parison of radiation effects with chemical effects is that tion,C - 25 mg/m3 (30 min /t)0 8.These concentrations there be no observable acute effects, would be irritating and would have on obiectionable odor, but would not prodo;c any escape-impairing symptoms in summary, the acute effects of fluoride ions by them-or any permancta Ufects.

selves are uhimportant relative to the acute effects of either the uranium or the hydrogen fluoride.

3.4 Fluoride Toxicity

4. ComnariSon of the ChemlCal This section discusses the toxicity of the fluoride ion (f~).

The Quoride ions can also have harmful effects and can Tox. city of Uranium IIcxafluor,de i

cause systemic fluoride poisoning, even death from car-With Radiationi DoScS diac or respiratory failure. The fluoride ions can pene-trate the skin, des roy tissue under the skin, and cause The Advance Notice of Proposed 1(utemaking for ura.

inhibition of vital enzymes and dangerous disturbances in nium enrichment facilities proposed "using quantitics or metabolism (e.g., calcium and carbohydra:e balance) by concentration values [for toxic chemicals } w hich are at the chemical bindmg of the fluoride ion to calcium or magne-lower range or average threshold level for chemically 7

NUlti!G-1391

toxic effects which, if exceeded, could cause transient or C - 25 mg/m3 (30 min /t)u permanent injury.,,

As can be seen from the previous sections, the efft ts of

• Ihe values developed in this report for uranium intake radiation, soluble uranium, and hydrogen fluoride are and hydrogen fluoride exposure comparable to a 25. rem different, llowever, it is possible to identify uranium in.

whole body dose are values that can be used in the design takes and hydrogen fluonde exposures that will not cause of a plant and the evaluation of c(msequences in the event

. transient or permanent injury.

of certain specific postulated accidents. The values are neither acceptable exposures nor limits on exposures.

'lhc health effects from soluble uranium were reviewed in Section 3.1 and summarized in Table 2. Just and Emler

.Ihe values are not " acceptable" any more than a 25 rem 1

(1984) selected an mtake of 8 mg of uranium to be near whole body radiation dose is an " acceptable" dose. 'Ihe the threshold for mild tnmsient effects that,have no values are also not limits. The concept of a limit implies known long term effects. NRC regulations permit intakes that one has a choice and can control the exposure.'Ihe of up to 9.6 mg of soluble uranium for workers with the actual situation dunng an accident is that neither the assumption of no sigmficant adverse effects. An intake of situation nor the exposure that will result c:m be con-soluble uranium with no significant detectable health ef-trolled' fccts, transient er permanent, appears to be about 10 mg in round numbers.

One possible use of the values is to establish the size of an

- Ihc health effects of hydrogen fluoride were reviewed in exclusion area around the facility. To do this, a design

1. ' ion 3.3 and summarized in Table 4. From the infor-basis accident must be determined.The design basis acci.

j mation presented, it can be seen that exposures to ilF of dent is a hypothetical accident that a facility must be i

25 mg/m3 for 30 minutes would not cause "any escape-designed to cope with, but it is usually not the worst impairing symptoms or any irreversible health effects."

possible accident. 'the design basis accident postulates This exposure should not have any significant adverse certain equipment failures, but generally also assumes health effects and would not cause transient or perma-that other engineered safety systems will function. An-nent injury. For times other than 30 minutes, the concen-other possible use of these values would be to identify tration of hydrogen fiuoride considered to have an processing equipment for which there should be a high equivalent cffect can be calculated from the following degree of protection against a significant release of ura-equation:

nium hexafluoride.

e

)

l l

l.

NURiiG-1391 8

I L

~

~ -. -.-....-..,, - - -

REFERENCES Abrahamson, S., et al., "licalth liffects hiodels for Nu-Just, R. A.,"ilport on Toxicological Studies Conecrnmg clear Power Plant Accident Consequence Analysis,"

F.xposures to Uli and Uli liydrolysis Products," DOli NRC Report NUREG/CR-4214 Revision 1, Part II, Report K/D-5573 Revision 1,1984.

1989 Just, R. A., and V. S. Emler,"Genenc Report on llcalth American Conference of Governmental Industrial lip Effects for the U.S. Gaseous Diffusion Plants," DOli gienists, "TIV's: Threshold Limit Values for Chemical Report K/D-5050,Section VIII, Part 1,1984.

Substances in the Work Environment Adopted by ACGill with Intended Changes for 1986-87," Cincinnati, Kathren, Ronald L, and Robert 11. hioore,

• Acute Acci-Ohio,19S6.

dentalInhalation of U: A 38-Year Follow-Up " Health Physics. 31.609-619,1986.

American Industrial livgiene Association, "limergency Response Planning Ghidelines-llydrogen I'luaride,"

Kathren, R. L, and J. R. Weber, Editors, "Ultrasensitive Akron, Ohio,1988.

Techniques for hicasurement of Uranium in Iliological Samples and the Nepnrotoxicity of Uranium," NRC lle-

"ILEIR V," Committee on the Biolcgical Effects of !oniz.

port NURl!G/CP-0093,1988.

ing Radiations, National Research Council Health Effects of Lposure to Low Lerc/s ofIonizing Radiation: BEIR l',

i.essard, lidward T., et al., " Interpretation of Ilicassay National Academy Press, Washington, DC,1990.

hicasurements." NRC Report NURl!G/CR-4884 (llNL-NUREG-52063),1987.

liraun, J.,11. Stross, and A. Zober *Intoxicalion Follow.

ing the Inhalation of flydrogen Fluoride," Archives of Lu%, Iloward R.. editor," Documentation for immed,-

To.dcology, Volume $6, pp. 50-54,1984.

ately Dangerous to Life or IIcalth Concentrations, Draf t, National Institute for Occrational Safety and Chilk, Samuel J., Secretary of the Commission, hiemo-llealth, Cincinnati, Ohio, July 1990. (Copies may be ob-tained from 11. R.1.udwig, NIOSil,4676 ( olumbia 1 ark.

randum to Victor Stello, Jr., I!xecutive Director for Op-erations, " Staff Requirements hiemo Re Proposed w y, Cincinnati, Ohio 45226.)

Rule," hiay 9,1989. Available in the NRC Public Docu-hiachle, W., et al., "The liffects of the Inhalation of ment Rmm.

Ilydrogen Fluoride.1.The Response Followinglixposure E

Eckerman, Keith F., Anthony 11. Wolbarst, and Allan C.

l

I45, 34' B. Richardson, Limiting l'alues of Radionuclide intake and Air Concentration and Dose Conversion Factorsfor Inhala.

NlOSl1, Cnteriafor a Recommended Standard-Occupa.

tion. Submersion. and Ingestion. Federal G uidance neport tional Wsm to Hydrogen 17aoride, IIILW Publication No. I1, EPA Report EPA-520/1-88-020,1988.

NIOSil 76-143,1976.

Environmental Protection Agency," Summary Review of NIOSil, "NIOSil Pocket Guide to Chemical llazards,"

llealth Effects Associated with Ilydrogen Fluoride and ilHS Publication NIOSil 85-114,1985.

Related Compounds: llcalth issue Aussment," !!PA Report EPA-600/8-89-002F,1988.

Patty, Frank A., Editor, 'ndustrialHygiene and Toricolog, Volume II, Second Revised Edition, John Wiley & Sons.

Fisher, D. R., " Uranium /' in Handbook on the Toticity of New York,1962.

Inorganic Compounds, Chapter 6S, pp. 739-748,11. G.

Seiler and 11. Sycl editors. hiarcel Dekker, Inc., New Rosenholtz, hiJ., et al., "A Toxicopathological Study in York,1988.

Anunals After Brief Single lixposures to flydrogen Fluo-ride," Am. Ina. Hyg Assoc. J., 24,253-261,1963.

Fisher, D. R., hi. J. Swint, and R. L Kathren,"I! valuation of flealth Effects in Sequoyah Fuels Corporation (SFC)

Sulu and Fu-Yao Zhao,"Nephrotoxic 1.imit and Annual Workers from Accidental Exposure to Uranium Limit on Intake for Natural U," Health Physics, JS.

Hexafluoride,"

NRC Report NUR EG/CR-5566 619-23,1990.

(PNIc7328), hiay 1990.

j ten !!crge, W.F., A. Zwart, and L hi. Appelman," Con-1 International Commission on Radiological Protection, centration-Time hiortality Response Relationship of Ir-

"I imits for intakes of Radionuclides by Workers,"ICRP rilant and Systemically Acting Vapours and Gases," J.

Pubheation 30, Pergamon l'ress,1979.

Hu: Mat. 13, 301-309,1986.

9 NURI G-1391

,,m

I Turner, R.M., and S. Fairhurst, " Toxicology of Sub-United Nations Scien:lfic Committee on the Effects of stances in Relation to Major Hazards," Her Majesty's AtomicRadiation(UNSCEAR),Sounes EfectsandRisks Stationery Office London,1990. (Available for inspec-oflonizing Radiation, pp. 387,493-494 United Nations, tion or for copying for a fee at the NRC Public Document New York,1988.

Room,2120 L Street NW., Washington, DC.)

s NUREG-1391 10

1 ORM 336 U.6, NUCLE AR REGULATORY COfMSSON 1 HU R 1.'a n.v,.,. Aoo.eoem N,n.

NnCM,,m.

woi. nor BIBUOGRAPHIC DATA SHEET t*

"

• C is mstructions on ine rev.rs.)

NUREG-1391

2. TITLL AND 6VtiflILE

3. DATE HLPORT PVouSHL0 Chemical Toxicity of Uranium llexafluoride Compared to Acute Effects uONTH l

YrAR of Radiation February 1991 Final Report C FIN OR GRANT NUMBER

6. AVI M itb)

6. TYPE OF H6POHf Technical Stephen A. McGuire 7, PEROD COVERED (Inciustv. D.t.s)

4. PE.RFORMIN.G OHGAMZ.ATON = NAME m.D.no m.8E68 (aw.RC, provia. Devism. Orfic. cr H.geon, U. S. Nuca..r H. gut. tory Comm4ssa..no AN ADD tf N m mno oe ss: it contr ctor, orove. n mno s s. )

Division of Regulatory Applications Office of Nuclear Regulatory Hescarch U.S. Nuclear Regulatory Commission Washington, DC 20555

9. BPONBORIN.r R.gJ.At4ZATON = NAMEnd m ADOH1 SS.s(s-)NRC. tytm "3.m..s bow.* ; 4f castr ctor, provsoe NRC Division. Ofhc. or H.geon, G OHG AND if U. S. Nucl.

tory Comrnission.

lling 6ddr Same as 8. above.

10. BUPPLEMLNT ARY NOTE $

11. ABSTRACT (200 waros or 6.ss)

The chemical effects from acute exposures to uranium hexafluoride are compared to the nonstochastic effects from acute radiation doses of 25 rems to the whole body and 300 rems to the thyroid. The analysis concludes that an intake of about 10 mg of uranium in soluble form is roughly cornparable, in terms of early effects, to an acute whole txidy dose of 25 rems because both are just below the threshold for significant nonstochastic effects. Similarly, an exposure to hydrogen fluoride at a concentration of 25 mg/m3 for 30 minutes is roughly comparable because there would be no significant nonstochastic effects. For times t other than 30 minutes, the concentration C of hydrogen fluoride consid-cred to have the same effect can be calculated using a quadratic equation: C - 25 mg/m3 (30 min /t)0 6. The purpose of these analyses is to provide information for developing design and siting guidelines based on chemical toxicity for enrichment plants using uranium hexafluoride. 'These guidelines are to be similar,in terms of stochastic health effects, to criteria in NRC regulations for nuclear power plants, which are based on radiation doses, C r.oort.)

13. Av^A.ABUTY SrATEMENT

12. xry woRosoEseneroRs tust woros or pnr s.s tnat wm ssist res..ron-s in ico.iig Unlimited

14. SECURITY CLASSINCATON Uranium, uranium hexafluoride, chemical toxicity, enrichment, hydrogen fluoride, siting criteria Unclassified (Thu Report)

Unclassified 16, NUMBER OF f*AGt'$

16.F4UCE i

NRC FORM 335 (2-68)

9 THIS DOCUMENT WAS PRINTED USING RECYCLED PAPER.

I 1

UNITED STATES sese 4t soum etass r.au

(l

• "^t a n',*

- NUCLEAR CEZULATORY C ;MMISSION WASHINGTON,' D.C. 20565 I~,'

OFFICLAL BUSINESS PENALTY FOR PRfVATE USE, $300 120555139531 1 1ANIRH1Pu US NRC-0ADM hl DIV FOIA f.

PJ3LICATIONS SVCS TPS P3R-NUREG g

P-223 E

WASH!NGTJN CC 2055' h

F\\

'MCd p-ae e

Ez 1

-g 8

m.

i, J

l

m i

C;

2

'l L

g w 1 L

-