Regulatory Guide 1.3

Assumptions Used for Evaluation the Potential Radiological Consequences of a Loss Coolant Accident for Boiling Water Reactor

ML13350A383
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Issue date:	06/30/1973
From:	US Atomic Energy Commission (AEC)
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References
RG-1.003, Rev 1
Download: ML13350A383 (12)

.!aRevision 1PU.S. ATOMIC ENERGY COMMISSIONREGULATORYDIRECTORATE OF REGULATORY STANDARDSRevision IJune 1973GUIDEREGULATORY GUIDE 1.3ASSUMPTIONS USED FOR EVALUATING THE POTENTIAL RADIOLOGICAL CONSEQUENCESOF A LOSS OF COOLANT ACCIDENT FOR BOILING WATER REACTORS'A. INTRODUCTIONS.'i'Cllil 50..;,I fI I('FR PlaII 50( eiliuir ls th:t each:1pl'icailll l a ,oittl t lrlic n pli ltm l ilil or olperaling 'ro',idtc an :!lhlvsis mtid evahaltion ol" the design andpl' ci; Iiiice of1 sitlicitlres. anld Components ofihtc I:,,iility with the otive t" assessing the risk tolputllic h10:1t ll :aitd -:lfelv resl frm Im , oporation ol'thelaTilily. "h" de:;ipi basis loss (of' coolant accidentl()C' A i5 )IliC ,I I p[st lat3ted accidents used 1oevaluate fil ade(l'iacv ofi these Sliltctures. s. andc..'tIIIpolt0elli s will lrespecl It tile public health safely.This Inidle -,i\'es :,ccepltble assumlptions lhat mavy beiseal ill eva\tial l- tihe radiological ctnsequcuces of' thisaccident for a boiling wlei leactor. Ill soniLC CLasCs,ntiitsnltal site chlaractelrisltics. plant dest;i featlres. orothlr li' l tolls nav:y retqglire dilferetit asstinlotionls w\hichwiill ble Ctiside Led on anl illtividulial case basis. TheAdvisoty ('Cimmnitee Oil Reactor S:ile'quards hias been.consul ted con:ernini lt is guide altnd has conceturred in tlieregulatorvy pl ýili inl.B. DISCUSSIONArler reviewtitt a titinumber or" applicationls forconslitiet iin ,t nuits mnd opetating licenses for boilingwater reacolos. tile AEIC Regulaltury staff hasdeveloped a rilniber ofl' appropriately conservaliveal, ptinons. bliscd on en&inecring juidpneni and onapplicable eXperimnenltal results fromn sa 'ty researchprogratus cndudcted by the AEC and(l tie nuclearindustryv. that are used ti) evaluale calculalions of tlieradiological consequetces of1 various postulatedaccidelel s.This guide lists acceptable assumptions that may heu-sed to evalutate the design basis LOCA of' a BoilinlgWa enr Rcactor (IIWPR). It should be shown tlhal tlhetc.,lose cotnsequences will be within the guidelinesof I(I CFR Part 100.C. REGULATORY POSITIONI. aIlle ,ssutllptiotis elatied I ll lte tcle:se o' l;ldia:lct iiiilellit l front1 th11 f0 I andl collt iilnltiill alle ;as I",lfows:a. "\'i- t l >y-f'ive percent, of tile equilih)iilutnradioactive iodine invetn tory fromt mia\ iliintt!'uitl pow'er opeiatioi of thie core slhuhld IV JssI.niCId 1)he imtncdililely available I'Mti leakaue fioin the primar:iyvreactor conttaiinment. Nine tV-mit percent ito this 2perceill is to Ile assulmled ito he ill tile 'orto of'ei nlenialiodine. 5 percent of' this 25 percent ill ilic ltOnn oIparticulate ioidine. and -I p't.eent of this 25 percinti it!lhe l'orit of' orwanic iodides.h. One hluldred percent o1' the eqLlihibritinltradioaclive nhble gas itnVentorny developed Ir'omllIltaxitiltilM frill powver of' [lie %:oie should bleassumed it) lb ie tltedialtelv available lot hcakane It'oittle leactol Coll lailllltent.c. The .os tf' radiolo-ical deca, during holdupinl thle conwaiintient or othet bujildimes should ble taketninto accounltI.d. 'File reductiotn ill (hle alotii titt ' adioactivemtat.'rial :ivailfable for leaka! ito the ehnvironineut bvCloln[;,ilmllelln Spray'. recirtuilaing filter ni olhiereneih:eered sai'eity ftatlres mtay be takelil itlno :icclittl,bill the atounit of' reduction ihi concrentiation ofradioactive materiils shotuld be evtlualed on :anildividual case ba:sis.e. Tile primary conllaitnitent should ble assumed toleak at the leak rate incorporated or tio hie incolporatedin thie technical specifications f'or the duration ill' [lieacciden The shotild be assuiited ito passt"'l'iS guiidte is a revision Sate \l Giuide 3.2'lic on containni ent leakaee Iindcr atccid.nlconditio ot" I'e:ttlires protvidted to red ilce t' t':lkatpie of"radioalclive rtatlritits I'roll ItI" t'(l tnlit1inn n Will 11C he' eV3 litt 1 Lilt:nil individual case USAEC REGULATORY GUIDES Copies of published guides may he obtained by reqcuest indicating the. divisionsdeilred to the US. Atomic Energy Commisvon. Washington, D.C. 201545.Rcgulatnry Guides are issued in describe and make available to the public Attention; Director of Regulatory Stalndards. Comments and suggestion% lotmethods accptablte to the AEC Regulatory staff of implementing specilit part- of itiproverienti In theta guidemý ace ancouragd and should be sent to the Secretarythe regulations. tO delineale techniques used by the staff in of the Commitsion, US. Atomic Energy Commission. Washington, D.C. 20545.ealuating specific problems or postulated accidents, or to provide guidence to Attention: Chief, Public Proo-redinga Staff.applkOjlnts. Reoualo.yi Guides are not substitutes for regulations and compliancewith them is not requited. Mrthods and solutions different from those set out in The guides are itsuedt in the fortlowing ten broad divisior.:the u.-ris will be acceptahle it they provide a basis for the findings requisite tothe llluance or osntinuance of a permit or licante by the Commission. 1. Power Reactors 6. Products2. Research and Test Reactors 7. 'Transrptortation3. Fuels and Materials Facilities B. Occullationl HeialthPuhllshM quiewi will hbe revi-id periodically, as aip!iogilate. to accommodate 4. Environmental ard Siting 9. Antitrust Reviewcornrmenit 4nd in reflect new informatint, or experience. S. Materials and Plant Protection tO, General

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I *directly to the emergency exhaust system withoutmixing' in the. surrounding reactor building atmosphereand should then be assumed to be released as an elevatedplume for those facilities with stacks.4f. No credit should be given for retention ofiodine in the suppression pool.2. Acceptable assumptions for atmospheric diffusionand dose conversion are:a. Elevated releases should be considered to be ata height equal to no more than the actual stack height.Certain site dependent conditions may exist, such assurrounding elevated topography or nearby stnictureswhich will have the effect of reducing the actual stackheight. The degree of stack height reduction should beevaluated on an individual case hasis. Also. specialmeleorologicaI and geographical conditions may existwhich can contribute to greater ground levelconcentrations in the immediate neighborhood of astack. For example. fumigation should always beassumed to occur: however. tlh- length of time that arumigation condition exists is strongly dependent ongeographical and seasonal factors and should beevaluated on a case-by-case basis." (See Figures I Athrough ID for atmospheric diffusion factors for anelcvated release with fumigation.)b. No correction should be made for depletion ofthe effluent plume of radioactive iodine due todeposition on the ground. or for the radiological decayof iodine in transit.c. For the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, the breathing rate ofpersons offsite should be assumed to be 3.47x 10'cubic meters per second. From 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> followingthe accident, the breathing rate should be assumed to be1.75 x 104 cubic meters per second, After that until theend of the accident, the rate should be assumed to be2.32 x 10-4 cubic meters per second. (These values weredeveloped from the average daily breathing rate 12 x 107cm3/dayl assumed in the report of ICRP, Committee11-1959.)31n some c-ases, credit fur mixing will he allowed: however.the amount of credit allowed will be evaluated on an individualcase basis."Credit for an elevated release should be given only if thepitnt of release is (I) nire than two and one-half times theheight of any structure close enough to afrect the dispersion ofthe plume, or (2) located far enough from any structure whichcould have an efrect on the dispersion of the plume. For thoseIt\R's without stacks the atmospheric diffusion factorsassuming pround level release given in section 2.h. should be usedto determine site acceptability.For sites located more than 2 miles from large bodies ofwater such as oceans or one of (the Great takes. a fumigationcondition should be assumed to exist at the time of the accidentand continue for one-half hour. For sites located less than 2miles from large bodies of water, a fumigation condition shouldbe assumed to exist at the time of the accident and continue for4 hours.d. The iodine dose conversion factors are given inICRP Publication 2, Report of Comtmittee i1."Permissible Dose for Internal Radiation." 1959.e. External whole body doses should be calculatedusing Infinite Cloud" assumptions. i.e.. the dimensionsof the cloud are assumed to be large compared to ihedistance Ihat Ihic gamma rays and beta particles travel."Such a cloud would be considered atn infinite cloud fora receptor at the center because any additional (gammaandi beta emitting material beyond t(le clotuddimensions would not alter the flux of Igatmna raysandl beta particles to the receptor" (Meteorology andAtomic Energy, Section 7.4.1.1-editorial additionsmade so that gamnma and beta emitting material could beconsidered). Under ihese conditions the rate of energy.absorption per unit volume is equal to the rate ortenergyreleased per unit volume. For an infinite uniform cloudcontaining X curies of beta radioactivity per cubic meterthe beta dose in air at the cloud center is:D. = 0.457 EThe surface body dose rate from beta emitters in theinfinite cloud can be approximated as being one-half thisamount (i.e.. 01D- = 0.23 EOX).For gamma emitting material the dose rate in air at thecloud center is:DA= 0.507 E rXFrom a semi-infinite cloud. the gamma dose rate in airis:S=o.2s ExWhereD= beta dose rate from an infinite cloud (rad/sec)DE= gamma dose rate from an infimite cloud(rad/sec)EO = average beta energy per disintegration(Mev/dis)Ei = average gamma energy per disintegration(Mevldis)X = concentration of beta or gatnma emittingisotope in the cloud (curie/mr3)f. The following specific assumptions areacceptable with respect to the radioactive cloud dosecalculations:(I) The dose at any distance from the reactorshould be calculated based on the maximunmconcentration in the plume at that distance taking intoaccount specific meteorological, topographical, andother characteristics which may affect the maximiumplume concentration. These site related characteristics1.3-2 must be evaluated on an individual case basis. In the caseof beta radiation, the receptor is assumed to be exposedto an infinite cloud at the maxinmum ground levelconcentration at that distance from the reactor. In thecase of gamma radiation, the receptor is assumed to beexposed to only one-half the ckud owing to tciepresence of' the ground. Tile maxinmm cloudconcentration always should be assumed to be at groundlevel.(2) The appropriate average beta and gamniaenergies emitted per disintegration, as given in the Tableof Isotopes. Sixth Edition, by C. M. Lederer. J. M.Hollander, I. Perhlan; University ofCalifornia. Berkeley:Lawrence Radiation Laboratory: should be used.g. For BWR's with stacks the atmosphericdiffusion model should be as follows:(I) The basic equation for atmosphericdiffusion from an elevated release is:exp(-h2/2Oz 2)VQ Tu y 0zWherex = the short term average centerline value of theground level concentration (curie/meter3)Q = amount of material released (curie/see)u = windspeed (meter/sec)Gy = the horizontal standard deviation of theplume (meters) [See Figure V-i. Page 48.Nuclear Safety, June 1961, Volume 2.Number 4, "Use of Routine MeteorologicalObservations for Estimating AtmosphericDispersion," F. A. Gifford, Jr.)z= the vertical standard deviation of the plume(meters) [See Figure V-2. Page 48, NuclearSafety, June 1961, Volume 2, Number 4,"Use of Routine MeteorologicalObservations for Estimating AtmosphericDispersion," F. A. Gifford, Jr.)h = effective height of release (meters)(2) For time periods of greater than 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />sthe plume from an elevated release should be assumed tomeander and spread uniformly over a 22.50 sector. Theresultant equation is:2.032 exp(-h2/2oz2)x/Q =Wherex = distance from the release point (meters);other variables are as given in g(1).(3) The atmospheric diffuision model' for anelevated release as a function of the distance from thereactor, is based on the information in the table below.TimeFollowingAccidentAtmospheric Conditions0-8 hours See Figure 1(A) Envelope o1" Pastluilldiffusion categories based oil Figure A7NI 'teorolog' and Atomic I-netryo I tt(,1 ,assuming various stack heights: vindspeed Ime ier/see; uniform direction.8-24 hours See Figure ItB) lEnvelope of Pasquilldiffusion categories: windspeed I meter/see:variable direction within a 22.5 sector.1-4 days See Figure I[C) Envulope of Pasquilldiffusion categories with the followingrelationship used to represent maximnnumnplume concentrations as a tumeltion of'distance:Atmospheric Condition Case I40Y Pasquill A601'} Pasquill CAtmospheric Condition Case 250% Pasquill CPasqtill DAtmospheric Condition Case 333.3',` Pasquill C33.3% Pasquill D33.3% Pasquill EAtmospheric Condition Case 433.3!, Pasquill 1)33.3, Pasquill E33.3K- Pasquill FAtmospheric Condition Case 550r', Pasquill D501? Pasquill Fwind speed variable (Pasquill Types A. B. E.and F windspeed 2 memer/sec: PasquillTypes C nid D windspeed 3 meter/sec)variable direction within a 22.5" sector.4-30 days See Figure I(D) Same diffusion relations asgiven above- windspeed variable dependenton Pasquill Type used; wind direction 33.3"frequency in a 22.50 sector.11This model should be used until adequate sitemeteorological data are obtained. In smote cases. avaitableinformation, such as meteorology, topography and geographicallocation. may dictate the use of a more restrictive model toinsure a conservative estimate of potential offtsite exposures.1.3-3 Ih. For BIWR's without stacks dhe almosphericdiffusion inodel6,should be as follows:(I) The 0-8 hour ground level releaseconcentrations may be reduced b'y a factor ranging fromone to a nlaximum of three (see Figure 2) for additionaldispersion produced by the turbulent wake of thereactor building in calculating potential exposures. Thevolumetric building wake correction factor, as defined insection 3-3.5.2 of Meteorology and Atomic Energy1968, should be used only in the 0-8 hour period; it isused with a shape factar of 1/2 and the minimumcroms-sectional area ot the reactor building only.(2) The basic equation for atmosphericdiffuision from a ground level point source is:x/0 =41U y ozWherethe short term average centerline value of theground level concentration (curie/rmeter3)Q amount of material released (curie/see)u windspeed (meter/sec)O y =the horizontal standard deviation of theplume (nieters) [See Figure V-I. Page 48,Nuclear Safrity. June 1961, Volume 2.Number 4. "Use of Routine MeteorologicalObservations for Estimating AtmosphericDispersion," F. A. Gifford. Jr.]ID =the vertical standard deviation of the plume(meters) ISee Figure V-2, Page 48.NuclearSafety, June 1961, Volume 2, Number 4."Use of Routine MeteorologicalObservations for Estimating AtmosphericDispersion," F. A. Gifford, Jr.](3) For time periods of greater than 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />sthe plume should be assumed to meander and spreaduniformly over a 22.5" sector. The resultant equation is:2.032X/Q =azUX*Whe rex = distance from point of release to the receptor;other variables are as given in h(2).(4) The atmospheric diffusion model forground level releases is based on the information in thetable below.Ti meFollowingAccidentAtmospheric Conditions0.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Pasquill Type F, windspeed I meter/see,uniform direction8-24 hours Pasquill Type F, windspeed 1 meter/see,variable direction within a 22.50 sector1-4 days (a) 40% Pasquill Type D. windspeed 3meter/see(b) 60% Pasquill Type F, windspeed 2meter/sec(c) wind directionsectorvariable within a 22.504-30 days (a) 33.3% Pasquill Type C, windspeed 3meter/sec(b) 33.3% Pasquill Type D, windspeed 3meter/sec(c) 33.3% Pasquill Type F, windspeed 2meter/sec(d) Wiind direction 33.3% frequency in a22.5' sector(5) Figures 3A and 3B give the ground levelrelease atmospheric diffusion factors based on theparameters given in h(4),I I A 10-3SELEVATED RELEASEATMOSPHfERIC DIFFSON FACTORSS,0-8 HLJUR RiEtASE TIME* .FIGURE 1VA)10-4S10-5 _......_ .....L ..÷ .7. -Vb.... .. ... .......10-4S- .d_........___.....I -1 --*.102 103 10410Distance from Release Point (meters)1.3-5

-o : -T -r----.- ... -.... ................II ......... ' --10-310-io2 iO3 o oDistance from Release Point (meters)z -6i

.% -'Np..1ATMC.-LEXMATF&ULEASt. .kSH9R1C--D##ISMQ FACTORS1-4.C)A'Y.R:1LASE Tljfg.~FIGURE M()--t................. .*10-10-5E001010... .. ..Ii i.. ..I '*1* [ ....-4-2I I " /'---S --------sk TfI1It40# 1tI------------ L- ..I ýi ISI.:zzjzz~~I~VL~~I XA¶N.AIX-IIJpii:.i:F [ IxI '%71 ..1 1f-NI0l10-8102103Distance from Release Point (meters)1.3-7

• .. 4EUiVA"~bRIESATAMSW ON f-ORTtM..........* S* .,. ..~4-110-5i10-IL -L.4 -4T V : J. _ _7jI x___I Iv. I4N.NINi-- -------7:'.I~w z..L.JI102103.1o4Distance from Release Point (meters)1.3-8 r, EtVAMD. RELEASEATMOSPHERIC DISPERSION FACTORSFOR .FUMIGATION qONDITIONS-ATMOSPHER IC CdiNDITIONgS.PASOUILL TYPE FWINDSPEED I METER/SEC" F1GUHE It ......10-2i;h 60 ..... ..0C,,10-... ..... .. .............i i:Tj .7 : i..................................... ,.. ..... .. ..-.I : aw~ H-F-9 WTNI,.A7-n LTL4-. 4--410-510-6102103104105Distance from Release Point (meters)3..9)

w ~K"i32.5 h----00u0racc5iFIGU^R'E 2 1 :T .I-._ ... .. ...M. :Ii-77 It* I-I..* I I* I0.50102St.ii 3; 1* I-i.1. iTd~36i102104Dlsnme from Structur (won W~0.-

I AU V .-- ._.-.- ..I~ AVARIOUS TIN ESF LC14HN CI TFIGURE V(A)L-18-24 hours .~10a3 10 10Distance from Structure Imeters)10-5 L102

-lA0TMOSERL~qIF LLStOq Fibt~ .~ ~ .~... .. .. ..VARIOUS TIMES FOULOWING IAC Ir INT~ .~-.. FIGURE 3B) 300-8 hours.................... ..43.............................~~. ......ta .I JII. .... ......I. i4 -t103 10LLDit6Ic fromzz Stutr (meters