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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RG-1.003, Rev 1
Download: ML13350A383 (12)

.!a Revision 1 P

U.S. ATOMIC ENERGY COMMISSION

REGULATORY

DIRECTORATE OF REGULATORY STANDARDS

Revision I

June 1973 GUIDE

REGULATORY GUIDE 1.3 ASSUMPTIONS USED FOR EVALUATING THE POTENTIAL RADIOLOGICAL CONSEQUENCES

OF A LOSS OF COOLANT ACCIDENT FOR BOILING WATER REACTORS'

A. INTRODUCTION

S.'i'Cllil 50..;,I *it fI I('FR PlaII 50( eiliuir ls th:t each

1pl'icailll l a ,oittl t lrlic n pli ltm l ilil or olperaling lic*tise

'ro',idtc an :!lhlvsis mtid evahaltion ol" the design and pl' ci; Iiiice of1 sitlicitlres. s*:{;ems anld Components of ihtc I:,,iility with the otive t" assessing the risk to lputllic h10:1t ll

aitd

-

lfelv resl frm Im

,

oporation ol'the laTilily.

"h"

de:;ipi basis loss (of' coolant accident l()C' A i5 )IliC

,I

I

p[st lat3ted accidents used 1o evaluate fil ade(l'iacv ofi these Sliltctures.

syll.*y s. and c..'tIIIpolt0elli s will lrespecl It tile public health a*nd safely.

This Inidle -,i\\'es :,ccepltble assumlptions lhat mavy be iseal ill eva\\tial l- tihe radiological ctnsequcuces of' this accident for a boiling wlei leactor. Ill soniLC CLasCs, ntiitsnltal site chlaractelrisltics.

plant dest;i featlres. or othlr li' l tolls nav:y retqglire dilferetit asstinlotionls w\\hich wiill ble Ctiside Led on anl illtividulial case basis. The Advisoty ('Cimmnitee Oil Reactor S:ile'quards hias been.

consul ted con:ernini lt is guide altnd has conceturred in tlie regulatorvy pl ýili inl.

B. DISCUSSION

Arler reviewtitt a

titinumber or" applicationls for conslitiet iin

,t nuits mnd opetating licenses for boiling water p*,,\\er reacolos. tile AEIC Regulaltury staff has developed a rilniber ofl'

appropriately conservalive al, ptinons. bliscd on en&inecring juidpneni and on applicable eXperimnenltal results fromn sa 'ty research progratus cndudcted by the AEC and(l tie nuclear industryv. that are used ti) evaluale calculalions of tlie radiological consequetces of1 various postulated accidelel s.

This guide lists acceptable assumptions that may he u-sed to evalutate the design basis LOCA of' a Boilinlg Wa enr Rcactor (IIWPR).

It should be shown tlhal tlhe of*lsi tc.,lose cotnsequences will be within the guidelines of I(I CFR Part 100.

C. REGULATORY POSITION

I.

aIlle

,ssutllptiotis elatied I ll lte tcle:se o' l;ldia:lct ii iilellit l front1 th11 f0 I andl collt iilnltiill alle ;as I",lfows:

a.

"\\'i- t l >y-f'ive percent, of tile equilih)iilutn radioactive iodine invetn tory dovelo*.ed fromt mia\\ iliintt

!'uitl pow'er opeiatioi of thie core slhuhld IV JssI.niCId 1)

he imtncdililely available I'Mti leakaue fioin the primar:iyv reactor conttaiinment. Nine tV-mit percent ito this 2 perceill is to Ile assulmled ito he ill tile 'orto of'ei nlenial iodine. 5 percent of' this 25 percent ill ilic ltOnn oI

particulate ioidine. and -I p't.eent of this 25 percinti it!

lhe l'orit of' orwanic iodides.

h.

One hluldred percent o1'

the eqLlihibritinlt radioaclive nhble gas itnVentorny developed Ir'omll IltaxitiltilM frill powver o**ralion of' [lie %:oie should ble assumed it) lb ie tltedialtelv available lot hcakane It'oit tle leactol Coll lailllltent.

c.

The elfl*f .os tf' radiolo-ical deca, during holdup inl thle conwaiintient or othet bujildimes should ble taketn into accounltI.

d.

'File reductiotn ill (hle alotii titt ' adioactive mtat.'rial :ivailfable for leaka!

ito the ehnvironineut bv Cloln[;,ilmllelln Spray'.

recirtuilaing filter sys*cnis. ni olhier eneih:eered sai'eity ftatlres mtay be takelil itlno :icclittl, bill the atounit of' reduction ihi concrentiation of radioactive materiils shotuld be evtlualed on

an ildividual case ba:sis.

e.

Tile primary conllaitnitent should ble assumed to leak at the leak rate incorporated or tio hie incolporated in thie technical specifications f'or the duration ill' [lie accident. 2 The leaka*e shotild be assuiited ito pass t"'l'iS guiidte is a revision *l'ltirrittr Sate \\l Giuide 3.

2'lic e*t'iti on containni ent leakaee Iindcr atccid.nl conditio 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 I*saiis.

USAEC REGULATORY GUIDES

Copies of published guides may he obtained by reqcuest indicating the. divisions deilred 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% lot methods accptablte to the AEC Regulatory staff of implementing specilit part- of itiproverienti In theta guidemý

ace ancouragd and should be sent to the Secretary the Corirmisl*on'

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 compliance with 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 to the llluance or osntinuance of a permit or licante by the Commission.

6. Products

2. Research and Test Reactors

7. 'Transrptortation

3. Fuels and Materials Facilities B. Occullationl Heialth PuhllshM quiewi will hbe revi-id periodically, as aip!iogilat

e. to accommodate

4. Environmental ard Siting

9. Antitrust Review cornrmenit 4nd in reflect new informatint, or experience.

S. Materials and Plant Protection tO, General

---

I

directly to the emergency exhaust system without mixing' in the. surrounding reactor building atmosphere and should then be assumed to be released as an elevated plume for those facilities with stacks.4 f.

No credit should be given for retention of iodine in the suppression pool.

2.

Acceptable assumptions for atmospheric diffusion and dose conversion are:

a.

Elevated releases should be considered to be at a height equal to no more than the actual stack height.

Certain site dependent conditions may exist, such as surrounding elevated topography or nearby stnictures which will have the effect of reducing the actual stack height. The degree of stack height reduction should be evaluated on an individual case hasis. Also. special meleorologicaI and geographical conditions may exist which can contribute to greater ground level concentrations in the immediate neighborhood of a stack.

For example. fumigation should always be assumed to occur: however. tlh- length of time that a rumigation condition exists is strongly dependent on geographical and seasonal factors and should be evaluated on a case-by-case basis." (See Figures I A

through ID for atmospheric diffusion factors for an elcvated release with fumigation.)

b.

No correction should be made for depletion of the effluent plume of radioactive iodine due to deposition on the ground. or for the radiological decay of 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 of persons 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 /> following the accident, the breathing rate should be assumed to be

1.75 x 1 0 4 cubic meters per second, After that until the end of the accident, the rate should be assumed to be

2.32 x 10-4 cubic meters per second. (These values were developed from the average daily breathing rate 12 x 107 cm3/dayl assumed in the report of ICRP, Committee

11-1959.)

31n some c-ases, credit fur mixing will he allowed: however.

the amount of credit allowed will be evaluated on an individual case basis.

"Credit for an elevated release should be given only if the pitnt of release is (I) nire than two and one-half times the height of any structure close enough to afrect the dispersion of the plume, or (2) located far enough from any structure which could have an efrect on the dispersion of the plume. For those It\\R's without stacks the atmospheric diffusion factors assuming pround level release given in section 2.h. should be used to determine site acceptability.

For sites located more than 2 miles from large bodies of water such as oceans or one of (the Great takes. a fumigation condition should be assumed to exist at the time of the accident and continue for one-half hour. For sites located less than 2 miles from large bodies of water, a fumigation condition should be assumed to exist at the time of the accident and continue for

4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

d.

The iodine dose conversion factors are given in ICRP

Publication

2, Report of Comtmittee i1.

"Permissible Dose for Internal Radiation." 1959.

e.

External whole body doses should be calculated using Infinite Cloud" assumptions. i.e.. the dimensions of the cloud are assumed to be large compared to ihe distance Ihat Ihic gamma rays and beta particles travel.

"Such a cloud would be considered atn infinite cloud for a receptor at the center because any additional (gamma andi beta emitting material beyond t(le clotud dimensions would not alter the flux of Igatmna rays andl beta particles to the receptor" (Meteorology and Atomic Energy, Section 7.4.1.1-editorial additions made so that gamnma and beta emitting material could be considered). Under ihese conditions the rate of energy.

absorption per unit volume is equal to the rate ortenergy released per unit volume. For an infinite uniform cloud containing X curies of beta radioactivity per cubic meter the beta dose in air at the cloud center is:

D. = 0.457 E

The surface body dose rate from beta emitters in the infinite cloud can be approximated as being one-half this amount (i.e.. 01D- = 0.23 EOX).

For gamma emitting material the dose rate in air at the cloud center is:

DA= 0.507 E rX

From a semi-infinite cloud. the gamma dose rate in air is:

S=o.2s Ex Where D= 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 emitting isotope in the cloud (curie/mr3 )

f.

The following specific assumptions are acceptable with respect to the radioactive cloud dose calculations:

(I) The dose at any distance from the reactor should be calculated based on the maximunm concentration in the plume at that distance taking into account specific meteorological, topographical, and other characteristics which may affect the maximium plume concentration. These site related characteristics

1.3-2

must be evaluated on an individual case basis. In the case of beta radiation, the receptor is assumed to be exposed to an infinite cloud at the maxinmum ground level concentration at that distance from the reactor. In the case of gamma radiation, the receptor is assumed to be exposed to only one-half the ckud owing to tcie presence of'

the ground.

Tile maxinmm cloud concentration always should be assumed to be at ground level.

(2) The appropriate average beta and gamnia energies emitted per disintegration, as given in the Table of 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 atmospheric diffusion model should be as follows:

(I)

The basic equation for atmospheric diffusion from an elevated release is:

exp(-h 2/2Oz 2 )

VQ

Tu y 0z Where x

= the short term average centerline value of the ground level concentration (curie/meter 3 )

Q

= amount of material released (curie/see)

u

= windspeed (meter/sec)

Gy

= the horizontal standard deviation of the plume (meters) [See Figure V-i. Page 48.

Nuclear Safety, June

1961, Volume 2.

Number 4, "Use of Routine Meteorological Observations for Estimating Atmospheric Dispersion," F. A. Gifford, Jr.)

z= the vertical standard deviation of the plume (meters) [See Figure V-2. Page 48, Nuclear Safety, June 1961, Volume 2, Number 4,

"Use of Routine Meteorological Observations for Estimating Atmospheric Dispersion," F. A. Gifford, Jr.)

h

= effective height of release (meters)

(2)

For time periods of greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> the plume from an elevated release should be assumed to meander and spread uniformly over a 22.50 sector. The resultant equation is:

2.032 exp(-h2 /2oz 2 )

x/Q =

Where x

= distance from the release point (meters);

other variables are as given in g(1).

(3) The atmospheric diffuision model' for an elevated release as a function of the distance from the reactor, is based on the information in the table below.

Time Following Accident Atmospheric Conditions

0-8 hours See Figure 1(A)

Envelope o1" Pastluill diffusion categories based oil Figure A7 NI 'teorolog'

and Atomic I-netryo I tt(,1 ,

assuming various stack heights: vindspeed I

me ier/see; uniform direction.

8-24 hours See Figure ItB) lEnvelope of Pasquill diffusion categories: windspeed I meter/see:

variable direction within a 22.5 sector.

1-4 days See Figure I[C)

Envulope of Pasquill diffusion categories with the following relationship used to represent maximnnumn plume concentrations as a tumeltion of'

distance:

Atmospheric Condition Case I

40Y Pasquill A

601'} Pasquill C

Atmospheric Condition Case 2

50% Pasquill C

50Y%* Pasqtill D

Atmospheric Condition Case 3

33.3',` Pasquill C

33.3% Pasquill D

33.3% Pasquill E

Atmospheric Condition Case 4

33.3!, Pasquill 1)

33.3, Pasquill E

33.3K- Pasquill F

Atmospheric Condition Case 5

50r', Pasquill D

501? Pasquill F

wind speed variable (Pasquill Types A. B. E.

and F windspeed 2 memer/sec: Pasquill Types C

nid D windspeed 3 meter/sec)

variable direction within a 22.5" sector.

4-30 days See Figure I(D) Same diffusion relations as given above- windspeed variable dependent on Pasquill Type used; wind direction 33.3"

frequency in a 22.50 sector.

11This model should be used until adequate site meteorological data are obtained.

In smote cases. avaitable information, such as meteorology, topography and geographical location. may dictate the use of a more restrictive model to insure a conservative estimate of potential offtsite exposures.

1.3-3

I

h.

For BIWR's without stacks dhe almospheric diffusion inodel6,should be as follows:

(I)

The

0-8 hour ground level release concentrations may be reduced b'y a factor ranging from one to a nlaximum of three (see Figure 2) for additional dispersion produced by the turbulent wake of the reactor building in calculating potential exposures. The volumetric building wake correction factor, as defined in section 3-3.5.2 of Meteorology and Atomic Energy

1968, should be used only in the 0-8 hour period; it is used with a shape factar of 1/2 and the minimum croms-sectional area ot the reactor building only.

(2) The basic equation for atmospheric diffuision from a ground level point source is:

x/0 =

41U y oz Where the short term average centerline value of the ground level concentration (curie/rmeter 3)

Q

amount of material released (curie/see)

u windspeed (meter/sec)

O y =the horizontal standard deviation of the plume (nieters) [See Figure V-I. Page 48, Nuclear Safrit

y. June

1961, Volume 2.

Number 4. "Use of Routine Meteorological Observations for Estimating Atmospheric Dispersion," F. A. Gifford. Jr.]

ID

=the vertical standard deviation of the plume (meters) ISee Figure V-2, Page 48.Nuclear Safety, June 1961, Volume 2, Number 4.

"Use of Routine Meteorological Observations for Estimating Atmospheric Dispersion," F. A. Gifford, Jr.]

(3) For time periods of greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> the plume should be assumed to meander and spread uniformly over a 22.5" sector. The resultant equation is:

2.032 X/Q = azUX*

Whe re x

= distance from point of release to the receptor;

other variables are as given in h(2).

(4) The atmospheric diffusion model for ground level releases is based on the information in the table below.

Ti me Following Accident Atmospheric Conditions

0.8 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 direction

8-24 hours Pasquill Type F, windspeed

1 meter/see, variable direction within a 22.50 sector

1-4 days (a) 40% Pasquill Type D. windspeed

3 meter/see (b) 60% Pasquill Type F, windspeed

2 meter/sec (c) wind direction sector variable within a 22.50

4-30 days (a) 33.3% Pasquill Type C, windspeed 3 meter/sec (b) 33.3% Pasquill Type D, windspeed 3 meter/sec (c) 33.3% Pasquill Type F, windspeed 2 meter/sec (d) Wiind direction 33.3% frequency in a

22.5' sector

(5) Figures 3A and 3B give the ground level release atmospheric diffusion factors based on the parameters given in h(4),

I I

A

10-3 S

ELEVATED RELEASE

ATMOSPHfERIC DIFFSON FACTORS

S,0-8 HLJUR RiEtASE TIME

.

FIGURE 1VA)

10-4 S10-5

_

.

.

....

_

.

.

.

..L

.

.÷

.

7.

h* -Vb....

..

... . .

. . ...

10-4

'*'--Ar S-

.d_........___.....I

-1 -

-*.

102

103

10410

Distance from Release Point (meters)

1.3-5

-o : -T

-r----.-

.

..

-

....

................

II

......... ' --

10-3

10-

io2 iO3 o

o Distance from Release Point (meters)

z -6 i

. % -'N

p

.. 1 ATMC

.- LEXMATF&ULEASt.

.

kSH9R1C--D##ISMQ

FACTORS

1-4.C)A'Y.R:1LASE Tljfg.~

FIGURE M()

-- t.................

.

• 10-

10-5 E

0

010

10

...

..

.

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-

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I "

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---

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sk TfI1It40# 1 t

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.

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i I

SI.

zzjzz~~I~

VL~~I

XA¶N.AIX

-I

I

Jpi i:.

i:F [ I

xI

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71 ..1

1f

-NI

0l

10-8

102

103 Distance from Release Point (meters)

1.3-7

..

4 EUiVA"~bRIES

ATAMSW

ON f-OR

TtM

..........

S

.,.

.

.~

4-1

10-5i

10-

IL

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_7j I

x___

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--

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---

7:'.

I~w z..L.J

I

102

103

.1o4 Distance from Release Point (meters)

1.3-8

r

, EtVAMD. RELEASE

ATMOSPHERIC DISPERSION FACTORS

FOR .FUMIGATION qONDITIONS

-ATMOSPHER IC CdiNDITIONgS.

PASOUILL TYPE F

WINDSPEED I METER/SEC

" F1GUHE It ......

10-2 i

h 60 .....

..

0

C,,

10-

...

.....

..

.............

i i:

T

j

.7

i

.....................................

,.. .....

.*.

..

..-.

I

a w

~

H

-F-9 WT

N

I,.A

7-n LTL

4-.

4--4

10-

5

10-6

102

103

104

105 Distance from Release Point (meters)

3..9)

w

~

K"

i

3

2.5 h----

0

0

u

0

ra cc5i FIGU^R'E 2

1

T .

I-

._ ... ..

. .

.M.

Ii

-77 I

t

I

-I..

I

I

I

0.5

0102 St.

ii 3;

1

I

-i

.1.

iTd

~3

6i

102

104 Dlsnme from Structur (won W~

0.-

I A

U

V

.--

.

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.

.

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A

VARIOUS TIN ESF

LC14HN

CI

T

FIGURE V(A)

L-1

8-24 hours

.~

10a3

10

10

Distance from Structure Imeters)

10-5 L

102

-

lA0TMOSERL~qIF LLStOq Fibt

~ .~

~

.~...

..

..

.

.VARIOUS

TIMES FOULOWING IAC Ir INT

~

.

~-..

FIGURE

3B)

30

0-8 hours

....................

.. 43.............................

~~.

.

.....

ta

.

I

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I.

.

... . .

..

. .

I.

i

4

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Dit6Ic fromzz Stutr (meters