ML19322C803

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Reg Guide 1.78, Assumptions for Evaluating the Habitabitity of Nuclear Power Plant Control Room During Postulated Hazardous Chemical Release
ML19322C803
Person / Time
Site: Crane Constellation icon.png
Issue date: 08/02/1979
From:
US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML19322C797 List:
References
TASK-TF, TASK-TMR REGGD-01.078, REGGD-1.078, NUDOCS 8001240567
Download: ML19322C803 (10)
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Text

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55Ui_ YbRY GUIDE ci o

DIRECTORATE OF REGULATORY STANDARDS o,*

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REGULATORY GUIDE 1.78 ASSUMPTIONS FOR EVALUATING THE HABITABILITY OF A NUCLEAR POWER PLANT CONTROL ROOM DURING A POSTULATED e.D HAZARDOUS CHEMICAL RELEASE

ontrol rooms during the course of all postulated

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A. INTRODUCTION hazardous chemical releases.' However, the "Acci.

Criterion 4,," Environment:1 and misele desip dental. Episode Manual"2 prepand for the Environ.

bases," of Appendix A " General Desip Criteria for mental Protection Agency (EPA)in April 1972 presents Nuclear Power Plants," to 10 CFR Part 50," Licensing a method for the evaluation and estimation of the area of Production and Utilization Fa:Eities," requins, in affected by the release of hazardous chemicals as a fun:tton of source strength, type of chemical, dsstance part, that'atructures, systems, and components impor.

from s'ource, and meteorology.The " Accidental Episode tant to safety be desiped to accommodate the effects of" Manual" ntes accident potentials from both mobile and and to be ecmpstible with the envircamental conditions stationary sources and identifies some hanardous chemi-associated with normal operation, maintenance, testing, and pcstulated accidents. Criterion 19," Control room,"

cals that may be released. Human tolerance for hazard.

requnes that a control room be provided from whleh ous chemicals should be considered in the desip stage of, a:tions can be taken to operate the nu: lear powtr unit nuclear facilities.

safely under normal conditions and to maintain it in a For hazardous chemicals shipped on routes'near the' saf: condition under at:! dent conditions. Release of nuclear power plant, the shipment frequencies specified hazardous chemicals can potentia!!y resultin the control for consideration in this guide (Replatory Position 2)

>$1 room becoming uninhabitable. This guide des:ribes refie:t the relative a :ident probabilities for :ommon assumptions acceptable to the Regulatory staff to be modes of transportation. A discussion of accident rates used in assessing the habitability of the control room for various transportation modes can be found in V

during and after a postulated extemal release of hazard-Appendix A, " Analysis of Transportation Ac:idents/'

ous chemicals and dese:ibes criteria that tre generally or wAsg.1235.8 Consideratio:i is also grven to the a:ceptable to the Replatory staff for the protection of quandty of hazardous chemical shipped.

the control room operato:s.This guide does not consider the explosion or flammability hazard of these chemicals, The purpose of this guide is to identify thos:

which also must be addressed. The Adsisory Committee chemicals which,if present in sufficient quancties, could on Res: tor Safeguards has been conruited comeminS result in iT::ontrol room be:oming uninhabitable.The this guice and has con:urred in the replatory position.

general desip considerations that are used in w-mg

' A replatory pide is being developed to desenbe speciSc B. DISCUS 0lON design provisions and puroadures that are aceptable to mmrate

' hazards to control room operators from an conte chkxme Ihe control room of a nu: lear power plant should

' rele.ase,

  • Omcc of Air Programs. Publication ArrD.1114. copes be appropriately protected from hr.:ardous chemicals may be ettuned from National TecttnicalInfonnation Semce.

that may be discharged as a result of equipment fsilures, SJ85 Poj*. Royal Road, Spri gfrend, Virgtr:ss 22151.

operator errors, or events and conditions outside the

  • n ASH.1238, " Environmental Survey of Trar.sportaten f

Control of the nuclear power plant.

of Radion: tree Matenals to and from Nuencar Power riants" t'

Decernber 1972. Copes may be obtained from Natroom: Tech-At present, there is no one standani desip evalua-nical Ic!cnnatbn Semce, 5285 Port Royal Road, Spragnehi, tion method in use for CYaluating the habitability of

'Mrginia 22151.

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If maj:t depots or st: rage tani.s of huardous the capabEity of the control room, u designed, to chemicals such as the chemicals listed in Table C 1 of

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w'tIntand huardous chemical releases occurring c'ther on the site or within the surroundmg area are presented.

this guide are known or projected to be present within a

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< Some of the chemicals specificaDy identified, such as Ove-mile radius of the reactor facility, these chemicals helium and nitrogen, thould generally not present a should be considered in the evaluation of control room

, prob!cm except when very large quantities are stored on habitability.' Whether a major depot or storage area the site. Asphyxiating cherrucals such as these need not constitutes a hazard is detemuned on the basis of the J

be c:nsidered unless a significant fraction of the control quantity of stored chemicals, the distance from the

,F room, and the app!icable toxicity hmits(see Regulatory L

room air could be displaced as a recult of their release, nuclear plant, the inleakage charactensues of the contro!

F.tre fighting equipment taed for Sghting chemical Position 4 for definition). Table C 2 gives the critena and electrical fires should be considered as's potential to be used in evaluating the hazards of chemicah to source of hazardous chemicals.

control rooms. A procedure for adjusting the quantities given in Table C 2 to appropriately account This guide identifies chlorine as a potentiaDy haz-for the toxicity limit of a specific chemical, meteorology ardous chemical. Chlorine is used in a rnajority of conditions of a particular site, and air exchanSe rate of a nuclear power plants for water treatment and is nor-controt room is presented in Appendix A of this guide.

mally stored onsite as a liquified gas. A separate guide will be issued to describe the detailed design provisions Chemicals stored or situated at distances greater which ne considered adequate to protect control room than five miles from the facility need not be considered operators from an onsite chlorme release, because, if a release occurs at such a d: stance, atino-spherie dispersion will dilute ano disperse the incoming C. T'EGULATORY POSITION

  • The List of chemieu. pen in Table C t is riot alHncluuve but mdicates the chemeals most commonly encountemi. See in evaluating the habitability of a nuclear power als " Guide ice Emergency Sernces for Hazardous Marnals plant control room during a postulated hazardous 6 Furs. Emustion Arcu" @ Mch assy W chemical release the fotowing assumPticas should b*

obtained from the U.S. Department of Trur.s;nctation.Offkt of Hazardous Matenals, Weihinson, D.C.

made, O

TABLE C.1 SOME HAZARDOUS CHEMICALS POTENTI ALLY INVOLVED IN ACCIDENTAL RELEASES FROM STATIONARY AND MOBILE SOURCES

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Touterrv LN Tonictry Leser m&

mgfr) c Chemics!

ppm e

Chems:s!

pom Acetaldehyde 200 O

360 Ethylent exide 200 180 Acetone 2000 4800 Fluorine 2

4 Acrylonitrile 40 70 Formaldehyde 10 12 Anhydrous ammonia 100 70 Helium asphyxiant Aniline 10 38 Hydrogen cyanide 20 22 Benzene 50 160 Hydrogen suffide 500 750 j

Butadiene 0.1%'

2200 Methanol 400 520 I

Butenes asphyxiant Nitrogen (compressed Ca'non dioxide 1.0%'

1840 or liquified) asphyxiant Ca con monoxide 0.1%'

1100 Sodium oxide 2

Chlorine 15 45 Sulfur dioxide 5

26 i

2 Ethyl chloride 10000 26000 Sutturic acid Ethyl ether 800 2400 Vinyl chloride 1000 2000 Ethylene dichloride. _

100 400 Xylene 400 1740 a Thl: list is not all Irvr.lusive but indicates the hazardous chemicals most commonly encountered, b Adaceed from Sax's " Dangerous Properties of Industrist Materia!s."

C Paris of vapor or gs: per ml' lion parts of air by volume at 25*C and 760 torr (standard temperatsme and pressure).

Approximate milligrams of particulate per cubic mt.ter of air, at standard temperature and pressure, based on

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s Percent by volume.

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EXAMPLES OF WElGHTS OF HAZARDOUS CHEMICALS TH AT REQUIRF 0.

CONSIDERATION IN CONTROL ROOM EVALUATIONS (FOR A 50 mg/m)

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TOXICITY LIMIT AND STABLE METEOROLOGICAL CONDITIONSd)

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t Oathnce from Control Room Type A Type B Type C y.g Control Room Control Room control Room 0.3 to 0.5 9

2.3 0.1 3,.'

O.5 to 0.7 35 8.8 0.4 0.7 to 1.0 120 20 1.0 1 to 2 270 52 2.5 2 to 3 1300 280 13 3 to 4 3700 780 33 4 to 5 8800 1400 60

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a For different toxicity limits as given in Table C 1 and different meteorological conditions, the weights should be proportionately scaled as described in Appendix A.

A 1 hazardous enemicals present in weignts greater than 100 lb within 0.3 mile of the control b

room should be considered in a control room evaluation.

C Control room types (Appendix A illustrates the use of this table for other air exchange rates):

1 Type 4 - A " tight" control room having low leakage construction features and the capability of l

detecting at the fresh air intake those ha:arcous chemicals stored or transported near the site.

Detectin of the chemical and automati: isolation of the control room are assumed to have

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occurd An air exchange rate of 0.015 per hour is assumed (0.015 of the control room air by M.

_.. _ _. a.9ame jsfaple;af _with nut.<ide a3 in one hourl. The, control room volume is defined as the

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volume of the entire zone serviced by the control room ventilation system. The assumption that tne air exchange rate is less than 0.06 per hour requires verification by field testing.

Type S - Same as Tyoe A, but with an air exchange rate of 0.06 per hour. This value is typical of a control room with normal leakage construction features. The assumption that the air exchange rate is less than 0.06 per nour, requires verification ey field testing.

Type C - A cor' trol room that has not bNn isolated, her no provisir n for detecting hazardcus a

enemicats, and has an air exenange rate of 1.2 per hour.

P00RBRM1 plume to su:h a degree that there should be sufficient Shipments are defined as being frequent if there are i-f 3

time for the control room operators to take appropnate per year for tru:L traffi:,30 per year for rail traffi:

l 2;uun, in addition.the probability of a plume remammg 50 per year for barge traffic. 5 If the quantity..

I witiun a pren se: or for a long period of time is quite shipment, of h::ardous chemicals frequently shipps l

past a site is less than the adjusted quannty showt

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ima.

2.

If huardous ehemicals su:h as those indicated iii Table C 2 for the control room !ype being evaluated Ta'c;e C-1 are known or projected to be frequently s-ipments need not be considered in the analysis.

j 5

sh:pped by rail, water, or road routes within a five-mile radius of a nuclear power plant, estimates of these 3.

In the evaluation of control room habitabih slupments should be considered in the evaluation of during normal operation, the release of any hazardt contro! room habitability. The weight limits nf Table C 2 (adjusted for the appropnate tox2:ity limii meteo-

. For explosive hazards, a lower r: umber of shipmer rology, and control room air exchange rate) ap; y also wouta.be considered frequent smee the effects of an explow J

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to frequently shipped quantities of hazardous che. ti:als.

would be iridependent of wind cirection.

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pc swuncu ww-swrvu-orrme nunear-punrsac-m- a rotenu; nacIcegrarunsequencerw. usoi-ge,santity greater than 100 O should be considered. Any Coolant Accident for Boiling Water Rea, tors." and

% hazardous chemical stored onsia should be accompanied Regulatory Guide 1.4, " Assumptions Used for Evalual.

hoy instrumentation that will detect its escape, set off an ing the Pztential Radiolopcal Consequences of a Lus.

N alm and provide' a readout in the control room.

cf. Coolant Accident for Pressunted Water Reactors."

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6.

The value of the atmospheric dilution factor be.

4.

Re toxaca.ry limits should be taken from appro priate authontative sources such as those listed m the tween the release point and the control room that is used in the analysis should be that vaRe that is exceeded References,,section. Fnr each chemical considered, only 5%of the time.

the values of importance are the human detection

' threshold and the maximum concentration that can be When boiloff or a slow leak is analyzed, the effects tolerated for, two minutes without physical incapacita-of density on vertical diffusion may be considered if burn, or,an average human (i.e., severe coughing, eye adequately substantiated by reference to data from non c.

severe skm irntation). The latter concentration experiments. Density effect of heavier.than. air gases is considered the, toxicity hnut. Table C 1 pives the should not be considered for releases of a violent nature I

3 toxicity hmits (tn ppm by volume and mg/m ) for the or for released material that becomes entrained in the chemicals listed. Where these data are not avatlable, a determination of the values to be used will be made on a turbulent air near buildinp.

case-by-case basis.

7.

For both types of accidents described in Regulatory Position 5 above, the capability of closing the air ducts 5.

Two types of industrial accidents should be con-of the contro! room with dampers and thus isolating the sidered for each source of hazardous chemicals: maxi-control room should be considered in the evaluation of mum concentration chemi:al accidents and maximum control room habitability. In particular, the time re.

cen:entracon<!uration chemical a::idents.

quired to shut off or redirect the intake flow should be justified. The detection mechanism for each hazardo.is

[

a.

For a maxirnum coricentration accident, the chemical should be considered. Human detection may be quantity of the huardous chemical to be considered is appropriate if the buildup of the hazardous :hemical in 1

the mstantaneous release of the total contents of one of the control room is at a slow rate due to slow air the fo: lowing: (1) the largest storage container falling turnover. The air f4ows for infiltration. makeu-md utidn the guidehnes of Table C.2 and located at a recirculation should be considered for both normar and nearby stationary facility, (2) the largest shippin8 accident conditions. The volume of the control room E

centainer (or for multiple containers of equd size, the and all other rocms that share the same ventdating nr.

failure of ordy one container unless the failure of that during bcth normal conditions and accident condnions.

.:entamer could lead to successive fadures) fdhng within should be considered. The time required for buildup of the guidelines of Table C 2 and frequently transported a h zardous chemical frorn the dete: tion concentration

^

r. car the site, or (3) the largest certamer stored onsite to the azje.ity limit should be considered. ' Table C-3 inormally the total release from this container unless the of thS guide '.ontains a sample list of the chemical and I

contamers are tntercenne.-ted m such a manner that a control room data needed for the evaluation of control I

smpe failure could cause a release from several con-room habitability.

tamers i 8.

In the cal:ulation of the rate of air infiltration (air For cherni:ds that are not cases at 100*F and leaking into the contrel room from ducts. doors or nanu:.tmosphen: pressure but :re liquids with vapor other openings) with the control room isolated and not p:essures m excess of 10 'orr. consideration should be pressurized, use of the fellowing assumptons is sug.

pen to the rate of flashite and beiloff to determine the gested:

rate of re: case to the stmosphere and the appropriate ume dur:non of the release.

a.

A pressur: differential of 1/8 inch water gauge I

across ailleak paths. '

l The strnowheri diffusion model to be used in the evduatien shculd be the same as or similar to the model presented in Appendix B of this guide.

.

  • The tir,ne from dete: tion to mcapacitation snould be pester than two mmutes. Tuo intnutes is conuden d sufncient time for a tramed operator to put a self-contamuJ breathmg c.

r or a maximum conecntration.dur: tion acci-pparatus mto operatior. if these are to be uscJ.

dent. the continuous release of hazardous chemical; from the largest safety relief valve on a stationary

' This pressure differertial account. for wind offects, monile. or onsite source falhnc withm the guidelines 0; thermal column effects. and barometne prenure changes. It does l

Iable C ' 'hould be considered. Guidance on the

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of ventCation systems suppl >mg zones adjacent to the control atmospheric diffusion model is presented m Regulatory room. It should be ad;usted :.ppropnat::ly when the ventilation f.

Guide 1.3, ** Assumptions Used for Ev:luating the s> stem supplies :ones adscent in the co stret room.

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. TABl.E C 3 it. If credit is taken in the evaluati:n for the removal cf hazardous cherru:als by filtration or other tr. cans, the l

o TYPES OF CHEMICAL AND experimental basis for the dynami: removal capability of i

i CONTROL ROOM DATA FOR the rem: val system for the particular chemical being O-HABITABILITY EVALUATION c nsidered sh uld be est:bhshed.

I

12. Concurrent chemical release of container contents CHEM / CAL during an earthquake, tomado, or flood should be censidered for chemical contamer facihties that are not
1. Name of hazardous chemical, designed to withstand these natural events. It may also l
2. T pe of source (stationary, mobile, or onsite).

be appropriate to consider release from a single onsite S

3. Human detection threshold, ppm.

container or pipe coincident with the radioloccal

4. Maximum allowaole two minute concentration (tox.

consequences of a design basis loss-ol'cooIhit aWice'n'i,'

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I icity limit as defined in Regulatory Positic,n 4, ppm if the container factities are not designed to withstand and mg/m').

an earthquake.

5. Maximum quantity of hazardous chemical involved 13, (( con' sideration' of possibie accidents for any
  • *0' dent.
6. Maximum continuous release rate of hazardous hazardous chemi:a! indicates that the appli:able toxicity
chemical, limits may be ex:eeded,self contained breathing appara-tus of at least one. half hour capacity or a tank source of
7. Vapor pressure, torr, of hazardous chemical (at air with manifold outlets 'and protecuve clothing, if traximum ambient plant temperaturel,
8. Fraction of chemical flashed and rate of boiloff required, should be provided for each operator in the when sp,illing occurs, contro! room. Addit:ena! air capacity with appropnate
9. Distance of source from control room, miles.

equipment should be provided if a chemica! hazard can

10. mve per:entile meteorological dilution factor be-persist longer than one half hour. For accidents oflong duration, sufficient air for six hours (coupled with tween release pomt and control room for instanta-provisions for obtaining additional air within this time neous and contmuous releases.

period) is adequate. Each operator should be taught to CONTROL ROOM 6stinguish the smells of hazardous chemicals peculiar to the area. Instru:uon should include a penodic refresher

1. Volume of control room, ir.cluding the volume of course. Pracu:e drills should be conducted to ensure all other areas supplied by the control room emer.

that personnel can den breathing apparatus within two gency ventitation system, ft'.

minutes.

l

2. Normal flow rates for volume defined above, cfm:a

- unfittered inleakage or makeup air,

14. Detection instrumentation, iso'ation systems. filtra.

I

- filtered makeup air, tion equipment, air supply equipment, and prote:tive I

- filtered re:irculated air, clothing should meet the single failure criterion. (in the I

3. Emergency flow rates for volume oefined above, case of self-conta:ned breathing apparatus and protective l

cf m8 (as in item 2. above).

ciothing, this may be accomplished by suppipng one l

4. Time requked to isolate the contrel room, sec.

cxtra unit for every three units required.)

4 d " filtered a:r" refers to the a: Stered through Gters

15. Emergen:y procedures to be iruusted in the event i

shose remc+ l capabthty for the pam:ular chemical be:n! con.

of a hazardous chemical telease within or near the udered hu b en estabbshed.

station should be written. Tnese procedures should address both maximum concentration accidents and maximum con:entration. duration accidents and should b.

Tne maximum design pressure differential fcr identify the most probable chemical releases at the fresh air dampers on the suction side of recirculation station. Methods of detecting the event by station fans.

personnel, both dunns norma! workday operation and dunng minimum staf5ng penods (late night and week.

9.

When the makeup air flow rate required to pressu'r7, end shaft staffing), should be discussed. Spe:ia! instru-i:e the contre! room is calculated, a positive pressure

  • ment.? tion that has beeri prodded for'the detecucn of I

6fferemial of d4 inch water gauge should be assumed hazardous chenucal releases should be described includ-in the control room relauve to the space surrounding the it.g sensitivity, action initiated by detecting instrument control room.

a.d level at which this action is initiated, ar}d Te:hni:al Specification lim;tations on instrument availability. Cri-

10. To a::ount for the possible increase in :ir exchange

. tena should be defined for the isolation of the control due. to ingress or egress, an ad6 conal 10 cfm of room, for the use of prote:tive breathing apparatus or unfiltered air should be assumed for thost control rooms other protective measures, and for orderly shutdowm or

,[h mthout a:rlocks. This additions! leakage should be s: ram. Critena and procedures for evacuating nonessen.

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assumed whether or not 8e conti A room is pressurized.

tial personnel from the station should also be defined.

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7 ' Arrangement 'shouSd'D maB E3 @edbral, State, acci&nts involving Reardous chenucals have occuned and local ag-ncies cr cther cogniza:t crganizations f:r within five miles of the p! ant.

. the prompt notification of the cuclear power plant when 3;

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REFERENCES 1.

"Matheson Gas Data Book," Fourth Edition, The 4.

" Toxic Substances List,1973 Ed: tion," U.S. De.

Matheson Company, Inc., East Rutherford, New partment of Health, Education, and Welfare, Jersey (!966).

National Institute for Occupational Safety and Health, Rockville, Maryland 20S52 (June,1973).

2.

N. Irving Sax, " Dangerous Properties'of Industrial Prepared for NIOSH under contract by Tricor Jitco, Matenals," "Ihird Edition, Reinhold Book Corp.,

Inc.,1300 East Gude Drive, Rockvdle, Mar'; land New York, New York (1968).

203:2.

3.

" Hygienic Guide Series," published by the Ameri-5.

" Threshold Limit Values for Chemical Substances can Industrial liygiene Association, William E.

and Physical Agents in the Erkroom Ermron.

McCormick, Executive Director, 66 South Willer ment," American Conference of Govemmental in.

dustrial HyF enists, Cincinnati, Ohio (1973).

Road. Akron, Ohio 44313.

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~

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NECEa$1TATINGTHEIR The weights presented in Table C 2 are b: sed cn the room requires that the control room leakage rate be veri-

. W.

loll: wing assumptions:

Ged by periodic field testing.

~

1.

A eoxicity tir+r of $0 mg/m' For control rooms without automatic isol. tion 2.

Air exchange rates for the three control room capability, the weights F'sen for Type C control rooms types of 0.0lS,0.06,and l.2 per hour should be used, appropriately adjusted for the actual J.

Pasquilt stability category F fresh air exchange rate. Weig. hts for Type B control rooms should be med when the control room has auto.

These conditions are Fenerally apphcable to most of matic isolation. Weights for Type A control rooms, ap-today's plants for a pas such as chlort.c (toxicity limit of propriately adjusted for the design isolated air exchange i

tJ*mg/m'). If the toxicity limit, air exchanFe rate, or rate, should be used only when the control room has meteorological conditions are significantly different been designed specifically for low inteakage, from the assumptions used in Table C 2, simple correc-tions that result in only minor enors can be made.

Pamuill Stabihty r.atagory l

Toxicity 1.imit The weights gnen in Table C 2 are based on stable atmospherie dispersion conditions equivalent to Pasqui!!

The weights presented in Table C 2 are directly Condition F. This represents the worst five percentile proportional to the toxicity limit. If a particular chemi-meteorology observed at the majonty of nuclear plant cat has a toxicity limit of 500 mg/m,the weights from sites and, for most cases, tnere will be no need to adjust 3

the table (based on 50 mg/m')are increased by a factor the weights because of meteorology,if it is determmed of ten.

that the worst five percentile meteorology is better or worse than Condition F the following adjustments Air Exchange Rate should be made:

Table C 2 weights are inversely proportional to the tw eyreenple Npr Afu/rsplacerson air exchange rate. If a type C control room has an ex-onoemon oregory recror change rate of 2A per hour, the weights from the table (based on 1.2 per hour) are decreased by a factor of two.

E 2.5

...y g

When adjustments of this type are made the control room tvt'e ( A. B. or C) that has an air exchange rate F

1.0 closcat to that of the control room'in question ~stio'uldW ~~ ~ ~ ~ -

-~

~ ~ ~

G 0.4 selected.

It should be noted that the use of an air exchange Appendix b provides additional discussion of atmos-rate of less than 0.06 per hour for an isolated control phenc disperuon.

4 P00RORMA A

e 9

W 1.76-7

~.

.~.s.iwaamr xrw8:;tW.s.+, ccms.u;,xmzwMywaM:a n w xm -

n Lw \\.mN's>n&Mz:*.es :Lvm' ~1

.t.nvn.hM.-M.r;;;u :a.sna?<im newce n :.w. :m.

. 21:!=2;';t.*G4D'*W"??M4.:P'C?w:22';.CEth?d?:W W?TxC3.?n.271" a

wm. -

DIFFUSl_ N CAltuLATLONS FOR AW LNST/MTANEOUS (PsFF) REI. EASE e

S a

w,

4 1.

Diff:sion Equation Windspeed doe: r.ot enter inta the determination cf p) unit concentration per se, but does affect the time.

A The diffusion equation for an instantaneous (puff) integrated concentra'. ion S ee it determines c!oud v'

grandievel release with a finite initia1 volume is:'

passage time. The variation of unit concentration at a L

specific stationary receptor location is determined by r

1 g' '

evaluating x in the exponential term in the above

+ aj\\ fa* ^ #i /

equation as follows:

f y

2 7.87 0

2 x = D -ut

}-

2 2

2

- 73 y

g

  • cxp.%

+

+

0*+oj c'+aj c' + ej where D is the set ree. receptor distance, u is the x

y windspeed, and t is the time after release.

where:

2.

Determination <>f ineet Deta X

unit concentration at coordinates x, y, z

=

O!

from the center of the puff,m 3 The following assumptions and methods should be applied when analyzing worst case instantaneous source releases:

standard deviations of the gas concen, o,a.c

=

x yz tration in the horizontal alongwind,hori-Select the appropriate stability category based a.

zontal crosswind, and vertical crosswind directions, respectively (assume o = o ),

on the worst five percentile meteorology observed at the x

y site according to the.iT method. Regulatory Guide 1.23 m

(Safety Guide 23), "Onsite Meteorological Programs."

presents a classification of various atmospherie stabihty 31/2g'3/2 categones as a function of temocrature change (.iT) 7.87 with height. Normally, this category will be Pasquill l

o; mital standard deviation of the puff,m)

Condition F. In some cases, the worst case stabihty

=

category may be either Pasquill Condition E or G. This Or lI/3 occurs at sites having distinctly better or worse diffusion where Og is the puff re.

than is normally encountered. Figures I and 2 of this N.

=

L o

. lease quantity, g. and xo is appendix include conditions E, F,and G and encompass mc censitj c: :nc pratstr.ncarc'cond;--

t}r yo,3g expee ed itability coriditions at nearly all sites, twns, g/m.

b.

Determine the x, y, and z standard deviation

= distance from the puff center in the values based on the Pasquilt stability categones as x y.z horizontal alongwind, honzontal cross.

presented in Figures 1 and 2.

wmd. and vertical crosswind directions, respectively, m.

c.

Additional credit due to building wake or other d:spersive phenomena may be allowed, depending on the I

properties of the released gas, the method of release, and

  • CR E.H. Markte. Jr., and A.P. Richter "Chrna.

the intervening topology or structures.

Imachy a, Yarnhe),

the hat.ional Reactor Testutg Station, IDO.12048 knuar> 1966. Copics may be obtained from Nationat Technical information Service. $285 Port Royal Road. Spnnsfield, Vir.

d.

Windspeed should be selected to maximize the rmia 2151.

two. minute concentration within the control room.

P00R ORGIM v

W?

l.78 8

m. -- w.x4n.m - e r_ce,-je, e.w_,.,33. m;m*=.fe;n.m.;, m-,.my;; p;y, n... g' g

a 2

g h

a 4

3 g

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  • p 4':v ra n.m.*
  • e*,M b g-+. t m W.

~+

M,.

3 10 7--

s.

(

)

/

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-r g

Pasquill Type 2 %

o Pasquill Type F 2

A.

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Z

~

O 5

a O_

<c 2<-M 10 2

O I

. 1 ~

" i P00R ORE R l

I l 1 l Ill l

l l I I lII i

l l l 1

2 3

4 10 10 10 DISTANCE FROM RELEASE POINT (meters)

Figure 1. Horizontal Standard Deviation of Materialin a Plume s

1.78-9 t-9 4

y a

m' O

'a

  1. I eD7 NU e

,Y 7 e 3.

$h*a ce

.U*

Ef y

w g

oh 5N7

- =

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~(-

?t m

k.4. o e'

.,1

.w-we. v g... -

~.,-.m

.,,c,.

~.

,.."s

, l s

on e s e p,,

.A' e,', s

  • m m

e_...-

6 v. 4., 4 s,,.;.

'e

..,s.,.

w,,,,.%..,_,,..s...v.....,.,....u....m..

s-, s,, %.....c

- -.....r

-a % *,%.em. %. s..., -.,...

a.

- *,.=

.g e

e % a. m.. s

3 10

~

tou o..

g. -

Pasquill Type E w

I 3 10 Pasquill Type F m

Pasquill Type G

>Wo I

O i

e

+

C=<

P.m 10 1.

d

+

  • u i

1 5

pQhkh i

e l

l l l l lll l

l l 1 l lIl I

IIIll l 1

3 10' 10' 2

10 0

DIST ANCE FROM RELE ASE POINT (meters) i Figure 2. Vertical Standard Deviauon of Materialin a hume 4

l t

1.78 10 g

IO Of f

'g g9 9@h i P"OM

  • A y

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5 u. :.::. v<,+n- :sc + ~?.u s?. t. <r iw m ~d.w. +-:r.:.-y.wn, cm# n

u.%. w. nx ~ ::e. ;- v~n c: :...*.v.s :c-v: -

\\

w..~.n,.-w. : r.

m.P..s

. venv..w a m w e, r ;.

r.

.,- er n w -. - e.2 w

.r.<. a 1

dye appa gep i.s Aq w* dp *+,4s g,, t-,4 4.in p.#e 'y p h % = eh g 46'+& -

d FD M e4 4R e #toA

$ 4 e 5> -V

'6 #' v ** # W e e (

4.J$$ M e S.'4s W4 48*4944' a t $/.

wh 8 ewe a.e 'e"p.

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4 as M s ' mpsee sw e'b6 7. WJ#7 6 eC N 4 $ 4.*' - 4 ete h** w T',eshtme*Ji.#4m*d h e. 44* * # et * * #'

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