Regulatory Guide 8.19

Occupational Radiation Dose Assessment in Light-Water Reactor Power Plants Design Stage Man-Rem Estimates

ML13350A224
Person / Time
Issue date:	05/31/1978
Revision:	0
From:	NRC/OSD
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References
RG-8.019
Download: ML13350A224 (6)

U.S. NUCLEAR REGULATORY COMMISSION May 1978REGU LATORY GUIDEOFFICE OF STANDARDS.DEVELOPMENTREGULATORY GUIDE 8.19OCCUPATIONALRADIATION DOSE-ASSESSMENTIN LIGHT-WATER REACTOR POWER PLANTSDESIGN STAGE MAN-REM ESTIMATESA. INTRODUCTIONSection 50.34. "Contents of , nplications. Techni-cal.lnformation," of 10 CFR Par, 50, "Licensing ofProduction and Utilization Facilitk. ." requires thateach applicant for a permit to. con.,truct a nuclearpowcr reactor provide a preliminary safety analysisreport (PSAR) and that each applicant for a license toopcraic such a facility provide a final safety analysisreport (FSAR). Section 50.34 specifies in generalterms the inforniation to be supplied in these reports.A more detailed description, of the informationneeded by the NRC staff. in its evaluation of applica-tions is given in Regulatory Guide 1.70, "StandardFormat and Content of Safety Analysis Reports for.Nuclear Power Plants." Section 12.4. -Dose -As-sessment." of Regulatory Guide 1.70 states that thesafety analysis report should provide the estimatedW annual radiation exposure to personnel at the pro?"."posed plant during normal operations. The purpdse' ofthe man-rem estimate requirement is to ensuriý..thatadequate detailed attention is given during the pr.0,,liminary design stage (as described in thii well as during construction after compltbn of design(as described in the FSAR). to dose-causi fafcti vitiesto ensure that personnel exposures will be as low asreasonably achievable (Al:ARA). The safety analysisreport provides an opoiud ityjor the applicant todemonstrate the adequacy-,b thai'attention and to de-* scribe whatever,ý.esigaandý'rocdural changes haveresulted from tlikidose assessment process.* The objective 6(itthguide is to describe a method* acccptabldi.to the NRC stuff for performing an ;is-sessment of 'ollective occupational radiation dose as* *part of the process of designing a light-water-cooledpower reactor (LWR).B. DISCUSSIONThe dose assessment process requires a good work-ing knowledge.of (i) the principal factors contribut-ing tooccupational radiation exposures that oCcur ;t anuclear reactor power plant and (2) method-s andtechniques for ensuring that the occupational radia-tion exposure will be ALARA. In assessing the Col-lective occupational dose at a.pla'ntv.the applicantevaluates each potentially significant 'do.;e-causingactivity at that plant. specifically examining suchthings as design. shieldingp..Iant layout. traffic pat-terns, expected mainiLnancie arind radioactivitysources, with a vievtu: reducing unnecessary expo-sures and considering':the co ti-effecliveness of eachdose-reducing method and techniquc. This evaluationprocess aiid-the dose:.'reductions that nmav he expectedto resttI: nre ýtheK' principal objectives of the dose,, :,The pnpal benefits arising frotm this evaluationprocess Lccur. during the period of prelimlinary de-sign since many of the ALARA practices are part ofthe design process. On the other hand. additionalbenefits can also accrue during advanced designstages and even during early construction s tages. asbetter evaluation of dose-causing oporaiions areavailable and further design refinements can be iden-tified. In addition, operations that will need specialplanning and careful dose control can be identified atthe preoperational stage when the applicant can takeadvantage of all design options for reducing dose.C. REGULATORY POSITION'This guide describes the format and contentfor assessments of the total annual occupational(man-ren) dose at an LWR-principally during thedesign stage. The dose assessment at this stageshould include estimated annual personnel exposuresduring normal operation and dining anticipated opera-tional occurrences. It should include estimates of thefrequency of occurrence, the existing or resultingUSNYRC REGULATORY GUIDES Commnwta bh~uftil be swnt to It'. Stitievhsy of the Comnfnjvtsn.US Nu'ti-A. Areq,Fligullator Guefnw et lisued to deeehba ahu~natke &aiia&te to me pubic mqethods taint Comm~ts.t~n. Wath,,nqtun OZ. 20651j. Att..ntion Outbhethi; ..... 5in...aameotabl. to th*.NAC sMoll al .nnplamefiting specifi~c owls of the. Commtuoon's ofoied.igguitotiotti.1dodlineate tectinsquet ted by She %fall i nevaluoloqg tftiloc tsobiems The quitti ne.0-wsu"Io the tnilslwni t-, fw,..el 0tn-w,,or: poinulated accidents. at to PtoneS. ouicdance t0 moiticents. Rtegulatory Guirksare not gsastnuten kw regulationst. andS copitpance vvitf them it not rotsuired. 1.pow" fli ' &JPNfwcf.Mfithods aenc volutiott1 diffleten from thotse lt out in the VuKde¶ "nit be etcl1i 2. Research omtiTest Reatolw 7. tfin'ituawle it they provide a bouitfor the findig traquisiteto the iknce or conttinuance. 3. Fuelsand MairriAls Fdcatie 9. occu",iifmrufttefaltilof* & offitt of tkiceMe by the Cammts,.nn.. .Etn~nd ~l ~a Aflitmut At.omsComment s and iueUl antoi for improvements in thewe quidles we eescousepd! at 0eeal n ~n tt'to, 5 eeatimeW1. ared Qus~t e.~t be revised, as uopoatovito. to aco.rmmodate cornmertis and Aestuests Irv singte caione ol tivuem itpen lwh4,ch may to. me.'mslu.uJI to. Ito ut..rto #effect nowa inliomatirnn cit e.miernrce. Howevrr. common%%antt Ithi i quidt~it men rt on autctflonwlc dirlmithitstro- 1- ttot n%-91P..nnes oil iw,ottr qnet .sfo. tiraceid v.fttin~ about two rrinoftlt after its iuMSce, tvill be pt~itcultidv useful inl iftnu~nns dsicukl be nudfe in oakn w fqit. the US. Nurf"~ 6feqr.tutauts Ctsnc -nnn.esetustin,1 the neted lot an eary reCvisici, Whehnhsfltm, 0,C. M05$t. Attentiosi Doecois. 0-%o.nn it I Dii-otrent Custuro radiation levels. the manpower requiremients. and theduration of such activities. These estimates can bebased on operating experience at similar plants, al-though to the extent possible estimates should includeconsideration of the design of the proposed plant, in-cluding radiation field intensities calculated on thebasis of the plant-specific shielding design.The dose assessment process and the concomitantdose reduction analysis should involve individualstrained in plant system design. shield design, plantoperation. and health physics, respectively. Knowl-edge from all these disciplines should be applied tothe dose assessment in determining cost-effectivedose reductions.Plant experience provides useful information onthe numbers of people needed for jobs, the durationof different jobs. and the frequency of the jobs. aswell as on actual occupational radiation exposure ex-perience. The applicant should utilize personnel ex-posure data for specific kinds of work and job func-tions available from similar operating LWRs. (SeeRegulatory Guide 1.16. "Reporting of OperatingInformation-Appendix A Technical Specifica.tions." for examples of work and job functions.)Useful reports on these data have been published bythe Atomic Industrial Forum. Inc., and the ElectricPower Research Institute. and a summary report onoccupational radiation exposures at nuclear powerplants is distributed annually by the NuclearRegulatory Commission.The occupational dose assessment should includeprojected doses (luring normal operations. anticipatedoperational occurrences, and shutdowns. Some of theexposure-causing activities that should be consideredin this dose assessment include steam generator tubeplugging and maintenance, repairs, inservice inspec-tion. and replacement of pumps, valves, and gaskets,Doses from nonroutine activities that are anticipatedoperational occurrences should be included in the ap-plicant's ALARA dose analysis. Radiation sourcesand personnel activities that contribute significantlyto occupational radiation exposures should be clearlyidentified and analyzed with respect to similar expo-sures that have occurred under similar conditions atother operating facilities. In this manner, correctivemeasures can be incorporated in the design at anearly stage.Tables I through 8 are examples of worksheets fortabulation of data in the dose assessment process toindicate the factors considered. The actual numbersappearing in the dose columns will depend on plant-specific information developed in the course of thedose assessment review.An objective of the dose assessment process shouldbe to develop:(I) A completed summary table of occupationalradiation exposure estimates (such as TableI).(2) Sufficient illustrative detail (such as thatshown in Tables 2 through 8) to explain howthe radiation exposure assessment processwas performed, and(3) A description of any design changes thatwere made as a result of the dose assessmentprocess.During the final design stage. (lose assessment canbe substantially refined, since at this time details ofthe design will be known. In particular. completedshielding design and layout of equipment shouldpermit better estimates of radiation field intensities inlocations where work will be performed.As a result of the dose assessment process, it is tobe expected that various dose-reducing designchanges and innovations will be incorporated into thedesign.D. IMPLEMENTATIONThe purpose of this section is to provide informa-tion to applicants regarding the NRC staff's plans forusing this regulatory guide.This guide reflects current NRC staff practice.Therefore, except in those cases in which the appli-cant proposes an acceptable altcrnatlve method forcomplying with specified portions of the Commis-sion's regulations, the method described herein isbeing and will continue ito be used in the evaluationof submittals in connection with applications for con-struction permits or operating licenses until this guideis revised as a result of suggestions from the public oradditional staff review. For construction permit. thereview will focus principally on design consid-erations; for operating license, the review will focusprincipally on administrative and procedural consid-erations.TABLE 1TOTAL OCCUPATIONAL RADIATIONEXPOSURE ESTIMATESDoseActivity (nian-reinslyear)Reactor operations and surveillance(see Tables 2 & 3) *Routine maintenance (see Table 4)Waste processing (see Table 5)Refueling (see Table 6)Inservice inspection (see Table 7) -Special maintenance (see Table 8) -Total man-reins/year*Occupational exposures from Tables 2 through 8 arc enteredin Table I and added to obtain the racility's estimated totalyearly occupational dose.Values shown in Tables 2 through 8 arc typical examples (forBWRs and PWRs) for illustrative purposes only. Actual valuescan vary. depending on the facility type (BWR or PWR). de-sign. and size.48.19-2 TABLE 2OCCUPATIONAL DOSE ESTIMATES DURING ROUTINEA verage Exposuredose rate timeActivily Imremn/hir) (hr)OPERATIONS AND SURVEILLANCE*NumberofWalkingChecking:Containment cooling systemAccumulatorsPressurizer valvesBoron acid (BA) makeupsystemFuel pool systemControl rod drive (CRD) system:ModulesControlsFilters0.211.5105i0.510.20.20.2510.50.50.20.2workers2FrequetwyI/shiftI/dayI/dayI/day1/dayI/day1/dayIlshiftI/dayf)tse(man-rerns/v ear)0.220.360.540.730.360.090.360.270.09Pumps:CRDResidual heat removal10.50.50.51!°I/dayI/day0.040.07Total*'Te data shown are for illustrative purposcs only and would be expected to vary significantly from plant ,; plant.OCCUPATIONAL DOSEActivityOperation of equipment:Traversing in-coreprobe systemSafety injection systemFeedwater pumps &turbineInstrument calibrationCollection ofradioactive samples:Liquid systemGas systemSolid systemRadiochemistryRadwaste operationHealth physicsTABLE 3ESTIMATES DURING NONROUTINE OPERATION ANDA verage Exposure Numberdose rate time of(mrem/lr) (hr) workers Frequency251220.50.50.518222323/yearI/monthI/weekI/dayI/dayI/month4/yearI/dayI/weekI/daySURVEILLANCE*Dose(man-rems/yvear)0.020.060.050.731.830.03'0.020.733.751.46105I01031Total*The data shown arc for illustrative purposes only and would be expected to vary significantly from plant to plant.8.19-3 TABLE 4OCCUPATIONAL DOSE ESTIMATES DURINGA verage !ýxposuredose rate timeAciivity ( mren/Iir) ( hr)ROUTINE MAINTENANCE*NumberofworkersDoseFreeiuenc)v (mnimz-reinlfl/eur)0Mechanical:Changing filters:Waste filterLaundry filterBoron acid filterPressure valves13A makeup pumpBA holding pumpInstrumentation and controls:Transmitter insidecontainmentTransmitter outsidecontainmentStandby gas treatmentsystemRadwaste processingsystem100100100101010512100.50.50.50.50.30.30.522206/year10/year2/year1/weekiU;-4ck1/%,e:.k2/weckI/week2/year4/year0.30.50.10.260.160.160.520.10.021.6Total*The data shown are for illustrative purposes only and would be expected to vary significantly from plant to plant.TABLE 5OCCUPATIONAL DOSE ESTIMATES DURING WASTE PROCESSING*A verage Exposure Numberdose rate time of(mrem/hr) (hr) workers Frequency (manActivityDose-rems year)Control roomSampling and filter changingPanel operation,inspection, and testingOperation of wasteprocessing andpackaging equipment0.11012300042122I/year1/weekI/dayI/week0.32.10.732.5Total*The data shown are for illustrative purposes only and would be expected to vary significantly from plant to plant.8.19-4 TABLE 6OCCUPATIONAL DOSE ESTIMATES DURING REFUELING*A veragedose rate(nrentIhr)Exposuretime(hr)NumberworkersDoseFrequenc). (mn-rntrcslvear)ActivityReactor pressure vessclhead and intcrnals-removal and installationFuel preparationFuel handlingFuel shipping30102.5156024100156 I/year 10.82 I/year 0.484 L'year 1.02 I/year 0.45Total*The data shown are for illustrative purposes only and would be expected to vary significantly from plant to pla'ni.Most work functions performed during rcfueling. and the associated occupational dose received, will vary depending on facility design(BWR or PWR), reactor pressure vessel size. and number of fuel assemblics in the reactor core. For a detailed description of prc-planned activities, time. and manpower schedule, refer to the "'critical path for refueling task%.*' which should he available from theNuclear Steam Supply System tNSSS) supplier.TABLE 7OCCUPATIONAL DOSE ESTIMATES DURING INSERVICE INSPECTION'A veragedose rate(in rem Ih r)ActivityProviding access: installationof platforms, ladders.etc., removal ofthermal insulationInspection of weldsFollow up: installationof thermal insulationplatform removaland cleanupExposuretime(hr)30100Numberofsvorkers434Dose'Freqienc-Y (mian -rct:sl/v*arj4040I/yearI/yearI/Ycar4.812.06.44040Total*The data shown are for illustrative purposes only and would be expected to vary significantly from plant to plant.Estimates should be based on average yearly values over a 10-year period. Variations are expected as a consequence of reactorsize, design, number of welds to be inspected yearly. and the degree of equipment automation available for remote camination ofwelds.8.19-5 TABLE 8OCCUPATIONAL DOSE ESTIMATES DURING SPECIALA vero.e L'xiiositrc Nunberhiost rale lime offivioy (lir-in lir) (hr) workersMAINTENANCE "Fr*'qseitcY (inuni-renslls/etr)Servicing of controlrod drivesServicing ofin-core detectorsReplaccment ofcontrol bladesDechanneling of spentand channeling ofnew fuel assembliesSteam generator repairs5015Is0()100012101060432I/yea r1/yearI/yearI/year1/year1.1i0.30.31.224.026Total*Thc data shown are for illustrative ;Iurptisc only and would he epected to vary significantly front plant to plant.Nto%t prcplanned (or riwlinet rnt~enanicc ajoivities durink. otitage arc de-,ritcd in the -critical path fo'r refueling task-,".which%hould be availabule fromn the NSSS supplier, and ire performed in parallel with the critical path refueling tasks to %horiten reactoroutage timeActual d,.'e %kill depcndl on faeiliity desigzn a% wekll a!, %ize and thermal output and nuniher tit fuel assemblics in the rcicior cote.8.19.6