SAFETY REQUIREMENTS for a NUCLEAR POWER PLANT ELECTRIC POWER SYSTEM

XA04N2806 NRSC/R-4.88

INIS-XA-N-233

SAFETY REQUIREMENTS for A NUCLEAR POWER PLANT ELECTRIC POWER SYSTEM

Prepared byS L.F FOUAD & M.A.SHINAISHIN

Nuclear Regulatory and Safety Center Atomic Energy Authority

Date Published I June 198ft

NRSC Of CONTENTS

1. InTRoducTIon 1 2. SysTem DescRIpTIon 2 2. 1 ôweR DIsTRIbuTIon sysTem ^ 2.2 THe A.C. ôwER SysTem ^ 2.^ The D.C. iôweR SysTem ^ 2.4 NoN-lNTeRRupTabLe A.C. ôweR SysTem ^ 2.^ DIeseL GeNeRaTors ^

^. INfoRmaTIoN RequIremenTs FoR SafeTy ANaLysIs aNd Review 6 ^. 1 INfoRmaTIoN To be SuppLIed by The Licensee 6 ^.1.1 I^RefeRRed iôweR SysTem 6 ^.1.2 STandby ôwER SysTem 6 ^.1.^ D.C. ôweR SysTems 8 ^.1.4 FIRe ^RoTecTIon foR CabLe SysTems 8 ^.2 Scope of review by THe reguLaToRy body 8 ^.2.1 ^RefeRRed ôweR SuppLy 9 ^.2.2 STandby Ôwer SysTem 10 ^.2.^ DC ôweR SuppLIes 11

4. GeneRaL DesIgN CRITeRIa for ELecTRIc iôweR SysTem 11 ^. MeaNS for ImpLemenTaTIoN/ReguLaToRy guides aNd BRaNcH TecHNIcaL ôsITIoNS 14 ^. 1 INdepeNdeNce BeTween RedundanT STaNdby( ONsITe) ôweR sources aNd THeIr DIsTRIbuTIoN SysTems. 14 ^.2 SeLecTIon of DIeseL GeneRaToR SeT CapacITy foR STandby ôwer SuppLIes 16

- i - TabLE of CoNTEnTs

Iêriodic TesTIng of ^RoTecTioN SysTem AcTuaTIoN FuNcTIons 17 Seismic Design CLassificaTion 18 QuaLiTy AssuRance RequiRemenTs foR The InsTaLLaTioN, INSpecTiN and TesTiNg of InsTRuMenTaTIon and ELecTrIc EquIpmenT. 1^ CRITeRIa for SafeTy ReLeaTed ELecTrIc ôweR SysTem for NucLeaR ôweR ^LanTs 18 QuaLIficaTioN TesTs of CoNTiNuous DuTy MoToRS INSTaLLed INSide The ConTainmeNT of WaTeR CooLed NucLeaR ôweR ^LaNTs . 19 ^ReopeRaTioNaL TesTiNg of ReduNdaNT ONSiTe ELecTRicaL ôweR SysTems To VeRify ^RopeR Load GRoup AssignmeNTs 20 Bypassed aNd InopeRabLe sTaTus INdicaTion for NucLeaR ôweR ^LaNT SafeTy SysTems. 21 AppLicaTioN of THe SiNgLe FaiLure CRiTeRioN To NucLeaR ôweR ^LaNT ^RoTecTioN SysTems. 21 MaNuaL INiTiaTioN of I^RoTecTive AcTions 22 ELecTRicaL êneTRaTioN AssembLies in ConTainmenT STRucTuRes for LigHT WaTer- CooLed NucLeaR TôweR ^LanT. 2^ IniTiaL TesT ^RogRams for WaTeR CooLed NucLeaR iôweR ^LanTs. 24 QuaLificaTion TesTs of ELecTRic VaLve OpeRaToRs InsTaLLed Inside THe ConTainmenT of NucLear Iôwer ^LaNTs. 26 of CONTENTS

^HysIcaL IndependeNce of ELecTRIc SysTem 27 ShaRed EmeRgeNcy aNd SHuTdown ELecTrIc SysTems for MuLTIÛnIT NucLear ôweR ^LanTs 27 QuaLIfIcaTIoN of CLass IE EquIpmeNT foR NucLeaR iôweR I^LanT. 28 AvaILabILITy of eLecTRIc power sources 29 Seismic QuaLIfIcaTIoN of ELecTRIc EquIpmenT foR NucLeaR Tôwer F^LaNTs ^0 THeRmaL OveRLoad ^RoTecTIoN foR ELecTRIc MoToRs ON MoToR OpeRaTed VaLves ^0 êRIodIc TesTINg of DIeseL GeNeRaToR UnITs Used as ON-sITe ELecTRIc FôweR SysTems aT NucLeaR ôweR ^LaNTs ^1 INSTaLLaTIoN DesIgN and INSTaLLaTIoN of LaRge Load SToRage BaTTeRIes foR NucLeaR

MaINTeNaNce, TesTINg, aNd RepLacemeNT of LaRge Lead SToRage BaTTeRIes for NucLeaR

DIeseL-GENeRaToR ReLIabILITy QuaLIfIcaTIoN TesTIng

RequIRemeNTs on MoToR OpeRaTed VaLves 1^

THe EmeRgency CoRe CooLing SysTem AccumuLaToR

Lines

Use of DieseL-GeneRaToR SeTs for Load

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^.27 STabILITy of Off-SITe ^oweR SysTem ^.28 ReacToR CooLanT ^ump BReakeR QuaLIfIcaTIon ^.29 DIeseL-GeneRaToR F^roTecTIve Trip CIRcuIT by Masses ^^0^ AppLIcaTIon of THe sIngLe FaILuRe CRITeRIon To MaNuaLLy ConTRoLLed ELecTRIcaLLy-OpeRaTed VaLves 6. ConcLusIoNS RefeRences AbsTRacT

woRk alms at IdentifYINg THe safety RequIRemENTs foR THE eLEctric power systEm In a typIcal NucleAR power plant, In views of The USNRC aNd THe IAEA. DescriptioN of a typical sysTem is pRovided^ followed by a pReseNtatioN of ThE scopE of THE InfoRmatioN RequIRed for safEty EvaLuatioN of The system desigN and perfoRmance^ The acceptance and desigN cRiteria ^î musT bE mET as being SpEeified by boTh REgulaTory sysTems, aRe compared. Means of ImpLemeNTaTion of Such criTeria as beiNg described in ThE USNRC ReguLATory guIdes and bRanch TEchnical posIti^^ on one haNd aNd In The IAEA safety guta^ ON The other haNd arE investigated. IT is concludEd that ThE IAEA REgulations address ThE pRobLems That may be faced with In countries having vaRying grid siês Ranging fRom LARge stabLe To Small potENtiaLLy unstaBLE oNes; and that ThEy put Emphasis on ThE onsitE standby power Supply. Also, in This RespeCT The Americans identify the grid as ThE pREfERREd power supply to The plant auxiliaries, whiLE The IAEA Leaves the possibiLity ThaT The pRefeRREd power suppty couLd bE Either ThE grid oR The uniT mrin geneRAToR depeNring on The ReliabilitY of Each. THÊfoRE, it is found that it ^ paRticulaRly NEcessary In Th^s aRea of clEcTric power supplies To dEal wiTh The IAEA and The American SEti of REgulations as if Each compLeMents and noT SuppLEmEntS ThE other.

1^ INTRODUCTION

Th^ paper pResEnTs a compREhEnsivE coveRagE of The REgulaTory REQuiREmEnts coNCERNIng ThE ELEcTric ^ower Supply (E^S) To a NuclEaR ^ower ^^1 (N^) in gENERAL, and To EnginEered SafEty FEatuRes (ESFs) and Safety RELated EQuipmEnt in paRticuLaR. IT also aims at making a criticAL comparison bEtwEEn ThoSE REQuIREmENts as being described by ThE United States NuclEaR REgulaTory Commission USNRC, and by The InTeRnationAL Atomic ENergY IAEA REguLations. ThE scope of This woRk ExTEnds from outliniNg ThE infoRmation nEcessary To ENABLE foR maKing a SouNd ET^S EvaluatioN, IdEntifying ThE GENERal DesigN

^ 1 - - 2 - CRiteria GDC THat muST be fullflled in order To assurE a safe desIgN and ReLIabLe perfoRmaNce, and ENds witH a descriptioN of THE methodoLogY ThaT shouLd bE followed IN order To achieve a good impLementatioN of Thos

However, it SEEmed NEcessary To fiRST pRovidE a brief dEScription of a typical E^S foR a N^, and THat wHat was donE THRough ThE following SEction. ThE comparison paRAllELs EAch of The subJEcTs (infoRmation, criTEria, and mCThodoLogy) iNcluded in ThE Siudy. A gEneRal coNclusioN is madE at The end; and REferENCes aRE LisTed. 2^ SYSTEM ThE ELEctrical power sysTems at a NucleAR power plant aRE designed To providE diveRSE ReLtabLE powER souRces To plant componEntS and EquipmEnt in additioN to s^ptying power fRom ThE plant To ThE off-stiE trAnsmissioN neTwork. ThE station power is supplied by Either The off-sitE mrin disTribution grid oR by The unIT maIN gEneR^ToR. In CASE of Loss of offsitE power supplies, Including uniT gEneRAToR^ and the grid, the power REquIreD foR safE shutdown of THE ReaCToR is Supplied fRom diesEL gEneRatoRS Located on-site and known as THe standby AC power Source. ThE station cleCTrical system ^ designed to ensuRE ELECTrical isolation and physicaL separation of The The Redundant power supplies foR station equipment REQuiRed for safeTy; and due to liMitations Imposed by The power whicH can bE dElivered by thE dIeseL genEratoRS thE UN^T power suppty is spllT beTwEEn ENgiNEered Safety FEatuRe^ (ESF) buses which can bE SupptiEd by The diesELs, and non-ESF buses. Redundant trAIns of EngineeRed Safety FEatuRes equipmEnt aRe maintained ELEctrIcally SEpaR^TE by having each TRain powered by Its own diesEL. This EnsuRes t^^T a sIngLE active faILuRe (e.g., Loss of a diescl) will noT JeopaRdi^e a Safe shutdown of The REacToR. BaTtaries aRe pRovided as a source of power for vitaL instrumEntation, bReaker contRolleRS, emergencY llghting, eTc. In ^SE of station blackoat, i.e. TotaL Loss of plant off-site and on-site AC-power, baitaries are

In view of ThE USNR unit gENERaToRS ARE considered parT of The off- SitE power supply bEcauSE Loss of ThE griD ^ assumed to automaticaLLy Lead To Loss of The unit gEneRAToR^ ESFs include eQuipmEnt REquiREd foR SafE ReacToR shut down, ResIduAL hEat rEmoval, and Radiation coNfinEmEnt. ThE oNty souRCE of power LefT^ They are maIntaInEd fully chaRged by baTtary chARgers fRom so- called vitaL bus^ which arE fed fRom ThE ESF buses vta

FIguRE 1, bclow, shows a typIcal ELectrIcal power SySTem of a NucleaR power statioN, a descriptioN of which is given 2^ 1 To The grid ^ Supplied fRom The mriN gENeratoR ThRough ThE maiN power TRAnsfoRmer. THE station distribution buses (1^.4^ ^v bus^ CAN REceivE power EitHer from THE mrin gEnEratoR ThRough ThE uniT transfoRmer OR from ThE gRid through ThE stariup transfoRmer. 2^2 THe ^C^ ThE station AC power system has four 4160 voll buses which REceivE power fRom ThE two 1^.4^ ^v distrIbutioN bu^^ vta two unti substation transfoRmerS and individual bREakERS. Two of thesE buses aRE EnginEerED SafEty FEataRE (ESF) buses, The other two cARRy servicE Loads wnich ARE noT ReL^ed to emergencY safEguards. ThE two non ESF buses arE capable of being cRoss coNnECTed. ThE ESF bu^^ havE pREfERRed power coming fRom The stariup transfoRmeRS, wtih The power coming fRom THe uNit TRAnsfoRmer during NoRmal plant opeRatioN. All 4160 voll buses suppty a 4^0 voLT distribution system ThRough Load cEnter step-down TransfoRmers. THE 4^0 voLT system Reccing power fRom tHe two ESF buses is compLeTeLY isolaTed fRom that REceiving power fRom THe other two 4160 voll non-ESF buses^ ESF LoaDs are divided beTwEEn thE mrin 4160 v^T buses Such tHat ThoSE The same function are supplied fRom differEnt souRces.

The DC power supply system, shown in Fig. 1, consists of onE ^0 voLt DC and two 12^ voLT DC sysTems desigNed To pRovide an adequate and RELtabLE SourcE of continuous DC pow^ ThE 2^0 voLT DC system Supplies power for LARgE DC motoR-drivEn pumps such as THE EmergEncY bEaring oll and emergency SEaL oll pumps. This system is not esSEntial foR a SafE shat-down of ThE plant. IT has Its owN batTEry, batiERy chaRger and diStributioN bus, and is Located in Its own SEpARatE vEntiLated Room in THE Turbine buiLding. The two 12^ voLT DC systems supply power foR emergency tighting, DC contaoL functions foR ciRcuIT breakeRS^ various RELays, SoLEnoid valves^ NuclEar instrumEnTatioN, AC iNveriERS and small DC motoR drivEn Equipment. THis equipment ^ part of The ESFs, and ^ Located in The auxiLiary

IT ^ comprised of two baTTEries, Each having two batiERy cHaRgeRS powered fRom RedunDANT bus^ aNd The NEcesSARy disTribution

This portion of ThE sysTem is designed to pRovidE reLiabLE eLEctric power foR conTroL and instrumentatioN. IT consists of 120 voLt InsTRumEnt AC-aNd pREfERR^ AC SySTems^ ThE 120 voll Instrument AC sysTem contains THREE buses aNd supplies contRoL and instrumENtatioN power foR EQaipmEnt noT ReQuiRed foR The safE shutdown of The ReactoR. ThE pREferred instruMEnt AC sysTem supplies continuous and RELtabLE 120 voLT AC power REquiRed foR safE shut-down of ThE REacToR^ THE pREfErred instrumEnt AC system, compRised of fouR ESF-RELated buses, supplies ReLiabLE 120 voLT AC singLe-phaSE power to ThE ESF channeL EqaipmEnt and The ReactoR pRoTection chanNELs. Each pREfERRed instrumEnt AC bus can be supplied from one of ThREe SouRces of power as sh^^n in Fig. 1. ThE noRmaL SouRCE of power is Its associated static inveRTer wnicH Receives its power from an ESF 4^0 voLT motoR center. THE backup pow^^ supply foR The inveRTERS is a connection to the 12^ voLT DC station batieries. If it is necessary to take an invEnter ouT of servicE, its pREfeRRed instrument Bus may be manuallY transfeRREd to ITs associated 1^0 voll InstrumEnt AC bus. THE two Incoming fEeder bReakeRS foR EacH pREfERRed Instrument AC bus aRe manuaLLY opERated and mEchanicaLLY InterLocked to pRevent boTH bReakeRS fRo^ being closed at THe same time.

In casE of Loss of off-sitE power, ThE eQuipment esseNTIal to safe shutdown of The pLAnt wiLL bE supplied by The diescl gEnERatoRS. DieseL genERAToRS automaticAlly staRT and tiE i^ the 4160 voLT vitaL bu^ on a Loss of voLtage on The bus. Each diesEL ^ designed to REach Rated spEed and voLtagE witnin Ten SEconds ^f Receiving the StaRT signal, and to automaticallY accepT ESF LoAds in a spEeified sequence^ To pREvEnt oveRLoading and Tripping THE diesEL, ThE maJoR Loads aRE Tripped off bEfoRE ThE diescl bREaker closes. The LaRgE Loads wILL then be seQuenced back one at a time. The entiRe sequEncE takes about ^0 SEconds ANd ^ accompLished by an automatic SEquEnc^ The seQuencer pRevents oveRLoading by pErioRIti^ing vitaL EquipmEnt among thE^SELves. - 6 -

SAFETY In THis sectioN we pResENT THE infoRmatioN wnicH sHouLd concerning ThE eLEcTric poweR SY^Tem, by a licensEE of a nuclEAR power plant as paRT of THE safety aNalysis RepoRTs. This section shall aLso includE iaEntIfIcatioN of ThE scope of clEctric power systEm REview To be perfoRmed by THE REgulaTory body^ HowEv^ bEfoRE going inTo thesE subjects we havE to cLarify the dIfferEnce beTwEEn thE American and THE IAEA ReguLAtions regaRDing THEIR difIniti0N of ONE Of THE TERMS Wnich is COntiNUOUSly REfERRed To in W^^T follows; nameLy ^thE pREfERRed power sysTEm^ ThE off-Site powER sysTem is known in ThE AmericAn INduSTry StandaRDs and NucleaR REgulaTory gaides to be The pREferRed po^^ SysTem ^2^ IT includes two oR moRE idEntified power souRces capabLE of opeRating idEpEndEnt of THE on-stiE (standby) power sources; and Encompasses^ THE grid, transmission lines (overHEad oR undergRound) , trAnsmission llnE toWERS, transfoRmeRS, switchyard and contRoL systems, SwitcHyaRd battery systems, THE mrin and d^sconneCT switches. In The IAEA REguLations REf. (^^, THE pREfeRRed power system may be EitHer THE clEctric grid, oR The unIT mrin gEnERatoR. ThE REiabiLity of Each SysTEm contRols ThE seLEction of The pRefeRRed poweR suppty wrich shouLd bE thE moRe RELiabLE of ThE two.

To be In view of thE American ReguLAtions, infoRmation to be supplied by licEnseE shouLd cover Those 1 ^REfERRed ThE ctrcuits that suppty power for safCTy Loads fRom The TRansmission network shouLd be identified and shown To meet voLtagE LEvcl and Length of Each trAnsmission tinE from THE sitE to ThE first major substation THat connects THe tine to The grid^ Description and layout drawings of The cIRcuITs T^T conneCT THE onsitE distribution system to The pREfeRred power suppty, incLuDing trAnsmissIoN Lines, switchyard arrangEmEnt, rights of way CTc. shouLD also be provided^ The resuLTs of stEady statE and transIEnt stabILity analysis shouLD be given. Information and discussion of grid avaILabIlity, Including the frequency, Duration, and cAuses of outa^^ must be provIded^ ^^1^2 Standby ^ower Description of the on site AC power systEms with Emphasis placed - 7 - on ThoSE poRtions of THE sysTem which arE safety RelaTed muST be THose poRtions T^T are not RElaTed to safEty NEed oNLy to bE described IN suffIeiEnt dEtaIL To pERmit an undERStanding of TheIR IntERActions witH THE safEty ReLated poRtio^ The description of The safety RelaTed portion shouLd iNclude^ (I) 1^^ Suppty FeedeRS. (^) Busing ARRANgemEntS. (^) Loads Supplied from each bus^ (4) ManuaL and automatic IntercoNnEctions between buses and Loads, and buses and Suppll^ (^) InterconnEctions beTweEN safeTy RELated and NonsafEty RELated buses. (6) ReDuNdAnt bus SEparatioN. (7) EQuipmEnt CApacities. (8) Automatic LoadiNg and Tripping of (9) SafEty-RELated EQuipmEnt (10) Instrumentation and contRoL systems for tHE appllcabLe power systems wtih The assigNed power suppty idEntification. (II) ELEcTric ciRcuit pRoTEction System neTwoRk. (1^) ThE schemE foR TestiNg thesE systems during power opeRation. (1^) Any systems and equipmEnt shARed bEtwEEn units. The basis foR thE power REQuiRed foR Each safety Load shouLd bE given. The continuous and shoRt teRm Ratings foR thE on-stiE power SouRcE shouLd bE given. ThE following design aspecTs of thE onsitE EmergEncY eLEctric power souRces (e.g. diescl gENeRatoRS) shouLd be described in tHE Safety Analysis

(1) StaRting initiating ciRcuits. (^) Starting mechanism and system. ( ^ ) Tripping dEvices . (4) IntERLocks and pERmissives. (^) Load sHEdding cIRcuits (6) TestabiLitY (7) FueL oll stoRAgE and transfer systEm. (8) Coollng and hEating systems^ (9) InstRumentation and contRoL systems, incluDIng status aLaRms and indIcations wtih power (10) Prototype QUALIfIcation ^ 8 ^

Any fEaTu^s or componenTs NoT pRevIousty used IN simILar applicAtions In nucLeaR gENeRating stations sHouLd bE ideNTIfIe^ SIngLe Line diagRam of The onsite AC disTributioN sysTems, IncLuding IdENtifIcatioN of all safety Loads' shouLd bE pRovid^ ThE phYSIcal aRraNgEmEnt of ThE components of The SysTEm shouLd be dEScribed In suf fIcIEnt deTaIL to peRmit INdEpENdEnt vErificatioN That singLE EvEnTs aNd accidEntS will not disabLE ReduNdant fEatuRes. ^lant tayout dRawIngS shouLd bE suffieiEnt To peRmti evaLuatioN of ThE phYSical sepaRation and isolatioN of RedUNdant poRtions of The SysTem. A tabLe That ILLusTRates The aatomatIc and manual Loading and unLoading of Each standby power supply shouLd bE provided^ ANALYSis To demonstratE compllance wtih REguLatory REQuIREmEnts Identified In The following SEctioNS shouLd bE made^ All Safety ReLaTed EquipmEnt which is expECTed to operate in a hoStiLE EnviRonmEnt due To RAdIation, TempERaTuRE, pResSuRE, and humidity following a poSTuLated accident shouLd bE Identified, all Such conditions shouLd be tabuLated, and The completion of appllcabLe quaLIfication Tests OR plans and scheduLes foR perfoRming incompLeTed Tests shouLd bE DocumEnted. ThE mEa^S proposeD to Distinguish betWEEn Redundant cLass IE sysiems and iTs associaTed cIRcuITs on onE hand and The non-cLass IE system on THE other hanD, shouLd bE described. ^. 1 ^ D.C. ôwer SysTems.^ A description of The DC power SYSiems wnich cleaRLy dEfinE THE safety RElaTed portion^ shouLd bE pRovid^ THE description shouLD includE REquiRemEnts for SEpaRation, capacity, charging, vEntiLAtion, Loading Redundancy, and Testing^ ThE Safety Loads shouLd be cleaRly identified and The LengtH of time ThEy sHouLd be opeRabLE in ThE EVEnt of Loss of aLL AC power (iê^ station blackouT) shouLD bE stat^ Analysis to demoNSTRatE comptiancE with safety ReQuiRements shouLd be made. ^.1.4 FIRe ^RoTection foR CabLe The mEaSuRes EmpLoyed foR THE pRevention of and pRoTEction againsT fires in eLEcTrical cabLes shouLD bE REferEnced. however, The following shouLd be Described^ a) CabLe deRating and cabLe TRAy fill, and b) FIRe baRrieRS and SEpaRation bEÊen RedundAnt ^^2 Scope of Review by The infoRmation to bE pResEnted in This SEction compLEmEnts (and - 9 - does NoT itERatE) t^^T gIveN in sec^ ^1 In deallng witH THe safety aspects of a NUcleaR powER pLAnT eLecTric power supplies^ IT ideNtifies tHose features T^^T sHouLd be emphasiêd in view of The AmeRican REgulaToRy

^RefERRed ThE pRefERRed power sysTEm aRRANgEment ^ RevIEWed To dEteRmInE THat ThE ReQuiRed minimum of two SEpaRatE ciRcuiTs fRom THat sysTEm To THE standby power disTributioN system ^ provide ThE indepEndencE of THe pRefErred power system with respECT to ThE standby power systEm is Evaluated^ The scope of REview ExTEnds to The SafEty RelaTed disTributioN sysTem buses That aRe capabLe of being powered by standby power souRces. IT does noT includE ThE supply bReakeRS of The safety-RelaTed distrIbution sysTem bus^ This evaLuation wILL IncLude a Review of The clEctrical pRoTEctivE RELaying and bREaker controL cIRcuITs and power supplies to assuRE that Loss of ONE pReferRed systEm cIRcuit wILL not cause OR ResuLt in Loss of thE RedunDant pari noR any standby power system. Design information and anaLysis dEmonstrating ThE suItability of thE power sources, trAnsmission lines, bREakeRS, and ^^^0^^^ used foR supptying pREfERRed power fRom a distant SOURCE aRE REviEWed to asSuRE ThaT each path has SuffieiEnt capacity, capabILity and RELiabILity To pôRm Its IntEnded function. ThE InsTRumEntation REQuIRed foR monitoring and inDIcAting ThE status of thE pRef eRREd powER system ^ REvIEWed to assuRE that any changE In thE pREfERRed powER system which wouLD pREvEnt ti from perfoRming ITS IntEnded function will bE ImmEdiatEly idEntified by thE contRoL Room opERatoR. All inStrumEntation foR initiating safeTy actions associated wtih the pRef ERRed power system aRE aLso REvIewed. ^REopERatIonal and 1^^^^ staRtup tests and pRogRams anD periodic testing CApabilitIes aRE REviewed. The Review shouLd aLso incLudE.^ a-EnviRonmEntaL conditions foR thE pREfERRed power system To deteRmInE any EffEct on function^. b-QuaLity gRoup classificAtioN of EQuipmEnt of thE pREfeRRed power system, and c-ThE EQuipmEnt and fuNctions of thE pREfeRRed powER systEms ARE used as a basis foR assumptions in tHE accIDEnt Standby The following fEaTuRes of THE standby power sysTem aRE To bE 1- ConfoRmancE witH THe SingLe FaILuRe CriTerIoN^ IN This REgaRd boTh eLectrIcal isoLAtioN and physIcaL sepaRatioN of ReduNdant power sources and associated disTributioN sysTems aRE Examined to assess THE INdEpendEncE beTwEEN Redundant poRtions of ThE sysTEm. 2- Standby and ^REferred (off-stie) ôwer SysTem Independence^ ThE scopE of REvIEW shouLd covER ThE Station disTribution Load cEntERS wnicH aRE powerEd fRom ThE uniT transfoRmer and ThE StaRTup transfoRmer. IT shouLd aLso IncLudE THE Supply bReakERS connecting The (Low) side of these trAnsfoRmeRS to The distrIbution buses incluDiNg TheIR contRoL ciRcuITs and power suppty. ^- Standby ôwer Supp^ DiesEL gEnERatoRS capacity, and RELiabiLIty to perfoRm ThEiR intended function sHouLd be dEmonsTRatEd. THis includes an Examination of ThE charactEristics of Each Load and ThE Length of ^^ each Load is RequiRed, THe combined Load dEmand connECT^ to eacH diesEL gEnERatoR during THe woRST opeRating conditions, automatic and manual Loaring and unLoading of EacH dieseL gEneRatoR, voLtagE and fREQUEncy REcovery cHaRaCTeRIsticS of The diescl generatoRS, continuous and sHori teRm Ratings foR THe aiesEL gEneratoR Tests and aLLowabLE faiLuRes to demonsTRatE accEptabiLity, and stariing and Load sHeDring ciRcuits. In addition, wHerE THe pRopoSed Design provides for The connEction of non-safeTy Loads to THE diesEL gEneratoRS OR sHaring of dieseL gENERAtoRS bEtwEEn nuclEaR units at THE SitE, EmphASis is To bE gIvEn To THe possIbility of ^RgInaL CApacity and degRAdation of ReLiabIlity that may Resuit, and THE adeguacy of such design to mEET ThE singLE faILuRE cRiterioN. 4^ VItaL SuppoRting SysTEms^ The InstrumEnTation, contaoL cIRcuITs, and power connEctions of vItaL SuppoRting sysTEm aRE examined To deTERmInE that ThEy are desIgned to The same criTeria as ThoSE foR The cLass IE Loads and power systems that ThEy SuppoRT. Th^s shouLd includE examination of The vItaL Supporting sysTem compoNEntS^ Redundancy, power feed assIgNMEnt to InstrumEntation, conTRoLs and Loa^ Initiating ciRcuITs, Load chaRACTeRistics, And Equipment identification SchEmE and quALification. DesIgN criTEria and bases foR The InstaLlation of Redundant cabLes shouLd be verified, and The means and scHEmes pRopoSed foR IdEntifIcation of cabLes, RAceways, and TeRMInal eQuipment shouLd be evaluated^ TestiNg and SuRveIllaNce^ ^REopERatioNal and INItiaL startup TesT pRogRamS aNd periodic 0N-sitE TestiNg capabILities aRE To be Review^ The means pRoposed foR auTomaticAlly monitoRing ThE status of system opeRAbility shouLd be evaLuated. ^2^ DC ^wer Supplies ^ DC SysTem RELEVAnt REvIew items simiLaR To ThoSE foR THe standby AC power sysTem shouLD be consiDered^ ELEcTricaL drawings including voLtagE profllE curves^ dischARgE raTE curves^ TempeRaTuRE effect cuRves, aNd ELEcTrical DIsTribution diAgRAmS IncludiNg Load IdenTIfIcaTIon^ ShouLD be provided^ TabuLatioN of all safEty RELated Loads To bE conNEcTed To Each DC Suppty, tHe chaRAcTERisties of Each Load and ThE bases us Ed to establish ThE power REQuIRed To eacH Safety Load sHouLd bE estabLisHed^ QuaLification TesT pRogRam, and TesT ResuLTs demonStRating THE Suitability of the battaries and batTery cHaRger as DC power supplies ShouLd bE described. The IAEA REguLations (^ addresses this subJecT of The ELEcTric power Suppty system infoRmatioN NEcessaRY foR SysTem SafeTy EvaLuation, by indIcatiNg That a discuSsIon of the System ShouLd bE gIvEn. Emphasis ShouLd be put on fEatuRes wnich aSSuRE continuity of power for safety nEeds. REliabiLity anAlysis of The power souRces, THE distrIbutioN systems, and EqaipmEnt sHouLd aLso bE givEn. ThE distribution and intercoNNEctioN of clEctrical supplies witnin THe nuclEAR poweR plant ShouLd bE shown. ThE aRRangEment of bus bars, ThEiR switcniNg and Loading, and ThEiR physical SEpaRation, inDepEndEncE and isolation wheRE appRopRiaTE, ShouLd bE discussed. The ARRAngeMEnt of conNEctions to The mrin grid, THe geNeRal oRgariâtion of THE neTwoRk (grid) and The IndEpEndEncE of THe exTernal souRces of power suppties to The NucleAR plant sHouLD bE shown^ ^RotEction fEatuRes foR THe transmission lines and tRAnsfoRmERS, THe Local ENviRONmenTaL factoRS T^T can affEct THe grid RELiabilIty shouLd aLso bE discussed. AliernatE ENergy souRc^ exTernal or inteRnal, shouLd be described in teRmS of their ReLiability, ThEiR indEpendEnce and adequacy of thEiR capacity^ 4^ GENERA^ DESIGN CRITERIA FOR ELECTRIC Ê^ SYSTEM AccEptancE criteria foR eLEctric power system ^2,6^ aRE pResEnted in THis SEction. ImpLemEntation of thÊ criteria will provide asSuRAncE safeTy RElated clEctrIc power systems will perfoRm design safety - 12 - fUNCtions as REQUIRE Off-site power sysTem pRovIded descriptioN Is consIDered acceptabLE whEN it CAN bE coNcLuded That ThE InteRRELatioNShips betweEN ThE NuclEaR unti, and ThE interconnEcting grid ARE clEaRly de^^ The Identification of safety Loads is acceptabLe whEn it can be concLuded t^^T all systems and dEvIces That REquIRE clEcTric power (AC OR DC) to perfoRM safety functions are desIgNated. Acceptance of ThE pRoposed TEchNIcal spEeifications ^ based on THE avaIlabiLity of SuffieiEnt EQuipmEnt To mEeT ThE sIngLE faILuRE criTeria under The Limiting coNditions for opERation, and on That ThE pRovisIons of ThE TEchnical speeifications ARE compatibLE w^th The safCTy analyses^ THe ELecTric power sysTEm ^ acccptabLE If it satisfIes GEnERal Design CriTERia GDC 17 and 18 ^ wnich aRE cITed bELow duE to theiR almost importance. HowEv^ power sysTem sHaLL aLso satisfy GDC-1 concerniNg The QuaLity assurance, TestiNg, and sysTem opERAbility SuRvEIllance. GDC^ for pRoTEction againsT NaTuRal phEnomEna, GDC-^ foR fIRE pRoiEction, GDC-4 foR pRoTEctioN agaInsT missiles, GDC-^ In case of sharing ThE onsitE pOWer Supplies bEtWEEN twO (OR mORE) NUclEar UNitS ON ThE SamE SitE, GDC 1^1,^,^,^,^,^ a^d ^4 with REgaRd to providing adequatE, capabLe, and ReLIabLE power supplies to ReacToR pRoiEction, ReacToR makE up, Residual hEat REmoval, EmergENCY coRE coollng, coNtainmEnt hEat REmov^ containment atmosphere clEan up, and cootiNg water systems, RespectivEly. IN addition The DC power system ShouLD Satisfy GDC-^2 wrich concerns REaCToR pRoiEction SysTEm indEpendEncE. CriiErion 17^ ELEctric Rower SysTem An onsitE clEctrIc power sysTem and offsitE eLecTric power sysTem shall be pRovIded to pe^^T fuNctioning of sTRucTures^ sysTems, and componenti impoRtant to safety^ ThE safety function for Each sysTem (assuming The other sysTem is NoT fuNctioNing) shall be to pRovide SuffieiEnt capacity and capabiLITy To assuRE ThaT^ ( 1 ) SpEcIfIed accEpTabLE f ueL desigN 11^1^ and design condItions of The ReacToR cooLant pRessure boundary aRE not ExcEedEd as a ResuLT of antieipated opeRatioâL occuRences, and 1^^ (2) ThE coRE is cooLed, and contaiNmEnt InTegrity and other vital functions are maintaIned In ThE EVEnt of poSTuLated accIdEnts. ThE onSitE clEcTric power supplies IncludI^^g ThE baTtaries and THe onsite eLEctric disTribution sysTem shall havE suffIeiEnt independEnce, and TestabILIty To perfoRm Their Safety functions assuming a singLe faILure^ ELectric poweR fRom THe TRAnsmissIoN nEôRk To the 0NSite eLecTric disTributioN SysTem sHall be supplied by two pHysIcAlly INdEpENdEnt cIRcuITs (noT Necessarily ON SEparaTE righTs of way) designEd and Located so as To minimiÊ To The exTenT pracTIcal The llkELihood of Their sImuLtaneous faILuRE uNder opERating and poStuLated accIDent and enviRonmental coNditions^ A switchYaRd commoN To both ciRcuits is acceptabLe. Each of these ciRcuiTs shall bE desigNEd to bE avaILabLe in suffIeient time following a Loss of all onsitE aLTernating cuRREnt powER supplies and The other offsite eLectric power ciRcuits, To assuRe ThaT spEcif led accpeTabLE f ueL desIgn LImITs and desIgN condItions of The^ ReACToR coolant pRessuRE boundary aRE noT exceeded. One of thesE cIRcuITs shaLL bE designed To bE avaiLabLE witniN a few SEcoNds following a Loss of coolaNT accidEnt To assuRE that coRE cooting^ coNTaiNmEnt integRity^ and oTher vitaL Safety fuNctions are maintaiNed^ ^Rovisions shaLL be iNcluded To minimise The Loss of any of The two (off-stie and 0N-sitE) power systems as a ResuLt of Loss of The oTh^ CritERion 1^ .^ InSpecti^N and TestiNg of ELectricAL ôwer SysTEm ôwer sysTemS impoRtanT to safety shall bE desigNed to pERmit appRopRiaTE periodic InSpEction and TestiNg of impoRta^t aREaS and fEatuRes, Such as wiring, Insulation, coNnEctions, and switcH boards To assess ihE continuitY of THE systems and ThE condition of TheIR componenTs^ The system shall bE desigNed with a ^pabI^^y To periodicaLly Testi 1 ) The opERabiLity and f unCTionaL peRf oRma^ce of The compoNEnts and systems sucH as onsitE power sources, ReLays, switcHes, and buses, and 2) ThE opERabiLity of THE sysTEmS as a wHoLe and under conDItions as cLoSE to ThE desIgn as pRactical, ThE full operation SEQUENCE T^T brings The sysTEms into opEration iNcluding operation of appllcabLE portions of ThE proTEction system, and The tRanSfer of power among The nuclEar power unti mrin gEnERatoR, The grid, and THE onsitE power system. On the other haNd The IAEA CodE of DesigN ^ 7 ^ ^^s indicATed The various means of supplying emeRgENcy power incLuding watER, sTEam or gas TuRbines, diescl Engines aNd baTtaries^ The criTerioN given by T^^s code StaTes SELEcted combiNation of The means to suppty EmergEncy power sHall have a REliability and foRm which aRE consisTEnt witH all The ReQuiREmeNts of THe safety sysTems To be suppll^ and shall meCT ITS duti^^ assumiNg a siNgLe fallure^ IT shall be possibLE to TesT The fuNctioNal capabiLity of ThE EmergENCY power suppty^^ comparing ThE StaTmEnT aNd ThE iNTEnt of Th^ critErioN to Those of GDC 17, and 18, ONE can dRaw THE foLLowiNg REmaRks^ 1- The IAEA REfRatN fRom dEfining ThE eLecTric power sysTEm configuRation and fRom specifying ThE NatuRe of The power supplies to be installed. 2- The IAEA criTErion, aLThough sTated in bRoad tERmS is eQuivaLEnt To THE AmERicAN CriTEria in w^^T coNCerns EmergEncy ôwer Supply RELiAbILity, capabILIty, and Testibility^ HowEver, in This REgaRd WE wouLd likE to point ouT ThaT^ aLthough ThE IAEA code of desigN LimiTs ThE scopE of ThE eLEcTric emeRgenc^ power suppty to THE standby AC poRtion, ThE IAEA SafEty gridE of Ref. ^ ExTends this ScopE to incLude off-site grid and unit gEnERatoR, in addition To the standby on-SitE AC and DC power Supplies. ^- The IAEA-codE o^^ not REfer ^ in any way to ThE possibiLitY of using ThE grid as a power suppty (if it is avaiLabLE) in CASE of EmergencY, aLthough The AmEricans consider The grid to be the pREfeRaBLe power supply under noRmal and EmergEncY conditions.

GUIDES AND ^RANC^ TEC^NIC^^ POSITIONS In Tris section WE put empHASis on THE methods RecommendEd, as the mEans foR impLemEnting ThE acceptance cRitERia, by ThE USNRC and the IAEA. THESE meThods aRE described in ReguLatory and safeTy guides and bRAnch Technical positions^ (^9 - ^^.^ d bT ddT Tdb ^it) souRces

GenERal design criTErion 17 given befoRE REQuiRes That onsitE eLEctrical power systems havE suffieient indEpEndEncE to peRfoRm thEiR safety fuNctions assuming a singLE faiLuRE. An accEptabLE dEgRee of indepEnDEncE BetwEEn REduNdAnt standby (onsitE) power SouRces and theIR distribution sysTEmS ^ asSuReD pRovIded That (9^

HowEver, mEntion of ThE grid as a powER Suppty is pRovIded In ^^D^^^ ThesE aRe USNRC documenTs wnich take ThE RoLE of a REguLatory guidE RG but foR pRobLEmS f OR which no RG has bEEn issued. The eLEcTricallY powERed safety Loads (^C and DC) aRE bE sepaRATed I^To ReduNdant Load groups such that Loss of any one gRoup will noT pREvEnt ThE miNimum safety functions fRom being perfoRmed^ Each AC Load gRoup have a connEction to The pRefERRed (off-sITe) power source and to standby (oN-site) p^wer source (usually a singLe diesEL gEVErator)^ ThE standby power source shouLd havE no automatic connEction To any oTher Redundant Load group^ At muLtipLe NuclEaR unti sites, ThE standbY power Source ôr onE Load gRoup may have an automatic connection To a Load gRoup of a differEnt unti^ A pref erred powER souRcE bus, hêv^ may êrvE ReduNdAnt Load groups^ Each DC Load gRoup ^ ENergiêd by a batiaRy and baTtaRy chargEr. ThE baTtary-chaRger combination sHouLd havE no automatic connEction to any other Redundant DC Load gRoup. Redundant Load gRoups and THE REdunda^T standby souRces aRE independEnT of Each oTher^ whEn opeRating fRom The standby souRces A single genERatoR driven by a sIngLe primE mover ^ acceptable as The standby power source foR each AC Load gRoup of The sIê and chaRaCTERisties typical of RECEnt appticAtioN. If other aRRangEmEnTs such as muLtipLe dieseL gEnesatoRS opERated in paRallEL OR muLtipLE primE movers driving a singLe gEnEr^ToR arE propose it shouLd be dEmEnsTrated That The proposed arRANgEmEnt Has an EQuivalent RELiabILity. Common modE failuRes as w^LL as Random singLE faiLuRes shouLD be considered in The analysis. In The IAEA REguLations (sec. 6.1, 6.2 and A-^2 of Ref. ^)), THis tiem of Redundancy and indepEndEnce is expRessed by indicatiNg THat The Emergency ôwer SysTem E^S shall be divIdeD InTo DIvisIons, each consisTEnt with THe sysTEm ti SERves; and as a minimum shall be two iNdependent divisions^ Automatic connections REdundAnt divisions shouLD bE avoidEd, a^nd if any connection ^ made ti shall bE shown That ThE REQuiremEnTs of ThE coNnEcTed safety Loads arE mET taking into account ThE poTEntiaL for propagation of failuRes and for overLoading The power source S^feTy sysTemS suppori fEatures shall bE assigned to ThE SamE Division o^ The E^S as The safety sysTem ti ^ supporting^ Non-safety sysTems ^Hich are supplied from THe shall be connEcTed to The E^S îth safCTy grade isoLation of DIeseL geneRaT^ s^T This SEction describes an acceptabLE basis ^10^ foR ThE SELection of diescl gEneRatoR seTs of sufficiEnT capacity and margin To ImpLEmEnt gENERal desIgN criTErion 17. A diesEL genEratoR SET seLEcTed foR USE as a standby power suppty shouLd havE The cApabILity to^ 1 ^ StaRT and accELeratE a Number of LaRgE matoR Loads in rapid succession^ and be abLE to sustain The Loss of any such Loads. 2^ Suppty continuousty The sum of The Loads nEeded to be powered at any onE timE^ AT a time whEn ThE charAcTERisties of LoaDs are not accuRately known, such as during ThE stage of desigN, each DEiseL genEratoR SET on a standby (on-SitE) power Supply ShouLd bE SELECTed to havE a continuous Rating EQual to oR gREater thaN ThE sum of The conservativEly estimated Loads nEeded to bE powered CT any one timE^ In The abSEnce of fully substantiated perfoRmancE chaRacTeristics foR mEchanical EQuipmEnt such as pumps, ThE eLEctiRc motoR drive Ratings shouLd bE calcuLated using conservativE esTmates of thesE cHaRacTEristics (Iê. pump Ran out condItions and motoR effEeiEneiES of 90^ oR Less^ ^ÎdE The above REQuiREmEnTs, EacH diEdeL gEneratoR sCT sHouLd be capabLE of starting and accELeratiNg to RateD spEed, in the REQuiRed REQuEncE, all The nEeDed engineered safEty feaLuRe and EmergENcy shutdown Loads. AT no timE during The Loading SEquEncE ThE fREQUEncy and voLtagE dECREASE shouLd bE Less ThaN 9^ of nominal and 7^^ of nominal RespEctivEly. During REcovery fRom TransiEnTs cauSeD by sTEp Load inerEases oR ResuLting from THe des connection of LARgesT singLE Load, The spEed of ThE diesEL geneRAToR SET shouLd noT excEed 7^^ of ThE differEncE betWEEn nominal SpEed and ThE ovERSpEed Trip seT point oR 11^ of nomiNal wnich Ever is Lower. VoLtagE shouLD be ResToRed To witnin 10^ of nominal and fREQuency shouLd bE RestoRed to witnin ^^ of nominal in Less Than 4^^ of Each Load SEQUENCE time interval. The suitabiLity of Each diescl generaToR set of The standby power Suppty shouLD bE ^^1^^ by pRoTotypE quaLIfIcAtion TesT data and pREopERationaL Tests. According to ThE IAEA, (SEC A^ 4^2 REf^ ^^), ThE standby eLecTric power sySTem shall have suf fIcienT capabILitY under antieipated operational and accIdEnt conDitIons To StaRT and Suppty all Load as spEtifiEd in ThE design basis. Loads noT impoRtant To safety that arE not auTomatically disconnEcTed shall bE assumed connEcTed and shall bE included in THe calculation of TotaL Loads. Load cApabiLity REQuiRes ThaT ThE standby - 17 -

unIT shall maIntaiN voLtage aNd fREqueNcy within time aNd LeveL Limits That wILL noT dEgRAdE ThE perfoRmancE of any Load beL^w ITs minimum ReQuiREmENTs EVEN duriNg TRAnsiEnTs caused by The LARgesT Load addition oR Load REmoval^ ^ Periodic Testing of ^roTecTi^N SysTem GeneraL desIgn critErion ^0 REQuiRes That The pRoTection sysTem bE desIgned to InitiatE ThE opeRatioN of Systems and componEnti ImpoRtant To safEty^ WhILe genERAL desIgN critErion ^1 REQuIRes That The pRoTEction sysiEm bE desigNed To pERm^T periodic Testing of ITS functioriNg when ThE ReacToR is in operation. In cuRREnt designs The ability of The pRoTection sysTem to IniTIate operation of safety sysTems depENds on The pRoper perfoRmaNce of acTuation dEvic^ ThEREfoRE thesE dEvices aRE To bE TesTed^ This section describes accEptabLE meThods ^11) of INcLuding The aCTuatioN dEvices in ThE periodic tests of ThE pRoTEction sysTem during ReactoR opERation as follows^ 1. THE pRoTEctioN sysTem shouLd bE desigNed To pERmti pErioric TestiNg To exTEnd To and include The aCTuatioN dEvices and acTuated eQuipmEnt. a. ThE pEriodic Tests shouLd dupLIcriE, as cloSEly as pRacticabLe, thE peRfoRmancE that is REQuIRed of ThE aCTuation DEvices in ThE EvEnt of an actidE^ b.ThE pRoTEction sysTEm ANd ThE sysiems ti initiates shouLd be designed To peRmit TestiNg of aCTuation dEvices during REactoR operatioN. ^. AccEptabLE mEthods of including THE acTuation dEvIces In The perioric Tests of ThE pRoTection systems ARE (11^ a. TestiNg sImuLTanEousLy all actuation dEvices and acTuated EQuipmEnt asSocIated with each REduNdant pRoiection sysTem output sign^ b.Testing all aCTuation dEvices and aCTuated EquipmEnT individuAllY oR inJudieiously SclECTed gRoups. c. ^REVEnting ThE opeRation of ceRtain aCTuated eQaipment during a TesT of TheiR actuation dEvices. d^Roviding ThE aCTuated equipmEnt wtih moRE ThaN one acTuation device and TestiNg each dEvicE individually. As REQai^ed by ThE IAEA REguLation (SEC A^ ^.4 REf^ ^^), automatic contRoL shall bE pRovided uNLesS SafeiY actions witnin Each division of THE E^S can bE ReL^^Y perfoRmed maNuaLLY. THE functions of The contRollERS includE The following^ Automatic dis connection of appRopRiaTE Loads (as specif ied in design basis) and all other power supplies fRom THE disTribution systEm - 18 -

when The standby OR aLTeRNAtive poÊR suppty is ^ Automatic staRT and connEction of ThE standby eLEcTric power sysTem and The Loads To THE disTribution sysTem in THe pRoper sequEncE^ ^ SyNchRoniâtion of ThE E^S To thE noRmal supply whEn THE LAtter is being Reinstated^ IsoLation dEvices foR inStrumEntatioN and contRoL cIRcuitS shall be pari of The E^ ThesE dEvices shall bE such ThaT^ ^ The maximum erEdibLE voLtagE OR cuRREnT ^ applied To The dEvice output, and ^ ShoRTs, gRouNds, oR open cIRcuits occuring at The output will noT dEgRadE ThE ciRcuit coNnEcted to The device input To bclow an accepiabLE LEveL^ ^.4 Seismic Design This guide describes a mCThod accpetabLe for iaEntifying and ThoSE feaTuRes of lignt water cooLed nucleaR power plants that shouLd be desIgned to withstand ThE effects of The safE shatdown EaRThQuatE. The class IE clECTric system incluDIng The sppoRting systems foR the on-stie AC and DC eLEctric power suppll^ tHat pRovIdE thE emergency eLEctric poweR needed foR functioniNg of plant featuRes; shouLd be desIgned to withstand thE effecTs of the safe shutdown EArihQuake and functional^ Quality AssuR^ce êûIre^^Ts for THe iNStaLLATIoN^ insêctiN of insTRuê^TaTIoN a^d eLecTric safety guidE describes an accEptabLE method of emptying the USNRC REgulations wtih REgard to thE QuaLity asSuRancE REquiREmEntS foR the instALlation, inspEction and testing of nuclEar power plaNT instrumEntation and eLectric eQuipment. The ReQuiRements foR tHe instaLLation, inspEction and testing of nuclEaR power plant instRumEntation and clEctric equipment wnich aRe included In ANSI N4^-2-4-19^2 In conjunction w^ ANSI N4^ ^^-^^^^ and IEEE Std ^^6-1971 arE gEnerally acceptable^ AccoRding to IAEA, Sec^ 7 Ref. ^^ avaiLabiLity assurance LeveLs sHaLL bE in accoRdancE with No^ ^0-C-QA and RELated Safety guIDes. ^^6 CriTeria for safety relaTe^ eLecTRic ôêR sysTems for

FoR safety RELated eLEctric power systems Recommendations in IEEE Std ^8-197^ aRE acceptabLE subJEct to thE following^ - 19 -

AvaILAbILIty of Off-SitE ^ower^ A pREfeRRed desIgN wouLd incLudE two ImmEdIatE access cIRcuITs from THE TRAnsmissIon nEtwoRk^ AccEptabLE desigN wouLd substitute a delayed Access cIRcuit foR one of THE immEdiaTE access cIRcuITs pRovided ThE availabILitY of ThE dElayEd access cIRcuit conforms to cRiteriAn 17. The capacity of The bati^y chaRger suppty shouLd be based ON ThE laRgesT combIned Demands of The various sTeaDy-StaTe Loads and THe chaRgIng capacity To ResToRe The baTTa^ fRom The DesIgn minimum chaRgE staTE to The fuLLy chaRged staTe iRrespectivE of THE staTus of ThE plant during wnich these demanDs occuR. The IAEA REf^ ^, SEC A^2^ HAS ExacTLy ThE SamE staTemEnt. THE baTtaRy ServicE TesT described in IEEE STd ^^^1^^^ shouLd bE perfoRmed In addition to ThE baTta^ perfoRmaNCE DischARge TesT^ The baTta^ servicE TesT sHouLd bE perfoRmed during REfuElling operatioN or aT somE other outages wtih intervaLs bEtwEEn Tests noT to ExcEed 18 months. IAEA reguLAtion, Ref^ ^^ Sec^ A-^^2 Ref. addResses This SubJeCT and has an EQaivalEnt meaning. QuaLIficAtioN TesTs of ^^11^0^ duty motors of SEction iaENtifIes aN accEptabLE mCThod of complying wtih THE USNRC REguLatIons wtih REgaRd To THE QUAlificAtioN Testing of pRoTotypE continuous duty c^ss I motoRS installed insidE ThE containmEnt of water cooLed nuclEaR power plaNTs^ THE meThod ^ described in THE IEEE STd ^^4- 1971. IT delineates sperifIc pRocedures for THe QualifIcatIoN Testing of class I motoRS to dEmonsTRatE adEquacy of desIgn foR ServIce witHIn The containmEnts of nuclEaR power plaNts^ ThesE pRoceduRes pRovide foR Testing uNder conditions simuLating ThoSE imposed During noRmal opeRation In addition To ThoSE ResuLtiNg fRom a design basis Loss of coolant aceidENT^ ThE StanDArd aLso spEeifIes pRocEduRes foR accomplisning acceLerated aging of componEnto to sIMUlaTe The effects of Long-TeRm opERation, iNcluding Radiation effecTs^ and foR subjecting a pRototypE aged moToR to combined (sTEam) pResSuRE, TempeRaTuRE, and chEmical EnviRonmENT appRoximating ThoSE of ThE design bases Loss of coa^^t accidEnt^ ThesE pRocEduRes aRE gENERallY accEptabLE and pRovidE an adEquaTE basis for complying wiTh The QuaLIfication Testing ReQuIREmenTs of criterion ^ of AppENdix B to 10 CFR pari ^0, to vErify adEQuancy of desIgn foR servIcE under The most adverSE desIgn coNdItions, sub JecT To The followIng^ ^ 20 -

To The ExTEnt pRActicabLe, ^^^1^^ eQuIpmEnt THat will bE parT of THe InsTalLed motoR asSEmbly sHouLd aLso be QualifIed in accoRdance w^ IEEE STd ^4^ 1971^ THe qualification Tests sHouLd simuLatE as cloSE as pRacticabLe all design basis evEnTs wnich affEcT opERatioN of The moToRS auxiLIary Equipment. THesE REQuiRemEntS haVE no EQuiValENCE in THE IAEA rEguLations^ Testing of red^da^T o^sITe eLecTricaL power verify proper Load dEvIces ThaT aRE RequIRed To opERatE dEpendEnt EquipmEnt bE supplied from a RELated bus SEctioN to pREvEnt thE Loss of clecTric power In onE Load gRoup fRom causing THe Loss of EQuipmEnt In aNother Load gRoup. ThE IndependEncE amoNg ReduNdAnt 0N-sitE power souRcE and ThEiR Load gRoups shouLd be Such T^^t The successfuL opERation of any power SouRcE and ITS Load gRoup ^ in no way affEcTed by ThE paRtial oR compLeTE faILuRe of any other power SouRcE and iTs Load gRoup. SincE ThE RELIabILity of an onsitE power sysiem is pRedicatEd on ThE ExIsTencE of Thi^ IndepEndEncy a SuItabLE pREopeRational tesi to deTecT any lack of indEpEndEncE shouLd be performEd. As a minimum a SuitabLE TesT shouLd aSSuRE T^^T each RedundAnt on-site power SouRcE and ITS Load gRoup can function wtihouT any dcpEndencE upon any other REdundant Load gRoup oR poRtion therE of^ To verify THE ExisTEncE of indEpEndence among Redundant on-sitE power SouRces and ThEir Load gRoup, ThE on-sitE eLEctric power sysTem shouLd be TesTed as follows^ 1 . ThE plant clEctric power disTribution sysTem, noT nEcessarily incluDINg ThE swtichyarD and ThE StaRTup and unti^ trAnsfoRmeRS, ShouLd bE isolaTed from ThE off-sitE TRAnsmissIon nEtwoRk. ^. Under The condition mEntioned abovE, THE onsitE eLectric power sysTem sHouLd be functionally TesTed successively in iHe various possibLe combination of power souRces and LoaD groups wtih all dc and on-SitE ac power souRces foR one Load gRoup at a timE compLeiEly disconnEcTed. Each Tesi shouLd incluDE injection of simulaTEd acri^^T signaLs, stari up of on-SitE power souRces and Load gRoups under TesT, SEQUEncing of Loa^ and ThE functional perfoRmancE of The Loa^ Each TesT shouLd be of SufficienT duration To achieve StabLe opeRAting conditIons and THus pErmit ThE onsET and detEction of adveRSE conDItions which couLd ResuLt from ImpropER assignmEnt of Loads. - 21 -

During each TesT, The DC and onsite AC buses and rELATed Loads noT uNder TesT should be monitoRed to verify abSEncE of voLtagE at ThESE buses aNd Loads^ for safety CuRREnt desIgns of pRoTEctioN sysTEms aNd ENginEered safety featuRes such ^î cERTAin safety RElaTed functions of NuclEAr power pLa^T may bE bypassed or madE InoperabLe during ThE perfoRmaNce of periodic Tests OR maInTenaNCE^ GEnERally^ The ptanTs adminisTRAtivE pRoceduRes RequiRE That The operatoR^S permissioN bE obTaIned prior to initiating aNY activity that wouLd oR couLd aff ECT a safety ReLatEd sysTem^ Howev^ experiEncE fEedback indIcates T^^t wHen The mEasuRes used To indicatE inopErabLE status consists SoLeLy of adminisTRAtive pRoceduRes, ThE opER^ToR is noT aLways fully aware of ThE Ramification of Each by pasSEd oR inoperabLe co^pone^ Thus, an accEptabLe way of riring THE opERAtoR kNowLedgE of plant status is to suppLEment adminiStrativE pRocedu^^ wtih automatic indicAtion of ThE inopERAbiLity oR ThE bypass of Each ReduNdAnt portion of a safCTy sysiem^ Automatic inaication of a bYpasS OR induced inopERAbiLity ^ nEcesSary if.^ a. The bYPasS oR iNopeRabILity affects a SysTem that is desigNed to pERfoRm auTomaticAlly a function wnich is impoRiant to publlc safety^ b^The bypass or iNopERAbILity is noRmaty REQuiRed to bE opeRabLe^ c^THe bypass or iNopeRabiLity ^ expEct^ to bE moRE fReQuent^ The indication of The bypass condition shouLD be at The sysTem LEveL, whETher oR NoT ti ^ aLso at ThE componEnT oR channeL LeveL^ For exampLe, in a design wnich utiliês A DC poweR to contaoL C^s, or DEENeRgiîng a DC power JusT during maIntanancE shouLD ResuLT in indiREcT inopeRAbility foR Each safety sysiem whoSE opERation is dEpEndEnt on That power sysTem. BY-passing a pRoTective function of a shaRed SYSTem shouLD bE iNdicated in Each nuclEar uriT affECTed by The bypass. of THe singLE f aILure criTerI^N to

THis SEction describes an acccptabLE method ^1^ of comptyIng THe USNRC ReQuiREmEnts wtiH RespeCT to satisfying THe singLe-faiLuRe criTerion^ THE guidance IN TRiaL use THE IEEE STd ^^9-1972, foR apptyiNg The SingLE faILuRE criTErion To THe design and analysis of nucLEaR power plant pRoTEction sysTem is gEneRally acceptabLe and pRovides an Adequate inteRIm basis foR comptyIng with section 4^2 of IEEE STd 279-1971, subject To THE 1-IT mAy bE nEcessary IN spEeifIc InstaNCes To deparT from oNe OR moRe of ITS pRovisions^ ^E^TIoNS ^2 and 6^2 of IEEE STd ^79-1972 sHouLd bE SuppLEmEnted^ ThE detEctabILity of a SingLE faILuRE is pREdIcated on ThE assumption That THE TesT ResuLTs IN ThE pResENCE of a faILure aRe ^If f e^^^T fRom ThE ResuLts THat wouLd bE obtaiNed if no faILuRE is pResent^ Thus, incoNclusIvE TestiNg pRoceduRes such as ^CoNtiNuIty checks^ of RElay cIRcuit coILs IN lleu of ReLay opERAtions shouLd noT bE consideRed as adequAtE bases To cLASSify as dETEctabLE all poTEntiaL faILuRes wnich couLd NEgatE ThE fuNctioNal capabiLity of ThE TesTed

In addition, where a sIngLE modE swtich supplies sIgNaLs To REdundAnt channeLs, it shouLd bE consIdered thai sIngLefailuRe criterion wILL noT be satis fied if either^ a. INdividual switch sections Suppty sIgnaLs to REDuNdant chaNnELs, OR b. Redundant ciRcuitS contRollEd by ThE switch aRE SEpaRated by Less Than six inch^ without SuitabLE baRrieRS. ^ 1 1 MaNuaL INitiAtioN of ^RoTective Actions^ This section describes REQuiREmEnTs ^19^ for includiNg means in ThE pRoTection sysTems, for manuaL initiation of pRoTEctivE action as follows^ 1. Manual initiation of each pRoTEctivE action aT ThE systEm LEveL, shouLd bE pRovided, REgaRDLess of whether means aRE aLso pRovided to initiatE The pRoTEctive action at ThE componEnt oR channeL Levcl. 2^ No singLe faiLuRe shall pREvent initiation of pRoTEctivE action^ ^. ManuAL Initiation of pRoTEctive action at ThE sysTem LEveL shouLD perfoRm all actions perfoRmed by automatic iNItiation^ 4. ThE switches foR maNual initiation of pRotEctivE actions at ThE sysTEm LeveL shouLD bE LocATed in ThE coniRoL Room and bE Easily accessibLE to ThE opERatoR. ^ ThE amount of EQuipmEnt common To both manual aNd automatic initiation sHouLd be kepT To minimum^ 6. Manual Initiation of pRoTective actions shouLd depEnd on The operation of a minimum equipmEnT^ 7. Manual initiation of a pRoTective action aT ThE sysTEm LEveL shouLd be designed so That once initiated, it will go on to completion. AccoRding To ThE IAEA, SEc^ A ^^, REf^ ^^ manual conTRoLs shall be pRovIded To peRmit SwitcHing The various avaiLabLe power supplies and Loads To The disTribution SYSTem as reQuired^ ThEy aLso facILItatE THE various plant mod^ 1^ e^ opeRation, TestiNg, maintEnaNCE, and E^S ^12 ELecTricaL ^ENeTRATIoN ^SSe^bLIes IN

This SEctioN describes a meThod accEptabLe ^20^ to ThE NRC Staff foR desigN qualificatioN, construction, insTallAtion, aNd TestiNg of clECTric pENEtRatioN assemblies iN coNtainmEnt structuRes of lighT-water cooLed nuclEaR power plants^ ThE IEEE STd-^17, 1976, foR clectrIc assemblies pENEtRatioN in coNtaiNmEnt sTRucTuRes foR Nuclear power geneRatiNg statioN is acceptabLE pRovided That ti is SuppLEmEnted by ThE following^ 1. The clecTric peneTRatioN asSEmbly shouLd bE designed To withstand, witHout Loss of mEchanical inTEgRity, ThE maximum shoRT cIRcuIT cuRREntS vs. timE coNDitions That couLd occur givEN SingLE Random faiLuRes of ciRcuit ovERLoad pRoiEction device ^. The maximum shoRT ciRcuit cuRREnt asSesSEd CT ThE peneTRAtion asSEmbly shouLd bE consisTEnt with ThE cRiteRia used In establisniNg The intErrupting capabiLity of ThE pRoTEctive dEvicE associated witH THE pEneTRAtion asSEmbly conduCToRS. DiclEctric-StrENgth TesT shouLd bE SuppLemEnted foR QuaLification TestiNg in The following waY^ Each meDium-voLtagE power conduCToR shouLd bE gIvEn an ImpuLSE withstaNd TesT by applyIng a I.^^^O us ImpuLse voLtage TesT series consisting of Three positive and ThRee negative ImpuLse voLTAges FLashover occuRS on onLy one TesT during any gRoup of Three consecutive tests; three moRe Tests shall be madE^ If no fLashover occurs In ThE SEcond group of t^ti, The flasHover In ThE first group shouLD be consIdered as a Random ftas Hover and The EQuipmEnt shouLd be consIdered as havINg passed The TesT. The ^^^-hr aging timE at mIniMu^ aging TemperatuRe shouLd be corrEcted to ^0^0-hr. AccoRDing To THE IAEA, Sec^ A-4^4^ Ref. (^^, all cleCTric peneTration asSEmblies In contaInMeni StrucTuRes and passages pRovIded foR THe conductoRS fRom circuits originating In The E^S shall be REgaRded as Safety system equipment; They shall thereforE be Rated aNd QualIfIed for THE expeCTed servIce and EnvIronmEntaL conDItions THat incLuDE THE cumuLativE RAdiation EffECTs expecTed ThrougHout Their d^^gn llfE^ ContAinmEnt penEtrAtions shall havE a continous servicE voLtagE rating grEater Than oR EQual To ThE voLtagE of THE system of wnich The conductors are parti ^ 24 -

They sHAll aLso have an ImpuLse RatiNg gReater ThaN oR EQual To THE maximum cREdIbLE TRAnsIent voltage^ THe peNETRAtions shall bE si^ To caRRy saf eLy THe cuRReNTs that takE Into accounT voLtagE vaRiations and shori ciRcuITs, as WEll as dEmaNds fRom Loads withouT ExcEEding allowabLe coNductoR TEmpERatuRes OR dEgRaDing pResSuRE bouNdAries of ThE asSEmblies^ ThE pENETRation asSEmbly shall bE desigNed To withstand, witHouT Loss of mEchanical intEgRity, THe max^ poSsIbLE ovERcurrEnt coNditIons THat couLd occuR given a singLE Random falluRE of ciRcuit ovERLoad pRoTection dEvic^ THe pENEtratIoNS shall be installed To meeT The same SEpaRation criTEria as well as THE cabLes To which ThEy aRe TesT Programs for The SEctioN describes ThE gENERal scope and depTh of initial TesT pRogRams acceptable ^21^ to The USNRC staff for L^R-N^s^ design fea^^s and perfoRmance cApabILIty TesTs that shouLd be dEmonsTRated foR planT ELecTric sysTems (among otHERS) during ThE Initial TesT pRogRam, shouLd

( 1 ) NoRmal AC ôwer ^^^^^^1^ ^ EmergEncY AC DisTributioN SysiEms. ^Roper opeRAtion of pRoTEctivE dEvices^ initiating dEvIces, RelayINg and Logic, Transfer and Trip dEvIces, peRmissive and pRonibit intERLocks, instrumEntation and aLaRmS, and Load sHeddiNg or stripping fEaTuRes, shouLd bE demonstrated. Testing shouLd aLso be conducTed To demonsTRatE pRopER opeRation and LoaD-caRrying capabilIty of bREakERS, moToR controllERS, SwitchgeAR, TRAnsfoRmERS, and cabLes^ Th^s Testing shouLd simuLatE as as pRActicaL, acTual SERvicE coNditIons. Redundancy and clEcTrical sHouLd be dEmonstrated wheRe appropriaTE. Tests of noRmaL AC power sHouLd demoNStratE THAT ThE intEgRated sysTem shall RespoNd as designed to a sImuLated paRT^L and full Loss of off- SitE power SouRces. Tests ShouLd aLso dEmonstratE ThE desIgn capabILIty to transfer fRom on-sitE to of f-site poweR souRces. Tests of The Emergency AC power sysTem shouLD dEmonstratE EmERgEncy OR vital Loads will StaRt In THE pRoper SEquEncE and unDer sImuLated aceident conditions wtiH boTH noRmaL (pREfeRRed) AC souRces and The EmergEncy (standby) poweR SouRc^ EmergEncy Loads shouLd aLso bE TesTed To dEmonsTRatE THat ThEy can staRT and opERatE wtih ThE maximum and minimum desIgn voLtagE AvaIlabLe^ To THe ExTEnt pRActical, THE Testing of EmergEncY oR vItaL LoaDs sHouLd bE conducTed for a sufficiEnt period of TimE To provide asSuRAncE T^^T EQuilIbrium conditions ARE attained^ Loads such as motor gENERAToR (m-g) seTs witH fLYwhEELs, wnich aRE supplied fRom The sysTem aNd wnich aRe desIgNed To pRovIde NON-IntERRuptibLE power To plant LoaDs shouLd be TesTed To demonsTRate proper operation. If appllcabLE foR ThE facILitY d^g^ Testing sHouLd includE UNder-fREquENcy and UNdervoLtage ReLaYS associated witH sucH LoaDs (m-g SEto^ Full-Load Tests for vital buses shouLd bE coNducted uSiNg NORMal and EmergEncY souRces of power supplies to ThE bus^ Tesing shouLd aLSo dEmonsTrate ThE adEquacY of ThE plant EmergencY and esSEntial tighting SysTEm^ Tests shouLd bE conduCT^ to dEmonsTRatE The pRoper opeRAtion of Indicating and aLaRm devIces used To mo^ôr The avaIlabilIty of The emergENCY power sysTem iN THE conTroL room^ 2^ EmergENcy or StaNdby AC ô^^ SuppLIs^ AppRopRtatE Tests sHouLd be conduCTed To dEmonsTraTE RELiabiLity, and pRoper voLtagE and frequency REguLation undeR TRAnsient AND sTeadystatE conditions. AuxILIary systems sucH as Those foR starting, cooting, heating, vEntiLating, Lubricating, and fueting shouLd aLso be appRopriatEly tesTed To dEmonstrate That Their peRformancE ^ INaccordance wtih design. TestiNg shouLd bE conducTed for a SuffieiEnt time To EnsuRE 1^^ EquILibrium ^ ReacHed^ TestiNg shouLd aLso dEmonsTRatE THE pRoper Logic, coRReCT SETpointS for Trip dEvIces, and pRoper operatioN of InitiatiNg devices and permissives and pronibit intERLocks and shouLd aLso demonsTRatE redundancy and eLEctrical iNDEpendEncE^ Emergency Loads Supplied shouLd be confIrmed to be in agREement wtih Design siting assumptions used for The poweR

^^ D.C^ System ^Roper CALIbRAtion and Trip seTtingS of pRoTEctivE DEvIces, including ReLaying, and pRoper operation of permissivE and pRonibit inTeRLocks sHouLd bE demonsTRated^ DeMOnstration sHouLd aLso incLudE design capabiLity of baitery cHargers^ TRAnsfer devices and invERTERS, and THE EmergEncy ligHting sysTemS. Testing sHouLd aLso bE conduCTed to demonstratE pRoper operation of bReakeRS, transfer dEvices, inveriErs, and cabL^ This Testing shouLd simulaTE, as cloSEly as prActical, actuaL service conditions. DEmonstrate opeRation of instrumentation and aLarmS and ground deTection instrumEntation^ DEmonsTratE redundAncY and clEctrical IndEpendence, and T^^T acTual totaL sysTem Loads are In agrEEment witH desIgn Loads. A discHargE TesT of each batieRy bank sHouLd be conduCTed AT full Load ^ 26 - and foR desIgN duRation To dEmoNSTRatE THAT The baTTEry baNk voLtagE LImit aNd 1^^^^^ cell limits are NoT ExcEeded^ to IAEA, SEcs^(ii), aNd A- ^ of REf ^ Tests Shall cARried out to vErify That each dIvisIoN of The E^S perfoRmS as intENded uNder coNditions as sImILaR as practicabLE To ThoSE ENcountered duriNg opERAtioNal states aNd aceidEnt coNdItions^ poweR SouRces shall be capacity TesTed if such Tests havE NOT bEEN caRried out bEfoRe^ Load Tests shall bE perfoRmed Either by paRaLLELINg The staNdby power suppty with The NORmal suppty oR by using a substiTutE Load^ ARRANgEmENTs sHouLd bE such THat dEmand foR Safety action ovERrides ThE TesT SEQUENCE^ Load SEQUEnriNg and Load Tests utiLIÎNg The aCTual LoaDs shall bE pERfoRmed whEn ThE plant ^ shut down. Onty ONE gENERator shall bE TesTed at A TesTs of of section indicates a mEtHod accEptabtabLE To THE USNRC REguLatory Staff ^22^ foR comptyIng witH REgulations coNcerNINg QualIfIcation toting of cLASS I eLeCTric valvE opERatoRS foR servIce witniN The c^ntaiNmEnt of lignt waTer cooLed NUclEaR power plants To aSSuRE ThaT ThE vaLvE opeRatoR desIgn wILL mEeT ITS peRfoRmancE RequiRemEntS. IEEE STd ^82 - 1972 spEcifies pRoceduRes foR accomplishing accclERated agging of compoNEnTs to siMuLatE ThE EffECTs of Long-TeRm opE^âtioN under noRmal opERating conditIons^ ThesE effects INcLude ExposuRe to nuclEAR , TempERatuRE, pRessuRE, humiditY ^^d chEmical spRayS. The pRoceduRes aLso pRovide foR coNducting QualificAtion TesTs of clEctrical valvE opERatoR under conditions simuLating ThoSE that wouLd bE imposed during aNd afTer a desigN basis Loss of coolant accIê^ subject To The following^ 1- To the exte^ pRActicabLe, a^xiLIARy eQuipmENT (E.g. 11^^ switches) ThaT ^ noT INTEgRal with ThE valvE operatoR mechanism but will be pari of THE installEd valve opeRatoR assEmbly shouLd bE ^1^ in accoRdancE with The SubJeCT standard. 2- The t^T SEQUENCE described in The standard shouLd be used unLess ThE antieipated aCTual SERvicE opERating SEquEncE for ThE vaLvE opERatoR is ExpEcted To cReATE a moRE SEvere opeRating coNditions^ In such CASE, THE actuaL service sequence sHouLd bE used in ThE TesT. ^- TesT coNdItions shouLd bE based on conservativE calculations to assuRE T^^T ThE valve opERaToR is TesTed uNder EnviRonmEnTaL coNditions ThaT simuLatE The condItions To wnich The valvE opERatoR is ExpEcTed To be exposed-to during and following a design basis of IEEE STd ^^^-^^^^ seTs foRTh cRitERia foR ThE SEpaRation of ciRcuITs Equipment ThaT are RedundanT^ THE staNdaRd aLso seTs foRTh rELatiNg To TesTs and aNaLYSis foR DetErmIniNg The f chaRAcTeristies of pRopoSed cabLe INStaLlations^ ThE criTeria arE appllcabLE pRovided such TesTs aNd aNaLYîs are based on REaListic pREmises aNd aRE othERWisE fully AppllcabLE To ThE acTual cabLE instaLLations^ AccEptancE ^ howEver, subJecT To ThE following ^2^ 1- ThE standaRd defines îsolatioN devic^, of The noncLaSS IE ciRcuits fRom cLASS IE or associaTed cIRcuITs, as Those preventing maLf unctions In ONE section of a ciRcuiT fRom causing unaccEptabLe infLuEnces in other SEctions of That cIRcuit oR other ciRcuits^ This staTEment sHouLd be suppLEmEntEd as follows ÎnterRupting dEvIces aCTuated o^^ by fauLt cuRrEnt arE noT consIDeRed To bE isoLatIoN dEvic^^ ^- Locating RedundAnt cIRcuitS and EQuipmEnt in SepaRatE safety-class StrucTuRes^ This mEThod of SEpaRation shouLd bE used whEnEver practicabLE and whê iti USE does noT conftiCT with other Safety obJEctives. ^- Associated cIRcuits InstaLLEd shouLd bE SubJEct to all placed on cLASS IE ciRcuITs. and sHuTdown eLecTric sysTemS f ^R muLti-unit

This section poinTs out a mEThod accEptabLE to ThE USNRC staff RespECT to ThE sharing of onsitE EmergencY anD shutdown eLEcTric foR muLti-unIT NUclEAR power plants. Sharing of onsite power SYSTems at muLti-unit poweR plant sites genERally ResuLts In a Reduction In The numbeR and capacity of The onsitE power SouRces to LEVELS bclow ThoSE RequiREd foR ThE SamE number of UNITS Located at SEpaRaTe sites. The Reduced capacity couLd ResuLT in undesIRabLe IntERActions, ThuS^ 1- DC sysTemS In muLti-UNit nuLcEAR pow^^ plants shouLD noT bE shaRed 2^ ThE desIgn of sHARed onsitE EmergencY and shutdown a. c. eLEcTric SysTEms shouLd satisfy ThE following^ a. THE sharing of onsitE AC clECtric systems shouLd bE limited to two

A sINgLE faILuRE shouLd NoT pREcludE The capabiLity to automaticAlly minimum ENginEered Safety fEatuRes (ESF) Loads in aNY onE and To safeLy sHuT down The REmaining unit, assumiNg a Loss of of fsitE - 28 -

c^ ONSite power cApacity shouLd be pRovta^ To energIÊ seismic-CatEgory- I EquipmENT To aTtaIN a Safe and oRdERLy coLd shuTdowN of all UNITS, assumINg ThE Loss of offstie poweR and The moST SEverE design basis EvEnt aNd a singLE faILure in The onsitE ELEctric sysTem^ d^ THE InteRActioN beTweeN eNgINEeRed safEty fEAtuRE ELecTric eiRcuits of Each uriT shouLd bE 1^^^ That any allowabLe combINAtion of maintENAncE IN The unITs will NoT pREcludE ThE capabILIty To auTomaticAlly Supplying power To minimum ESF Loads in aN^ unti, assumiNg a Loss of offsite poweR^ e^ CompLeTe iNfoRmation REgaRding ThE StaTus of ThE sHARed sysTems shouLd be provided for eacn unIT operator^ ^- For muLti-uNit nucLEar poweR plaNTs each un^T shouLd have SEpaRatE and indEpENdEnT 0N-site emergencY aNd shutdown eLectric sysTemS, boTh AC and DC, capabLE of SupplyIng minimum ESF LoaDs and The Loads REquiRed foR attaining a Safe and oRdeRLy cold shutdown of ThE unti, asSumIng a sIngLe faILuRe and Loss of off-SitE power. AccoRdIng to IAEA, Ref. (^, Sec. 6.9. each ReaCToR in a muLti unIT station shouLd have a SEpaR^TE And indEpEndEnt E^S. Howev^ if poRtions of ThE E^S aRE shaRed ti shall bE shown that safety RequiREmEnts of each ReaCToR individually, and of all REActoRS simuLtanEously, are of cLass IE eûIêNT for

This section indicates a method acceptabLE To THE USNRC REgulatory staff for complyIng wtih THE commissIons^ REguLation wtih REgard To design vErification of cLass IE EQuipmEnT foR SERvicE in lighT-watercooLed nuclEar power plants ^2^^ ThE IEEE STd ^2^-1974^ describes basic pRocEduRes foR quaLifYing cLass IE EQuipmEnt and Interfaces T^T aRE to ^ ^^ 1^ nuclEaR power plants, and qualifYing componEnti OR EQuipment of any inteRfacE whoSE faILuRE couLd adveRSeLy affEcT any class IE EQuipmEnt. The ReQuiremenTs ouTlined Include pRineipLes, procEdur^ and mEthods of QuaLifIcation wnich, when satis fi^ wiLL confirm THE adeQuacy of The eQuipment desIgn for The perfoRmancE of cLaSS IE funCTions under norm^ abNORmal^ design basis EVEnt, post design basis EVEnt, and containmEnt TesT conditions^ AccoRding To The IAEA, REf ^^, Sec.8, EQuipmEnt uSed in ThE E^S shaLL be qualified by confirming T^^t ti will mEEt OR ExcEed its design basis perfoRmancE REQuiRements wHILE subJeCTed To THe envIronmEntaL conditions Exiting at ThE timE of nEed. QuaLification may bE caRried ouT by mEans of^ ^ 29 ^

(a) type TestiNg of aN acTuaL EquIpment perfoRmaNce using sI^uLA^ service

(b) consIdering opERAting Experience foR simILaR EquipmEnt ^nder compaRabLe ServicE conditIons; oR bY ( c) aNAlySis, pRovided THat JustificatioN of THE assumptions aNd valldatioN of The mode's used ^ givEn^ of eLecTric This section outlines oprating pRocEDuRes and ResTrictions, acceptable To The USNRC REguLatory staff, wnich shouLd be impLEmEnted if ThE avaiLabLE clEcTric power souRces do NOT mEET ThE Limiting Condition foR OpeRation (LCO) ^26^ THEy aRE appllcAbLE to siNgLE and muLti unti pLAnTs, incLuding muLti unii plants ThaT shARE ThE ELEcTric power source ELEcTric Loads impoRtant To SafEty of NuclEar power pLAnts aRE served by an clECTric power system wnicH confoRms to GDC- 17. ^LAnTs with moRE power souRces Than aRE REQuiRed by GDC 17 can toLERatE The Loss of one OR moRE SouRces and still mEeT ThE LCO. During ThE noRmaL couRSE of opeRAtion, hoWEver, any nucleAR power plant may LooSE po^^ souRces to ThE ExtEnt that ThE LCO is noT mET^ Th^s SEction addResses Such CAS^ GDC 17 spEcifies design REquiRements, not opeRatin^ REQuiRemEnTs, it therEfoRE does noT stipuLatE opERational Restrictions ^n ThE Loss of power souRces^ NEvERtheLess, opERAtional ResTrictions based ON ThE Intent of GDC- 17, on ThE Loss of power souRces, have been included In The TEchnical spEeifIcAtions of REcentLy constructed nuclEar power plants. Such spEeifIcations are basEd on ThE following consiaERations^ ^ ThE LCO of nuclEar power plaNts is meT when all ThE eLecTric power SouRces RequiRed by GDC- 17 are avaIlabLE^ ^ UndeR ceRtain conditions, it may be Safer to continue opeRation at full oR Reduced power foR a limiteD TimE than to affEct an imêdIAte shatdown on The Loss of somE of The RequIRed eLeCTric power souRces^ Such dEcisIons shouLd bE basEd on an EvaluatioN THat balances ThE Risk associated with ImmEdiatE sHuTdown agaInSi ThAT asSociated with contiûed opeRAtion^ If ImmEdtaTE shutdown is thE Safer couRSE, ThE unit shûLD bE bRoughT to an oRdeRLy sHutdown and to a coLd sHutdown statE as sôn as If continued power opERation is ThE safer couRSE, The period of opeRation shouLd be u^ to RestoRE ThE Lost SouRce. If The LCO has Noi bEEN achIEved during That pEriod The unti shouLd bE ^RompTLy bRoughT To an oRdERLy shutdown, and to a coLd shutdown StaTe as sôn as poSSIbLE, THese activities do noT Risk fuRTheR dEgRAdation of The eLEcTric power sysTem OR in any way JEopaRadiÊ plant safety^ of ELecTric EÎê^T for USNRC REguLatory position about This SubJEct ENdorses ThE staTemEnt coNfoRmance with THE REQuirEmEnts aNd REcommendatioNS spEeifIed by THE IEEE Std ^44-197^, wILL coNfIrm THE adEquacy of THE EQuipmEnt desIgN foR The perfoRmaNCE of cLASS IE functions, subJECT to The following ^27^ (1)A static coEfficiEnt of 1^ Is used for EQuipmEnt SEismic aNalysis to take InTo accounT The EffEcts of boTh muLtifREquEncy E^cItatioN and muLtimode Response^ The use of This coeffIcienT is acceptabLe foR verifying integRity of fRame-type structuRes^ FoR equipmEnt having coNfIguRatIons other ThaN a fRame-typE, Justification shouLd be pRovta^ foR ThE USE of a static coefficient (2) For EQuipmEnt with moRE ThaN ONE pReDomInant fReQuency, The shakE tabLE motion shouLd pRoducE a TesT Rônê Spectrum (TRS) wnich closely Env^p The appllcabLe poRtion of The REQuiRed ResponSE SpECTRum (RRS)^ ^^ THeRmaL OverLoad ^R^TecTIoN fo^ ELecTric ^tors on Motor OpeRated

section ouTLInes a method accEptabLe To ThE USNRC staff coNCerning ThE appliCAtion of ThEmaL ovERLoad pRoTection dEvices that aRE intEgRal wtiH The moToR StaRtaR foR ELEcTric motoRS on motoR operated valves. This meThod wouLd EnsuRE ThaT ThE thERMal ovERLoad pRoiEction DEvices will not ^E^L^Sty pREVEnt ThE moTor fRom perfoRmIng Its SafEty RelaTed function^ TheRmaL ovERLoad dEvices aRE designed pRimariLY To pRoTEct continuous dutY motoRS whllE ThEy aRE RunniNg Rather Than during starting^ HowEver USE of ThesE ovERLoad dEvices To pRoieCT intERmittEnt duty motoRS may TheREfoRE ResuLT In undesiRed actuation of THE dEvices if ThE cumuLative EffEcT of hEating caused by successivE StaRTs aT shori intervaLs is noT takEn into account in dETERmIning ThE overLoaD Trip

IT is gEnERally vEry difficult for any theRmaLLY SEnsItivE to adeQuatELy appRoxImatE The va^^ying ThERmal chaRActERisticS of an IntERmitTEnT-duty moTor over its full range of StaRtiNg aNd Loading coNditions^ This is mrinty cauSEd by ThE wide variations In moToR hEating cuRves for ThE various sI^es and desIgns and aLso by diffIcuLty in obtaiNINg moTor heating data to an acceptabLE accuracy^ The accuracy obtaInabLe with thE ThERmal oveRLoad reLay Trip gENERally varies from-^ To 0^ of Trip sCT poI^ SIncE thE pRImary conceRn in THE appllcation of oveRLoad devIces is To pRoTecT THe motor wInDings againsT excessive Heating, THe above negative ToLeRance in Trip cHaracTeriStics of THe pRoTEctioN dEvicE is considered in THE Safe dIREctioN for motoR pRoTection^ HowEver, The conseRvativE desigN fEataRe buILt into these ovERLoad dEvices foR moToR pRoTectioN couLd interfacE wiTh ThE successfuL fuNctioniNg of a safEtyRElaTed sysTem; i. E^, ThE THERmal ovERLoad device couLd opEN To RemovE power fRom a motoR bEfoRE THE safety function has bEEn compLeTed OR even 1^11^^ Thus, pRovIded That The compLetion of ThE safety fuNctioN is noT JeopaRdI^ed oR That oTheR SafEty sysTEmS are noT degraded^ onE of THE foLLowIng two aLTERNatives sHouLd bE impLemeNTed^ a) TheRmal ovERLoad pRoTection devices shouLd be continously bypassed and TempoRArIly placed In foRcE onLy wHEn ThE valve moTors ARE undERgoIng pEriodic Testing maintENAncE, oR b) THeRmal ovERLoad protection dEvices that aRE noRMaLLY 1^ foRcE during plant opeRation shouLd be bypassed under aceidEnt

Another meThod of SoLution ^ estabLished if all uncer^tainties in The Trip seTpoint of The ThermaL oveRLoad pRoTection devices aRe compensated in favoR of completing safety RELated actions^ 1 Periodic Testi^^ of DIeseL GeneRATor ^nITs used as On-site ELecTric aT NucLear This section poinTs out a meThod accEptabLE to ThE USNRC staff foR complying witH The commission^s REgulations ^9^ witH regard to periodic TestiNg of dieseL geneRator unITs to EnsuRE THat ThE diescl eLeCTric power sysTemS will meeT Their availability rEquiRements^ The dieseL genE^^toR unti consists of The EngInE, gEnEraTor, combustion rir sy^Tem, coollng water sysTem up To ThE suppty, fuEL supply sysTem, Lubricating sysTEm, starting EnergY SouRc^ auToStarT contaoLs^ manual and dIescl gEnERatoR breaker^ Testing of dIesEL gEneratoR uniTs shouLd^ ( 1 ) DEmonsTRatE pRoper startup opeRation bY simuLating Loss of all AC voLtage and dEmonsTraTE THat THE dieseL gEnERATor uriT can start aatomaticAllY And attain THe RequIRed voLtage and frequency witHin acceptable LimiTs and time^ (2) DemoNSTRate proper opeRation foR desIgN accideNTLoadiNg SEquencE and dEmonsTRATE full Load CArRying capabiLITY, verifY That voLtage and fREquEncy ARE maiNtaINed within THE rEQuiRed Limits; aNd That THE cooll^g SYSTEm fuNctions within desigN LImITs^ (^) DemonsTRatE proper opeRatioN during diescl gEnEratoR Load shEdding, iNcLuding a TesT of compLETE Loss of Load, and vErifY ThaT thE voLtagE REQuiRemENTs are met and That ThE over-spEed Limits aRE noT Exceeded^ (4) DEmonsTRate fuNctioNal cApAbiLity aT design basis TEmpeRaTuRe condition (^) DEmonsTRatE ThE abiLIty to^ (a) SyNchRoniê THE dIesEL geNeRatoR witH The of f-stie power whILe coNNEcTed to THe emergENCY Load, (b) Trans fer laod to ThE off-sitE power, (c) IsoLATe ThE diesEL gENeRatoR unit, and (d) RestoRE it to standby status^ (6) DEmonstRatE that THE ENginE will pERfoRm pRopeRLy if switched from one fueL oll suppty sysTem to anoTh^ (7) DEmonstratE REadiNesS foR supptying EMergENcy power whILE THE dieseL gENERAToR unIT is undER TesT. (8) DemonsTRatE The REQuIRed ReLiability by RerunniNg consEcutivE vaLid Tests (1^ with no faiLuRes) for 69/n times per wHere n is THE numbeR of dieseLs of THE SamE desIgn and InsTaLLATIo^ Design a^d INSTALLATION of ârge ôad for NucLear SEction descRIbes a mCThod acceptabLe^to The USNRC staff foR perfoRming THe inStallatIon desIgn and InstaLlatioN of LaRgE LEad StoragE baTterIes foR nucleAR power plaNTs ^0^ THe IEEE Sid ^4-197^ REcommENded pRacticE for inStaLlation desIgN and InstaLlatioN of LaRgE Lead StoragE batiEries for gENerating stations and substiTutions, ^ suppLEmented with The followiNg infoRmatioN ThaT takes inTo considERatioN ThE REcommEndations on fire pREvEntioN by ThE NRC appoInted spEctaL REview gRoup following ThE bRowns fERRy fire of march 1979^ ( 1 ) The vENtiLLation sysTem shall limit HydRogen accumuLAtion To Less than two percent by voLume aT any Location ^1^^ The baTTery AREA^ (2) ResTRaIning chANneL bEams and tie Rods sHouLd be eLEctricallY InsuLated fRom THE cells ^ statioNary water faciLities aRE pRovIded witnin Room, Their desigN shouLd be such as to pRecLude aN spilling of water fRom THese faciLities on The batieRY InstallAtion

(4) Any ceLL ThaT Exnibits an ELEctrolyTE LEVEL of 1/2 an Inch oR moRE bELow ThE Top of plates shouLd bE REplaced^ (^) CEllS shouLd noT bE Exposed To ExTREmeLy Low ambIEnt TEmpERatuRes oR Localiêd sources of heat during storage^ (6) HYdrogEN suRvEy shouLd bE perfomed to estabLish BaSELiNE data foR LocatiNg HydRogEn dETEctoRS^ AccoRDing To THE IAEA, SEc^ A-^2^ of REf^ ^, ventIlation shall bE pRovided To avoid combuStibLe gas coNCEntRations in baTTery Rooms, a^d To maintaiN Such coNCENtration beLow an accEptabLe maximum^ ThE vEntiLation sysTem shall be powered by ThE E1^ of Large Lead storage f section points out a meThod accEptabLE to The USNRC staff foR perfoRming ThE maintEnancE, TestiNg, and REpLacemEnt of LaRgE LEad stoRagE baitaries foR all types of nucleAR power plants. IEEE Std 4^-19^, Includes maintEnancE, iesT ScheduLes, i^ting pRoceduRes, and REplacEmEnt criTeRiA foR LaRge LEad stoRAgE battaries. ThE standard does not incLudE surveILLance and testing of The DC sysTem EvEn Though ThE batieRy is paRT of ThaT sysTem. The USNRC REguLatory position IdEntified in THIS SEction indicates THat all RequiRemenTs as WEll as REcommEndations of that IEEE standard consTitutE an aDEQuatE basis foR comptying witH THe RequIRmEnTS of ThE comm^sIon REgulations with RespECT To maintEnancE, Testing, and ReplacEmEnt of LaRgE LEad sToRagE baTtaries SubJECT to THE following.^ - ServIcE TesT DescriptioN, shouLD bE perfoRmed In addition to The bati^y perfoRmancE dischaRgE TesT. ThE bati^y servIcE TesT shouLD be perfoRmed during REfuEllng opERatIons or at somE other outagE, wtih IntervaLs bEtÊEn Tests noT to ExcEed 18 montHs^ In addition, If THE sysTem desIgn is chaNged so that ThE pREvIous ServIcE TesT is no Longer a vatid TesT of ThE capabILIty of The baitEry to meCT The changed desIgn REQuIREmEnts of The sysTem, ThE user shouLd conducT thE servicE TesT foR ThE new sysTem design^ ^^24 DIeseL-GeêRatoR ReLIAbILIty ûALIfIcAtion Testing^ A staRT and Load ReLiabIlity TesT progRam is ReQuiRed ^2^ foR all dieseL geNERatoR sets of a typE OR siÊ noT pREviousty us Ed as a standby emeRgency power souR^ IN NucleAR power pLaNTs^ An acceptable TesT pRogRam shouLd incLude The followINg^ (1) AT LEAST ô fuLL-Load Tests shouLd be perfoRmed on each dIesEL-gENERatoR seT To demonsTRate THE staRT ANd Load capabILITy of THe units witH some margIN in Excess of THe perfoRmaNCE REquiREmENTs Such TestiNg is Evaluated on a casE bY casE bÎs^ (2) ^rioR to 1^^^ fueL Loao^^, aT LEasT ^00 vaLId stari and Load TesTs sHouLd bE perfoRmed^ 90^ aT THE LeasT of these Tests shall be madE fRom desIgN coLd ambIEnt condition and 10^ fRom desIgN hoT EQuILibRium TempERaTuRE^ ThE ^00 vaLue incLudes all vaLid Tests perfoRmed off-site^ (^) A faILuRe RatE In Excess of 1^ LeaDs to ThE RequIRemeNT foR fuRTher Testing as well as Review of The sysTEm desIgn adEquEcy^ A success is dEfined as a stari fRom ThE spEeifIed TempeRatuRe coNditions with Loading To at LeAST ^0^ of continuous Rating îÎn The REQui^d time interval, and continued opeRation untiL Equilibrium is aitained. on ôtor OperaTed VaLves In Tê Emergency Core Coollng

This section gIves a guiDancE In mEeting The IEEE STD-^79 REQuiREmEnt by ThE MotoR OpERated IsoLation Valves (MOIVs) on THE lines BeTweEn ThE REaCToR Coolant SysTem (RCS) and ThE safety inJEction Tanks ( accumuLatoRS ) , foR TheiR being opeRating bypasses^ ThE following fEataRes shouLd bE incoRpoRated^ 1 ) Aatomatic opEring of The valves when Either ThE RCS pResSuRE is Reduced To a seT valuE, oR a safety injection signal is pResent^ ^) Visual indication in The conTRoL Room of The open oR closed SiaTus of The v^^ ^) An audibLE aNd visual aLaRm, wnicH ^ acTuated by a SEnsoR ON THE vaLvE whEn The valvE is noT In ThE fullyopEn position. 4) UtiLI^ation of Safety Inaction sIgnal as an automatic ovERRIDing signal To ThE MOIVs^ of DIeseL^GENERatoR SeTs for Load ALthough neti^^ The GDC 1^, noR ThE IEEE STd ^08 pRonibit THE USE of EmergnECY dIesEL foR non-Safety puRpoSes, THe USNRC staff coNcLudes ^4^ That ThE poTEnTtaL foR common modE faiLuRes shouLd pREcLude interconnEction of on-stie standby diesELs and off-sitE power souRces foR short pEriods foR ThE puRpoSE of Load Testing^ In particuLar, EmergEncy power dIesEL geNeRatoR seTs shouLd noT be used foR Load peAking servIces foR THe grid^

IT ^ obvious That isolaTed power SysTEmS aRE INhERenTLY Less StabLE ThaN EQuivalEnt SYSTems with Supporting gRid intEries ANd aRE more vuLNERabLE to NatuRal disasTERS^ Thus, as a conservativE appRoach, ThE USNRC staff ExaminE The avaiLabLe gENERating capacity of such sysTems to witHstaNd ThE outage of The laRgesT uri^ ^^ FoR such isoLated grids mEasuRes foR additioNal capabiLIty and maRgin foR ThE 0N-sitE poweR sysTEm beyond ThoSE noRmally used may bE REQuIR^ Other mEasuRes may bE moRe appRopRtaTe based on 1

ThE IniEnt of This SEction is To explain how To meet ThE concern ThE rEQuiRed disENgagemEnt of ThE ReacToR Coolant ûmp (RC^) motoR fRom thE grid whEN it ExpERIENces underfREQUENCY conditioN, mignt noT occur. Thus ^6^ (1) Tripping of The RC^ bREakeRS is considered a REquired Safety action u^^s it ^ demonsTrated (aNaLyticAlly) ThaT pump coasTDown is noT pREVEnted at an uNderfREquEncy RatE of 1^ H^/SEc^ (^) If crEdit is to be takEN foR RC^ coasTdown In THE accIdEnT aNalySes, THe pump bREakers muST bE quaLifIEd in accoRdancE with ThE REquIremEnTs of IEEE STd ^79 and IEEE Std ^0^^ In addition, ThESe bREakERS shouLd bE HouSEd In a SEismIc category-I strucTuRe. (^) RCR sysTEm Trip SEnsoRS associated with thesE bReakers shouLd meet The reQuiRemEnts of The IEEE STd ^79, wheTher or noT creDit is taken foR pump coastdown^ ^.^9 DIeseL-GeneRATor ^RoTectiê Trip CIRcuit By passes Bypasses of The diesEL-gENERator Trips sHouLd be goveRNed by THe following ^^ (1) THe desIgn of standby diescl geneRator shouLd be such T^T aLL Trip sIgnaLs, excepT THose from ovERSpEed OR THE geNerator DIfferEntial, arE bypassed u^^ acciaEnt coNdItions. HowEver, for routinE Tests all Trips sHouLd bE retain ^ (^) If other Trips^ in addition to THe EnginE overSpEed and gEneRator differENtial, aRE retained for accidEnt conditions, an acccptabLE desing wouLd bE THat which pRovides two or moRe indepEndEnt mEaSuREmentS of each of thesE Trip paramETers^ The bypass dRcuiTry shouLd be designed To meet THe RequiRemenTs of THe IEEE STd 279; and abNORmal values of all THe bypass paRametERS shouLd bE alaRmed in The co^R^L Room^ of Tê siN^Le ÎLê CriTeRio^ To

section estabLisHes THe acceptabiLITy REQuriEmENts ^8^ foR discoNNEcting power fRom eLEcTRIcally opERated valves of a fLrid SysTEm as one meAns of guaRding againsT a SingLE FaILuRE (SF) That mIgnt cauSE uNDesiRAbLE valvE actioN whicH iN-TuRn ResuLTs in Loss of a safeTy sysTEm function^ THesE REQuiRemEnTs incLudE ThE following^ ( 1 ) ^LanT TEchnical speeifIcations shouLd incLudE a LisT of all clEctricaLLy opERated valves, and TheIR REQui^d position (2) THesE valves shouLd havE ReDuNdant position Indication In The main contRoL Room^ and The position Indication sysTem sHouLd ITseLf meCT The sIngLe faiLure criTerion^ In Th^ concERn, it ShouLd bE cLARified that ELEcTricallY opeRated ^ valves wnicH aRE classified as ^ active^ and wnich are manually contRolled wouLd bE included among Those from wrich power is To bE Removed in oRDer To mEet ThE singLE faILuRE criTErion pRovided ThAti (a) ELEctrical power can bE RestoRed to ThE vaLves fRom The mrin contRoL Room, (b) ValvE opERation (from ThE conTroL Room) is noT nEcessary for aT Le^sT TEN minutes following occuRREnce of ThE EvEnt REQuiring such opERAtion, and (c) IT is dEmonsTRated ThAt all NEcesSary operatoR actions will be perf oRmed witnin THE timE shown to bE adeQuatE by The analysis^ Finally, it shouLd aLso bE pointed out That^ êLecTricAlly operated valves^ incLude boTh valves opeRated dIRectLy by an eLEctrical device (e.g., a motoR-operated vaLvE OR a soLEnota opERated valvE) and valves opERated indIRecTly by an ELEcTrical dEvIcE (E. g^ an atr-opERatEd valvE whoSE air supply is controlled by an clEctrical SoLEnoid valvE) ^ ÊfoRe WE StaRt ouR comparison beTweEn ThE American REgulatory Gaides and ^Ranch TEchnical ôsitions on onE hand and ThE IAEA SafCTy Guides on The other hand in this arEa of eLeCTric power sysTemS we wouLd llke To point out T^^t thE IAEA safety guidE SG-D7, is noT coNfiNed To describing meThodoLogy but aLso pResENts cRITEriA^ MovIg THEN to ouR comparison we found 1) In boTh REgulaTory sysTems The E^S shouLd at THe LeasT satisfy THe S^gLe FaILuRe CRiterioN (SFC)^ However, we dRaw THE atiENtioN To that in THE USNRC REguLatioNS SFC is deTERministic w^llE in THe IAEA viEW SFC sHouLd bE dictaTed by Random faiLuRE pRobabILIties^ 2) THE IAEA sTResSes THe need for an eLectric grid stabILity evaLuAtion during The 1^^^ site seLectioN phase of InsTallINg a NucleaR power plant^ IT made The staTEmEnts THaT^ ^where TheRE is pooR grid stabILIty, mEasuRes foR ImpRovIng grid StabiLity at The site may be considered^ On The American side, we found That aLthough The ^SNRC staff have made ThE concLusIoN THat grid avaIlabILity criTEria is met with SomE margIn foR mosT plaNts ON The U^S^ maInLaNd, ThEy as a consERvativE approach ExamInE ThE avaILabLE geneRating capacity of an isolaTed power sySTem on Loss of its LaRgesT unit, and indicatioN was madE T^^T pRovisions for addItioNal, bEyond noRmaLLy used on-stiE cApabilities may be Required^

^) The IAEA indIcates T^^T The numbeR of connections to The clEcTric grid dEpENds on The desIgN CApabilities of The whoLe grid, and on ThE assign of ThE NuclEAR power plant ITseLf^ A sIngLe connEction may bE accEptabLE In situations wherE ThE nuclEaR power plant REpResEnts a LaRgE pRoportion of ge^ERatioN on THE eLECTric grid OR wherE ThE ELECTric grid StabILity is Such T^^T ThE Loss of that NuclEaR power plant will LEad dIRecTly to The collapse of ThE grid. In Such situations ThE pRovision of a second TRansmissioN connection adds LItiLe To The ReLiabIlity of The E^S; other oN-site meASu^^ shouLd therE by be taken^ WHere THe geneRAtioN of The NuclEaR power plant ^ a small pRopoRtion of ThE totaL geneRation and The grid is consIDered stabLe followiNg The Loss of The plaNT (or a uriT of it) The pRefErred appRoach is To pRovidE at LeasT two transmission coNnEctions beTWEeN ThE pLaNT sitE and ThE eLecTric grid^ These trAnsmissioN llNES shouLd bE aDEQuatELy SEpaRated In ora^ To avoid common cauSE faILuRE^ An Indication was aLso madE That THE uSE of moRE ThaN two conNections to The grid may noT ResuLT in incReased RELiabiLity^ In This RegaRd The AmErican madE ThE clEaR cut ReQuiRment T^^t two pHysically independEnT TraNSmission circuITs shall supply power fRom ThE grid To ThE onsite power disTribution sysTEm^

(4^ FoR a muLti-ReaCToR units NUclEAR power plant ThE IAEA and ThE USNRC agREE That it is very ImportanT to fEed power To The emergency power sysTem of any one reacToR u^T fRom The mri^ generAtoR of other REacToR unITs iNdepeNdent of THe state of THE TRANSmissioN liNes fRom THe eLecTric grid^ (^) In THE AmericAN sysTem there is No ReferEnce To aLTeRnativE on-stiE oR off-sitE power souRces whllE, THE IAEA rEgulations IndIcatE THat therE may bE aLtERNativE 0N-SitE or off-sitE power SouRces That can bE used To INcREasE ThE ReLiabiLIty of The emergeNc^ power sysTems, buT which are noT To be consIDered thEmsclves as paRT of thesE systems; e^, fossil fuEL gEneRatoRS NORmaLLy used for Load peakiNg duties oR offsite spEcIal purpose Locally ed gRid neTworks^ (6) WHILE ThE American sysTEm Takes ThE position T^^t THE off-stiE grid power souRcE is the pREfERRed power suppty, THE IAEA indicates T^^t ThE pRefeRRed power sysTem may be eITheR thE off-site gRid oR The main gene^^tor DEpENdiNg on ThE RELiAbILIty of each sysTem and CApabILitY of ThE nuclEar plant conTroL and heat dissipatioN systems To Reduce The power gEnERATed To THe House-Load in a spEeifIed period of time. WHiLe The American rEgulaTory gri^ describE In-detaiLs THe bases, Limitations, and mEans of impLEmEntatioN to acHieve a^ accpetabLe ELEcTric power sysTem wnich satis fies safety RequiRemenTs foR a nuclEar power plant; THE IAEA safeTy guides; nameLy ThaT of REf^ ^, speaks in gEneraL and sometimes in brief Terms about The techniQues for acnieving acceptabLE desigN and perfoRmancE of eLectric power sysTem as a whoLE and ThE standby power supplies in particuLAR.

ThE accptaNCE cRitERia wrich musT bE applied f oR eLEcTric power sysTem, as well as impLEmEntatioN methodoLogies of THesE cRiteRia as being described In reLevanT safety guIdes are RevIEWed according To boTH THe USNRC and THe IAEA REguLAtio^ THe pREfeRRed power sysTem seLECT^ for noRmaL pL^^t opERation may be Either ThE eLectric grid, or The uriT main gENERAtoR. The ReLiability of Each sysTem conTroLs The sclEction. ReLiability depEnds essentIally on The easting grid, beiNg small or Large, stabLe oR poTENtiaLly u^stabLE^ and To SomE E^TEnt on thE typE of ThE Nuclear power plant^ where ^WR plants are more stabLe ThaN BWRs and among The ^WR plaNTs TÊmS^^ ThoSE rEctrcuLAtion typE sTEam gENEratoRS are more StabLe Than oNes onceTHrougH type STeam Long TERm utiLIâTIon of standby power souRces can decReASe TheiR ReLiAbILity and incReasE Their maINTEnaNCE fREquency and outage timE in a manNer That may noT bE compatibLE with The opeRating limits and condition FoR THese Reasons, THe standby souRces sHouLd NoT bE used To suppty powER To The clectric emergencY power sysTem EE^S ON a periority basis but RatHer THe off-site OR aLTerNativE power supplies aRE pREfERred (in This RespEctivE oRdeR) whEN boTh oR one of Them is avaILabLe^ However, when The REliability of THe off-sitE souRcE is ReLativELy L^ ThE REliAbILitY of The 0N-sitE power supply sHall bE inerEased so That all safety sysTems wouLd have The necessary power foR Them to perfoRm Their SafCTy functions when calLed upoN to do so^ A fInaL gENERaL coNcLusIoN wnich can bE made w^th Regard to Regulations, out of This stady is T^^ w^Ê ThE American REguLatIons describe ThE bITs of dEtaILs coNCerning design, pERfoRmance, mainTEnancE, TestiNg, and all other aSpEcts of ThE ELEcTric poWER sysTEm compoNEnti and equipmEnt, and of THe sysTEm as a whoLE, ThE IAEA REgulations address ThE gEnERal pRobLEmS That may bE faced wtih In countrIes havIng grid sIês RAnging fRom LARgE StabLE To small poTeNtiALLy unstabLE As a ResuLT we fined that ti is paRticuLaRLy nEcessaRY in This aREA of ELEctric powER supplies to dEal wtih these iwo seTs of REgulations as if Each compLemenTs noT suppLemEnts The oTh^ This sTems fRom The faCT ^î clEctric power is mainLy a sTRong and ReveRSibLe link beTweEn ThE nuclEAR plant and its ouTsIde^ REFERENCES 1. ^WR-InfoRmation Manu^^ WestingHouSE ELEcTric coRpoRation, NuclEAR SeRvicE Division, OpeRation TRAiNing, Feb. 1979. ^ USNRC-SR^ ch^8^ ÊLECTric 1^^, NUREG-7^/087^ REvî, Nov^ 197^^ ^ SafeTy SEries No^ ^0-SG-D7, ÊmergeNCY ôwer SysTemS at NuclEar ôwer ^^NT^^ IAEA, VienNA, 19^^ 4. USNRC-RG 1^70, ^StaNdaRd FoRmat and ConteNT of SafeTy Analysis REpoRTs foR NuclEaR ôweR ^lants^, REv^, Nov^ 197^ ^. SafEty SER^ No^ ^0-SG-G2, ÎnfoRmation to be SubmIti^d In Support of licensINg Applications foR NuclEaR ôwer 1^^^, IAEA, VIENNA,

10 CFR ^ART ^0, AppEndIx A, ^GEnERal DesIgN CrITeria foR NuclEAR ^, USNRC RuLes and REgulations^ ApriL - 40 ^

SafeTy Series No^ ^0-C-D, ^DesIgN foR Safety of NuclEAr IAEA, VIeNNa^ 1978^ Safety Series No. ^0-SG-D11, ^GENEraL DesIgN Safety ^rineipLes foR NuclEaR êr ÂnTs, ÎAEA, Vienna, Rev^ 8, ûne 1^^^^ USNRC-RG 1^6, ÎndependeNce BeTwEEn ReduNdant Standby (oN-SitE) 1^^ SouRces aNd beTwEEn ThEIR DisTribution SysTems^, MaR^ ^ ^^^ ^ USNRC-RG 1^9, ÊÊ^TIo^ DesIgN, and QualifIcation of Diescl-GENERatoR UnITs Used as on-SitE ELEctric F^^ SysTEms aT NucleAR Rower ^lanTs^ REvî, Nov^ 1978^ USNRC-RG 1^22, ^ Periodic Testing of ^RoTection SysTem Actuation

USNRC-RG 1^29, ^SEiSmic DesigN ClaSSificatioN^, USNRC-RG 1^0, ^QuaLity ASSURANCE REquiRmEnTs for ThE InstallAtioN, InspEction^ and Testing of InstrumEntAtion and ELEctric

USNRC-RG 1.^, ^CriTERta for SafEty-RElaTed ELEcTric ôwer SysTemS for NuclEaR ôwer ^LanTs^, êv^ FEb^ 19^7. USNRC-RG 1^40, ^QuaLIficaTioN Tests of Continuous DuTy MotoRS InsTalLed In sIdE ThE ContAinmEnt of Water CooLed NuclEar ôwer ^LANTs^, MaR.

USNRC-RG ^ ^ ^ ^ ^^ReopeRatioNaL TestiNg of RedundAnt On-stiE ELEctric ôwer SysTEms to VErify ^Roper Load GRoup AssignmEnti, ^Mar^ 1^ ^^^ USNRC-RG ^47, ^Bypassed and InopERabLE Statas INdiCAtion foR NuclEaR 1^^ ^lant Safety SysTems^^ May 197^ USNRC-RG 1^^, Âppllcation of ThE SIngLE-FaILuRE CRitErion to NuclEar ôwer ^lant ^RotEction SysTems^, ûne 197^. USNRC-RG 1^6^, ^ManuaL INitiation of T^RoiEctive ActionS^^ Oct. 197^^ USNRC-RG 1.6^, ÊLecTRic ÊNETRatioN AsSEmblies In CoNTaiNmEnt StrucTuRes f oR LIgnt-âTer-CooLEd NucleaR ôwer ^LANTs^ Rev. 2, TuLy 1978. USNRC-RG 1.68, ÎnitiaL TesT ^RogRamS for WaTeR^CooLed ReactoR ôwer ^LanTs^ Rev^ 2^ Aug^ 1978^ USNRC-RG 1^^^ ^QuaLificatioN TesTs of ELecTric ValvE OpeRatoRS Installed In-sIdE The ContaiNmEnt of NuclEar 1974^ ^ USNRC-RG 1^, ^h^si^ INdependence of ELecTric Sep^ 1978^ ^ USNRC-RG ^ ^ ^ ^^ ^SHaREd EmERgency and Shutdown ELecTric SysTems foR MuLti-UNit NuclEAR ôwer ^LAnTs^ Rev^ ân^ ^^^^ ^ USNRC-RG 1^89, ^QuaLifIc^TIoN of CLaSS IE EQuipmEnt foR NuclEaR F^WER ^NTs^ Nov^ ^^^^ ^ USNRC-RG 1.9^, ^ÎÎLIT^ of ELecTric Ê^ ô^c^S^^ Dec^ 1974. ^ USNRC-RG 7 ^ ^ ^^^ ^Seismic QuaLifIcatioN of ELectric EQaipmEnt foR NuclEar ôWER ^LaNTs^^ REv^ 1, Aug^ 1977^ ^ USNRC-RG ^ ^ ^^^^ ^THeRmaL OvERLoad ^RoTEctioN of ELEctric MoToR-OpERatEd VaLv^, REv^ 1, Mar^ ^^^^ USNRC-RG 1^10^ ^êrIodIc TestiNg of DIescl GEneraToR UnITs UseD as On-sitE ELEcTric ôwER SysTems aT Nuclear ôwer ^lants^, Rev^ 1, Aug^ 1977^ ^^ USNRC-RG 1^128, ÎnStaLLatioN DesigN and InstallatioN of Large Lead SToRage Batieries foR NuclEaR ôwer ^lants^, REv^ 1, ^ USNRC-RG 1^129, ^MaInTENANCE^ Testing^ and REpLacEmEnt of StoRagE BatiEries foR NuclEAR ôwer ^lants^, REv^ 1, . BT^ ICSB-2, ^DIeseL GENERATOR REliAbiLity Quallf ication USNRC-SR^, Appendix-^, Rev^ 1^ OcT^ ^^^^^ . BTI^ ICSB-4, ^REQuiRemenTs on MoToR-OpERatED Valves In THE ECCS AccumulaToR LINes^, USNRC-S^^, AppEn^^, REv. 1, OcT^ 197^^ BT^ ICS^-^, ÛSE of DIeseL-GENERatoR SeTs f^ Ê^îN^^^ USNRC—SR^, Appendix-8, Rev. 1, Oct^ 7^^^^ ^. BT^ ICSB-11, ^STabILIty of Off-site F^^ SysTems^, USNRC-SR^, Appendix 8^ Revî, OcT^ 1978^ ICSB-1^, ^êacToR Coolant ûmp BREaker QuaLIfIcation^, USNRC , AppeNdix-8, Rev^ 1, Octi 1978^ ICSB-17, ^ÎeSEL GENeRatoR ^RoTective Trip CIRcuIT Bypasses^, USNRC-SR^, Appcnrix-^, REv^ 1, OCT^ 1978. BT^ ICS^-18, ÂppLIcaTion of The SingLE FaiLuRE CRitErion To ManuaLLy ContRolled ELEcTricaLLy OpeRated Valves^^ USNRC -SR^, Appendix^,