SAFETY REQUIREMENTS for a NUCLEAR POWER PLANT ELECTRIC POWER SYSTEM
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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 ^oweR DIsTRIbuTIon sysTem ^ 2.2 THe A.C. ^owER SysTem ^ 2.^ The D.C. i^oweR SysTem ^ 2.4 NoN-lNTeRRupTabLe A.C. ^oweR 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 i^oweR SysTem 6 ^.1.2 STandby ^owER SysTem 6 ^.1.^ D.C. ^oweR SysTems 8 ^.1.4 FIRe ^RoTecTIon foR CabLe SysTems 8 ^.2 Scope of review by THe reguLaToRy body 8 ^.2.1 ^RefeRRed ^oweR SuppLy 9 ^.2.2 STandby ^Ower SysTem 10 ^.2.^ DC ^oweR SuppLIes 11 4. GeneRaL DesIgN CRITeRIa for ELecTRIc i^oweR SysTem 11 ^. MeaNS for ImpLemenTaTIoN/ReguLaToRy guides aNd BRaNcH TecHNIcaL ^osITIoNS 14 ^. 1 INdepeNdeNce BeTween RedundanT STaNdby( ONsITe) ^oweR sources aNd THeIr DIsTRIbuTIoN SysTems. 14 ^.2 SeLecTIon of DIeseL GeneRaToR SeT CapacITy foR STandby ^ower SuppLIes 16 - i - TabLE of CoNTEnTs I^eriodic 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 ^oweR SysTem for NucLeaR ^oweR ^LanTs 18 QuaLIficaTioN TesTs of CoNTiNuous DuTy MoToRS INSTaLLed INSide The ConTainmeNT of WaTeR CooLed NucLeaR ^oweR ^LaNTs . 19 ^ReopeRaTioNaL TesTiNg of ReduNdaNT ONSiTe ELecTRicaL ^oweR SysTems To VeRify ^RopeR Load GRoup AssignmeNTs 20 Bypassed aNd InopeRabLe sTaTus INdicaTion for NucLeaR ^oweR ^LaNT SafeTy SysTems. 21 AppLicaTioN of THe SiNgLe FaiLure CRiTeRioN To NucLeaR ^oweR ^LaNT ^RoTecTioN SysTems. 21 MaNuaL INiTiaTioN of I^RoTecTive AcTions 22 ELecTRicaL ^eneTRaTioN AssembLies in ConTainmenT STRucTuRes for LigHT WaTer- CooLed NucLeaR T^oweR ^LanT. 2^ IniTiaL TesT ^RogRams for WaTeR CooLed NucLeaR i^oweR ^LanTs. 24 QuaLificaTion TesTs of ELecTRic VaLve OpeRaToRs InsTaLLed Inside THe ConTainmenT of NucLear I^ower ^LaNTs. 26 of CONTENTS ^HysIcaL IndependeNce of ELecTRIc SysTem 27 ShaRed EmeRgeNcy aNd SHuTdown ELecTrIc SysTems for MuLTI^UnIT NucLear ^oweR ^LanTs 27 QuaLIfIcaTIoN of CLass IE EquIpmeNT foR NucLeaR i^oweR I^LanT. 28 AvaILabILITy of eLecTRIc power sources 29 Seismic QuaLIfIcaTIoN of ELecTRIc EquIpmenT foR NucLeaR T^ower F^LaNTs ^0 THeRmaL OveRLoad ^RoTecTIoN foR ELecTRIc MoToRs ON MoToR OpeRaTed VaLves ^0 ^eRIodIc TesTINg of DIeseL GeNeRaToR UnITs Used as ON-sITe ELecTRIc F^oweR SysTems aT NucLeaR ^oweR ^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 - iii - of ^.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 ^^i 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 si^es 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. TH^EfoRE, 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.