Module 02Module 02PressurizedPressurized

WaterWaterReactorsReactors

(PWR)(PWR)

Prof.DrProf.Dr. . H. H. BBööckckVienna University of Technology /AustriaVienna University of Technology /AustriaAtominstituteAtominstituteStadionalleeStadionallee 2, 2, 1020 Vienna, Austria1020 Vienna, Austriaboeck@ati.ac.atboeck@ati.ac.at

•• PWR BasicsPWR Basics•• Technical DataTechnical Data•• Safety FeaturesSafety Features•• Reactivity ControlReactivity Control•• Fuel AssembliesFuel Assemblies•• Reactor Pressure VesselReactor Pressure Vessel•• Steam GeneratorSteam Generator•• Reactor Cooling CircuitsReactor Cooling Circuits•• PressurizerPressurizer

ContentsContents

•• HH22O as coolant O as coolant andand moderatormoderator•• Pressure in primary circuit: 160 bar (16 Pressure in primary circuit: 160 bar (16 MPaMPa))•• No boiling in primary circuitNo boiling in primary circuit•• Temperature about 300 Temperature about 300 ººCC•• Heat transferred by 2 Heat transferred by 2 -- 6 steam generators to 6 steam generators to

secondary circuit (pressure about 50 bars) secondary circuit (pressure about 50 bars) •• Produced steam is dried and transferred to Produced steam is dried and transferred to

turbine generatorturbine generator•• AverageAverage power power densitydensity in in corecore: 93 : 93 kW/litrekW/litre•• BurnBurn--upup: ca. 53 000 : ca. 53 000 MWd/tMWd/t UU•• Thermal Thermal netnet efficiencyefficiency: 35.5%: 35.5%

PWR BasicsPWR Basics

•• OriginallyOriginally developeddeveloped forfor Nuclear Submarines, Nuclear Submarines, IcebreakersIcebreakers, , AircraftAircraft CarriersCarriers (USS (USS NautilusNautilus1955)1955)

•• Generation 1:Generation 1: Prototype NPP 1960s, Prototype NPP 1960s, aroundaround 250 250 MWMWee to 300 to 300 MWMWee (Obrigheim), (Obrigheim), shutshut down down permanentlypermanently in 10/05in 10/05

•• Generation 2:Generation 2: Medium power NPP 1970s Medium power NPP 1970s aroundaround600 600 MWMWee to 800 to 800 MWMWee ((StadeStade), ), shutshut down down permanentlypermanently in 11/03in 11/03

PWR PWR GenerationsGenerations

•• Generation 3:Generation 3: N4 (F) N4 (F) oror Konvoi (D) NPP Konvoi (D) NPP 1980s 1980s aroundaround 1000 1000 MWMWee to 1300 to 1300 MWMWee(Biblis B)(Biblis B)

•• Generation 3+:Generation 3+: EPR 2008 EPR 2008 aroundaround 1600 1600 MWMWee ((OkiluotoOkiluoto--FINFIN, , FlamanvilleFlamanville--FF))

•• Generation 4:Generation 4: PresentlyPresently underunderdevelopmentdevelopment byby 10 10 industrialindustrial nationsnations, to , to bebe availableavailable aroundaround 2030 2030

PWR PWR GenerationsGenerations

ExampleExample: : TheThe PWR PWR BrokdorfBrokdorf

•• BuiltBuilt–– 19861986–– Generation 3Generation 3–– byby KWUKWU

•• 1370 1370 MWMWee netnet

•• 3760 3760 MWMWthth

•• FuelFuel rodsrods: : –– OuterOuter diameterdiameter: 9.50 mm: 9.50 mm–– Wall Wall thicknessthickness: 0.64 mm: 0.64 mm–– FuelFuel: 3% : 3% enrichedenriched UOUO22, , sinteredsintered to to ceramicceramic

pelletspellets of 92% of 92% theoreticaltheoretical densitydensity–– CladdingCladding material: material: ZircaloyZircaloy 4 (99% Zr, Sn, 4 (99% Zr, Sn,

Fe, Ni)Fe, Ni)

TechnicalTechnical Data of Data of thethe PWR PWR BrokdorfBrokdorf

UOUO22 PelletsPellets

IndividualIndividual FuelFuel RodRod

PWR PWR PelletPellet--RodRod--FuelFuel--AssembliesAssemblies

•• FuelFuel assembliesassemblies::–– NumberNumber of of fuelfuel assembliesassemblies: ca. 200: ca. 200–– Total Total lengthlength: 4.83 m: 4.83 m–– ActiveActive lengthlength: 3.96 m: 3.96 m–– LatticeLattice: 16 x 16 : 16 x 16 rodsrods = 256 = 256 positionspositions per per

assemblyassembly–– WeightWeight: 750 kg: 750 kg–– NumberNumber of of rodsrods per per assemblyassembly: 236: 236–– PositionsPositions forfor absorberabsorber fingersfingers: 20: 20

TechnicalTechnical Data of Data of thethe PWR PWR BrokdorfBrokdorf

PWR PWR AssembliesAssemblies

•• ControlControl rodsrods::–– NumberNumber of of controlcontrol rodsrods: 61: 61–– 20 20 fingersfingers penetratingpenetrating intointo thethe fuelfuel assemblyassembly–– Absorber material: Ag80In15Cd5Absorber material: Ag80In15Cd5–– Absorber Absorber lengthlength: 3.72 m: 3.72 m–– DrivenDriven byby electricalelectrical motormotor in in -- outout–– In In casecase of fast of fast shutshut down: Absorber down: Absorber isis relasedrelased

fromfrom electromagneticelectromagnetic clutchclutch and and dropsdrops bybygravitygravity intointo thethe corecore

TechnicalTechnical Data of Data of thethe PWR PWR BrokdorfBrokdorf

•• Short Short termterm byby controlcontrol rodsrods:: 50 to 80 50 to 80 controlcontrolrod rod assembliesassemblies forfor normal normal operationoperation

–– startstart--upup–– power power changeschanges–– normal normal shutshut downdown

and and forfor emergencyemergency shutshut downdown

•• LongtLongt termterm byby boricboric acidacid: : –– B: (n,B: (n,αα)) reactionreaction, cross , cross sectionsection: 3,8.10: 3,8.10--2121 cmcm22

–– For For longlong--termterm reactivityreactivity controlcontrol: : WhenWhen loadedloaded withwithfreshfresh fuelfuel, , coolantcoolant containscontains ca. 1200 ca. 1200 ppmppm boricboric acidacidwhichwhich isis graduallygradually removedremoved parallel to parallel to uraniumuraniumconsumptionconsumption ((fuelfuel burnburn--upup) )

ReactivityReactivity ControlControl of of PWRsPWRs

Cross Cross SectionSection

•• For uniform power For uniform power distributiondistribution uraniumuraniumenrichmentenrichment higherhigher at at corecore edgeedge

•• InsideInside corecore chesschessboardboard distributiondistribution

•• ControlControl rodsrods positionpositionsymmetricallysymmetrically to to centrecentre

FlowdiagramFlowdiagram PWRPWR

1 1 ReactorReactor vesselvessel 8 8 FreshFresh steamsteam 15 15 CoolingCooling waterwater2 2 FuelFuel elementselements 9 9 FeedwaterFeedwater 16 16 FeedwaterFeedwater pumppump3 3 ControlControl rodsrods 10 High 10 High pressurepressure turbineturbine 17 17 FeedwaterFeedwater prepre--heaterheater4 4 ControlControl rod rod drivesdrives 11 Low 11 Low pressurepressure turbineturbine 18 18 ConcreteConcrete shieldshield5 5 PressurizerPressurizer 12 Generator12 Generator 19 19 CoolingCooling waterwater pumppump6 6 SteamSteam generatorgenerator 13 13 ExciterExciter7 Main 7 Main circulatingcirculating pumppump 14 14 CondenserCondenser

FlowFlow Diagram of a PWR Diagram of a PWR -- DetailsDetails

•• In In PWRsPWRs water has a water has a negative void coefficientnegative void coefficient as as steam has poorer moderator qualities than steam has poorer moderator qualities than water, the fission reaction slows down water, the fission reaction slows down

•• TwoTwo independent independent shut down systemsshut down systems•• 3 x 100% redundancy3 x 100% redundancy in safety systemsin safety systems•• Diverse functionsDiverse functions for safety related actionsfor safety related actions•• Physical separationPhysical separation of safety relevant systemsof safety relevant systems•• Five barriersFive barriers between the fission products and between the fission products and

the environment the environment

SafetySafety of of PWRsPWRs

MultipleMultiple

BarrierBarrier

SystemSystem

InspectionInspectionofof

a a newnewFuelFuel

AssemblyAssembly

Initial Initial FuelFuel LoadingLoading•• Initial Initial loadingloading: : FuelFuel

assembliesassemblies areare loadedloadedfromfrom centrecentre to to edgeedge

•• SubcriticalSubcritical neutronneutronmultiplicationmultiplication isismeasuredmeasured

•• FollowFollow up up loadingloading: : AboutAbout 1/3 of 1/3 of fuelfuelassembliesassemblies areare changedchangedeacheach yearyear

•• MeanMean life time of life time of fuelfuel in in corecore: 3 : 3 yearsyears

•• Basic Data:Basic Data:–– HeightHeight: 12.00 m: 12.00 m–– Inner Inner diameterdiameter: 5.75 m: 5.75 m–– Design Design pressurepressure: 176 bar: 176 bar–– Wall Wall thicknessthickness: 25 cm: 25 cm–– Total Total weightweight: 876 t: 876 t

ReactorReactor PressurePressure VesselVessel (Brockdorf)(Brockdorf)

PWR PWR –– ReactorReactor PressurePressure VesselVessel DevelopmentDevelopment

1969 1970 1972 1977

PWR PWR –– ReactorReactor PressurePressure VesselVessel DevelopmentDevelopment

ReactorReactor

PressurePressure

VesselVessel

CrossCross

SectionSection

ForgingForging a a SeamlessSeamlessPressurePressure VesselVessel

RingRing

•• LowerLower partpart of PV of PV isisweldedwelded togethertogether fromfromseveralseveral seamlessseamless shellshellringsrings

•• FlangesFlanges, rings and , rings and bottombottom domedome areare mademadeof of lowlow--alloyalloy, fine , fine grainedgrained structuralstructural steelsteel

•• VeryVery good good weldingweldingpropertiesproperties, , veryvery littlelittleembrittlementembrittlement

ViewsViews on on thethe PressurePressure VesselVessel

PressurePressureVesselVesselbeforebefore

InstallationInstallation•• LowerLower partpart of a of a

pressurepressure vesselvessel isismovedmoved intointo thethereactorreactor buildingbuilding

•• NozzlesNozzles forfor coolantcoolantpipespipes areare visiblevisible

PressurePressureVesselVessel

InstallationInstallation•• PressurePressure

vesselvessel (French (French N4 N4 typetype) ) duringduringplacementplacement

•• NozzelsNozzels arearevisiblevisible

SteamSteam GeneratorGenerator•• Thermal Thermal contactcontact betweenbetween primaryprimary

and and secondarysecondary coolingcooling systemsystem•• AboutAbout 4000 m4000 m22 of of heatheat transfertransfer

areaarea

SteamSteam GeneratorGenerator

•• PrimaryPrimary coolantcoolant entersentersbottombottom leftleft and and exitsexitsbottombottom rightright

•• PrimaryPrimary waterwater insideinside tubestubes•• SecondarySecondary waterwater entersenters toptop

rightright•• DryDry steamsteam leavesleaves to to turbineturbine

generatorgenerator at at toptop

PressurizerPressurizer

•• ResponsibleResponsible forfor keepingkeepingthethe operatingoperating pressurepressurewithinwithin +/+/-- 2 2 barsbars

•• IfIf pressurepressure isis tootoo lowlowelectricalelectrical heatersheaters produceproducemoremore steamsteam

•• IfIf pressurepressure isis tootoo high high coldcold waterwater sprayssprayscondensescondenses steamsteam

•• On On toptop pressurepressure reliefreliefsafetysafety valvevalve, , herehere startedstartedthethe TMITMI--2 2 accidentaccident

•• World Nuclear Organisation:World Nuclear Organisation:–– www.worldwww.world--nuclear.orgnuclear.org

•• TypesTypes of Nuclear of Nuclear ReactorsReactors::–– hyperphysics.phyhyperphysics.phy--astr.gsu.edu/hbase/nucene/reactor.html#c3astr.gsu.edu/hbase/nucene/reactor.html#c3

•• Nuclear Regulatory Commission:Nuclear Regulatory Commission:–– www.nrc.govwww.nrc.gov

•• Nuclear Energy Institute:Nuclear Energy Institute:–– www.nei.orgwww.nei.org

•• Mitsubishi Heavy Industry (Japan):Mitsubishi Heavy Industry (Japan):–– www.mhi.co.jp/atom/hq/atome_e/index.htmlwww.mhi.co.jp/atom/hq/atome_e/index.html

•• AtominstituteAtominstitute of the Austrian Universities:of the Austrian Universities:-- www.ati.ac.atwww.ati.ac.at

•• MovieMovie: : FramatomeFramatome--ANPANP–– www.framatomewww.framatome--anp.comanp.com>EPR a large >EPR a large advanvcedadvanvced evolutionary reactor>the EPR a evolutionary evolutionary reactor>the EPR a evolutionary

reactor>3D animation > in the heart of a PWRreactor>3D animation > in the heart of a PWR

–– http://http://www.francenuc.org/toc_e.htmwww.francenuc.org/toc_e.htm

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