Nuclear Safety in Light Water Reactors. Severe Accident Phenomenology

716 Pages·2012·28.77 MB·English

by  Bal Raj Sehgal (Eds.)

Nuclear Safety in
Light Water Reactors
Severe Accident Phenomenology
Edited by
Bal Raj Sehgal
Support provided by the SARNET (Severe Accident Network)
in the Framework Programmes of Research
of the European Commission
AMSTERDAMlBOSTONlHEIDELBERGlLONDON
NEWYORKlOXFORDlPARISlSANDIEGO
SANFRANCISCOlSINGAPORElSYDNEYlTOKYO
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ISBN978-0-12-388446-6(alk.paper)
1.Lightwaterreactors–Riskassessment.2.Lightwaterreactors–Safetymeasures.
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Preface
Theideaofdocumentingtheadvancesachievedinthefieldoflightwaterreactor
severe accident safety research in the form of a book originated during the
developmentoftheresearchprogramfortheSevereAccidentResearchNetwork
of Excellence (SARNET), coordinated by IRSN France, that was started in
March2004,undertheauspicesoftheSixthFrameworkResearchProgramofthe
European Commission. After some discussion, it was decided that the book
should be a textbook for students and young researchers in the field and not
ahandbook.Itwasalsodecidedthatthebookshouldnotbeacompendiumofall
theresearchinthefield,butrathershouldbewrittentoimpartunderstandingand
knowledgeaboutthecomplexphysicsofsevereaccidents.Thephysicsofsevere
accidents involves several disciplines, including probability theory, neutron
physics,thermalhydraulics,high-temperaturematerialscience,chemistry,and
structuralmechanics.Thus,impartingunderstandingandknowledgeofsevere
accidentsisnotasimpletask.Itisnonethelessanimportanttaskinreactorsafety,
sinceasevereaccidentistheonlysourceofrisktothepublicfromanoperating
lightwaterreactorpowerplant.Preventingandmanagingtheconsequencesof
asevereaccident,whichisthemaingoalofsevereaccidentresearch,contributes
greatlytoreducingthepublicriskofnuclearpower.
The importance of severe accident research was recognized by the
EURATOM Part of the Framework Research Programs of the European
Commission. The Framework Program No. 4 was totally focused on severe
accident(SA)research.TheEuropeanCommissioniscontinuingitssupportof
SAresearchand,throughitssupportofSARNET,isencouragingthefocusof
nationalresearch effortson an integratedEuropeanprogram of thisresearch.
This book, Nuclear Safety in Light Water Reactors: Severe Accident
Phenomenology,describestheresultsobtainedfromtheseresearchprograms,
conductedoverthelast15yearsinEurope.Thebookalsocontainstheresults
of SA research conducted over the years in the United States, Japan, Korea,
Russia, and other countries. The research conducted in the United States, in
particular, was the forerunner of the research that has been conducted in
Europe. The knowledge gained in the U.S. research forms a very important
base for SA research conducted throughout the world. The book, therefore,
documents the data, phenomenology, and methodology developed for the
description of severe accidents in all countries.
ThisbookisajointeffortsinceitisaproductofSARNET,anetwork.Itwas
conceivedasapedagogicaleffort,however,writtenbyacknowledgedexpertsin
xiii
xiv Preface
the different areas of the SA field. It was coordinated, chapter by chapter, by
different expertsandfinallycompiledand edited bythe undersigned.
Chapter1ofthebookprovidesahistoricalreviewofthewholefieldofreactor
safety,withshortintroductionsonthevarioussevereaccidentphenomenological
topics.Italsoattemptstoprovideaninsightintothelogicofadvancementsin
rectorsafetysincethebirthofnuclearenergy.Themostrecenttragiceventat
Fukushima is also briefly described in Chapter 1, based on the information
gainedasoftheendofJune,10,2011.Thisdescriptionmayneedcorrectionsas
morecompleteinformationaboutthesesevereaccidentsatFukushimaemerges
in time. Chapter 1 also briefly deals with the advances in mitigating severe
accidentsachievedinthedesignsofsomeofthenew(GENIII+)LWRs.
The remaining contents of the book follow the severe accident scenario,
starting with the loss of cooling of the decay-heated core. The resulting core
heat-up,coredegradation,hydrogenproduction,coremelting,accumulationof
melt in lower head, failure of the lower head, hydrogen combustion, steam
explosion, molten corium– concrete interactions (MCCI), fission product
release, transport in the primary system, containment, and the like, are the
subjectstreatedin the book.
A question that arose early in deliberations on the contents of the book
concerned the maturity of the SA field. We believe that nearly all the knowl-
edgegainedthroughSAresearch,anddescribedinthebook,ismatureenough
and will stand the test of time. It should also be stated that severe accident is
still an active field of research, and some issues remain open; notably, the
knowledge base still has uncertainties, and more research (experimentation,
modeling,validation,etc.)isneeded,andindeedisbeingperformed.Evenfor
theseissues,however,asufficientknowledgebasehasalreadybeenacquiredto
document these areas ofuncertainties.
Thebookisaproductoftheeffortsanddedicationofthecontributorslisted
withthetextinthebook.Verysubstantialeffortswereinvolvedineditingthe
various contributions and organizing the book. We hope that it will be
a worthwhile book for the education of nuclear engineering students and
a reference text for the young researchers who want to work, or are already
engaged, inthe field of LWR severeaccident safety.
Last,butnottheleast,wethecontributors(authors)andtheEditorwishto
acknowledge with thanks, the steadfast and continous support of M. Michel
Hugon, the EU Program Manager for the SARNET Network of Excellence.
The Editor, also wishes to acknowledge with thanks, the able assistance of
Dr. Van Dorsselaere inthe “final-edit”of the book.
Bal Raj Sehgal
Contributors
Hans Alsmeyer, Karlsruher Institut fu¨r Technologie (KIT), retired, Technologies
Institut fu¨r Kern- und Energietechnik (IKET), Hermann-von-Helmholtz-Platz 1,
D-76344 Eggenstein-Leopoldshafen, Germany
Eberhardt Alstadt, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of
Safety Research, P.O.B.510119,D-01314 Dresden,Germany
Marc Barrachin, Institut de Radioprotection et de Suˆrete´ Nucle´aire (IRSN),
Cadarache, BP3,13115, Saint-Paul-lez-Durance, France
Ahmed Bentaib,IRSN, BP17,F- 92262, Fontenayaux Roses, FRANCE
Jonathan Birchley, Paul Scherrer Institut (PSI), CH- 5232, Villigen PSI,
SWITZERLAND
ManfredBurger,Universita¨tStuttgart(IKE),Pfaffenwaldring31,D-70569Stuttgart,
Germany
CataldoCaroli, IRSN,BP17, F-92262, FontenayauxRoses, FRANCE
Michel Cranga,IRSN,Cadarache, BP3, 13115,St Paul-lez-Durance, France
TrucNamDinh,RoyalInstituteofTechnology(KTH),AlbaNova,10691Stockholm,
Sweden and IdahoNational Laboratory,Idahofalls, USA
Jean-Pierre Van Dorsselaere, SARNET coordinator, IRSN, Cadarache, BP3, 13115
Saint-Paul-lez-Durance,France
Gerard Ducros, Commissariat a` l’Energie Atomique et aux Energies Alternatives
(CEA), Cadarache Baˆt.315,F- 13108,St Paul-lez-durance, FRANCE
Peter Eisert, Gesellschaft fuˆr Anlagen Und Reaktorsicherheit mbH (GRS),
Schwertnergasse7,D-50461,Ko¨ln, Germany
FlorianFichot,IRSN, Cadarache,BP 3,13115St-Paul-lez-Durance, France
ManfredFischer,AREVAGmbH,D-91050,Erlangen,Germany
Jerzy J. Foit, KIT, Technologies Institut fu¨r Kern- und Energietechnik (IKET),
Hermann-von-Helmholtz-Platz1,D-76344Eggenstein-Leopoldshafen, Germany
Salih Guentay,PSI,CH- 5232,VilligenPSI, Switzerland
TimHaste,IRSN, Cadarache,BP 3,13115Saint-Paul-Lez-Durance Cedex, France
Luisen Herranz, Centro de Investigationes Energeticas Medio Ambientales Y
Tecnologicas (CIEMAT),Avda. Complutense, 22,E-28040, Madrid,SPAIN
ZoltanHozer,KFKIAtomicEnergyResearchInstitute(AEKI),KonkolyThegeut29-
33, 49,H-1525, BUDAPEST,HUNGARY
Christos Housiadas, “Demokritos” National Center for Scientific Research, PO Box
60228, 15310Agia Paraskevi Attikis,Greece
xv
xvi Contributors
Ivan Ivanov, Technical University of Sofia (TUS), 8, Kl. Ohridski Blvd., Block 12,
Office 12440, 1797,Sofia, BULGARIA
Thomas Jordan, KIT, Technologies Institut fu¨r Kern- und Energietechnik (IKET),
Hermann-von-Helmholtz-Platz 1, D-76344Eggenstein-Leopoldshafen, Germany
Christophe Journeau,CEA,Cadarache, F- 13108,St Paul-lez-Durance, FRANCE
Martin Kissane,IRSN, Cadarache,BP 3,F- 13115,St-Paul-lez-durance,FRANCE
Ivo Kljenak, Jozef Stefan Institute (JSI), Reactor Engineering Division, Jamova 39,
Ljubljana, Slovenia
MarcoKoch,Ruhr-Universita¨tBochum,LEE,IB4/127,Universita¨tsstr.150,D-44801,
Bochum,GERMANY
Jean-Sylvestre Lamy, Electricite´ de France (EDF), R&D, SINETICS, 1 avenue du
Ge´ne´ral de Gaulle,92140Clamart, France
Jean-Claude Latche,IRSN,Cadarache, BP3,F- 13115,St-Paul-lez-Durance,France
Terttaliisa Lind,PSI, CH-5232, Villigen PSI,SWITZERLAND
WeiminMa,RoyalInstituteofTechnology(KTH),NuclearPowerSafety,AlbaNova,
10691Stockholm,Sweden
Daniel Magallon, retired Scientist, Joint Research Centre (JRC), European
Commission, Institute for Energy and Transport (IET), P.O. Box 2, NL-1755 ZG
Petten,The Netherlands, seconded toCEA/Cadarache
ManiMathews,AtomicEnergyofCanadaLimited(AECL),ChalkRiverLaboratories,
ChalkRiver,Ontario,K0J1J0,Canada
Leonhard Meyer, KIT, Technologies Institut fu¨r Kern- und Energietechnik (IKET),
Hermann-von-Helmholtz-Platz 1, D-76344Eggenstein-Leopoldshafen, Germany
Christoph Mueller, GRS mbH, retired, Forschunginstitute, 85748, Garching b.
Mu¨nchen,Germany
PascalPiluso,CEA, Cadarache,13108Saint-Paul-lezDurance, France
Horst Schnadt,Tu¨vRheinland Industrie Service GmbH,retired, Cologne,Germany
Andreas Schumm, EDF - R&D, SINETICS, 1 avenue du Ge´ne´ral de Gaulle, 92140
Clamart, France
Bal Raj Sehgal, Emeritus Professor, Royal Institute of Technology (KTH), Nuclear
Power Safety, AlbaNova,10691Stockholm,Sweden
Jean-Marie Seiler,CEA, 17,av. desMartyrs, F- 38054,Grenoble, France
Juergen Sievers,GRSmbH, Schwertnergasse 1,50667Ko¨ln, Germany
ClausSpengler,GRS, Schwertnergasse7,D- 50461,Ko¨ln, Germany
Bertrand Spindler,CEA, 17av.des Martyrs, F-38054, Grenoble, France
Bruno Tourniaire,CEA, 17av.des Martyrs,F- 38054, Grenoble, France
Klaus Trambauer, GRS mbH, retired, Forschunginstitute, 85748, Garching b.
Mu¨nchen,Germany
George Vayssier, Consultant, Nuclear Services Corporation (NSC), Kamperweg 1,
4417PC Hansweert, TheNetherlands
Jean-Michel Veteau, CEA,retired, 17av.desMartyrs, F- 38054, Grenoble, France
Chapter 1
Light Water Reactor Safety:
A Historical Review
Bal Raj Sehgal
Chapter Outline
1.1. Introduction 2 1.10.1. Backgroundand
1.2. TheEarlyDays 3 RBMK
1.3. TheDevelopmentof Specifics 33
CivilianLWRS 3 1.10.2. HowandWhy
1.4. EarlySafetyAssesments 5 Chernobyl
1.5. TheSitingCriteria 5 Happened 37
1.5.1. Assumptionsand 1.11. TheDifficultYears 44
Requirements 1.12. SevereAccidentResearch 45
ofTID-14844 1.12.1. In-vesselAccident
and10 Progressionfora
CFR100 6 PWR 48
1.6. SafetyPhilosophy 7 1.12.2. In-vessel
1.6.1. TheDefense-in- Accident
DepthApproach 8 Progressionfor
1.7. SafetyDesignBasis 10 aBWR 49
1.7.1. LOCAandthe 1.12.3. FissionProduct
ECCS Releaseand
Controversies 12 Transportduring
1.8. PublicRiskofNuclear theIn-vessel
Power(WASH-1400) 15 Accident
1.8.1. TheReactorSafety Progression 50
Study 16 1.12.4. Ex-vessel
1.9. TheTMI-2Accident 27 Accident
1.9.1. Descriptionofthe Progression 51
Accident 27 1.13. SevereAccident
1.9.2. TheAftermathof Management 57
TMI-2Accident 32 1.13.1. Cooling
1.10. TheChernobylAccident 33 aDegradedCore 58
NuclearSafetyinLightWaterReactors.DOI:10.1016/B978-0-12-388446-6.00001-0
(cid:1)2012ElsevierInc.Allrightsreserved. 1
2 NuclearSafetyinLightWaterReactors:SevereAccidentPhenomenology
1.13.2. Managementof 1.14.3. TheActual
Combustible Progressionofthe
Gases 60 Fukushima
1.13.3. Managementof Accidents 69
Containment 1.14.4. Concluding
Temperature, Remarksonthe
Pressure,and Fukushima
Integrity 60 Accidents 75
1.13.4. Managementof 1.15. NewLWRPlants 78
Radioactive 1.15.1. TheIn-Vessel
Releases 61 MeltRetention
1.14. TheFukushimaAccidents 62 (IVMR)Strategy 80
1.14.1. Introductionand 1.15.2. TheEx-Vessel
Plant MeltRetention
Characteristics 62 Strategy 82
1.14.2. Consequencesof Conclusions 85
aConservative References 86
Core-melt
Scenariofor
Fukushima
Reactors 68
1.1. INTRODUCTION
Thelightwaterreactor(LWR)safetythatweareconcernedwithinthisbookis
basically about estimating the risks posed by an individual or a population of
nuclear power plants (NPPs) to the public at large and the efforts to reduce
theserisks.Thepublicofmostconcernisthatwhichresidesinthevicinityof
anuclearpowerplantbutalsoatotherlocations,whichcouldbeaffectedbyan
accident in aNPP locatedanywhere.
The basic goal of safety is to ensure that a LWR will not contribute
significantlytoindividualandsocietalhealthrisks.Thisbasicgoaltranslatesto
the prevention of the release of radioactivity into the environment from the
NPP.Acomplementaryaimistopreventdamagetotheplantandtoprotectthe
personnel at the plant frominjury ordeathin anaccident.
SinceLWRsafetyaimstoprotectthepublicatlarge,itisheavilyregulated.
Each nuclear power country (and even some without NPPs) has regulatory
commissions (bodies) that regulate every aspect of a NPP from design and
construction to operation and any modifications. They require very extensive
analyses,documentation,andqualitycontrol.Thereactorsafetydesignhasto
follow definite rules and regulations. Some of these requirements will be
described inthischapter.
Chapter | 1 LightWaterReactorSafety:AHistoricalReview 3
The reactor performance, on the other hand, is concerned with long-term
steady-state operations, since most LWR plants are base-loaded and strive
to operate at full power, without interruption, between scheduled outages
for maintenance. Reactor performance is also concerned with efficiency, the
capacityfactor,fuelcyclecosts,maintenancecosts,andtheradiationdosetothe
operatingstaff.Thus,itisnotregulated.However,ithasbeenfoundthatawell-
runningLWRplantis,generally,asaferplantwithamuchlowerfrequencyof
incidents,which,generally,aretheprecursorstomoreseriousevents.
1.2. THE EARLY DAYS
The nuclear era started with the natural uranium-graphite pile built by Fermi
and his associates at Stagg Field at the University of Chicago [1]. It did not
involve light water as a coolant since only natural uranium was available
and criticality could be achieved only with graphite or heavy water. The
safetyconceptsdevelopedthere,however,wereadoptedbytheLWRplantsthat
developedseveralyeas later.EnricoFermi andhis associatesrecognizedthat:
l Nuclear fission reactions, which are the basis of nuclear power, emit high
levels of radioactivity and thus could be a health hazard to any person
exposedtoit. This impliedshielding,containment,and remote siting.
l The safe operation of the reactor (or pile) would require protective and
control measures, as evidenced by the provision of a control rod in the
pile that Fermi and his associates built.
Shieldingandremotesitingwererequiredfortheplantsthatwerebuiltfor
theproductionofplutoniumintheUnitedStatesandothercountriesduringthe
years before and after World War II. Remote siting of these plants not only
protectedthepublicbutalsomaintainedthesecrecysurroundingtheproduction
of nuclear weaponsfor anumberofyears.
Thecontainmentaspectofprotectingthepublicfromanuclearaccidentwas
notconsideredoremployedfortheplantsgeneratingplutonium.Thosewerethe
yearsofabove-groundnuclearweaponstests,whichinanycasewerereleasing
considerableamountsofradioactivefissionproductsintheatmosphere.Fortu-
nately,therewerenoreportedaccidentsofanygreatsignificanceintheplutonium
productionplantsineithertheUnitedStatesorotherWesterncountries.
Leak-tightcontainmentasasafetysystemforacivilianNPPwasnotlongin
coming.Itwasproposedin1947[2]fora sodium-cooledfastreactorthatwas
thefocusofthepowerreactordevelopmentbytheU.S.DepartmentofEnergy
at that time. Later, the LWR plant developers adopted leak-tight containment
fortheirplants.
1.3. THE DEVELOPMENT OF CIVILIAN LWRS
TheLWRdevelopmentstarted asamilitaryprogramintheUnitedStates and
stemmedfromtheinitiativeofAdmiralHymanRickover,whoisconsideredthe
4 NuclearSafetyinLightWaterReactors:SevereAccidentPhenomenology
fatheroftheU.S.nuclearnavy[3].Histeamconceivedthepressurizedwater-
cooled reactor (PWR) as the NPP for submarine propulsion, since a sodium-
cooled fast reactor, the focus of the U.S. national program, was considered
unsuitable for a nuclear submarine submerged in water. Admiral Rickover
obtained the necessary funding and the considerable intellectual resources
neededtogeneratetheextraordinarilyrapiddevelopmentofthePWRplantfor
the U.S. submarine fleet.
PresidentDwightEisenhowerissuedthecallforAtomsforPeacein1954[3],
whichbecamethesignalforadaptingmilitarydevelopmentsforcivilianpurposes.
TheconstructionoftheShippingportPWR,Pennsylvania,USA.[3],whichwas
completed in 1957, provided the prototype for NPPs, generating a reasonable
amountofelectricalpowerforpublicconsumption.EBR-1,afastreactor,wasthe
firstnuclearreactorintheUnitedStatestogenerateelectricalpower.However,the
quantitygeneratedwasinsufficienttotransmitforpublicconsumption.
The development of the other civilian water-cooled nuclear power reactor,
thatis,theboilingwaterreactor(BWR),wasstartedalmostinparallelwiththatof
the PWR and the construction of the Shippingport PWR plant. The BWR
developmentwasspearheadedbytheGeneralElectric(GE)Company,aprivate
enterprise, which, in fact, invested its own funds to develop the BWR as
acommercialNPP.Inthisefforttheywereaidedbynationallaboratoriesinthe
UnitedStatesdforexample,ArgonneNationalLaboratory,whichbuilta5-MW
BWRsystem[3],andtheIdahoLaboratories,whereexperimentswereperformed
[4]todemonstratethestabilityandsafetyoftheBWRsystem.Thefirstprototype
commercialBWRplantwasdesignedandbuilt,asadual-cycle(i.e.,ithadasteam
generatorforthesteamthatwenttotheturbine)plant,alreadyin1960byGE.
In the United States, the first truly commercial NPP was the Yankee-Rowe
plant, a PWR, which was also built in 1960. This plant was conceived as
acommercialventureand wasspecificallycommissionedbyautilitycompany
thatsuppliedelectricity tothe public. The Yankee-Roweplant was constructed
withaleak-tightcontainment,anditwasapprovedforcommercialoperationby
theregulatoryauthoritiesintheUnitedStatesAtomicEnergyCommission(AEC).
Theplantdesignersatthattimedidnotrealizethattheirdecisiontoemployaleak-
tight,pressure-bearingcontainmentwastheirmostimportantsafetydecision.
Thecivilianuseofnuclearenergywasverypopularwiththepublicduring
1960s. Claims were being made that nuclear energy could provide unlimited
andcheapelectricpower:toocheaptometer.Projectionswerebeingmadeof
constructinghundreds(orevenathousand)powerreactorsintheUnitedStates
alone.Someproposalsinvolvedthelocationofplantsveryclosetothecitiesto
providegenerationsourcesnearlargeconsumptioncenters,inordertobecome
moreeconomicinthetotalcostoftheelectricitytotheconsumers.The1970s
saw a large number of orders placed by U.S. utility companies with U.S.
vendors. The most prominent of these companies were: Westinghouse for the
PWRplants,sinceitwasthevendorforthenavalPWRs;GeneralElectricfor
the BWRs, since they were the developers of this reactor type; and Babcock