GENERATION IV NUCLEAR REACTORSPreliminary safety considerations on SFR GEN-IV PrototypeG.B. Bruna IRSN/DSRVHTRTRISOSFR
IntroductionGIF FrameworkObjectives for the GEN-IV Systems Insight on the French strategyExpectations for the safety demonstrationOverview of the main features of the GEN-IV reactor concepts focusing on :A short descriptionAdvantages & DrawbacksFocus on the SFR concept and its safety features
Reference : document on the web site of the IRSN :
GENERATION-FOUR (GEN-IV) REACTORS / SUMMARY REPORT / MARCH 2007
[www.irsn.org/en/document] Others public references:www.gedeon.prd.fr / GEDEPEON May 2007www.physor2004.anl.gov/PlenarySessions.htm / PHYSOR, Chicago, 2004
Parameters to account for Energy marketFinancial riskEnvironmentprotection Public acceptanceThe designer?GIF FrameworkObjectives and Context for the GEN-IV SystemsHazards
Objectives and Context for the GEN-IV SystemsDesign and operating feedbackSafety issues derived from licensing processNew safety objectives, new standardsSpecific issues for GEN-IV new systems (technological orientations, challenges, etc.)Should they exist !
It is difficult to go beyond the main safety principlesRequirements: what it is wished and what it is possible: thats the question !
Participants in the G.I.F.Russian ConfederationPeoples Republic of China
Objectives for the GEN-IV Systems
Economic competitivenessCompetitiveness of the nuclear KWh cost, vs fossil energiesSustainabilityIncreased reactor lifetime (over 60 years)Optimization of fissile material inventoryDecrease of the waste volume and storage costsSafetyVery low probability of severe damage of the coreNo need for off-site emergency plan for severe accidentsResistance to proliferation and to acts of malicious damageFuel cycle minimizing the production of weapon-grade materialsEfficient protection against internal and external hazards
ENHANCED SAFETYObjectives for the GEN-IV Systems
Reduction of fault rate of normal operation equipments,Increased protection against external attacks and hazards (plane crash, malevolence, etc.),Very low probability of major core damage:Design featuresPassive protection system, No need for off-site emergency plan for severe accidentsAccording to a defense in depth design approach including severe accidents in the design basis.
Optimization of the uranium resources and the fissile material inventory (closed fuel cycle),Decrease of the waste volume and storage costs, Waste management taken into account in the design,Multi-functionality (hydrogen, electricity, industrial heat).Objectives for the GEN-IV Systems
Generation IV Systems HTR/VHTR
Insight on the French Strategy January 2006, impulse of President J. Chirac for the operation of a GEN-IV reactor prototype by 2020
June 2006, adoption of a new Law on the management of radioactive materials and waste, with two milestones:
2012: definition of an industrial scenario for GEN-IV and ADS system
2020: operation of a GEN-IV prototype
Insight on the French Strategy December 2006, decisions of the French Council of Ministers, and of the Atomic Energy Committee including different representatives of the French Government (Research, Industry, Environment, etc.):
involvement of France in the design of GEN-IV systems, in the aim of an industrial deployment in the 40 priority to the fast reactor systems allowing a closed fuel cycle support to the industry for advanced VHTR system design
Insight on the French StrategyCurrent Systems Evolutionary Advanced and Revolutionary
About Licensing in France Planning proposed by CEA for the GEN-IV prototype:
SFR : 2010 : principles of innovative safety options 2012 : proposal of a set of options for the prototype
GFR : 2009 : evaluation of safety options 2012 : safety report
A part of the IRSNs assignment is to serve as the TSO
for the French Nuclear Safety Authority
Licensing proceduresDISMANTLINGFINAL SHUTDOWNFINAL OPERATIONOPERATINGCONSTRUCTIONDESIGNFSARPSARPrSARSORFSARGOREPGSSREPSOR: Safety Option ReportPSAR: Preliminary Safety Analysis ReportGOR: General Operating RulesPrSAR: Provisional Safety Analysis ReportEP: Emergency PlanFSAR: Final Safety Analysis ReportGORAuthorisation DECREEEP
General expectations for the safety demonstration of GEN-IV systems Enhanced safety compared to GEN-III and GEN-III+ (EPR, AP1000, etc.) At least equivalent criteria (probabilistic approach for severe core damage) and confidence level in the safety demonstration
From the IRSN point of view, the current safety approach must be adopted: defense in depth principle,deterministic approach, supported by extended PSA insight (including safety margins assessment) For systems which have been already built and operated (such as HTR, SFR, LFR, etc) design and operating experience, must be accounted for by the designers to increase the safety.
Safety margins Approach Definition of the Risk Space and its sensitivity to NPP design changesGeneral expectations for the safety demonstration of GEN-IV systems
General expectations for the safety demonstration of GEN-IV systems
The demonstration of the exclusion of events consequences of which are not accounted for in the design (practically eliminated): big graphite fire in VHTR, big sodium fire in SFR ? complete break of pipes in VHTR, SFR, GFR ? melting of the core for TRISO type fuel, for SFR, GFR ?
Which kind of demonstration (lines of defence, PSA, ) and which confidence level ?
General expectations for the safety demonstration of GEN-IV systems : main challenges The definition of the most severe accident retained in the BDBA scope, with dedicated safety systems, the prevention, the mitigation of the consequences, mainly concerning the containment/confinement Co-generation: the safety approach retained for coupled VHTR and industrial installations for production of industrial heat, hydrogen, etc. What are the events generated by industrial facilities which must be taken into account as operating conditions or external hazards in the safety assessment ?Does it exist a safety assessment for such facilities? Is their safety assessment consistent with the assessment for nuclear reactors ?
General expectations for the safety demonstration of GEN-IV systems Ambitious targets for the radioprotection and the radiological consequences for the public and workers in operation (DBA, BDBA) and in presence of hazards, A clear identification of the containment/confinement barriers and safety systems, their functional requirements vs. operating, incidental and accidental conditions and hazards
General expectations for the safety demonstration of GEN-IV systems : main challenges The core characteristics, mainly those involved in the safety studies (neutronics, feedback coefficients, etc.)
The study of the most severe reactivity accidents (if not included in the BDBA): prevention, detection and consequences The extensive use of PSA, with topics which need improvements (data bases for equipment, reliability for passive systems, probability evaluation for rare hazards, etc.)
Main features of the reactor concepts
Maturity of concepts
Advantages & Drawbacks
Summary Review (1/2)Elements of comparison between GEN-IV concepts
ConceptSafety / Safe natural behaviourUranium resource usingQuantity / Waste managementSFRNo++ (if multi-recycling)GFRNo (semi-passive for some accidents)++ (if multi-recycling)HTR/VHTRYes- or =- (graphite, production of plutonium and M.A.)SCWRNo??LFRYes (for medium powers)++ (if multi-recycling)MSRYes (severe accidents to explore)Using of Th, more abundant than U++ (but risks dues to the salts traitment)
Summary Review 2/2
No system is able satisfying all the GIF criteriaThe six concepts do not enjoy the same maturity level : the SFR and the HTR enjoy the most advanced technologiesThe VHTR does not permit a closed fuel cycle (as far as current designs and technology are concerned), it needs enriched uranium fueling, but shows some major advantages: a resistant barrier around the fuel, a safety founded on a natural behavior of the reactor, a capacity to be coupled to industrial processes (heat, H2, etc.)The SFR allows a closed fuel cycle and enjoys: a proved technology, a widespread operating experience, nevertheless it needs some major improvements (neutronics, risks dues to the sodium, ISI, etc.)
Westinghouse concept (INEL)
Power: thermal / electric3575 MW / 1600 MW Temperature of the water: inlet / outlet of the core 280C / 500C FuelU; enrichment: 5% Pressure of the water250 bar BU 45 GWj/t
Westinghouse concept (INEL)ADVANTAGES:Direct conversion cycle: the vapor which enters the turbine is produced into the core (no benefit for the safety)Fast neutrons (breeder reactor) or thermal neutrons concept
INCONVENIENTS and/or INUMBENT DIFFICULTIES:The heat exchange between the fuel and the water is not uniform Great uncertainties on the fuel cooling (especially for the super-critical water)Difficulties with the core design and layout: need for multi-enrichment zonesAt the stage of feasibility studi