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GENERATION IV NUCLEAR REACTORS

G.B. Bruna IRSN/DSR. GENERATION IV NUCLEAR REACTORS. Preliminary safety considerations on SFR GEN-IV Prototype. TRISO. SFR. VHTR. SUMMARY Introduction GIF Framework Objectives for the GEN-IV Systems Insight on the French strategy Expectations for the safety demonstration

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GENERATION IV NUCLEAR REACTORS

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  1. G.B. Bruna IRSN/DSR GENERATION IV NUCLEAR REACTORS Preliminary safety considerations on SFR GEN-IV Prototype TRISO SFR VHTR

  2. SUMMARY • Introduction • GIF Framework • Objectives for the GEN-IV Systems • Insight on the French strategy • Expectations for the safety demonstration • Overview of the main features of the GEN-IV reactor concepts focusing on : • A short description • Advantages & Drawbacks • Focus on the SFR concept and its safety features

  3. 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 2007 • www.physor2004.anl.gov/PlenarySessions.htm / PHYSOR, Chicago, 2004

  4. GIF Framework Objectives and Context for the GEN-IV Systems Energy market Financial risk Parameters to account for … Hazards ? Public acceptance Environment protection The designer

  5. Objectives and Context for the GEN-IV Systems Should they exist ! Design and operating feedback Safety issues derived from licensing process It is difficult to go beyond the main safety principles Requirements: «  what it is wished and what it ispossible: that’s the question » ! Specific issues for GEN-IV new systems (technological orientations, challenges, etc.) New safety objectives, new standards…

  6. Participants in the G.I.F. Russian Confederation People’s Republic of China

  7. Objectives for the GEN-IV Systems

  8. Objectives 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 features • Passive protection system, No need for off-site emergency plan for severe accidents • According to a defense in depth design approach including severe accidents in the design basis. ENHANCED SAFETY

  9. Objectives for the GEN-IV Systems • 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). SUSTAINABILITY

  10. Generation IV Systems • HTR/VHTR • SFR • GFR • LFR • MSR • SCWR SFR GFR LFR MSR HTR/VHTR SCWR

  11. 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 Very challenging context !

  12. 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 Very challenging context !

  13. Insight on the French Strategy Current Systems Evolutionary Advanced and Revolutionary

  14. 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 »

  15. Safety Authorities • Generalists: • power reactors • fuel cycle facilities • experimental reactors • waste Request forms 2 Applications 1 4 • Specialists: • mechanical engineering • hydraulics, thermal eng. • reactor control • I&C • severe accidents • human factors • neutronics • seismic studies, etc. Technical assessments Authorizations 5 3 Technical relations Operator • Integrating knowledge, summaries • Research and development requirements A part of the IRSN’s assignment is to serve as the TSO for the French Nuclear Safety Authority

  16. OPERATING LICENCES DISMANTLING DECREE Licensing procedures FINAL OPERATION DESIGN CONSTRUCTION OPERATING DISMANTLING FINAL SHUTDOWN SOR PSAR PrSAR FSAR FSAR GOR GOR GSSR EP EP EP Authorisation DECREE SOR: Safety Option Report PSAR: Preliminary Safety Analysis Report GOR: General Operating Rules PrSAR: Provisional Safety Analysis Report EP: Emergency Plan FSAR: Final Safety Analysis Report

  17. 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.

  18. A’ Risk B’ Loss of Safety margins C B A General expectations for the safety demonstration of GEN-IV systems « Safety margins » Approach Definition of the “Risk Space” and its sensitivity to NPP design changes

  19. 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 ? What is not taken into account ?

  20. 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 ?

  21. 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

  22. General expectations for the safety demonstration of GEN-IV systems : main challenges • The core characteristics, mainly those involved in thesafety studies (neutronics, feedback coefficients, etc.) • The study of the most severe reactivity accidents (if not included in the BDBA): prevention, detection andconsequences • The extensive use of PSA, with topics which need improvements (data bases for equipment, reliability for passive systems, probability evaluation for rare hazards, etc.)

  23. PART II • Main features of the reactor concepts • Maturity of concepts • Advantages & Drawbacks

  24. Elements of comparison between GEN-IV concepts Summary Review (1/2)

  25. Summary Review 2/2 • No system is able satisfying all the GIF criteria • The six concepts do not enjoy the same maturity level : the SFR and the HTR enjoy the most advanced technologies • The 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 SFRallows a closed fuel cycle andenjoys: • a proved technology, • a widespread operating experience, nevertheless it needs some major improvements (neutronics, risks dues to the sodium, ISI, etc.)

  26. SCWR

  27. Westinghouse concept (INEL)

  28. 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 zones • At the stage of feasibility studies / Non nuclear design and operating feedbacks

  29. MSR

  30. Molten Salt Reactor

  31. Molten Salt Reactor • ADVANTAGES: • No risk of core melting ! • Possible on-line extraction of the PFs  low consequences in the case of salts leakages • Thorium fuel: abundant « fertile » material • Less waste produced by MWe

  32. Molten Salt Reactor INCONVENIENTS and/ or INCUMBENT DIFFICULTIES: Salts are corrosive ( non-metallic materials) and the solubility of the PFs is various in the salts Melting temperature of the salts > 500°C Irradiation of the primary circuit structures Neutronics: complexity (fissions in all the primary circuit !) This concept has not passed the experimental stage

  33. LFR

  34. Lead Fast Reactor

  35. ADVANTAGES: • The reactor can be operated with natural or depleteduranium • Lead boiling is almost impossible (T>2000°C) • No strong pressurization • Passive behavior in case of accidental transients  reactor control without immediate acting of protective systems or operators • Good compatibility with water (secondary coolant), and no fire risk with air

  36. INCONVENIENTS and/or INCUMBENT DIFFICULTIES: • Molten lead is very corrosive (pumps, clad, vessels, etc.) • Difficulty to wash and decontaminate the equipment immerged in the lead  maintenance ? • Significant hydrodynamic pressures (BREST: ~ 1,6 bar) • ISI: not possible for internal structures (BREST) • Difficulties for an core unloading, in case of emergency ? • Activation of lead and bismuth: production of long life  waste • Not satisfying operating feedback (submarines) • Maturity: not advanced

  37. HTR/VHTR

  38. High or Very High Temperature Reactor

  39. HTRs : Design and Operating Experience

  40. US Experience Peach Bottom 1 – 1966 -1973 U/Th (high enrichment) 40 MWe Helium : 350°C / 750°C

  41. US Experience Fort Saint-Vrain – 1976-1989 842 MWth et 330 MWth Spherical coated particles and put into hexagonal graphite blocks Helium : 350°C / 750°C

  42. AVR German Experience AVR (KFA – Jülich) / 1966 -1987 P = 46 MWth / 15 MWe Tmax helium : 850°C (up to 950°C in 1974)

  43. HTRs : Design and Operating Experience New low power experimental reactors HTR-10 China / 10 MWth / pebbles Tsinghua University HTTR Japan / 30 MWth / prismatic blocks Oarai

  44. Technical Orientations for New Power Reactors Plants Technical and Technological Challenges • EUROPE: ANTARES (VHTR- 600 MWth), + R&D project RAPHAEL • SOUTH AFRICA: PBMR (400 MWth  pebbles) • RUSSIAN FEDERATION: GT- MHR (600 MWth  prismatic blocks of compacts) • JAPAN: GTHTR-300 (600 MWth  prismatic blocks of compacts) • CHINA (Chinergy): HTR-PM (195 MWe)

  45. The VHTR The VHTR is seen as more efficient than reactors in operation in several aspects: • A higher thermodynamic efficiency and a wider scope of applications, because of the very high temperature gas supply, • A different commercial approach, to serve the market segment of medium-scale electricity production, as opposed to the traditional nuclear plants for large-scale production of electricity. • A minimized environmental impact owing to the robustness of the fuel that retains fission products under both normal and accidental conditions, • A better resource utilisation and a contribution to waste minimization owing to • Its thermal efficiency, • Its quite high burn-up, • Its large capacity to transmute Actinides [both Plutonium and Minor Actinides].

  46. “ The VHTR Core: A Very Heterogeneous System” Core design

  47. Core heterogeneities (1)[www.physor2004.anl.gov]

  48. Core heterogeneities (2) [www.physor2004.anl.gov]

  49. Control rod penetrations Reactor vessel ANTARES( free references : [www.areva-np.com] and [www.iaea.org]) [www.physor2004.anl.gov] Helium fan Primary circuit and exchangers Isolating valves Heat removal system after reactor shut down Wall of the reactor building Plates type exchanger

  50. ADVANTAGES: • Resistant first barrier up to 1600°C • Very low power density (few MW/m3) • Large inertia due to the important quantities of graphite; fuel temperature 1600°C in case of non protected loss of active systems for the heat removal • Design and operating feedbacks noticeable (Peach Bottom, AVR, THTR, Fort Saint Vrain, etc.) • Advanced maturity, but for limited reactor powers

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