CONTINUOUSLY IMPROVING SAFETY
OF NUCLEAR INSTALLATIONS :AN APPROACH TO BE REINFORCED
AFTER FUKUSHIMA ACCIDENT

Michel SCHWARZ
Scientific Director

Contents▌ Nuclear Safety approach in France• Institutional framework• Role of IRSN in licensing process▌ Major safety improvements in French NPPs
▌ Impact of Fukushima▌ International cooperation between TSO▌ Conclusions

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 Nuclear safety approach in France

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Institutional framework (1/2)▌ Long maturation of the French organization in nuclear safety
and radiation protection▌ Nuclear transparency and security (TSN) act of 16 June 2006 :establishing the nuclear safety authority (ASN), and the rights andresponsibilities of operators and stakeholders.

▌ TSN act imposes Periodic Safety Review (PSR) of all nuclear
installations, every ten years or less :▌ Review compliance with safety reference of installation▌ Update safety reference according to operating experience
feedback and progress in knowledge

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Institutional framework (2/2)
Responsible for security and safety
Operator
EDF, AREVA, CEA
Technical and scientificassessment

Defining and enforcing
regulation
Nuclear Safety
Authorities

TSO

ASN, DSND

IRSNSocietal vigilance
Public
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Role of IRSN in licensing process (1/2)▌IRSN: a public body with industrial and commercial activities, under
the joint supervision of the Ministers of Ecology, of Industry, ofResearch, of Defense and of Health▌Its main missions: research and risk assessment, in particular forASN, in nuclear safety and radiation protection▌1700 employees, including more than 1000 specialists:
researchers, engineers, biologists and Ph.D. students, post-docs▌A budget of €300 million with 45% committed to research▌Operating experimental facilities and having access to research
reactors (CABRI, PHEBUS, recriticality facilities…)

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Role of IRSN in licensing process (2/2)▌ Regulatory framework not as prescribed as in other countries,
mainly for historical reasons▌ Thus, safety analysis performed by IRSN not just based oncompliance to regulations :▌ IRSN analysis progressively focused on highly safety relevant
points of safety demonstration provided by operators▌ Following defence-in-depth approach▌ Counter-calculations performed by IRSN when judged necessary
using often its own computer codes (ASTEC…)▌ Importance of:▌ Quality of contradictory dialog with operators▌ Competence of IRSN experts based on analysis of operating
experience, research, safety studies (e.g. PSA) to identify any
possible weakness▌ Technical review of IRSN analysis by independent experts groups
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 MAJOR SAFETY IMPROVEMENTS IN FRENCH NPPSGLOBAL 2011 – Makuhari, Japan – Dec. 11-15, 2011

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AFTER TMI2 (1/2)▌ Procedures “H” to manage beyond design situations for “plausible”
durations, for instance :▌ H1 to cope with LOHS
▌ H3 to cope with SBO▌ Deployment of H3 boosted by “le Buget 4” SBO in 1984 :▌ Adding turbo-alternator using steam produced by SG▌ Adding a 3rd electro-generator (diesel/gas turbine) per site▌ H1 used at “Cruas 4” in 2009 during LOHS for 10 hours
Such LOHS
probability
rated 10-5,
occured after
1500 operating
reactor year!

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AFTER TMI2 (2/2)▌ Procedures “H” completed by SAM procedures (named “U” for“ultimate”), for instance :▌ U5 to cope with spray failure in containment, calling for containment
venting 24 hours after core melt onset▌ Plant modifications :▌ Higher reliability of valves used to depressurize primary circuit▌ Containment venting
line with metallic andsand filters (Cs filter
performance: 99.9%)▌ H2 passive recombiners

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RECENT SAFETY IMPROVEMENTS▌ After Le Blayais flooding (1999):▌ Revisiting flooding risk assessment▌ Rising dam around NPPs
▌ Cofferdam in rooms with equipments
important for safety▌ Revising guides to assess floodinghazards▌ Planned 900 MWe Plant modifications(after PSR 3):▌ H2 concentration measurements▌ Vessel melt-through detector▌ Reinforcement of lock bolts

GLOBAL 2011 – Makuhari, Japan – Dec. 11-15, 201111/22SAFETY IMPROVEMENTS FOR GENERATION III PLANTS▌ General safety objectives approved by German and French Safety
Authorities in 1993
▌ Calling for significant plant improvements in order to achievesignificant reduction of :▌ global core damage frequency (<10-5) for all type of failures andhazards and with uncertainties▌ radioactive release even in case or core melt-down (no emergency
evacuation, limited sheltering nearby plant, no long term
consumption restrictions)▌ IRSN contributed toimplement technicalguidelines▌ Used as reference forFlamanville 3 EPR
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SAFETY IMPROVEMENTS CONSIDERED FOR LTO▌ EDF information to ASN in 2009: intent to seek licence for extending
plant lifetime significantly beyond 40▌ Generation II and generation III plants on French territory fordecades▌ Thus strong societal request (already before Fukushima) to raisesafety reference for generation II plants level with LTO as close as
possible to generation III▌ IRSN R&D programs orientated towards this objective

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 IMPACT OF FUKUSHIMAGLOBAL 2011 – Makuhari, Japan – Dec. 11-15, 2011

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AFTER FUKUSHIMA (1/3)▌ French Prime Minister requested ASN to perform complementary
safety reviews (CSR) of NPPs on March 23rd
▌ European Council called for stress tests (ST) of NPPs on March 26th
▌ French CSR based on WENRA specifications (as ST) issued April 21stand extended to fuel cycle plants, test reactors…
▌ Main objective is to assess :▌ Installation robustness in case of external hazards (earthquake,flooding, earthquake and induced flooding, industrial risks…)▌ Installation robustness in case of SBO, LOHS, both
▌ SAM robustnessand▌ By using progressive approach (in intensity, duration,accumulation, one to multi-units concerned on a site) to identify
possible cliff edge effects (core damage, recriticality…)▌ Highlighting possible improvements
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AFTER FUKUSHIMA (2/3)▌ CSR reports for 80 installations sent by operators (EDF, AREVA, CEA,ILL) on September 15th
▌ CSR analysis by IRSN (500 p. report) reviewed by experts groups onNovember 8 - 10
▌ Main conclusions:▌ Huge efforts in short time for operators and IRSN
▌ Continuous safety improvement process has contributed to makeplant safer than originally▌ Some local no-compliance identified to be promptly corrected▌ At some locations,external hazards evaluation needs to be revisited▌ Significant safety improvements still required to cope with extreme
beyond design situations

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AFTER FUKUSHIMA (3/3)▌ Proposal to design a “hard core” of robust, well protected and secured
SSCs crucial to controlling plants safety during extreme hazards inorder to▌ Prevent core damage▌ Limit as much as possible radioactive release▌ 2012 devoted to identify this “hard core”▌ “Hard core” easier to design for EPR▌ Note that learning from Fukushima will take years!

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 INTERNATIONAL COOPERATION BETWEEN TSOGLOBAL 2011 – Makuhari, Japan – Dec. 11-15, 2011

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INTERNATIONAL COOPERATION BETWEEN TSO▌ Networking TSOs, already recognized at the time of “nuclearrenaissance” even more strongly needed after Fukushima to :▌ share lessons learned▌ harmonize safety analysis tool
▌ share R&D load and results▌ train new generation of experts▌ European initiative :▌ ETSON▌ Bel V (Belgium), GRS (Germany), IRSN (France), LEI (Lithuania), UJV(Czech Republic), VTT (Finland), VUJE (Slovakia)▌ Associated members in 2011 : JNES (Japan), SSTC (Ukraine)▌ IAEA initiatives :▌ TSO conference in Aix-en-Provence (2007) and Tokyo (2010)▌ Creation of “TSO forum” under consideration

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 CONCLUSIONSGLOBAL 2011 – Makuhari, Japan – Dec. 11-15, 201120/22

▌ Continuously safety improvement approach in France, in particular atthe occasion of the PSR, has contributed to make NPPs safer▌ Approach to be reinforced in France after Fukushima considering
extreme hazards▌ Importance of the scientific and technical assessment by a public bodyof highly competent experts as enhancing nuclear safety is based onprogress in science and technology▌ TSO networking to share experience, perform cooperative researchharmonize practices and train new generations of experts even morestrongly necessary after Fukushima

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Thank you for yourattention

www.irsn.fr

Enhancing nuclear safety
GLOBAL 2011 – Makuhari, Japan – Dec. 11-15 2011