Implementation of the EU stress test in European nuclear power plants

Transcription

1 Implementation of the EU stress test in European nuclear power plants Dr. Cord-Henrich Lefhalm Nuclear Regulation and Licensing RWE Power AG Essen, Germany RWE Power PAGE 1

2 The Fukushima nuclear accident in March 2011 RWE Power PAGE 2

3 Great East Japan Earthquake on March 11 th 2011 Magnitude 8.9 Among 10 strongest earthquakes ever 11 of 14 reactors were automatically shut down into a safe mode, 3 reactors have been in annual outage Onagawa (76 km from epicentre) Fukushima I (Daiichi) (154 km) 3 BWR / 2,090 MWe 6 BWR / 4,546 MWe Tokyo Tokai (258 km) Fukushima II (Daini) (163 km) 4 BWR / 4,268 MWe 1 BWR / 1,060 MWe BWR = Boiling water reactor RWE Power PAGE 3

4 Loss of safety functions as a consequence of tsunami > Earthquake followed by tsunami flooding caused the complete loss of safety functions: electrical power supply and heat sink. > Due to insufficient cooling fuel assembly damage resulted in hydrogen production and consecutive explosions. > Radioactive release by unfiltered venting and damage of the containments. RWE Power PAGE 4

5 What did the EU stress test check? > The stress tests were defined as a targeted reassessment of the safety margins of NPPs in the light of the lessons drawn from the events in Fukushima related to extreme natural events challenging the plants safety functions: Basic design requirements and existing protection. Postulates of beyond-design hazards together with additional non-availability of existing safety systems and measures. Identification of potential cliff-edge effects. Analysis of grace periods for emergency measures. Potential measures for improvements. Robustness of NPPs in the case of extreme external events. RWE Power PAGE 5

6 Technical scope: initiating external hazards 1. Earthquake 2. Flooding 3. Extreme weather conditions Specifications by 6. Severe accident management 5. Loss of heat sink 4. Loss of power RWE Power PAGE 6

7 Technical scope: coping with the loss of safety functions 1. Earthquake 2. Flooding 3. Extreme weather conditions Specifications by 6. Severe accident management 5. Loss of heat sink 4. Loss of power RWE Power PAGE 7

8 Loss of offsite power due to earthquake induced damage of switchyard 1. Earthquake Picture source: TEPCO April 2011 RWE Power PAGE 8

9 Flooding of the emergency diesel building Flooding 3 4 Picture source: TEPCO April 2011 RWE Power PAGE 9

10 Recovery of power supply 6. Severe accident management Picture source: TEPCO April 2011 RWE Power PAGE 10

11 EU stress test Implementation of the EU stress test Mar 11 Apr 11 May 11 Jun 11 Jul 11 Aug 11 Sep 11 Oct 11 Nov 11 Dec 11 Jan 12 Apr 12 Jun Resolution of EU Council 1.6. Start of Proposal by review by licensees WENRA 1 Proposal by Commission and ENSREG Licensee progress report National progress report Licensee final report Progress report to EU-Council Peer reviews National final report June 2012 Final report to EU Council (deferred) > All fourteen EU Member States that operate nuclear power plants plus Lithuania participated in the assessments on a voluntary basis (145 units in total). > Switzerland and Ukraine participated fully in the stress tests, too. > The safety assessments were organised in three phases: 1. Self assessments by nuclear operators. 2. Review of the self assessments by national regulators and preparation of national reports. 3. Peer reviews of the national reports including site visits. > Guiding principles are openness and transparency 1 Western European Nuclear Regulators' Association 2 European Nuclear Safety Regulators Group RWE Power PAGE 11

12 Endorsement of results in final reports on 26 April 2012 Peer-Review result reports 80 reviewers from 24 nations involved Review of national regulator reports including site visits One general result report with main findings on topic level 17 country reports with detailed result from each national review Four main areas for improvements on EU-Level Issuing guidance on assessment of natural hazards and margins taking existing IAEA guidelines into account. Underlining the importance of Periodic Safety Review. Implementing measures to protect containment integrity. Minimizing accidents resulting from natural hazards and limiting their consequences. RWE Power PAGE 12

13 Actions are kicked off in all countries based on the individual results of the EU stress test > Improvement of robustness against natural events Detailed margin assessment for earthquake and flooding to improve qualification of systems Additional flood protection and improvement of site access where applicable > Improvement of electrical power supply capability Improvement of DC power supply (battery) for vital functions in case of station black-out Additional mobile or fixed emergency diesel generators protected against external events > Increasing reliability of cooling means Alternative cooling routes and water sources Additional means for spent fuel pool cooling > Improvement of severe accident management measures Filtered venting and passive hydrogen recombiners to protect containment integrity Improvement of emergency response and installation of control centres RWE Power PAGE 13

14 Publication of the EU commissions communication to the EU council on 4 October 2012 > Nuclear stress tests: confirmation of high safety standards but need for further improvement The standards of safety of nuclear power plants in Europe are generally high but further improvements in the safety features of almost all European nuclear power plants are recommended. > Interpretation of EU stress test results EU commission created their own report with a summary of the individual national results without involvement of ENSREG. By selecting 10 areas for improvement and 5 areas of good practise they gave no consideration to the very individual characteristics of sites and plant design as well as the national regulatory environments. In a matrix checkmarks were applied for every single plant in the areas for improvement and good practise, which led to misinterpretation and mistakes. RWE Power PAGE 14

15 Results in the media > Counting checkmarks led to the assumption that all reactors have deficiencies. > Overemphasizing of negative aspects ignoring the context and good practise. > Public confidence in EU stress test process was undermined! RWE Power PAGE 15

16 Reactions of national authorities GERMANY(PR October 1, 2012) Ministerium: Keine schweren Sicherheitslücken bei deutschen AKWs UNITED KINGDOM (PR October 4, 2012) Dr. Mike Weightman, UK chief nuclear inspector, Office for Nuclear Regulation The European Commission s communication does not reflect the evidence-based findings of the stress tests process, the conclusions of the European Nuclear Safety Regulators Group or those of other independent, expert national nuclear regulators. SWEDEN (PR October 4, 2012) EU report: no justifications for shutting down nuclear power plants FRANCE (PR October 5, 2012) ASN has reservations about the communication of the European Commission RWE Power PAGE 16

17 Conclusions In the wake of the Fukushima accident, the EU stress test was for the first time a comprehensive targeted safety assessment of all European nuclear power plants based on a common specification. The joint effort of operators, regulators and international experts created a unique knowledge base on individual plant behavior in extreme situations initiated by external events. In an open and transparent way the peer-review process ensured a high quality of the results and avoided biased conclusions or interpretations. Potential improvements beyond the reassured level of existing safety were identified to further strengthen the robustness against external hazards. Embedded in the ENSREG follow-up action plan the implementation of the results on national levels will be monitored and reviewed. Authorities and operators are committed to utilize all findings of the EU stress test to further improve nuclear safety in Europe. RWE Power PAGE 17

18 Thank you! Dr. Cord-Henrich Lefhalm Head of Regulation/Licensing Nuclear Power Plant Division RWE Power AG Huyssenallee Essen, Germany T E cord-henrich.lefhalm@rwe.com RWE Power PAGE 18