outcome of the eu nuclear safety stress tests andrej stritar chairman, ensreg
TRANSCRIPT
European Scene
• In European Union …• … there are almost 150
power reactors…• …in 15 EU member
countries,• producing ~1/3 of all
electricity in EU
We must keep them operating safe!
Before 2000
Country 1
Operator
RulesRegulator
Country 2
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RulesRegulator
Country 3
Operator
RulesRegulator …
E. CommissionDGTREN
• Nuclear Safety was only national responsibility
WENRA, a voluntary club
• “Bottom up” approach to harmonisation
E. CommissionDGTREN
WENRA – nuclear regulators
Regulator
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Country 1
Operator
RulesRegulator
Country 2
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RulesRegulator
Country 3
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ENSREG – after 2007
• “Top down” advisory body
ENSREG – 27 EU regulators + EC
Country 1
Operator
RulesRegulator
Country 2
Operator
RulesRegulator
Country 3
Operator
RulesRegulator …
E. CommissionDGTREN
E. CommissionDGTREN
Regulator
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What is now better?
ENSREG – 27 EU regulators + EC
Country 1
Operator
RulesRegulator
Country 2
Operator
RulesRegulator
Country 3
Operator
RulesRegulator …
E. CommissionDGTREN
WENRA – nuclear regulators
WENRA Reference Levels
Nuclear Safety Directive, RW Directive,Stress Tests
• The feedback loop for assuring perfection has failed!
• Trust of the society was lost!
Regulators
Operators
MediaDOUBT
CONFIDENCEPERFECTION
•G
Public
ELECTRICITY
TRUST
DOUBT
Stress Tests were about restoring confidence and regaining trust by further improving nuclear safety
Why Fukushima has happened?
• Tsunami is a very rare natural disaster.• It was underestimated during the design,
there was not enough knowledge about it.• Safety margins were too small.• Uncertainty of our understanding of
natural phenomena should have been compensated by bigger conservatism – higher protective dikes!
Fukushima concerns
The main lessons learned from Fukushima were actually the main objectives of our
Stress Tests:
• Did we properly take into account uncertainties of all potential external hazards?
• Are our plants robust enough, are safety margins big enough?
• Are we able to cope even with extremely low probability events?
Stress Tests
• 11 March: Fukushima accident occurs• 24 – 25 March: European Council Requests
– Stress tests to be developed by European Nuclear Safety Regulators Group (ENSREG), the Commission and WENRA
– Safety of all EU plants should be reviewed
– Scope of review developed in light of lessons learned from Japan
– Assessments conducted by national Authorities
– Assessments completed by a peer review
Development of Stress Test Methodology
• Methodology drafted by WENRA in April• Agreed to by ENSREG in May• On 25 May 2011 ENSREG including the
European Commission published the ENSREG declaration that described EU Stress Tests methodology
Stress Test Implementation
15. 8. 2011 Operators submitted progress
reports
15. 9. 2011 National progress reports submitted
31. 10. 2011 Operators submitted final reports
8. 12. 2011 EU Council informed about progress
31. 12. 2011 Final National reports submitted
The process
• WENRA prepared first draft in June
• Task Force formed in July
• Involvement of stakeholders
• Number of meetings and discussions
• The Methodology endorsed by ENSREG on 12 October
The process
• The Peer Review Board• Three topical reviews in parallel, January
and February 2012– Initiating Events– Loss of Safety Functions– Severe Accident Management
• 17 country visits in 6 parallel groups,March 2012
• About 80 experts involved• ENSREG Report + 17 Country Reports
Milestones
• EU Council expected the final report in June 2012
• EC needed the report from ENSREG by end of April
• Peer Review started on 1 January• Majority of work was done in
February/March• The report was finalised in April
General conclusion over Europe
• Significant steps taken in all countries to improve safety of plants
• Varying degrees of practical implementation– Regulatory systems– Extent of programs
Consistency of approaches in European countries
• Global consistency over Europe in identification of:– Strong features– Weaknesses– Measures to increase robustness
Measures to increase robustness of plants
• Significant measures to increase robustness already decided or considered, such as:– Additional mobile equipment– Hardened fixed equipment– Improved severe accident management with
appropriate staff training
• Details available in Country Reports and Main Report
Example: New equipment in Krško NPP
Pumps
Portable fire system
Additional connection points
Portable external diesel generators
Assessment of natural hazards and margins
• Recommendation no.1:– WENRA, involving the best available
expertise from Europe, should develop guidance on natural hazards assessments, including earthquake, flooding and extreme weather conditions, as well as corresponding guidance on the assessment of margins beyond the design basis and cliff-edge effects.
Periodic safety review
• Peer review demonstrated efficiency of periodic safety reviews – Maintain and improve safety and
robustness of plants– Specially relevant, in the context of the
peer review, for protection of installations against external hazards
Periodic safety review
• Recommendation no. 2:– ENSREG should underline the
importance of periodic safety review. In particular, ENSREG should highlight the necessity to re-evaluate natural hazards and relevant plant provisions as often as appropriate, but at least every 10 years.
Containment integrity
• Fukushima disaster highlighted once again the importance of the containment function
• Last barrier to protect people and the environment against radioactive releases
• Issue already considered as follow-up of previous accidents and possible improvement already identified
Containment integrity
• Recommendation no. 3:– National regulators should consider
urgent implementation of the recognized measures to prevent containment integrity.
Containment integrity
• Measures vary depending upon the design of the plants
• For water cooled reactor, they include equipment, procedure and accident management guidelines to:– Depressurize primary circuit to prevent high
pressure core melt– Prevent hydrogen explosions– Prevent containment overpressure
Prevention of accidents resulting from natural hazards and limiting
their consequences
• Preliminary lessons learned from Fukushima: Necessary increase of defense in depth to take into account severe accidents resulting from extreme natural hazards exceeding design basis or current safety requirements applicable to plants
Prevention of accidents resulting from natural hazards and limiting
their consequences
• Such situation can result in:– Devastation and isolation of site– Event of long duration– Unavailability of numerous safety
systems– Simultaneous accidents in several
plants, including their spent fuel pools– Radioactive releases
Prevention of accidents resulting from natural hazards and limiting
their consequences
• Recommendation no. 4:– National regulators should consider
necessary implementation of measures allowing prevention of accidents and limitation of their consequences in case of extreme natural hazards
Prevention of accidents resulting from natural hazards and limiting
their consequences
• Typical measures:– Bunkered equipment including
instrumentation and communication means– Mobile equipment protected against extreme
natural hazards– Emergency response centers protected
against extreme natural hazards and radioactive releases
– Rescue teams and equipment rapidly available to support local operators
Follow-up
• Most actions are being prepared and implemented by operators and national regulators
• Special Task Force is preparing EU action plan to be endorsed by ENSREG on 3 July
What is still missing?
• The Security Track of EU Stress Tests was conducted in parallel.
• During the year the issue of off-site emergency preparedness has proven to deserve even more attention.
• Long term ENSREG action plan is being prepared.
Global Impact
• EU Stress Tests became a global model
• Directly used in some countries (Japan, UAE, South Africa, Russia)
• Important reference for all the others, including IAEA
What next?
• Stress Test campaign is over!• All lessons learned and actions to be done will
be included in our normal working processes.• Majority has to be done by operators and
national regulators.• Common technical issues will be dealt by
WENRA.• ENSREG’s special Task Force is preparing our
action plan.• Additional plant visits will be organised after
proper objectives are defined.