Publication Laka-library:
Critical Review of the EU Stress Test performed on Nuclear Power Plants
| Author | Greenpeace, A.Wenisch, O.Becker |
 |
6-01-3-10-85.pdf |
| Date | May 2012 |
| Classification | 6.01.3.10/85 (NUCLEAR SAFETY - REACTORS - GENERAL) |
| Front | 
|
From the publication:
Critical Review of the EU Stress Test performed on Nuclear Power Plants Study commissioned by Greenpeace Antonia Wenisch, Oda Becker Wien, Hannover, May 2012 Table of Content EXECUTIVE SUMMARY............................................... 3 Stress Test Peer Review ................................................ 6 2 THE EU STRESS TEST ................................................... 11 2.1 Content of the EU stress test ................................... 11 2.2 Shortcomings of the EU “Stress test” .............................. 14 3 COMPARING THE EU STRESS TEST WITH CURRENT SAFETY OBJECTIVES ........ 20 4 REVIEW OF 13 SELECTED NPP .................................... 24 4.1 NPP Almaraz, Spain ...................................... 24 4.2 NPP Doel, Belgium ......................................... 29 4.3 NPP Tihange, Belgium........................................... 33 4.4 NPP Gundremmingen, Germany ...................................... 40 4.5 NPP Krško, Slovenia ............................................. 46 4.6 NPP Mochovce, Slovak Republic ................................. 50 4.7 NPP Muehleberg, Switzerland ....................................... 57 4.8 NPP Ringhals, Sweden .............................................. 62 4.9 NPP Temelín, Czech Republic ....................... 68 4.10 NPP Wylfa, UK ................................................. 73 4.11 NPPs Fessenheim, Gravelines and Cattenom, France ............... 80 5 POTENTIAL IMPACTS OF SEVERE NUCLEAR ACCIDENTS IN EUROPE ........... 88 GENERAL DESCRIPTION OF REACTOR TYPES ....................... 96 Boiling Water Reactor (BWR) ........................................ 96 Pressurized Water Reactor (PWR) .................................. 96 WWER-type reactor plants ...................................... 97 REFERENCES .......................................... 99 ABBREVIATIONS .................................... 103 EXECUTIVE SUMMARY The March 2011 accident at the Fukushima I nuclear power plant proved that highly unlikely incidents cannot be excluded. Contrary to accepted practice Probabilistic Safety Assessments (PSA) do not constitute a sufficient basis to declare a plant operation safe. Safety of nuclear power plants (NPPs) needs to be backed by deterministic assessments, which excludes initiating events and accident scenarios only if they are proven to be physically impossible. Events at Fukushima compounded public mistrust towards nuclear power worldwide. In Europe, the European Commission welcomed a suggestion by the government of Austria to conduct stress tests at all nuclear power plants in the European Union. The EU nuclear safety regulators – ENSREG – took over this task. The tests were introduced to improve confidence in the safety of European NPPs. In particular, they should examine the consequences of earthquakes and floods, and the combination of events previously excluded. However, the tests would be limited in scope: safety features such as ageing or design faults would not be taken into account. The EU stress test focused on analysing of the plant’s robustness to cope with consequences of loss of power including station black-out, loss of ultimate heat sink1, and a combination of both. Safety reserves (margins) should also be assessed. The best outcome of the stress test could be an analysis of multiple faults and common mode failures at the NPP sites. “Cliff edge” effects, which could result in core melt, would be investigated and improvements proposed for water and power supply in emergency situations. The lesson from Fukushima is clear: take the unthinkable into account and develop adequate emergency measures for the protection of the population in the densely populated regions of Europe. The exclusion of unlikely accidents from the analysis is not justified without a deterministic verification. The majority of the European reactor fleet is old, and based on decades-old design. Not all operators have reassessed the site hazards in compliance with state-of-the-art methodologies. This report offers a review of selected NPPs based on National Stress Test Reports. The review details the main weakness of each reactor identified by the national regulator and the remedial measures suggested in its report. Important shortcomings not mentioned in the National Stress Test Report are listed and discussed at the end of each chapter. Those evaluations do not claim to be exhaustive, but it is hoped that the findings will contribute to a more complete understanding of nuclear power plant safety in Europe.