Publication Laka-library:
Critical Review of the EU Stress Test performed on Nuclear Power Plants

AuthorGreenpeace, A.Wenisch, O.Becker
6-01-3-10-85.pdf
DateMay 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.