Switzerland has five nuclear power plants: Beznau I & II, Mühleberg, Gösgen and Leibstadt. In addition to the nuclear power plants, three research reactors are in operation: at the Paul Scherrer Institute in Würenlingen, the Swiss Federal Institute of Technology (ETH) in Lausanne and the University of Basel. And finally, the national central interim storage facility for radioactive waste (ZWILAG) at Würenlingen is also monitored by ENSI.
In the summer of 2012, findings are detected in the basic material of the reactor pressure vessel of the Belgian nuclear power plant Doel-3. As a result, nuclear power plants in Switzerland also have to carry out inspections. Since findings are also detected in the reactor pressure vessel of Beznau 1, Axpo needs to prove it was safe. The Swiss Federal Nuclear Safety Inspectorate ENSI accepts this proof in 2018.
A few days ago, Leibstadt Nuclear Power Plant (KKL) informed the Swiss Federal Nuclear Safety Inspectorate (ENSI) that some fuel elements do not fulfil the requirements of the applicable specifications. Accordingly, KKL decided to replace them for safety reasons. The safety of man and the environment was ensured at all times.
The steam generators at Beznau and Gösgen do not deviate from the design requirements in terms of their carbon content. This is the result of a review of the manufacturing documents. The structural integrity of the steam generators’ individual components is ensured by a large margin.
ENSI has issued Leibstadt NPP approval to restart subject to conditions. In an interview Ralph Schulz, Director of the Safety Analyses Division, shares some background insights.
Leibstadt NPP can restart power operation after an extended annual overhaul. The Swiss Federal Nuclear Safety Inspectorate has checked the clarification of the causes and measures derived from it for the avoidance of critical boiling conditions or dryouts. Safe operation without risk to humankind or the environment is ensured.
Georg Schwarz, ENSI Deputy Director and head of the NPPs Division, explains the background and context in the following interview.
An inspection of fuel elements in Leibstadt NPP revealed that critical boiling states – so-called dryouts – had systematically occurred over several cycles.
The Swiss Federal Nuclear Safety Inspectorate (ENSI) requires that the Beznau and Gösgen nuclear power plants check the quality and design of the forgings of the steam generators in respect of adherence to the material specifications.
On Monday, Axpo submitted the documents for characterisation and assessment of the findings in the base material of the Beznau 1 reactor pressure vessel. The Swiss Federal Nuclear Safety Inspectorate (ENSI) will review these and decide whether Beznau 1 nuclear power plant will receive permission to restart.
