ENSI Report on Fukushima III: Lessons Learned


The analysis of the accidents at Fukushima confirms that Swiss nuclear plants are safe. However, the Swiss Federal Nuclear Safety Inspectorate (ENSI) has identified a variety of findings (Lessons Learned) from Fukushima which should now be utilised to continue optimising the safety of Switzerland’s nuclear power plants. All the measures that need to be implemented on the basis of these findings should be in place by 2015.

Clearance work at Fukushima two months after the accident.

Directly after the accident in Japan’s Fukushima Dai-ichi nuclear power plant on 11 March 2011, ENSI ordered immediate measures for a review of the safety of the Swiss nuclear power plants. In parallel, an interdisciplinary team of experts from ENSI (the “Japan Analysis Team”) reconstructed the events of the accident and subjected them to in-depth analysis. The results were presented to the public in two reports at the end of August 2011.

Checkpoints for greater safety

The third report on the Fukushima accident outlines how Switzerland can continue to optimise the safety of its own nuclear power plants on the basis of experience gained in Japan. Swiss nuclear power plants do not display any significant shortcomings as regards safety. Nevertheless, on the basis of knowledge gained from Fukushima, ENSI has investigated whether further optimisation of the existing assessment of precautions against severe reactor accidents is required, and whether any additional measures need to be initiated in order to protect the population.

In order to identify the potential for optimisation, ENSI developed 37 checkpoints which form the content of the report that is now available. The terms of reference for the review cover the following areas: plant design, emergency management, feedback of experience, supervision, radiation protection and safety culture. One key aspect here is the optimisation of emergency preparedness in Switzerland. Some of the checkpoints relate to higher levels; these fall mainly within the areas of responsibility of the Federal government and the cantons, but they are also relevant for ENSI. At Federal level, the Interdepartmental Working Group to Review Emergency Protection Measures in case of Extreme Events in Switzerland (IDA NOMEX) has been operational since May.

In the interests of the population

To some extent, the reviews required by ENSI have already yielded measures, and some of them have already been implemented. These measures require the operators of the Swiss nuclear power plants to make additional investments in the safety of their plants. ENSI consistently monitors the implementation of back-fitting measures. ENSI accords the topmost priority to protecting the interests of the population. Back-fitting measures are implemented within the scope of the statutory provisions which guarantee the operators’ interests in legal security and the protection of their investments.

The checkpoints presented today are based on the analysis of the events during the accident that ENSI carried out for its first two reports on Fukushima, in which the Japan Analysis Team assessed the behaviour of people, technology and organisation in response to the accident, with the inclusion of internationally available sources. The results of this analysis are appended to the new report in the form of summarised “Lessons Learned”.

Measures to be implemented by 2015

The cause and circumstances of the accident at Fukushima have not yet been finally clarified. ENSI is therefore proceeding with its analysis of the events during the accident on a continuous basis, and – where indicated – will derive additional checkpoints from this work. The completion of the inspection assignments, the development of measures and their subsequent implementation will be key points of ENSI’s supervisory activities in the future. The necessary reviews and and the measures to be derived from them will be collated in an action plan, according to their importance and urgency. The action plan will be effective from 2012 onwards and is designed to cover four years.

Further information

The other three reports