ENSI, the Swiss Federal Nuclear Safety Inspectorate is the national regulatory body with responsibility for the nuclear safety and security of Swiss nuclear facilities.
ENSI is the successor body to HSK from whom it took over on 1 January 2009. It has the same remit and staff as HSK but whereas HSK was part of the Swiss Federal Office of Energy, ENSI is an independent body constituted under public law – similar for example to SUVA, the Swiss National Accident Insurance Fund and the Swiss Federal Institute of Intellectual Property.
ENSI is located in Brugg in the canton of Aargau.
ENSI is responsible for the supervision of Swiss nuclear facilities, i.e. the nuclear power stations, the interim storage facility for radioactive waste, the nuclear research facilities at the Paul Scherrer Institute (PSI) in Villigen and the Ecole Polytechnique Fédérale in Lausanne. Its regulatory remit covers the entire life of a facility, i.e. from initial planning, through operation to final decommissioning including the disposal of radioactive waste. Its remit also includes the safety of staff and the public and their protection from radiation, sabotage and terrorism. ENSI is also involved in the transport of radioactive materials to and from nuclear facilities and in the continuing geoscientific investigations to identify a suitable location for the deep geological disposal of radioactive waste.
ENSI supports research into nuclear safety and is represented on more than 70 international commissions and specialist groups working in the field of nuclear safety. It makes, therefore an active contribution to new international safety guidelines. Through its network of contacts, ENSI is in touch with current developments in science and technology and discharges its regulatory remit on the basis of global experience in nuclear energy.
More information
News
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2024 Oversight Report: Nuclear power plants complied with approved operating conditions
ENSI assessed the safety condition of the nuclear power plants as good overall for 2024. All reportable events were of minor significance for nuclear safety. This is the conclusion reached by ENSI in its 2024 Oversight Report.
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Long-term strategy for IAEA safety standards adopted
The Commission on Safety Standards (CSS) of the International Atomic Energy Agency (IAEA) has unanimously adopted the “Long-term Plan”, a strategy for the long-term development of safety standards. The plan aims to keep these globally applicable standards fit for purpose and forward looking, and to maintain their effectiveness in a rapidly evolving environment. A concrete…
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Federal Council approves ENSI Board’s 2024 activity and business report
The ENSI Board has assessed ENSI’s regulatory activities in relation to Switzerland’s nuclear installations as responsible, appropriate and of high quality.
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EU Topical Peer Review on fire protection in nuclear facilities: ENSI assessments confirmed
Switzerland participated in the EU’s Topical Peer Review on fire protection in nuclear facilities. The now published report summarizes the expertise and in-depth discussions of the other supervisory authorities. As ENSI had already explained in its national report at the end of 2023, fire protection concepts need to be updated for certain nuclear facilities.
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8th Review Meeting of the Joint Convention: Switzerland receives positive overall assessment
From 17 to 28 March 2025, ENSI participated in the Eighth Review Meeting of the Contracting Parties to the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. The Swiss National Report received one « good practice », three « areas of good performance » and one…
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The ENSI Board learnt about nuclear safety in Finland and Sweden
In autumn 2024, the Board of the Swiss Federal Nuclear Safety Inspectorate (ENSI) visited the Finnish Radiation and Nuclear Safety Authority (STUK) and the Swedish Radiation Safety Authority (SSM). A visit to the nuclear power plants at the Olkiluoto site in Finland was also on the programme. The main objective of the meetings with the…
Background articles
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Ten Years on from Fukushima (6/6): Conclusions
The disastrous accident in Fukushima Daiichi occurred exactly ten years ago, on 11 March 2011. In the last few weeks, our article serie has highlighted the causes, the sequence and the effects, as well as describing the conclusions that we have been able to draw from the accident.
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Ten years on from Fukushima, the ENSI Board still holds that safety has priority over political or economic interests
Where there are conflicts of interest between politics, safety and profitability, safety must always take priority. This is one of the most important lessons learnt from the Fukushima nuclear accident.
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‘Switzerland is regarded as very reliable in nuclear matters’ – a commentary by former Federal Councillor Doris Leuthard
At the time of the fateful accident in Fukushima, Doris Leuthard was head of the Federal Department of the Environment, Transport, Energy and Communications (DETEC). To commemorate the tenth anniversary of the nuclear disaster, the former Federal Councillor explains why it was essential to provide political support for nuclear safety after the accident.