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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Detailed exchange with the Polish Nuclear Regulatory Authority
A high-ranking delegation from the Polish Nuclear Regulatory Authority (PAA) visited Switzerland from 17 to 19 November 2025. The programme included an exchange of experiences on regulatory activities, safety culture, research and deep geological disposal of radioactive waste.
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IAEA General Conference 2025: lively exchange to promote nuclear safety
ENSI was part of the Swiss delegation at the 69th IAEA General Conference. It took the opportunity to exchange views with numerous regulatory authorities, thereby promoting the safety and security of Swiss nuclear facilities.
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Convention on Nuclear Safety: Switzerland submits 10th national report to IAEA
Switzerland has submitted its 10th national report on the Convention on Nuclear Safety (CNS) to the International Atomic Energy Agency (IAEA) in Vienna. The report shows that Switzerland is complying with the requirements of the international convention.
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Welcome to the new ENSI Board website!
The redesign of the ENSI Board website focuses on the needs of the target groups. The structure of the new website has been slightly streamlined and new functions have been integrated. All ENSI Board announcements are still available under News. The News can now be displayed as a list or as tiles. Links in the footer…
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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…
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.