Swiss federal authorities

Nuclear Facilities

Switzerland has the following nuclear power plants: Beznau (units 1 and 2), Gösgen and Leibstadt. Also in operation is a research reactor at the Federal Institute of Technology in Lausanne (EPFL). The Central Interim Storage Facility for radioactive waste (Zwilag) and the Federal Government’s Interim Storage Facility in Würenlingen are also monitored by ENSI.

The no longer operational Mühleberg Nuclear Power Plant is being decommissioned. Three research reactors at the Paul Scherrer Institute PSI in Würenlingen have nearly been fully dismantled.

  • NPP Beznau
    Beznau NPP comprises two largely identical two-loop pressurised water reactor units, which began commercial operation in 1969 and 1972 respectively. The net electrical output per unit is 365 MW.
  • NPP Gösgen
    Gösgen NPP is a three-loop pressurised water reactor system. It began commercial operation in 1979. The net electrical output is 1010 MW.
  • NPP Leibstadt
    Leibstadt NPP is a boiling water reactor that began commercial operation in 1984. The net electrical output is 1233 MW.
  • Former Mühleberg Nuclear Power Plant (permanent shutdown)
    Mühleberg NPP, which began commercial operation in 1972 and shut down in 2019, was a boiling water reactor with a net electrical output of 373 MW. Mühleberg NPP ceased power operations on 20 December 2019. In 2020, all fuel elements were transferred from the reactor pressure vessel to the fuel pond and the necessary measures implemented to establish safe technical post-operation. In 2022 and 2023, during decommissioning phase 1, Mühleberg NPP transported all its fuel elements to the Central Interim Storage Facility of Zwilag in Würenlingen, completing the first decommissioning phase in 2023. Since then, Mühleberg NPP has been in decommissioning phase 2.

Decommissioning of the following plants has been completed:

  • Lucens experimental nuclear power plant
  • Basel University Research Reactor
    Up until its final shutdown in 2015, the research reactor of Basel University was used to teach students and for neutron activation analysis. After the Federal Department of the Environment, Transport, Energy and Communications (DETEC) had ordered the decommissioning of the research reactor on 13 February 2019, ENSI approved the dismantling of the plant. Dismantling was completed in 2019. With the removal of the plant from federal government oversight, the first decommissioning project in Switzerland under the current nuclear energy legislation was completed.

News

  • News, Posts

    Chronology: from the findings in Belgium to the proof of safety from Beznau 1

    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…

  • News, Posts

    Quality assurance errors relating to some fuel rods in the Leibstadt Nuclear Power Plant

    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.

  • News, Posts

    The carbon content of the steam generators at Beznau and Gösgen is not too high

    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.

  • News, Posts

    “Cladding tube damage poses no risk to mankind or the environment”

    The Swiss Federal Nuclear Safety Inspectorate (ENSI) has issued Leibstadt Nuclear Power Plant (KKL) approval to restart subject to conditions. The conditions under which dryouts have occurred at KKL are known. KKL has instigated counter measures. Consequently operation is safe. In an interview Ralph Schulz, Director of the Safety Analyses Division, shares some background insights.

  • News, Posts

    ENSI issues Leibstadt Nuclear Power Plant approval to restart subject to conditions

    Leibstadt Nuclear Power Plant can restart power operation after an extended annual overhaul. The Swiss Federal Nuclear Safety Inspectorate (ENSI) has checked the clarification of the causes and measures derived from it for the avoidance of critical boiling conditions or dryouts. After the circumstances that led to the dryout had been identified, the supervisory authority…

  • Georg Schwarz
    News, Posts

    “The inspection of the steam generators of the Gösgen and Beznau Nuclear Power Plants will not require a temporary shut-down”

    At the beginning of December 2016 the Swiss Federal Nuclear Safety Inspectorate (ENSI) requested the inspection of the steam generators at the Gösgen and Beznau nuclear power plants. Georg Schwarz, ENSI Deputy Director and head of the NPPs Division, explains the background and context in the following interview.

  • News, Posts

    Findings on fuel elements in Leibstadt NPP: ENSI is classifying the incident as INES 1 and checking the submitted measures

    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) is classifying this incident as Level 1 on the International Nuclear and Radiological Event Scale (INES). It is currently checking the documents and actions submitted…

  • News, Posts

    Beznau and Gösgen nuclear power plants must check their steam generators

    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. In doing so, ENSI is reacting to information from France.

  • News, Posts

    ENSI reviews reactor pressure vessel safety case submitted by Beznau 1

    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. In its assessment, ENSI will be advised by the…