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.

Background Articles

  • Background articles, News, Posts

    New study on extreme flooding of the River Aare is also relevant for nuclear power plant sites

    Today, the Federal Office of the Environment, FOEN, published its study “Extreme Flooding of the River Aare”. Their findings also include a re-evaluation of the flood risk to nuclear installations located on the Aare. ENSI will now require those nuclear installations concerned to update their safety cases.

  • Background articles, News, Posts

    All Swiss nuclear power plants comply with the updated earthquake safety standards

    For the second time since the Fukushima accident in 2011, power plant operators have demonstrated that their plants are capable of withstanding an extremely rare, severe earthquake. The safety case for a flood caused by an earthquake has also been checked. The findings from the safety proofs generated in the aftermath of Fukushima have been…

  • Background articles, Posts

    Series of articles on barriers 6/6: The containment holds radioactive substances in the reactor building

    The reactor pressure vessel is enclosed by the containment as the third barrier. This consists of a steel primary containment and a concrete secondary containment.

  • Background articles, Posts

    Series of articles on barriers 5/6: The water circuit (primary circuit part 2 of 2)

    With its pipelines, shut-off valves and other components, the cooling circuit, together with the reactor pressure vessel, is the second barrier for trapping radioactive substances.

  • Background articles, Posts

    Series of articles on barriers 4/6: The reactor pressure vessel (primary circuit part 1 of 2)

    The reactor pressure vessel, together with the water’s cooling circuit, is the second barrier for trapping radioactive substances.

  • Background articles, Posts

    Series of articles on barriers 3/6: The fuel rod cladding tubes (fuel assemblies part 2 of 2)

    The fuel pellets are filled into metal tubes. Together with the nuclear fuel matrix, the cladding tubes are the first barrier for trapping radioactive substances in nuclear power plants.

  • Background articles, Posts

    Series of articles on barriers 2/6: The nuclear fuel matrix (fuel assemblies part 1 of 2)

    The nuclear fuel is pressed into pellets and compacted using the sintering process before use in nuclear power plants. This process transforms the nuclear fuel into a ceramic material, which is able to retain the fission products that arise during operation in the nuclear fuel matrix.

  • Background articles, Posts

    Series of articles on barriers 1/6: Barriers protect people and the environment from radioactive substances

    The barrier concept aims to trap sources of radiation in nuclear facilities across several levels. Similar to the layers of an onion, independent barriers ensure that the risk from sources of radiation are minimised for people and the environment.

  • Background articles, Posts

    Dryout: Preventing inadequate cooling of fuel rods

    Heat is generated in the reactor as a result of nuclear fission. To guarantee optimum cooling of the fuel rods, their cladding tubes must always be covered with a film of water. If they are not completely covered with water in specific areas, this is referred to as “dryout”.