Beznau nuclear power plant: Both units back on grid

28.08.2026 - Axpo reconnected Unit 2 of the Beznau Nuclear Power Plant (KKB) to the grid following the completion of the refuelling outage. Unit 2 is now gradually returning to power operation and is expected to reach full capacity within approximately two days. Unit 1 has been back in operation since 21 August 2026, following the cooling of the River Aare. 

Unit 2 was taken offline as planned on 4 August 2026 for refuelling. During the outage, 20 of the 121 fuel assemblies in the reactor core were replaced. The refuelling was verified by the International Atomic Energy Agency (IAEA) and the Swiss Federal Office of Energy (SFOE). In addition, Axpo carried out inspections, system tests and scheduled maintenance work on individual components during the outage. KKB employees were supported by around 150 external specialists. 

Following approval by the Swiss Federal Nuclear Safety Inspectorate (ENSI), Unit 2 gradually resumed power operation yesterday. Once full capacity is reached in approximately two days, both units of the KKB will once again be generating electricity at full output. During the restart, water vapour may occasionally be visible above the non-nuclear part of the plant, particularly above the turbine building. This poses no risk to people or the environment. 

Summer operations during High River Aare temperatures 

The summer months were characterised by unusually high water temperatures in the River Aare. In accordance with the provisional ruling issued by the Swiss Federal Office of Energy (SFOE), KKB reduced its output as required from May 2026 onwards. In June, July and August, KKB was temporarily required to shut down one or both reactor units. Unit 1 has been back in operation since 21 August 2026. During the heatwave, Axpo provided continuous updates on the impact of the high River Aare water temperatures on KKB operations via its cooling-water ticker

KKB produces around 6 terawatt-hours of electricity every year, covering approximately one tenth of Switzerland’s electricity demand. The two reactor units are regularly taken offline in spring and summer for refuelling or an overhaul. They then resume contributing to the electricity supply for around another year, particularly during the winter months.