Eidgenössisches Nuklearsicherheitsinspektorat ENSI
2025 Oversight Report: Compliance with approved operating conditions
Brugg (ots)
The Swiss nuclear installations complied with the legal requirements for their operation. There were no impermissible releases of radioactive substances into the environment. This is the conclusion reached by ENSI for the 2025 oversight year.
The safety status of the Beznau and Leibstadt nuclear power plants (NPPs) was good. ENSI is not issuing an overall assessment for Gösgen NPP while the findings concerning its feedwater system are still being evaluated and the plant remains in an extended shutdown.
In 2025, Swiss nuclear installations recorded 43 reportable events that were relevant to nuclear safety. ENSI classified the deviation during the loading of a transport and storage container at Leibstadt NPP as Level 1 (anomaly) on the International Nuclear and Radiological Event Scale (INES), and all other events as Level 0 (events of minor safety deviation).
During the reporting year, a possible design weakness in the feedwater system was identified at Gösgen NPP as a result of new calculation methods. Gösgen NPP had to prove that it can control the "break of a feedwater line" accident scenario. This resulted in a prolonged shutdown.
No impermissible releases of radioactive substances from Swiss nuclear installations were registered during the reporting year. The releases were significantly below the legal limits.
Media contact:
Swiss Federal Nuclear Safety Inspectorate (ENSI)
Communications Section, 5201 Brugg, Tel.: +41 56 460 85 70, info@ensi.ch
For more information: www.ensi.ch