Switzerland’s Federal Nuclear Inspectorate (ANSI - Eidgenössisches Nuklearsicherheitsinspektorat) said that Switzerland's nuclear facilities had operated safely in 2020.
The number of reportable incidents was slightly below the average of previous years. ENSI said that, despite the pandemic situation, it had regularly carried out both registered and unannounced inspections throughout 2020 and also conducted the necessary supervisory discussions.
The Mühleberg nuclear power plant, which closed in December 2019, is considered to have been permanently out of operation since September and is now formally being decommissioned. In June, ENSI had approved the first decommissioning phase after a detailed review.
In view of the coronavirus situation, the operators of the Beznau, Gösgen and Leibstadt plants had adjusted their plans for annual outages but ENSI said it is convinced that the scope of the revision work nevertheless complied with the legal requirements in all cases.
In December 2020, the Beznau NPP discovered installation deviations in the vibration dampers of two emergency diesel engines as part of an earthquake safety review required by ENSI. This resulted in a preliminary rating of 1 on the International Nuclear and Radiological Event Scale (INES). The assembly deviations were rectified and both units were put back into operation. However. further clarifications are ongoing and the INES assessment could change as a result of the final assessment, ENSI said. Information on the final results willo be posted on ENSI’s website and in its 2020 Supervisory Report in the course of the year.
Photo: Switzerland's Beznau nuclear power plant