For the year as a whole, the potential doses to the population from the operation of nuclear installations were less than 0.01 millisieverts, and therefore at a very low level. The limit set out in the Radiological Protection Ordinance for annual radiation exposure of the population from releases from nuclear installations is 1 millisievert.

Continuous dose rate monitoring available online

ENSI operates the MADUK system for automatic monitoring of the dose rate in the vicinity of nuclear power plants. It comprises 57 measuring probes, whose readings are recorded every 10 minutes and published on the ENSI website in real time.

Legal limits for personnel met

Throughout the year, ENSI inspectors were regularly present at all nuclear installations, including during maintenance shutdowns and refuelling. The evaluations confirmed that all legal requirements for the radiation exposure of personnel were met in 2025.

Particular focus on decommissioning and dismantling

ENSI also oversees the dismantling of decommissioned nuclear installations. Work such as the dismantling of core internals, as is currently taking place at the Mühleberg Nuclear Power Plant, is radiologically demanding, requires adapted protection and monitoring measures, and requires ENSI to adapt its oversight accordingly. Looking ahead to the decommissioning of Beznau Nuclear Power Plant announced by Axpo from 2032/33, ENSI is drawing on its experience from Mühleberg in its preparatory work.

Outlook: new reactor technologies and digital safety

With regard to new technologies such as small modular reactors (SMRs), in 2025 ENSI worked on the further development of the regulatory framework in preparation for possible licensing procedures. Security issues at nuclear installations remain of central importance. These include developments in drone technology and risks arising from vulnerabilities in electronic components, which must be appropriately taken into account during design and operation.

Through the interplay of regulatory requirements, inspections and measurements, as well as the continuous training of specialist personnel, ENSI was once again able to contribute to ensuring the protection of people and the environment against ionising radiation during the year under review.