The European Commission’s European Nuclear Safety Regulators Group (ENSREG) has published its Country Review Report (CRR) Switzerland on the state of fire protection in Swiss nuclear facilities. This report summarizes the assessment by the other participating supervisory authorities (peer review) and the in-depth discussion of their findings, which took place in autumn 2024 in Luxembourg. It is based on the National Assessment Report which ENSI submitted to ENSREG at the end of 2023.

“The aim of the EU Topical Peer Review is to find opportunities for improvement in fire protection at nuclear facilities in the various participating states,” explains Felix Altorfer, member of the ENSI Management Board. “For ENSI, such independent checks by external experts are therefore valuable and important”.

ENSI and the external supervisory authorities (ENSREG) have identified four Areas of Improvement and two Areas of Good Performance in the Country Review Report (CRR).

The four areas for improvement will be set out in a National Action Plan. On this basis, ENSI will define measures by the end of 2025. Most of the areas for improvement were mentioned in the ENSI National Assessment Report from 2023. The two areas of good performance should be seen as examples of possible further optimization in other nuclear facilities in Switzerland and abroad.

In the new guideline ENSI-G18, which was published at the beginning of October 2024, ENSI provides guidelines for fire protection in terms of construction, technology, organization and preventive fire protection. The fire protection guideline is in line with IAEA (Safety Requirements) and WENRA (Safety Reference Levels) regulations.

• Areas for improvement and areas of good performance

  Based on the Swiss national report on fire protection in nuclear facilities and the assessment by the participating supervisory authorities (Peer Review), the Country Review Report identified the following four areas for improvement and two areas of good performance:

  • Area for improvement (1) for the Beznau and Gösgen nuclear power plants and the Beznau interim storage facility (Zwibez): Need to revise the fire protection concept into a “comprehensive fire protection concept” and detailed building-specific fire protection concepts.
  • Area for improvement (2) at Leibstadt nuclear power plant: there are two different IT systems to support fire load management. This makes it difficult to collect information efficiently.
  • Improvement area (3) for the Zwilag central interim storage facility: fire protection concepts and corresponding documentation need to be updated and supplemented in line with the current state of the art.
  • Area for improvement (4) for all Swiss nuclear power plants: it is necessary to review the detection principle in zones/areas with high or very high radiation exposure. This is because the design of fire detection systems is mainly based on the “Fire Detection Systems” guideline issued by the SES (Swiss Association of Safety System Manufacturers), which covers the current state of the art in industrial installations. The need for different detection principles should be justified by a risk assessment taking into account nuclear safety and radiation protection.

  • Area of good performance (1) for the Zwilag interim storage facility: fire caused by the crash of a military aircraft was taken into account in the design of the spent fuel and radioactive waste storage buildings. This is because detailed analyses were carried out during the design phase for the spent fuel and radioactive waste storage buildings in the event of impact by a military aircraft. The analysis of a post-crash fire involving the combustion of aircraft fuel is not generally carried out for radioactive waste storage facilities.
  • Area of good performance (2) for all Swiss nuclear power plants: robustness of the fire detection system against individual failures. This is based on the fact that “the fire detection stations used to monitor the various redundancies in the safety and emergency systems must be functionally and physically separate from each other” (guideline -ENSI-G18, paragraph 6.1.2). This requirement ensures robustness against a single failure affecting more than one redundancy.

On June 18, 2025, ENSREG will hold a final public meeting for stakeholders in a hybrid format in Brussels. The aim is to present the results of this second topical peer review on fire protection in nuclear installations to a wider audience of interested parties.

• Topical Peer Review and public participation

  Following the Fukushima nuclear disaster in 2011, all nuclear power plants in the European Union, Switzerland and Ukraine were subjected to stress tests. Certain situations (ranging from incidents to accidents) were grouped together, and the lessons learned were recorded in order to improve nuclear safety and radiation protection. The reports were then reviewed by international experts and published.

  In 2014, the Council of the European Union updated the European Directive on the safety of nuclear installations. Among other things, this provides for “topical peer reviews” for nuclear facilities – a process of expert appraisal by partner countries on a given priority topic. Every six years, the focus is on a different aspect of the safety of nuclear installations.

  The first topical peer review was conducted from 2017 to 2018. The topic was ageing management of nuclear power plants. In October 2018, ENSREG approved the review report and the related country-specific results.

  The second topical peer review focuses on fire protection in nuclear facilities. Switzerland and the other participating countries submitted their national reports in 2023. In these reports, the technical provisions for fire protection in the respective nuclear facilities were presented and evaluated.

More Information

• Country Review Report Switzerland_2nd Topical Peer Review_’Fire Protection’
• Summary Report_2nd Topical Peer Review ‘Fire Protection’
• ENSI publishes new fire protection directive (in German)
• Fire Protection in Nuclear Installations: Swiss National Report Submitted to ENSREG