Recognising that cooperation between Member States can give added value in terms of nuclear safety, transparency, and openness towards stakeholders, as well as delivering continuous improvements, the revised Nuclear Safety Directive introduced a European system of ‘Topical Peer Reviews’ (TPR) that commenced in 2017 and take place at least every six years thereafter.The purpose of Topical Peer Reviews is to provide a mechanism for EU Member States to jointly examine topics of importance to nuclear safety, to exchange experience and to identify opportunities to strengthen nuclear safety. The process also provides for participation, on a voluntary basis, of non-EU countries hosting nuclear installations.
Second TPR
The second topical peer review (TPR II) activities started in 2021 with the nomination of experts from participating countries to peer review the topic of 'fire protection at nuclear installations'. In total, 22 countries took part developing their national assessment reports. 18 EU countries took part, plus 4 non-EU countries (Switzerland, Turkiye, Ukraine and United Kingdom).
On the basis of terms of reference adopted by ENSREG, and a technical specification developed by the Western European Nuclear Regulators Association (WENRA), the licensees of nuclear installations performed self-assessments, based on which national regulators prepared the National Assessment Reports, published in October 2023. These reports were then peer reviewed by teams of experts, and were also made available for questions and comments from stakeholders. A number of site visits by the peer review experts to nuclear (research) reactors were also organised. More than 2690 questions were asked by peer review experts, national regulatory authorities, and civil society groups and other stakeholders. In September-October 2024, two peer review workshops were organised in the autumn of 2024 involving the participation of representatives of licensees, national regulatory authorities, TSOs and the European Commission with a view to discuss the national approaches described in the national assessment reports, outcomes of the peer review, and proposed findings, conclusions and recommendations. These discussions led to the development of a final TPR II summary report and 22 country review reports which were issued in 2025.
First TPR
The first topical peer review was carried out from 2017 to 2018. The topic was ageing management of nuclear power plants and research reactors. This review was the most important safety-related exercise after the post-Fukushima stress tests in Europe.
In October 2018, ENSREG approved the report on the review and related country specific findings.
The timely and effective completion of this review highlights the continuous improvement of nuclear safety in the EU and neighbouring countries. In total, 19 countries (16 EU countries, Norway, Ukraine, and Switzerland) participated in the peer review. The process continued with the establishment of national action plans addressing the peer review results.
The subject of the first review (ageing management) was chosen on the basis of the age profile and the potential long term operation of European nuclear power plants. The exercise was developed by ENSREG with the technical support of the Western European Nuclear Regulators Association. The licensees made self-assessments, based on which national regulators prepared the National Assessment Reports, published at the end of 2017. In January 2018, these reports were made available for questions and comments from stakeholders. More than 2300 questions were asked by peer reviewers, experts and civil society when reviewing the reports. In May 2018, ENSREG organized a one-week workshop involving around 140 experts to discuss the results of the self-assessments, the questions and comments on the national reports, as well as the replies to the questions.
The preparation of this first topical peer review was fully transparent (more information on the TPR 1 public engagement page).
Press release issued by ENSREG on 29 October 2018.
Questions or comments on the Topical Peer Review should be sent in English to ener-ensreg@ec.europa.eu.
