The European Council of 24/25 March, 2011, requested that the safety of all EU nuclear plants should be reviewed, on the basis of a comprehensive and transparent risk and safety assessment ('stress tests'). These 'stress tests' were defined as targeted reassessments of the safety margins of nuclear power plants, developed by ENSREG, including the European Commission.
As security threats were not part of the mandate of ENSREG, a two-track process has been developed.
The 'safety track' covers extraordinary triggering events like earthquakes and floods and the consequences of any other initiating events (e.g. transport accidents, such as airplane crashes) potentially leading to multiple loss of safety functions requiring severe accident management. All the operators of nuclear power plants in the EU had to review the response of their nuclear plants to those extreme situations. The operators’ reports were first reviewed by the national nuclear regulators. They then prepared summary national reports.
The final national reports were peer-reviewed by review teams, set up by ENSREG. As soon as the peer review process started, the public and stakeholders were provided with the opportunity to engage in the 'stress tests'. In April 2012, ENSREG endorsed the Summary Report (http://www.ensreg.eu/EU-Stress-Tests/EU-level-Reports) with the 17 country specific peer-review reports attached to it.
The Commission presented an interim report to the European Council in December 2011 and another report in October 2012. The ENSREG Report was presented at the June 2012 European Council for information.
Regarding the 'security track', the Council's Permanent Representatives Committee (COREPER) decided on the establishment of the Ad Hoc Group on Nuclear Security, which presented it final report in June 2012.
The European Commission is also in close contact with countries outside the EU and is working with them on re-assessing their nuclear power plants.