Complementary safety assessments – Press Release, 14th September 2011

Published on 14/09/2011 at 12:38

Press release

The accident that occurred on 11th March 2011 at the Fukushima Daiichi nuclear power station in Japan, following an earthquake and tsunami of exceptional magnitude, is a major event from which every possible lesson should be drawn.

The French Nuclear Safety Authority (ASN), which in charge of monitoring French nuclear installations, has ensured that a process of extensive in-depth feedback regarding the accident at Fukushima has been swiftly undertaken. This will be a long process. It will take several years, as was the case after the accidents at Three Mile Island and Chernobyl.

The ASN has asked French operators to carry out complementary safety assessments. This assessment process is also in response to the request of the Prime Minister to carry out an audit of the safety of nuclear installations and to the concluding expectations of the European Council as set out on 24th and 25th March 2011. It incorporates the provisions of the specifications approved by ENSREG (European Nuclear Safety Regulators' Group) on 25th May. It has the following specific features:

  • It covers almost all of the 150 French installations (58 pressurised water reactors, EPR reactor under construction, research facilities, fuel cycle plants, ...).
  • The involvement of stakeholders, including the French High Committee for Transparency and Information on Nuclear Safety (HCTISN), has led to an emphasis on the inclusion of organisational and human factors, including the issue of subcontracting. The complementary assessments have been further extended to include these topics.

In the process of the complementary safety assessment of a wide range of installations operated by a limited number of operators, the ASN introduced an intermediate step in the assessment process: by 1 June 2011 operators produced notes detailing the methodology used for assessments, which were examined by the ASN and its technical support organisation, the French Institute for Radiological Protection and Nuclear Safety (IRSN).

For the 80 installations identified as priority, including nuclear reactors, operators must submit their findings by 15th September; for the others, operators must submit their report by 15th September 2012.

The reports on the complementary assessments of the safety of priority nuclear installations will be analysed by the ASN with the support of the IRSN and expert groups. Based on this analysis, the ASN will present its findings at the end of 2011. The French authorities will send their final report to the European Commission, in accordance with the specifications drawn up by the ENSREG, by 31st December 2011 at the latest.

1.The process for French complementary safety assessments

As with the accidents at Three Mile Island and Chernobyl, in-depth feedback regarding the accident Fukushima will be a long process lasting several years[1].

In the short term, the ASN has conducted complementary assessments of the safety of nuclear French installations in terms of events similar to those that occurred in Fukushima. The completion of these assessments is in addition to the safety procedure that is permanently in place as previously described.

These complementary security assessments are part of a twin framework: firstly, the organization of "stress tests" required by the European Council at its meeting on 24th and 25th March 2011 and secondly, an audit of the safety of French nuclear installations in the light of events at Fukushima, which was referred to the ASN by the Prime Minister under Article 8 of the TSN Act.

2. Methodological notes submitted by the operators

All operators involved in priority installations to be subject to complementary safety assessment in 2011 (EDF, CEA, AREVA and the Institut Laue Langevin) submitted their methodological notes by 1st June 2011, in accordance with decisions taken by the ASN on 5th May 2011.

These notes present the methodology used to conduct the complementary safety assessments, the organisation set up to meet the prescribed deadlines and the detailed structure proposed for the reports.

These notes have been subject to a preliminary analysis by the IRSN.

On 6th July 2011, groups of experts assembled by the ASN examined the methodological notes of the operators and the analysis carried out by the IRSN.

Expert groups in particular emphasized the ambitious nature of this exercise designed to assess, within the expected deadlines, the robustness of the installations in extreme situations.

Based on these findings, the ASN found that the methodological approaches submitted by the operators were generally satisfactory, provided that these include the additional features they have committed to provide during the course of the analysis and that they comply with the requirements of the ASN. These requirements essentially relate to:

  • the condition of the installation;
  • hazards: assessment of safety margins, robustness against flooding and taking into account the cumulative effect of earthquakes and flooding;
  • incidents in the installation caused by natural hazards and those related to its industrial environment;
  • management of serious incidents.

In particular, the ASN asked them to investigate the consequences of the dykes of the Grand Alsace Canal near the site of Fessenheim bursting, the dykes of the Donzère Canal near the site of Tricastin bursting and a breach of the Provence Canal near the site of Cadarache.

The ASN also believes that the quality of complementary safety assessments will depend on the ability of operators to deploy the approach they have proposed in sufficient depth.

No later than 15th September 2011 operators will submit a first report to the ASN on the results of complementary safety assessments on the installations to be checked in 2011. The ASN and its technical support organisation, the IRSN, will analyse these reports by the end of 2011.

The ASN has stated that the complementary safety assessments are the first step in the feedback process after the accident in Fukushima. This process will develop over several years.

3. Targeted inspections

In addition to complementary safety assessments, in 2011 the ASN initiated a campaign of targeted inspections on issues related to the accident in Fukushima. These inspections, conducted on all nuclear installations considered as priorities, are intended to check the compliance of materials and the organization of the operator with regard to existing safety standards.

The issues covered during these inspections are:

  •  protection against external hazards, especially resistance to earthquakes and protection against flooding,
  •  loss of electrical power supply,
  •  loss of cooling resources,
  •  operational management of emergency situations.

38 inspections have been planned and conducted by teams consisting of several inspectors from the ASN and IRSN experts. This inspection campaign represents 110 days of inspection on the ground.

These inspections are scheduled to take place between June and October 2011. They take place, for a given site, in the form of extended inspections over several days (continuous or not) to ensure all the issues mentioned above are covered. They are based firstly on common guidelines for nuclear power plants, and secondly on those for other nuclear facilities and emphasize on site visits to carry out documented inspections.

The inspections then immediately result in letters being sent to operators and posted online at

71% of "targeted" inspections have been carried out to date. ASN will analyse the results of all these inspections by the end of 2011. The findings of the ASN will be included in the report on complementary safety assessments, which will be forwarded to the government. If it deems it necessary, the ASN will impose additional requirements to enhance the safety of installations.

4. Following the process

Operators will submit their reports to the ASN on 15th September 2011. They will be published on

The ASN will report on the complementary safety assessments in late 2011.


The timing of the European "stress tests"

The carrying out of European "stress tests" stems from the European Council conclusions of 24th and 25th March which, two weeks after the occurrence of the accident in Fukushima, wanted to subject the European nuclear power plants to complementary safety assessments.

As mandated by the European Council, the final agreement of 25th May 2011 between the safety authorities and the Commission on the specifications of the "stress tests" for these plants establishes the broad stages of this process:

  • 1st June 2011 at the latest: formal launch of stress tests for European nuclear power reactors in European countries;
  • 15th August 2011: submission by operators to the safety authorities in each country of a progress report on their safety assessments;
  • 15th September 2011: submission by each Member State to ENSREG and the Commission of a provisional "national report";
  • 31st October 2011: submission by operators to the safety authorities in each country of their final report on the complementary safety assessment of their facilities;
  • 31st December 2011: submission by each member state of their final national report.

In addition to these scheduled items, the ENSREG (European Nuclear Safety Regulators Group) specifications also state that the final country reports will be subject to peer review, from January 2012. It added that the European Commission will submit an "interim report" to the European Council of 9th December 2011, and a final report to the European Council in June 2012.

Schedule for complementary safety assessments

Twelve decisions were taken by the College of the ASN on 5th May 2011 requiring a report from different nuclear operators responding to a precise specification according to the following schedule:

  • 1st June 2011 at the latest: submission of notes presenting the methodology used to conduct the complementary safety assessments, the organisation set up to meet the prescribed deadlines and the detailed structure proposed for the report;
  • 15th September 2011: for priority facilities including nuclear power plants, submission by operators of a report presenting the findings of the assessment. This report will propose complementary assessments, as well as a suitable schedule for these;
  • 15th January 2012: submission of methodological notes for lower priority installations;
  • 15th September 2012: submission of reports for lower priority installations.

To analyse the reports on priority installations, ASN consulted the IRSN in May 2011 and the two permanent groups of experts on reactors and plants in June 2011. The work of these experts has been organised according to the following schedule:

  • 6th July 2011: meeting and comments of expert groups on methodological notes;
  • 19th July 2011: position of ASN on methodological notes;
  • beginning of November 2011: IRSN report on complementary safety assessments of priority installations indicating the importance of each of the comments and distinguishing those likely to become requirements that are binding on the operator;
  • 8-10 November 2011: meeting of permanent expert groups to analyse the operators’ reports.

 The ASN will report on the complementary safety assessments in late 2011.

Press contact: Evangelia Petit, Media Relations Manager, Tel.: 01 40 19 86 61,

[1] For example, it took six years after the accident at Three Mile Island to assess the proportion of the core of the reactor which had melted.

Date of last update : 08/06/2017