ASN sets additional prescriptions for AREVA and CEA facilities and sites, concerning the hardened safety core and the management of emergency situations

Pursuant to the ASN resolutions of 5^th May 2011, AREVA and CEA carried out stress tests on each of their facilities for which there are major potential safety issues, in order to take account of experience feedback from the Fukushima accident. The stress tests performed in Europe on the nuclear power reactors were, in France, extended to cover all basic nuclear installations, including fuel cycle and research facilities. The particular aim of the stress tests was to determine the safety margins that exist on these facilities with regard to extreme hazards such as earthquake and flooding.

For AREVA, these stress tests were performed on the facilities on the La Hague, Romans-sur-Isère, Tricastin and Marcoule sites. For CEA, some of the Marcoule, Cadarache and Saclay facilities are concerned.

Following the analysis of these stress tests, ASN asked¹ AREVA and CEA to define a "hardened safety core” of robust material and organisational measures to:

• prevent a severe accident or limit its progression;
• limit large-scale releases of radionuclides into the environment in the event of an accident;
• enable the licensee to carry out its emergency management duties.

The concept of the “hardened safety core” aims to ensure that there are structures and equipment capable of withstanding extreme events and of performing essential functions for the safety of the facilities and management of the emergency on the site. This entails protecting the equipment needed to manage the safety functions against hazards that exceed those considered in the design of the facilities².

These provisions for the facilities concerned were examined by IRSN and then during the meetings of the Advisory Committees (GP)[1].On the basis of these reviews, ASN issued resolutions establishing additional prescriptions stipulating the requirements applicable to the hardened safety cores proposed by AREVA and CEA, as well as to the management of emergency situations. These resolutions clarify the design and sizing rules to be adopted for the structures and equipment constituting the “hardened safety core”. They must comply with the most demanding standards, so that their functions can be guaranteed until such time as the facility is returned to a safe state.

In addition to the requirements concerning the “hardened safety core”, ASN asked the licensees to take the necessary steps concerning the management of emergency situations, such as to ensure:

• independent operation of the “hardened safety core” equipment for the first 48 hours in an extreme situation, with provision being made for supplies to be received from outside the site (water, electricity, fuel, etc.) after this period;
• automatic and robust transmission of key data concerning the status of the facility (water levels, temperature, etc.) to the emergency management centres;
• reinforcements being sent to the site (personnel, equipment, etc.) to ensure long-term management of an extreme situation.

Moreover, for certain facilities which do not require measures such as the “hardened safety core”, ASN made additional requests in letters sent to the licensees[1]. Finally, for the lower priority facilities of CEA, EDF and the other licensees, the resolutions3 of 21^st November and 17^th December 2013 required submission of the stress test reports. They will be gradually submitted between now and 2019.