Les cahiers de l'ASN #03 - 10 years after Fukushima

Fukushima: a nuclear safety catalyst REINFORCING SAFETY IN FRANCE 124 b asic nuclear installations are subject to ASN regulation and oversight (as at 31 December 2020) T he safety improvements to nuclear facilities in France owe much to the Fukushima accident. The number one lesson is that, despite all the precautions taken in the design, construction and operation of nuclear facilities, an accident is always possible. After a period of audit and reflection, ASN issued 32 resolutions as of June 2012, each setting out thirty or so requirements stipulating that the nuclear licensees of 80 nuclear facilities with the highest potential consequences (CEA*, EDF*, Framatome*, Institut Laue‑Langevin* and Orano*) had to define arrangements to deal with extreme situations: The Fukushima accident highlighted the need to reinforce the resilience of nuclear facilities and organisations in the face of extreme situations. This accident led to significant progress being made in nuclear safety. * See glossary page 24 ∙ implementation of systems (water make-up, electricity supply, instrumentation) to improve the management of loss of electrical power or loss of cooling situations affecting the entire site; ∙ the definition of a “hardened safety core” * of material and organisational measures which, in extreme conditions, would be designed to prevent an accident with fuel melt or mitigate its spread, as well as to mitigate large-scale releases; ∙ reinforcement of emergency management resources on each site ; ∙ implementation of a nuclear rapid intervention force (FARN* for CEA and EDF, FINA* for Orano), to ensure an emergency response on a damaged nuclear site. ASN’s approach aimed to anticipate situations well beyond the situations normally included in the safety case. The stringency of its requests stand out on the international stage and are part of the “defence in depth” approach. The philosophy of this approach is based on a safety system with superposed, multiple layers (equipment, organisation and teams) so that if one layer fails, the next one can take over. Ten years after Fukushima, the results of the safety improvements to nuclear facilities in France are positive. Tomorrow, with the completion of the “hardened safety core”, the installations will be more robust to extreme situations. 8 • Les cahiers de l’ASN • March 2021