ASN Report 2017

364 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 12  - EDF Nuclear Power Plants implementation does not degrade the safety of the nuclear power plants. To take account of the engineering constraints involved in these major works but also the need to introduce the necessary post-Fukushima improvements as soon as possible, their implementation is planned by EDF in three phases: Phase 1 (2012-2015) Deployment of temporary or mobile measures to enhance protection against the main situations of total loss of the heat sink or electrical power supplies. At the end of 2015, EDF had deployed the planned measures. In particular, the FARN, which is one of the main emergency management measures, was deployed. Since 31st December 2015, the FARN teams have the capacity for simultaneous intervention on all the reactors of a site in less than 24 hours (up to six reactors in the case of the Gravelines site). Phase 2 (2015-2021) Deployment of certain final design and organisational means that are robust to extreme hazards, in order to deal with the main situations of total loss of the heat sink or of electrical power supplies beyond the baseline safety requirements in force. The most important measures are: ཛྷ ཛྷ installation of a large-capacity ultimate backup diesel- generator set, requiring the construction of a dedicated building to house it; ཛྷ ཛྷ setting up of an ultimate water source; ཛྷ ཛྷ creation of an ultimate water make-up system for each reactor and each spent fuel pool; ཛྷ ཛྷ reinforcement of the earthquake resistance of the containment venting filter; ཛྷ ཛྷ construction on each site of a local emergency centre capable of withstanding extreme external hazards (functionally independent in an emergency situation). On the various sites, EDF has begun to implement a large part of the final measures recalled above, more particularly the construction of buildings intended to house the high-capacity ultimate back-up diesel generator sets. ASN is inspecting the performance of the work. Phase 3 (as of 2019) This phase will supplement phase 2, in particular to take account of other potential accident scenarios. The most important measures are: ཛྷ ཛྷ removal of the residual heat by the steam generators, by means of an independent ultimate backup feedwater system supplied by the ultimate heat sink; ཛྷ ཛྷ addition of a new makeup pump to the primary system; ཛྷ ཛྷ completion of the fixed connection systems for the SG backup feedwater supply, the PTR cooling water tank and the spent fuel pit; ཛྷ ཛྷ installation of an ultimate instrumentation & control system and the definitive instrumentation of the “hardened safety core”; ཛྷ ཛྷ installation of a reactor containment ultimate cooling system that does not require opening of the containment venting- filtration system in the event of a severe accident; ཛྷ ཛྷ implementation of a solution for flooding the reactor pit to prevent corium melt-through of the basemat. The implementation of this “hardened safety core” and the provisions of phases 2 and 3 in particular, require validation of the design hypotheses for the material provisions and verification that the solutions proposed by the licensee can meet the safety objectives set and that they are technologically achievable. On the basis of the files transmitted by EDF and the studies carried out, ASN asked its Advisory Committee for Reactors (GPR) to submit its opinion on the more important points of these files. To date, three meetings of the GPR have been held: ཛྷ ཛྷ the GPR was consulted on 28th January and 10th February 2016 concerning the definition and justification of the natural hazard levels adopted by EDF for the “hardened safety core”. This review allowed the definition of the hazard levels to be considered for the design of the “hardened safety core” and, on certain points, led ASN to ask EDF for clarification; ཛྷ ཛྷ the session of 7th July 2016 concerned the new provisions proposed by EDF to mitigate the short and long term consequences of a core melt accident. This review enabled ASN to validate the principle of the new measures proposed by EDF in order to mitigate the consequences of a core-melt accident. On certain points, ASN asked EDF for clarifications and additional studies; ཛྷ ཛྷ the session of 2nd February 2017 focused primarily on the strategies for management of accidents that can occur on the reactor and pool and on the functional adequacy of the (new or existing) equipment for these accidents. 2.10 NPP operating life extension 2.10.1 The age of NPPs The NPPs currently in service in France were built over a relatively short period of time: 45 nuclear power reactors representing nearly 50,000 MWe, or three-quarters of the power output by all French nuclear power reactors, were commissioned between 1980 and  1990, and seven reactors, representing 10,000 MWe, between 1991 and  2000. In December 2017, the average ages of the reactors, calculated from the date of initial reactor criticality, were as follows: ཛྷ ཛྷ 36 years for the thirty-four 900 MWe reactors. ཛྷ ཛྷ 30 years for the twenty 1,300 MWe reactors. ཛྷ ཛྷ 20 years for the four 1,450 MWe reactors. 2.10.2 The periodic safety review The principle of the periodic safety review The periodic safety reviews of nuclear power reactors comprise the following two parts: ཛྷ ཛྷ A check on the condition and conformity of the facility: this step aims to evaluate the situation of the facility with respect to the rules applicable to it. It is based on a range of inspections and tests in addition to those performed in real- time. These verifications can concern checks on the initial design studies as well as field inspections of equipment not concerned by maintenance programmes, or tests conducted every ten years such as the containment pressure tests. Any