ASN Report 2017

352 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 12  - EDF Nuclear Power Plants FOCUS Significant safety event concerning a lack of seismic resistance of the surge tanks of the emergency diesel generators cooling systems On 17th January 2018, ASN rated as level 2 on the INES scale a significant safety event concerning a lack of seismic resistance on the part of the surge tanks of the emergency diesel generators cooling systems for reactors 1 and 2 of the Paluel NPP. This flaw is linked to a corrosion phenomenon: it is notably the result of insufficient maintenance of this equipment. This flaw was detected by EDF in the Penly NPP and was the subject of a generic significant event notification by EDF on 9th November 2017, with respect to several 1,300 MWe reactors. Work (repair or replacement) was carried out between August and October 2017 on the corroded surge tanks for the nuclear power reactors concerned. The ASN rating was: ཛྷ ཛྷ level 2 on the INES scale for the flaw concerning the two backup diesel generators for reactors 1 and 2 of the Paluel NPP, as the two redundant electricity generating sets were affected; ཛྷ ཛྷ level 1 on the INES scale for the flaw concerning only one of the two backup diesel generators for Nogent-sur-Seine 1, Penly 1, Belleville-sur-Loire 2, Cattenom 2 and Paluel 3 reactors, as only one of the two electricity generating sets was affected. Ten-yearly verifications: conformity checks EDF carries out periodic safety reviews of the nuclear reactors every ten years, in accordance with the regulations (see point 2.10.2). EDF thus compares the actual condition of the NPPs with their applicable safety requirements and identifies any deviations. These verifications can be supplemented by a programme of additional investigations designed to check the parts of the facility which are not covered by a preventive maintenance programme. The additional verifications in response to ASN requests In addition to the steps taken by EDF with regard to its operating baseline requirements, additional checks are carried out at the request of ASN, whether with regard to operating experience feedback about events which have occurred on other facilities, after inspections, or after examination of the provisions proposed by the licensee within the context of the periodic safety reviews. Informing ASN and the public When a deviation is detected, and in the same way as any BNI licensee, EDF is required to assess the impacts on nuclear safety, radiation protection and protection of the environment. If necessary, EDF sends ASN a significant event notification. As of level 1 on the INES scale, the public is informed on www.asn.fr of the events thus notified by the licensees. ASN’s remediation requirements On 6th January 2015, ASN published Guide No. 21 concerning the handling of non-compliance with a defined requirement for Equipment Important for Protection (EIP). This guide applies to all anomalies affecting an EIP that performs a function necessary for the nuclear safety case with regard to radiological accidents affecting a pressurised water reactor. It presents ASN’s requirements concerning the correction of non-conformities and presents the approach expected of the licensee in accordance with the principle of proportionality. This is based more specifically on an assessment of the potential or actual consequences of any deviation identified and on the licensee’s ability to guarantee control of the reactor in the event of an accident, by taking appropriate compensatory measures. Significant events EDF is required to notify ASN of and then analyse any significant events occurring in its NPPs (see chapter 4, point 3.3). Each significant event is, whenever appropriate, rated by ASN on the INES scale. This processing of notification and analysis of significant events contributes to operating experience feedback and to the continuous improvement approach for the protection of the interests mentioned in Article L. 593-1 of the Environment Code. At the local and national levels, ASN examines all significant events notified (a summary of their analysis for 2017 is given in point 2.4.8). The significant events considered to be noteworthy owing to their severity or their recurring or generic nature, are the subject of an in-depth analysis by ASN. During inspections in the NPPs and the EDF head office departments, ASN checks the licensee’s organisation and the steps taken to learn the technical and organisational lessons from operating experience feedback. Finally, at the request of ASN, the GPR in 2017 examined the experience feedback from PWR operations from the viewpoint of control of facility compliance with design, construction and operating requirements. 2.4.8 Evaluation of facilities compliance wtih the requirements The periodic tests, equipment maintenance and replacement programmes, the reactor periodic safety review approach and the correction of deviations should make it possible to check and ensure the lasting ability of the equipment in an NPP to perform the functions assigned to it for protection of the interests mentioned in Article L.593-1 of the Environment Code. The detection, characterisation and handling of deviations are covered by regulatory provisions of the Order of 7th February 2012. These provisions are important because they contribute to controlling the conformity of the facilities with the requirements for protection of the interests stipulated by the law, a pre- condition for their operation. Moreover, control of conformity should enable the improvements that result from the periodic