ASN Report 2020

In 2020, at ASN’s request, EDF ran operating tests on the emergency diesel generator sets during a period of high temperatures. The purpose of these tests is to confirm the qualification demonstration of this equipment. Lightning risks The inspections relating to lightning reveal the need on all sites to set up reinforced organisation and oversight to improve the integration of the regulatory requirements associated with the management of this hazard. The lightning risk assessments may be based on information which does not actually reflect the real situation on the facilities. Despite a few improvements in 2020, ASN observed a significant delay in the performance of the work identified in the technical studies. ASN also regularly finds that the deadlines for performance of the periodic checks on the lightning protection systems by the competent inspection organisations are not adhered to. These points were the subject of requests for corrective action. EDF has defined a programme of work to improve the situation. 2.4.7 Monitoring facilities compliance with the requirements Maintaining the conformity of the facilities with their design, construction and operating requirements is a major issue insofar as this conformity is essential for ensuring compliance with the safety case. The processes employed by the licensee, notably during reactor outages, contribute to maintaining the compliance of the facilities with the requirements resulting from this safety case. Reactor outages The nuclear power reactors must be periodically shut down for replacement of the fuel depleted during the electricity production cycle. One third or one quarter of the fuel is thus renewed at each outage. These outages allow temporary access to certain parts of the facility which are not accessible during production, although with specific radiation protection precautions. They are thus put to good use for verifying the condition of the equipment by carrying out checks, tests and maintenance, as well as for performing works on the facility. These refuelling outages can be of several types: ∙ Refuelling Outage (ASR) and Maintenance Outage (VP): these outages, which last a few weeks, are devoted to replacing a part of the fuel and to carrying out a verification and maintenance programme, which is more extensive during a VP than during an ASR. ∙ Ten-yearly outage (VD): this is an outage involving a programme of in-depth verification and maintenance. This type of outage, which lasts several months and takes place every ten years, enables the licensee to carry out large-scale operations such as the complete inspection and hydraulic testing of the reactor coolant system, hydrotesting of the containment or incorporation of design changes resulting from the periodic safety reviews. These outages are scheduled and prepared by the licensee several months in advance. ASN checks the steps taken by the licensee to ensure the safety of the facility, environmental protection and radiation protection of the workers during the outage, as well as the safety of the reactor for the next production cycle. In the light of the provisions of its resolution 2014-DC-0444 of 15 July 2014 concerning PWR shutdowns and restarts, the monitoring performed by ASN primarily concerns: ∙ during the outage preparation phase, the content of the outage programme drawn up by the licensee. As necessary, ASN may ask for additions to this programme; ∙ during the outage, through regular briefings and inspections, the implementation of the programme and the handling of any unforeseen circumstances; ∙ at the end of the outage, when the licensee presents the reactor outage review, the condition of the reactor and its suitability for restart. It is after this inspection that ASN may or may not approve reactor restart; ∙ after reactor restart, the results of all the tests performed during the outage and in the restart phase. The identification and processing of deviations The checks initiated by EDF within the framework of its operating baseline requirements and the additional verifications requested by ASN, on the basis more particularly of operating experience feedback, can lead to the detection of deviations from the defined requirements, which must then be processed. These deviations can have a variety of origins: design problems, construction errors, insufficient expertise in maintenance work, deterioration through ageing, organisational shortcomings, etc. The steps taken to detect and correct deviations, specified in the Order of 7 February 2012, play an essential role in maintaining the level of safety of the facilities. “Real-time” checks Carrying out periodic test and preventive maintenance programmes on the equipment and systems contributes to identifying deviations. Routine visits in the field and technical inspection and verification of activities considered to be important for the protection of persons and the environment are also effective means of detecting deviations. Verifications during reactor outages EDF takes advantage of nuclear reactor outages to carry out maintenance work and inspections which cannot be performed when the reactor is generating electricity. These operations more particularly correct deviations already known, but can also lead to the detection of new ones. Before each reactor restart, ASN asks EDF to identify any anomalies not yet remedied, to take appropriate compensatory measures and to demonstrate the acceptability of these anomalies with respect to the protection of persons and the environment for the coming production cycle. Processing of deviations A deviation is a non-compliance with a defined requirement or a requirement set by the licensee’s integrated management system. A deviation may thus affect a structure, a system or a component of the facility. It may also concern compliance with an operating document or the working of an organisation. The regulations require that the licensee identify all deviations affecting its facilities and process them. The activities related to the processing of deviations are activities important for the protection of persons and the environment. They are thus subject to oversight and monitoring requirements, the implementation of which is regularly checked by ASN. ASN Report on the state of nuclear safety and radiation protection in France in 2020 301 10 – THE EDF NUCLEAR POWER PLANTS 10