ASN Report 2018

• Other hazards The safety case for the EDF NPPs also takes account of other hazards such as high winds, snow, tornados, cold air temperature, man-made hazards (transport of dangerous goods, industrial facilities, airplane crashes, etc.), and hazards affecting the heatsink. 2.4.6  –  Evaluation of the risk prevention measures relating to hazards The Fukushima Daiichi accident led EDF to reinforce its organisation for the control of risks relating to hazards. More specifically, networks of coordinators were set up in all the NPPs to oversee the implementation of the actions defined to deal with these hazards. Annual reviews are also held to improve this organisation. • Fire risks On the basis of its inspections, ASN observes that the integration of operating experience feedback regarding the fire risk is on the whole satisfactory and that the refurbishment of the fire detection system is continuing on the nuclear reactors. The number of outbreaks of fire recorded for 2018 is below that for 2017. However, the findings made in previous years are still valid with regard to some of the sites inspected: ∙ ∙ management of zoning anomalies in the premises could be improved in order to prevent the spread of fire; ∙ ∙ deviations linked to the management of fire detection inhibitions; ∙ ∙ deviations in the management of stores of equipment representing significant heat potential, in particular during reactor outage phases; ∙ ∙ deviations in the use of fire permits and sometimes incorrect management of the compensatory measures defined in the fire risk assessments; ∙ ∙ weaknesses in the maintenance of the fixed sprinkler equipment; ∙ ∙ problems with the accessibility of fire-fighting equipment; ∙ ∙ weaknesses in the field of fire-fighting. In 2018, ASN carried out inspections on the topic of the control of fire risks in all the NPPs and asked for corrective measures to be taken to remedy the findings. ASN notes the efforts made by certain sites to reduce these deviations through the deployment of tools and action plans, but considers that if they are to be effective, the personnel must receive more comprehensive assistance with their implementation. ASN thus observed that in 2018, EDF had more specifically initiated an action plan aimed at identifying the premises particularly sensitive to the fire risk and, in them, to eliminate errors in the control of the risks entailed by this hazard. In addition the time taken to remedy certain deviations or to take corrective actions as a result of experience feedback could be reduced. ASN asked EDF to pay particular attention to the management of combustible materials brought into the reactor building, notably during the reactor outage phases. • Explosion risks Despite the steps taken by EDF, control of the explosion risks is not yet satisfactory on all the nuclear reactors. Certain maintenance work and inspections required by EDF’s internal doctrine are not always carried out satisfactorily. Furthermore, ASN observes that the updating of certain documents (periodic test procedures and documents concerning protection against explosions), the integration of lessons learned, the handling of certain deviations and the deployment of certain modifications are sometimes postponed, which cannot always be justified with regard to the potential safety consequences. ASN notes the efforts made by EDF to reduce these deviations through the implementation of reinforced monitoring and deployment of the action plan. However, ASN considers that EDF must continue to pay particular attention to this point and to application of the regulations concerning the explosive atmospheres formation risk (ATEX), and ensure that the explosion risks prevention approach is implemented with all necessary rigour on all the sites. • Internal flooding risks The provisions for the prevention and management of the internal flooding risk are also regularly checked by ASN. These inspections show that the steps taken to manage this type of hazard are not up to the level expected for all the sites. ASN more specifically observes that on some sites, the network of coordinators is still being set up and is not fully operational. EDF has initiated walkdowns to identify the piping which could cause internal flooding in the electrical buildings, which are particularly vulnerable to this risk, in order to assess the need to reinforce their maintenance. In accordance with ASN’s requests, EDF will extend these surveys to the other buildings. ASN sees as positive the fact that EDF has initiated the refurbishment of the circuits of certain cooling systems that are particularly susceptible to corrosion. In 2016 and 2017, EDF sent ASN notification of several significant safety events concerning the flow of water caused by leaks from piping in poor condition or valve lock-out errors during maintenance operations. Considerable efforts are required on most sites to improve the management of the flooding risk, in particular with respect to: ∙ ∙ maintenance of the necessary equipment (piping, floor drains, etc.); ∙ ∙ risk assessments during maintenance operations and in the event of detection of a malfunction of a necessary equipment item; ∙ ∙ compliance with the action deadlines identified by the annual reviews; ∙ ∙ the training of the coordinators and awareness-raising among the EDF and contractor personnel. • Seismic risks The operating and maintenance conditions of the seismic detection equipment are considered to be satisfactory. The annual reviews allow the identification of areas for progress and these are on the whole implemented. EDF is however required to continue with its efforts, notably with regard to the training of staff and awareness-raising among contractors. ASN notes that the operating instructions in the event of an earthquake are not always sufficiently operational and that more regular simulations would improve their applicability. 290  ASN report on the state of nuclear safety and radiation protection in France in 2018 10 – EDF NUCLEAR POWER PLANTS