ASN Report 2018

AUVERGNE-RHÔNE-ALPES REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION ASN drew up three violation reports in the exercise of its oversight duties. ASN was notified of 31 significant events rated level 1 on the INES scale, of which 29 occurred in BNIs and 2 in small- scale nuclear activities. In the small-scale nuclear activities, 10 events concerning radiotherapy patients were rated level 1 on the ASN‑SFRO scale and one was provisionally rated level 2. Bugey Site Bugey nuclear power plant The Bugey NPP, situated in the municipality of Saint‑Vulbas in the Ain département , 35 km east of Lyon and operated by EDF, comprises four pressurised water reactors, each of 900 MWe, commissioned in 1978 and 1979. Reactors 2 and 3 constitute BNI 78 and reactors 4 and 5 constitute BNI 89. The site accommodates one of the regional bases of the FARN (Nuclear Rapid Intervention Force), a special emergency response force created by EDF in 2011 following the Fukushima NPP accident. Its role is to intervene in pre- accident or accident situations, on any nuclear power plant in France, by providing additional human resources and emergency equipment. The Bugey site also accommodates Bugey 1, a graphite- moderated Gas-Cooled Reactor (CGR) commissioned in 1972, shut down in 1994 and currently undergoing decommissioning, and the Activated waste packaging and interim storage facility (Iceda). Lastly, the site accommodates an Inter-Regional Warehouse (MIR) for fuel storage. Reactors 2, 3, 4 and 5 in operation ASN considers that the nuclear safety, radiation protection and environmental protection performance of the Bugey NPP is in line with its general assessment of EDF’s performance. The NPPmaintains a high level of proficiency in the area of operating andmaintenance activities. ASN has nevertheless noted weaknesses in environmental protection and the control of fire-related risks. With regard to nuclear safety, the performance of the Bugey NPP in the areas of reactor management and periodic tests in 2018 is satisfactory. The site must remain vigilant in its preparation and performance of routine operating tasks such as themanoeuvring of valves or installation configuring actions carried out from the control room. With regard to maintenance, the 2018 workload was higher than in 2017, with three maintenance outages on reactors 4, 5 and 2. The performance of the Bugey NPP showed improvements and ASN notes that an effort has beenmade to limit the contingencies and technical events resulting from inadequate application of the procedures. With regard to protection of the environment, ASN notes that the Bugey NPP must improve its prevention of risks of leakage in buried structures (pipes and conduits) carrying radioactive and/or chemical fluids. ASN nevertheless notes that the overall performance of the NPP is satisfactory with regard to regulatory compliance in its management of effluents and waste. In the area of radiation protection, the performance of the Bugey NPP is mixed. Although the governance principles described in the organization are appropriate, they are not visibly applied in the field. In 2018, ASN noted a large number of deviations from requirements by workers (noncompliance with radiological zoning, noncompliance with radiological checks on leaving controlled areas, etc.).. Reactor 1 undergoing decommissioning Bugey 1 is a graphite-moderated Gas-Cooled Reactor. This first-generation reactor functioned with natural uranium as the fuel, graphite as the moderator and it was cooled by gas. The Bugey 1 reactor is an «integrated» Gas-Cooled Reactor, whose heat exchangers are situated inside the reactor vessel beneath the reactor core. ASN considers that the Bugey 1 reactor decommissioning and vessel characterisation operations are proceeding with a satisfactory level of safety. The licensee ensures rigorous monitoring of the equipment and the ongoing decommissioning works. Nevertheless, the main decommissioning operations, such as removal of the waste stored in the reactor vessel and decommissioning of the vessel itself, have been postponed due to difficulties in accomplishing the operations to decommission the reactor vessel under water. A scenario of decommissioning «in air» is therefore now being studied. This change of strategy would result in the decommissioning of the Bugey 1 reactor being pushed back by several decades, meaning that the decommissioning deadline (2027) set by its decree would no longer be met. (see chapter 13). In addition to this, EDF has carried out the Bugey 1 periodic safety review and submitted it to ASN in December 2018. 28  ASN report on the state of nuclear safety and radiation protection in France in 2018