ASN Report 2020

As a general rule, the management of radiation protection at the Saint‑Laurent‑des‑Eaux NPP on the whole meets the expectations of ASN. The number of deviations detected by ASN in 2020 is down compared with 2019, when a tightened radiation protection was carried out. This f inding must also be correlated with the fact that only one reactor outage took place in 2020, whereas usually there are two. The organisation of the site to meet the environmental protection regulatory requirements is considered satisfactory. The various facilities inspected are well kept. The management of waste, like the liquid and gaseous discharges, raised no particular remarks. As far as labour inspection is concerned, further to the f ire- risk inspection carried out in 2019, the NPP must continue its efforts regarding the utilisation and maintenance of the evacuation systems. Lastly, the licensee is also expected to take action in response to the f indings made during the inspections conducted in the buildings of the DUS. In the context of the Covid‑19 pandemic, various inspections concerning management of the health crisis were carried out on documents and in the field. The observations addressed to the NPP and to the subcontractor companies necessitated corrective actions. Reactors A1 and A2 undergoing decommissioning The former Saint‑Laurent‑des‑Eaux NPP constitutes a BNI comprising two “integrated” GCRs, reactors A1 and A2. These first-generation reactors used natural uranium as the fuel, graphite as the moderator and were cooled by gas. Their f inal shutdown was declared in 1990 and 1992 respectively. Complete decommissioning of the installation was authorised by the Decree of 18 May 2010. However, given the change in the decommissioning strategy for the GCRs indicated by EDF in 2016, ASN Chairman’s res- olution CODEP-CLG-2020-021253 of 3 March 2020 requires EDF to submit a new decommissioning f ile before the end of 2022, to modify the current decree in view of the changes in the scenario for decommissioning the reactor pressure vessel and the changes in the stated time frames (see chapter 13). The decommissioning worksites were delayed by several months in 2020 on account of the restrictions laid down to combat the Covid‑19 pandemic. EDF has nevertheless put in place its activity continuity plan to maintain some of the worksites and perform the periodic inspections and tests of its equipment. ASN considers that the level of safety of the Saint‑Laurent- des‑Eaux A reactors is satisfactory. ASN’s inspections found that the overall upkeep of the premises and worksites was good. In addition, the organisation put in place to control the static and dynamic containments of the facilities is satisfactory. ASN also notes that the radioactive effluents present on the nuclear waste storage areas have been repackaged in long- term containers better suited to the characteristics of the effluents. However, monitoring of ageing of the equipment used in the decommissioning operations must be improved. Saint‑Laurent‑des‑Eaux silos The facility, authorised by the Decree of 14 June 1971, consists of two silos whose purpose is the storage of irradiated graphite sleeves originating from the operation of Saint‑Laurent‑des‑Eaux A GCRs. Static containment of this waste is ensured by the concrete bunker structures of the silos, which are sealed by a steel lining. In 2010, EDF installed a geotechnical containment around the silos, reinforcing the control of the risk of dissemination of radioactive substances, which is the main risk presented by the installation. Operation of this BNI is limited to surveillance and upkeep measures: radiological monitoring inspections and measurements in the silos, checking there is no water ingress, checking the relative humidity, the dose rates around the silos, the activity of the water table, monitoring the condition of the civil engineering structures. ASN’s inspections found that these actions were carried out satisfactorily. In the context of the change of decommissioning strategy for the GCRs, EDF announced in 2016 its decision to start removing the graphite sleeves from the silos without waiting for a graphite waste disposal route to become available. To this end, EDF envisages creating a new graphite sleeve storage facility on the Saint‑Laurent‑des‑Eaux site. ASN is waiting for EDF to declare the f inal shutdown of the facility. Submission of the decommissioning f ile, which will take into account the emptying, post-operational clean-out and demolition of the existing silos, is planned for 2022. 56 ASN Report on the state of nuclear safety and radiation protection in France in 2020 REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION