ASN Report 2018

CENTRE-VAL DE LOIRE REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION Saint‑Laurent‑des‑Eaux site The Saint‑Laurent‑des‑Eaux site, situated on the banks of the river Loire in the municipality of Saint‑Laurent‑Nouan in the Loir‑et‑Cher département , comprises various nuclear installations, some of them in operation and others undergoing decommissioning. The Saint‑Laurent‑des‑Eaux NPP comprises two operating reactors, B1 and B2, which were commissioned in 1980 and 1981 and constitute BNI 100. The site also features two old gas-cooled nuclear reactors, A1 and A2, currently in the decommissioning phase, and two silos for storing the graphite sleeves from the operation of reactors A1 and A2. Saint-Laurent-des-Eaux NPP Reactors B1 and B2 in operation ASN considers that the performance of the Saint‑Laurent‑ des‑Eaux NPP is on the whole in line with the general assessment of EDF in the areas of safety, environment and radiation protection. With regard to nuclear safety, ASN considers that the site has regressed with respect to the previous years. ASN nevertheless underlines the good general upkeep of the worksites, the satisfactory condition of the components and equipment of the inspected systems, and a high- quality independent safety organisation. This being said, shortcomings in operating rigour and operational control management of the facilities were observed in 2018. Numerous events highlight, for example, deficiencies in the management of operating contingencies and poor monitoring of procedures. The NPP’s organisation for characterising deviations and justifying their remediation time frames is not sufficiently robust andmust be improved, as must experience feedback management. Generally speaking, Saint‑Laurent‑des‑Eaux shows satisfactory radiation protection performance, although it came down in 2018. Despite the involvement of the personnel responsible for radiation protection, the traceability and monitoring of dosimetry optimisation actions on high-risk work sites can in particular be improved. Several significant radiation protection events moreover reveal failures of workers to comply with requirements. The site’s organisation to meet the regulatory requirements with regard to the environment can be further improved in a number of aspects. The dedicated department demonstrates resolve to make improvements and progress, supported by an active independent environment organisation. Good practices are observed during the inspections on the various themes addressed. Nevertheless, deficiencies in deviation detection have again been observed in this area. In 2019, ASN will ensure that the site works actively on the reviews of the conformity of its facilities with the regulatory framework. Reactors A1 and A2 undergoing decommissioning The former Saint‑Laurent‑des‑Eaux NPP constitutes a Basic Nuclear Installation comprising two «integrated» Gas- Cooled Reactors, Saint‑Laurent‑des‑Eaux reactors A1 and A2. Their final shutdown was pronounced in 1990 and 1992 respectively. Complete decommissioning of the installation was authorised by the Decree of 18 May 2010. In March 2016, EDF announced a complete change of decommissioning strategy for its definitively shut down reactors (see chapter 13). Pending decommissioning of the reactor pressure vessels, other operations are performed outside the pressure vessel or to prepare for its decommissioning. Some worksites presenting a risk of contamination by alpha radionuclides (emptying tanks, characterising sludge, removing the source term from the Saint-Laurent-des-Eaux A2 pool) had been suspended in 2016 following the discovery of confirmed cases of internal contamination of personnel working on these sites. In 2017, EDF initiated an operating rigour plan which stepped up worker training and monitoring. The worksites were resumed in 2017. ASN has checked the measures defined in the plan and observed improvements in the management of the worksites involving an «alpha» contamination risk. The liquid and solid waste removal operations continued as part of the decommissioning of the Saint-Laurent-des-Eaux A reactors. Research is still in progress to create a new legacy waste characterisation chamber and to define a storage solution to bring together «legacy waste with projected disposal route» and «legacy waste without disposal routes». ASN considers that the level of safety of the Saint‑Laurent‑ des‑Eaux A reactors is satisfactory. To give an example, the organisation of the aids put in place to monitor waste management and the periodic checks of the installations are satisfactory. Saint‑Laurent‑des‑Eaux silos The facility, authorised by Decree of 14 June 1971, consists of two silos whose purpose is the storage of irradiated graphite sleeves (Low-Level Long-Lived Waste - LLW-LL) coming from the operation of Saint‑Laurent‑des‑Eaux A Gas- Cooled Reactors. 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 (BNI 74) is limited to surveillance and maintenance measures (inspections and radiological monitoring of the silos, checking there is no water ingress, checking the relative humidity, the dose rates in the vicinity ASN report on the state of nuclear safety and radiation protection in France in 2018  45