ASN Report 2020

approved by the Order of the Minister responsible for energy of 2 October 2008. 1.4  Fuel cycle consistency in terms of nuclear safety and radiation protection The “nuclear fuel cycle” comprises the fabrication of the nuclear fuel used in the nuclear power plant reactors, its storage and its reprocessing after irradiation. Several licensees are involved in the cycle: Orano, Framatome, EDF and Andra. ASN monitors the overall consistency of the industrial choices made with regard to fuel management and which could have consequences for safety. In this context, ASN periodically asks EDF to submit a “Cycle Impact” file prepared jointly with the fuel cycle stakeholders and presenting the consequences – for each step of the “nuclear fuel cycle” – of EDF’s strategy for use of the different types of fuel in its reactors. The last “Cycle Impact 2016” file, for the period 2016-2030, produced in collaboration with Framatome, Orano and Andra, more particularly identifies the maximum thresholds (capacity saturations, maximum isotope content of fuel reached, etc.) foreseeable until 2040, on the basis of various energy mix evolution scenarios. This update comprises a number of innovations with respect to the previous approaches initiated in 1999 and 2006: ∙ The study period, which habitually covered ten years, was increased to fifteen years, in order to take account of the time actually observed in the nuclear industry for designing and building any new facilities identified as being necessary for implementation of the strategy. ∙ Radioactive substances transport contingencies were explicitly taken into account. ∙ Nuclear reactor closures were studied for the period of time considered, in particular assuming stable electricity demand until 2025, to take account of the planning provisions included in the Energy Transition for Green Growth Act 2015-992 of 17 August 2015. ∙ The strategy for managing and storing spent fuels pending reprocessing or disposal was explained. After examination, ASN delivered its opinion on 18 October 2018, the main conclusions of which are as follows. ASN considers that the “Cycle Impact 2016” file provides a satisfactory presentation of the consequences on the nuclear facilities, transport operations and waste of the various “nuclear fuel cycle” evolution scenarios. However, the consequences of the contingencies which could affect the operation of the cycle need to be studied in greater depth. ASN underlines the need to anticipate any strategic change in the functioning of the fuel cycle by at least ten years so that it can be designed and carried out under controlled conditions of safety and radiation protection. This for example entails ensuring that – given the incompressible development times for industrial projects – the need for the creation of new spent fuel storage facilities or for new transport packaging designs are addressed sufficiently early. For the coming decade, it would notably appear that to avoid reaching the maximum capacity of existing storage facilities too quickly (spent fuel pools of nuclear reactors and of La Hague), any reduction in output by reactors consuming MOX fuel must be accompanied by a reduction in that from reactors consuming fuel obtained from Enriched Natural Uranium (ENU), so that all ENU spent fuels are reprocessed. In the longer term, it will be necessary either to have new storage capacities that are very significantly greater than the current and projected capacities, or to be able to use MOX fuel in reactors other than the 900 MWe reactors, which are the oldest. The time- frame required for the design and production of these options is about ten years. ASN therefore asks the industrial players to start examining these two options without delay. Every five years, the Government updates the Multi-year Energy Plan (MEP). The functioning of the “nuclear fuel cycle” is liable to evolve according to the orientations thus defined. ASN therefore urges the industrial players to study the safety and radiation protection consequences of implementing the MEP on the “nuclear fuel cycle”, and its consistency, at each of its revisions. Further to this examination, the year 2020 was marked by several events which disrupted the balance of the cycle: ∙ The Melox plant again experienced difficulties in producing MOX fuel of the required quality and quantity for the EDF fleet of reactors, although to a lesser extent than in 2019. The new production process in fact leads to a greater disparity in the size of the depleted uranium grains and thus a higher discard rate. This led EDF to reduce the number of MOX assemblies present in the core of certain reactors. This situation also leads to a lesser consumption of the plutonium produced by the La Hague plants and a larger number of spent fuel assemblies in the pools. The excess plutonium under the responsibility of Orano, and the non-conforming MOX, will eventually have to be resorbed. ∙ A fission products evaporator-concentrator at La Hague reached a level of corrosion requiring increased surveillance of its thickness, so as to guarantee its ability to withstand the pressure in an earthquake situation. In 2020, ASN thus authorised particular surveillance methods for this evaporator, which apply to its final operating phase. If the evaporator is shut down before it is replaced, this will lead to a reduction in the reprocessing capacity of the La Hague plants. These disruptions of the cycle back-end plants confirm the need for countermeasures identified by ASN in its opinion of 18 October 2018 should commissioning of the EDF centralised storage pool occur after saturation of French spent fuel storage capacity. 1.5  Outlook: planned facilities New uranium storage facility project on the Tricastin site In February 2015, Orano informed ASN that it wanted to create a new BNI on the Tricastin site intended for storage of uranium- bearing materials resulting from fuel reprocessing. Orano undertook work to optimise the existing storage facilities on the site in order to push back their saturation date from 2019 to 2021 and in November 2017 submitted a creation authorisation application for new storage buildings. In 2018, ASN informed the Minister responsible for nuclear safety that the content of the creation authorisation application was sufficient for its examin­ ation to take place. A public inquiry was held on this subject at the end of 2020. The project should receive an authorisation decree in 2021. “New concentration of fission products” project on the La Hague site In order to replace the fission products evaporator-concentrators at La Hague, which are suffering from a more advanced stage of corrosion than imagined in the design, Orano is building new units, called “NCPF”, comprising six new evaporators. This particularly complex project required several authoris­ ations and was the subject of an ASN resolution in 2020, concerning the process of three of these evaporators (NCPF T2). The authorisations for connection of this new equipment to the existing units will be the subject of other resolutions and authoris­ ations in the coming months. 326 ASN Report on the state of nuclear safety and radiation protection in France in 2020 11 – “NUCLEAR FUEL CYCLE” INSTALLATIONS