Abstracts ASN Report 2021

A weakened fuel chain, putting pressure on the electricity system The “fuel cycle” industry consists of all the facilities contributing to the production of f resh fuel, the reprocessing of spent fuels and the reuse of products f rom reprocessing. These non-redundant facilities are the links in a chain, the operation of which can be disrupted if one of them experiences a long-term failure. A series of events is currently weakening the entire “fuel cycle” chain and is a major strategic concern for ASN requiring particularly close attention, in that an unanticipated build-up of radioactive materials or waste could lead to storage conditions that are unsatisfactory from the safety standpoint. Construction of the centralised spent fuel storage pool being planned by EDF to address the risk of saturation of the existing pools by 2030, the need for which was identified as of 2010, has not yet begun. This pool will not be available before 2034 at best. This delay will require interimmeasures to increase existing storage capacity. The solution chosen by Orano, which consists in increasing the storage density in the existing pools at the La Hague facility, cannot be considered a longterm one, given the required storage periods of about a hundred years, and in the light of the most recent safety standards. Furthermore, the operating issues experienced by the Orano Melox plant in recent years, which worsened in 2021, are leading to the saturation of plutoniumbearing materials storage capacity as of 2022, owing to the production of a large quantity of manufacturing scrap. These issues are already leading to the “demoxing” of some of the 900 MWe reactors, which used MOX as fuel. They could also lead to saturation of the spent fuel pools at the La Hague facility earlier than 2028-2029. Finally, the detection of corrosion in the existing evaporators in Orano’s La Hague facility earlier than expected in the design has reduced reprocessing capacity until new fission product evaporators-concentrators are commissioned and could further degrade the saturation margins of the pools at La Hague. Overall, these situations reflect a lack of anticipation and precaution owing to the absence of margins, which is weakening the entire “fuel cycle” chain and which could, in turn, have consequences on the operation of the Nuclear Power Plants (NPPs). Pressure on the availability of the NPP fleet, underscoring the need to maintain margins for safety The winter of 2021-2022 was marked by a lower than anticipated availability of the NPP fleet. This was for a number of reasons, some of which could be foreseen, others less so. The postponed commissioning of the Flamanville EPR, the 2020 shutdown of the two Fessenheim reactors and the schedule of heavy maintenance operations (“major overhaul”), as of 2018, were known. In addition to this lower availability –which was predictable as of 2018, there was the unexpected impact of the Covid-19 pandemic– notably the f irst lockdown, identified as of mid-2020. This lockdown led to reactor maintenance and refuelling operations being spread out over a longer period, with the consequence of reducing production capacity margins over several consecutive winters. Finally, this winter, the four N4 series reactors of Civaux and Chooz, plus one reactor at Penly were either shut down or kept shut down, for in-depth inspections and repairs, following the detection of stress corrosion anomalies on welds on the reactors’ safety injection system. An inspection program for the reactors of the NPP fleet likely to be the most severely affected, extending over several months, has been proposed by EDF. This build-up of events illustrates the absolute need –as ASN has pointed out to the public authorities and nuclear sector stakeholders numerous times– to maintain design-basis margins for the electricity system and the installations, in order to deal with unexpected events and avoid having to resort to a trade-off between the safety of installations and the availability of electricity supply. … 4 ABSTRACTS – ASN Report on the state of nuclear safety and radiation protection in France in 2021 EDITORIAL BY THE COMMISSION