6 The need for a vision incorporating the “fuel cycle” 3. MOX fuel is a nuclear fuel consisting of a mixture of depleted uranium oxide and plutonium produced by Orano’s Melox plant. It can be used in the 24 reactors of 900 MWe. In France, MOX fuel uses only civil plutonium, extracted from spent fuel. The development of these modular reactor projects would appear to be inextricably linked to the availability of the fuel they need in order to operate. This availability refers not only to the existence of industrial production means for the fuels, but also the production capacity (see Table 4). Two SMR project developers have also initiated technical discussions with ASN and IRSN on projects to develop fabrication plants for their fuel: ∙Jimmy, concerning a project for a TRISO fuel fabrication plant; ∙Newcleo, concerning a project for a MOX(3) fuel fabrication plant for an FNR. With regard to the molten salt reactor projects (Naarea, Stellaria and Thorizon), these project developers are working in collaboration with Orano, which could eventually envisage developing production means for this type of fuel. Apart from the subject of fuel fabrication, ASN also underlines the need to have the transport systems approved for these fresh and used fuels, and to anticipate the development of technologies for reprocessing and for management of the associated waste. 7 Standardisation and international cooperation goals Despite the already high level of harmonisation of the safety standards of the International Atomic Energy Agency (IAEA) and the Europe-wide objectives and safety reference levels adopted by the Western European Nuclear Regulators Association (WENRA) each project to build a new reactor model in a country generally leads to the design being adapted to comply with the national regulations and the specific requirements of the local licensee (notably the organisation envisaged for routine operations, but also for management of emergency situations, jointly with the local public authorities). The economic model of the SMRs is based on mass production to reduce costs through economies of scale. The project developers thus aim to have a single model authorised in several countries. In order to remove the potential obstacles to the development of these new small reactors capable of contributing to decarbonisation of the global economy, a number of international initiatives are emerging. The IAEA is mobilising its members through the Nuclear Harmonization and Standardisation Initiative (NHSI) aiming to develop and encourage international cooperation modes for joint reviews of a given reactor model by several safety regulators, or to enable a country to familiarise itself with the evaluations already performed by other countries, in order to potentially reduce its own review workload. ASN is taking part in this work and at the International Convention on Nuclear Safety presented the lessons learned and the concrete results of the Joint Early Review (JER) of the Nuward reactor conducted with the safety regulators from Finland (STUK) and Czech Republic (SUJB). In view of the interest in and success of this cooperation between three safety regulators, Nuward aimed to take this JER further by launching a second phase in which the nuclear safety regulators from the Netherlands (ANVS) and Poland (PAA) joined the three regulators already involved. With respect to the European safety regulators, WENRA issued a position statement in 2021 on the fact that the safety goals set in 2010 for any new reactor remain applicable to the SMRs, but considered them to be a minimum level of requirement. WENRA felt that the state-of-the-art design and technologies used for these small reactors should enable a significant reduction to be achieved in radioactive releases following an accident, by comparison with the existing high-power reactors. Based on this observation, WENRA then set up a Working Group (WG) to draft proposed revisions to these safety goals. Within this WG, with the backing of other safety regulators, ASN supported the position presented to OPECST in January 2024, that is that the siting envisaged by the nuclear industry close to densely populated urban areas or industrial zones could only be envisaged if a higher level of safety is achieved, guaranteeing that any radiological releases would remain negligible in the event of an accident, including the most severe. Because at this stage no consensus has been reached at the European level on whether or not to revise the existing safety objectives, exchanges are continuing in order to explain this need for an increase in safety. Some countries are indeed defending the status quo regarding the published existing safety objectives (corresponding to the safety level of the EPR type reactors) and envisage ruling on a discretionary case-by-case basis with respect to the adequacy of the safety level of each project. TABLE 4 Presentation of technologies and corresponding fuels envisaged for the SMRs Technology Current availability of the associated specific fuel Light water reactor • Existing industrial capacity Fast Neutron Reactor, sodium or lead cooled • Industrial production capacity to be developed High-temperature reactor • No industrial production capacity for this particular type of fuel (TRISO)(*) + • Need for uranium enriched to nearly 20% (HALEU)(**) Molten salt reactor • No industrial production capacity for this particular type of fuel (mixture of U and PU integrated into chloride salts) • Need to develop natural chlorine(***) to chlore-37 enrichment capacity to avoid the formation of chlorine-36 * The particle fuel is referred to as “TRISO” for Tri-Structural Isotropic. The kernel consisting of uranium oxide, carbon and oxygen is surrounded by three insulating layers acting as the first containment barrier to retain the fission products. ** HALEU (High-Assay Low-Enriched Uranium) type uranium is enriched to a higher level of the uranium-235 isotope (from 5 to 20%) than the conventional Low-Enriched Uranium (LEU) used in the fuel for PWRs. *** Natural chlorine consists of two stable isotopes: chlorine-35 (75%) and chlorine-37 (25%). The problem with clorine-35 is that in the reactor core, it is transformed by neutron capture into chlorine-36 which is a very long half-life radioactive isotope and whose solubility and mobility through geological layers make it waste that is hard to manage. ASN Report on the state of nuclear safety and radiation protection in France in 2024 331 01 The emergence of small modular reactor projects 11 02 03 04 05 06 07 08 09 10 12 13 14 15 AP
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