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. The development of these modular reactor projects is dependent on 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 sponsors also initiated technical discussions with ASN and IRSN in 2023 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 a Lead-Cooled Fast Neutrons Reactor (LFR). 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 both internationally, with the safety standards from the International Atomic Energy Agency (IAEA), and at the European level, with the safety objectives and reference levels adopted by the Western European Nuclear Regulators’ Association (WENRA), each project to build a reactor model in a new country generally leads to modification of the original design to adapt to the national regulatory context and the requirements of the local licensee. Although the cost of these adaptations remains acceptable in the case of large nuclear power reactors, this is not necessarily the case for SMRs, for which the business model is based on mass production to reduce costs and achieve the profitability threshold, thus implying that a given model can be authorised by several countries. In order to remove the potential obstacles to the development of these new reactors, a number of international initiatives have emerged. The IAEA is mobilising its members through an initiative called “NHSI” (Nuclear Harmonization and Standardisation Initiative) 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 reduce its own review workload. ASN is taking part in this work and at the International Convention on Nuclear Safety presented the concrete results of the Joint Early Review (JER) of the Nuward reactor (see box next page) 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), Poland (PAA) and Sweden (SSM) joined the three regulators already involved. TABLE 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 * 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. ** High-Assay Low-Enriched Uranium (HALEU) 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 and Boiling Water Reactors (BWRs). *** Natural chlorine consists of two stable isotopes: chlorine-35 (75%) and chlorine-37 (25%). In the reactor core, the chlorine-35 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. 4 ASN Report on the state of nuclear safety and radiation protection in France in 2023 325 • 11 • The emergence of small modular reactor projects 11 05 15 08 04 14 06 07 13 AP 03 10 02 09 12 01
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