Several Small Modular Reactor (SMR) projects are currently being developed around the world. These are reactors with a power of less than 300 Megawatts electric (MWe), built mainly in a factory. They use a variety of technologies: that of the Pressurised Water Reactors (PWRs) or advanced technologies (high-temperature, molten salt, fast neutron, etc. reactors). The characteristics of the SMRs, in particular their low power and compactness, contribute to their safety. The French Nuclear Safety Authority (ASN) considers that the designers should take advantage of these characteristics to propose reactors meeting more ambitious safety objectives than the existing high-power reactors. ASN is also participating in international SMR working groups. Within this framework, it is holding discussions with its foreign counterparts in order to promote the definition of ambitious international baseline requirements, share its practices and benefit from operating experience feedback from its counterparts. 1 The Government’s call for project proposals 1. France opted for a “nuclear fuel cycle” including the reprocessing of spent fuel. This reprocessing enables reusable materials (uranium and plutonium) to be recovered, while the other compounds (fission products and minor actinides) constitute the ultimate waste. At present, only a part of the reprocessed materials can actually be reused to fabricate new fuels. The notion of a “closed’ nuclear fuel cycle” corresponds to the goal of reprocessing the fuels several times and reusing all of the recovered materials or even, for some innovative reactor projects, also consuming the waste such as the fission products and minor actinides. In March 2022, the Government launched a call for project proposals for innovative nuclear reactors, aiming to create a new ecosystem of nuclear start-ups, in addition to the existing heavyweights in the sector. This call for project proposals is part of the France 2030 Plan to decarbonise the economy, in particular aiming to develop new nuclear reactor concepts which: ∙in addition to producing electricity, will also meet the need for the production of heat with temperatures of several hundred degrees, offering an alternative to the use of gas for a large number of industrial processes; ∙can help close the “nuclear fuel cycle”(1) and improve radioactive waste management, by helping to reduce its volume or its activity. This was the context in which about ten new companies developing SMR projects appeared in France in 2022 and 2023. This emergence of numerous SMR projects is a global and not a purely national phenomenon: a large number of countries are concerned, especially the major nuclear nations: the United States, Canada, China and Russia. In total, more than sixty or so SMR projects are currently under development around the world. 2 From power reactors to small modular reactors The industrial nuclear reactors operated in France have until now only focused on the large-scale production of electricity. The French Nuclear Power Plant (NPP) fleet was gradually created with a regular trend being to increase the power of these reactors, from 900 MWe for the first reactors, to 1,600 MWe for the Flamanville EPR reactor. By more specifically targeting the market to supply energy directly to industrial customers, the new reactor designers responding to the Government’s call for project proposals are moving away from the traditional model, by developing reactors 10 to 400 times less powerful than the Flamanville EPR reactor, hence the term “small” reactors (see Table 1). This significant power reduction also implies a radical adaptation of the development business model for these small reactors, on the one hand by seeking to reduce construction times and, on the other, by relying on standardisation and mass production. This new industrial model with mass production involving a large share of prefabrication in the factory is why these small reactors are referred to as “modular”. TABLE 1 Comparative thermal power of the reactors Thermal power(*) of the reactor core (MWth) Flamanville EPR reactor 4,300 Small Modular Reactors which responded to the call for projects 20 to 540 * In the light of the supply of energy which is now not exclusively in the form of electricity, the characteristic power of these SMRs is expressed in terms of the thermal power of their core rather than the electrical power output. ASN Report on the state of nuclear safety and radiation protection in France in 2024 327 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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