BASE expert opinion on Small Modular Reactors (SMR): Doubts and a plethora of unanswered questions

How could small modular nuclear power plants (SMRs) be deployed, and what are the safety risks associated with them? The Federal Office for the Safety of Nuclear Waste Management (BASE) had commissioned an expert opinion on these questions, and the answers indicate that although SMRs may often be based on old technical concepts, they could pose a range of new challenges and difficulties in terms of hazards and economic viability. Only recently was an SMR concept in the US abandoned despite government support.

Having commissioned the Öko-Institut Freiburg, the Technische Universität (TU) Berlin and the Physikerbüro Bremen to render an expert opinion, BASE is now releasing an English-language summary of this 2021 report on small modular reactor (SMR) concepts. The English version of this scientific report is based on the data available in 2021. It analyses potential areas of application for SMRs, and identifies the safety risks and hazards associated with SMRs. The experts involved analysed a total of 136 older and current SMR concepts.

The report provides important findings, for example on the contribution of SMRs to combating climate change as propagated by manufacturers: For SMRs to be able to fulfil the expectations of the nuclear industry and make a significant contribution to the energy production in the world, thousand to ten thousand SMR plants would have to be built to generate the same electrical power as existing nuclear power plants. However, such a multiplication of units would increase other risks, for example in the area of safety and security (i.e. the protection of these plants against third-party attacks) - risks that have often been neglected in plans to date.

The report also assesses the economic viability of SMR concepts. This aspect has come under particular scrutiny following the recent failure of a US company to build an SMR power plant in Idaho. The report states that, due to their lower electrical output, the construction costs for SMRs are relatively higher than for large nuclear power plants. Consequently, an average of three thousand SMRs would have to be built for SMR production to become economically viable. An examination of existing SMR projects also shows that the original time horizons were generally exceeded many times over, meaning that promises of shorter construction times must also be viewed critically.

By way of categorisation: So-called SMR concepts date back to developments in the 1950s, but have seen a renewed interest in recent years. SMRs have gained in importance as a technology with supposedly low CO2 emissions, particularly in the ongoing discussions on possible measures to combat climate change. This is reflected, for example, in a draft report currently being voted on in the European Parliament's Committee on Industry, Research and Energy: It calls to expand the promotion of SMR concepts across the EU, and to include SMRs in the list of recognised "clean" technologies in the net-zero industry regulation. The BASE expert opinion comes to a different conclusion, however: the majority of concepts are currently still at the draft stage. Important questions about SMR technologies, therefore, remain unanswered - also with regard to potential safety risks, economic efficiency and disposal processes. SMRs also face the problem of managing high-level radioactive waste and the challenge of preventing proliferation.

The English summary of the report can be downloaded from the BASE expert opinion website here: https://www.base.bund.de/EN/ns/ni-germany/smr/small-modular-reactors_node.html

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