Safety Assessment Principles Applied to Small Modular Reactors

Much of the attention on small modular reactors (SMRs) has to date been focused on the technology or novel applications, however, this paper tries to set out some thoughts on some of the other issues, or “externalities” within which any SMR proposal must be brought to market. The Paper outlines the UK regulatory regime highlighting differences from that in the US. Regulation in the UK is based on Safety Assessment Principles rather than a prescriptive set of requirements; the amenability of such a regime to assessing novel reactor designs and applications is discussed in general terms. The Paper summarizes the licensing arrangement for nuclear facilities used by the UK nuclear regulator. It goes on to summarize the recent Generic Design Assessment (GDA) programme for new build in the UK in which Serco has been heavily involved. The Safety Assessment Principles reach further than just into the technicalities of engineering design. Two particular areas of interest are picked out: the availability of qualified and experienced personnel and the impact on plant as a result of grid and transmission system issues. With regard to the first of these, in the early days of nuclear power, the UK considered many different reactor designs including gas cooled reactors, fast reactors, heavy water reactors, high temperature reactors and later a small reactor design — the SIR (Safe Integral Reactor) — although this was never built; these are briefly described highlighting any similarities to current proposed small reactor designs and concepts and discussing any lessons that could be learned. Staff in Serco have been involved with all these developments as well as undertaking research in Generation IV concepts. To begin to address the impact on the plant from its interface with the external electricity grid system, the Paper discusses the energy market in the UK (one of the most deregulated), the state of the nuclear industry, the current political landscape as far as nuclear power is concerned, and the prospects for deploying small modular reactors in the UK. It then considers the implications of the European Union’s challenge to decarbonize electricity supply by 2050. Finally, the Paper considers other pertinent issues associated with small reactor concepts and the Safety Assessment Principles. It discusses some of the issues around inspection, given that many of the small reactor concepts are based on underground reactors. Given the smaller size of SMRs, the opportunities for association with novel non-power generating applications are greater than for conventional plant. Some differences associated with these proposals, compared to traditional nuclear power generation, are examined. The paper then also discusses the advantages and disadvantages, as far as safety is concerned, of a farm of small modular reactors compared with a single large reactor.