Briefing: Small modular reactors

The worldwide need for energy, and particularly energy that does not generate carbon dioxide, has led to the possibility of nuclear reactors being installed in countries that previously have not used them. In many of these countries the electrical grid system is limited and would not be robust enough for the large power reactors currently under construction. The result has been the development of what have been termed ‘small modular reactors’ or SMRs. Although there has been no formal definition of such reactors, they are generally assumed to be less than 300 Mw. Various international companies have begun the process of developing SMRs, some being merely at the concept stage whereas others have gone beyond that having initiated related research projects. This paper briefly outlines the most significant of these designs under the three broad headings of light water reactors, high-temperature gas-cooled reactors and liquid metal and gas-fast reactors, highlighting their key features and providing references for anyone wishing to follow up any of them in more detail. It also draws some general conclusions about the potential deployment of these reactor systems in the future.