Small modular reactors

This chapter describes the main features of small modular reactors (SMRs). A demonstration of all the advantages and disadvantages of SMRs is provided in comparison with high-power reactors used in nuclear power plants (NPPs). Special attention is given to the activities of the International Atomic Energy Agency (IAEA) to expand international cooperation and coordination in the design, development, and commissioning of small- and medium-sized reactors. The opportunities and prospects of development offered to mankind by small energy are demonstrated. The question of various options for the placement of SMRs is also considered. Special attention is drawn to the description of the main existing and perspective projects of SMRs being developed in various countries of the world, and analysis of their basic features (design, peculiarities of operation, assignment, etc.) is conducted. Separately considered are the most advanced and already implemented projects, such as NuScale, CAREM-25, SMART, ACP100, IRIS, and RITM-200. Special attention is paid to the issue of ensuring the safety of these reactors and the basis of the principles that carries them out. It should be noted that the requirements for safety at modern nuclear power plants after the Fukushima-1 accident are very high. At the same time, the small linear dimensions of the SMRs and the small amount of stored energy make it possible to use different approaches and design solutions of the main systems, in contrast to those acceptable at nuclear power plants. Special attention is paid to passive SMRs security systems. At the end of the chapter, the issues of international cooperation and harmonization of nuclear control standards are discussed. Also addressed is the problem of licensing MMR technologies, because these reactors must provide a high level of safety; however, to achieve this goal many innovations are needed in the projects (some of which have not been tested). Another important issue is public acceptance of such technologies.