The present NEA study is a synthesis report on the development status and deployment potential of SMRs. It brings together the information provided in a variety of recent publications in this field, and presents the characterisation of SMRs already available for deployment and those that are expected to become available in the next 10-15 years. It also highlights the safety features and licensing issues regarding such reactors.

Particular attention is paid to the economics of SMRs, and various factors affecting their competitiveness are analysed and discussed. Vendors’ data on the economics of different designs are compared with independent quantitative estimates of costs of generating electricity, and the deployment potential of such reactors in a number of markets and geographic locations is analyzed.

Currently, there are two definitions of such reactors widely used in the literature: Small and Medium-sized Reactors and Small and Modular Reactors. The same abbreviation is used — SMRs. Small and modular reactors have attracted much attention since 2008 when several very small reactors (less than 125 MWe) were announced in the United States. Since these reactors are a sub-class of the wider definition — Small and Medium-sized Reactors — in this paper we consider the general case of reactors with the effective electric power less than 700 MWe. However, the main focus in this report is on small reactors i. e. reactors with less than 300 MWe.

SMRs have been on the agenda since the early days of nuclear power. Historically, all reactors at that time were of smaller size compared to those deployed today[9], but the general trend has always been toward larger unit sizes (with lower specific costs due to the economy of scale), resulting in nuclear power plants with reactors of 1 000-1 600 MWe being most commonly commercialised today.

However, starting from the mid-1980s, a new set of requirements have motivated the development of intentionally smaller reactors in some countries aimed at the niche markets that cannot accommodate NPPs with large reactors. The main arguments advanced in favour of SMRs are:

• Because of their size, the upfront capital investment for one unit is significantly smaller than for a large reactor, and there is flexibility for increasing capacity. This reduces financial risks and could potentially increase the attractiveness of nuclear power to private investors and utilities.

• Smaller nuclear reactors could represent an opportunity to develop new markets for nuclear power plants. In particular SMRs could be suitable for areas with small electrical grids and for remote locations or, alternatively, in countries with insufficiently developed electrical infrastructure.

• SMRs often offer a variety of non-electrical energy products (heat, desalinated water, process steam, or advanced energy carriers) via operation in a co-generation mode[10].

Because of these arguments, there are currently about a dozen new SMR designs reaching advanced development stages, with one plant (a barge-mounted co-generation plant with two ice-breaker type KLT-40S reactors) currently under construction in the Russian Federation, three more in a formal licensing process in Argentina, China, and the Republic of Korea, and several others being under pre-licensing negotiations in the United States and India.

On the other hand, there are some issues regarding the viability of advanced SMRs, namely:

• A question on the economic competitiveness of SMRs, especially the higher specific construction cost of SMRs with respect to larger reactors.

• Potential concerns about the possibility of SMRs being sited in close proximity to end-users, based on the current regulatory norms and practices established to support the deployment of NPPs with large reactors.

• Legal and institutional issues regarding the possibility of international transport of NPPs with factory fabricated and fuelled reactors (a distinct group of advanced SMR designs) from one country for deployment in another.

The present study discusses these issues with a focus on the economic aspects and the competitiveness of a NPP with SMRs, in comparison to large reactors and non-nuclear technologies.