Review of nuclear microreactors: Status, potentialities and challenges

Nuclear energy is being reconsidered worldwide as a low-carbon and dispatchable energy source. Following the development of Small Modular Reactors (SMR) to reduce the capital costs and increase the safety of new nuclear power plants, microreactors are being designed by several companies. Microreactors are usually defined as SMR with a power output in the range 1–20 MWe. They can operate as part of the electric grid, independently from the electric grid or as part of a microgrid to produce electricity and process heat. In the present paper, some microreactors at an advanced design stage are presented: eVinci™, Aurora, Holos Generators, Xe-Mobile, NuScale, Sealer, U-Battery and Micro Modular Reactor. The main applications of microreactors and the technology features are then discussed to present the main potentialities and challenges. The main advantages are the small size, the simple plant layout and the fast on-site installation. The main challenges are the limited fuel availability, the security and proliferation risk and the licensing process. Finally, an economic analysis shows that, due to an economy of scale, despite the capital cost reduction, microreactors are not cost competitive with large nuclear plants, but they are competitive with technologies with similar scale and application, such as diesel generators and renewable sources in microgrids.