SMR

by Sérgio Granato de Araújo

Small in size and with a simple integration plan, small modular reactors (SMR) are advanced nuclear reactors w/ a power capacity of up to 300 MWe per unit, which is about one-third of the generating capacity of conventional nuclear power reactors, although intermediates (btw 300 to 700 MWe) can be included in this classification [WN, 2023].

This interest in small and medium nuclear power reactors is driven both by a desire to reduce the impact of capital costs and to provide power away from large grid systems [WN, 2023].  More than 80 commercial SMR designs being developed around the world target varied outputs and different applications, such as electricity, hybrid energy systems, heating, water desalinization, and steam for industrial applications [IAEA, 2021].

According to the IAEA, the four SMRs currently under construction lie in Argentina (CAREM reactor, 25MWe, adjacent to Atucha I NPP), China, and Russia [PT, 2023].  Russia’s Akademik Lomonosov, the world’s first floating nuclear power plant that began commercial operation in May 2020, is producing energy from two 35 MWe SMR.

Advantages of SMR [EG, 2021]

• Fuel Security: SMR can easily store two years’ worth of fuel on-site and, in some cases, multiple decades’ worth.

• Ramp Up & Ramp Down: certain SMR designs, like that of NuScale Power, LLC (“NuScale”), allow for output to be varied over days, hours, or even minutes.

• Islanding: SMR can operate connected to the grid or independently.

• Black Start: SMR can start up from a completely de-energized state without receiving energy from the grid.

• Underground Construction: SMR can be built underground, making them less vulnerable to natural phenomena, EMP, and other intentional destructive acts.

Schematic of a SMR

A key feature of the SMR is that all the main components such as i) pressurizer, ii) steam generators, and iii) reactor coolant pumps are installed inside the reactor pressure vessel, as shown in Figure 1.

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Key players

• Westinghouse Electric Company LLC (US).

• NuScale Power, LLC. (US).

• Terrestrial Energy Inc. (Canada).

• Moltex Energy (Canada).

• GE Hitachi Nuclear Energy (US).

• X Energy, LLC. (US).

Figure 1: Schematic representation of a SMR