SMR

by Sérgio Granato de Araújo

Small in size and with a simple integration plan, small modular reactors (SMR) are advanced nuclear reactors that have 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 MWe and 700 MWe) can be included in this classification.

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].  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]

Some advantages of SMR are:

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

• Ramp Up and 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 SMR

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

Figure 1: Schematic representation of a SMR