Small modular reactor

The small modular reactor (SMR) is a class of small nuclear fission reactor, designed to be built in a factory, shipped to operational sites for installation and then used to power buildings or other commercial operations. The term SMR refers to the size, capacity and modular construction. Reactor type and the nuclear processes may vary. Of the many SMR designs, the pressurized water reactor (PWR) is the most common. However, recently proposed SMR designs include: generation IV, thermal-neutron reactors, fast-neutron reactors, molten salt, and gas-cooled reactor models.^[1]

Commercial SMRs have been designed to deliver an electrical power output as low as 5 MW_e (electric) and up to 300 MW_e per module. SMRs may also be designed purely for desalinization or facility heating rather than electricity. These SMRs are measured in megawatts thermal MW_t. Many SMR designs rely on a modular system, allowing customers to simply add modules to achieve a desired electrical output.

Small reactors were first designed mostly for military purposes in the 1950s to power ballistic missile submarines and ships (aircraft carriers and ice breakers) with nuclear propulsion.^[2] The electrical output for modern naval reactors are generally limited to less than 165 MW_e and dedicated to powering turboshaft props rather than delivering electricity. In addition, there are many more safety controls absent from naval reactors due to the space limitations these reactors were designed for.

Modular reactors are expected to reduce on-site construction and increase containment efficiency. These reactors are also expected to enhance safety by using passive safety features that do not require human intervention, although this is not specific to SMRs but rather a characteristic of most modern reactor designs. SMRs are also claimed to have lower power plant staffing costs, as their operation is fairly simple,^[3][4] and are claimed to have the ability to bypass financial and safety barriers that inhibit the construction of conventional reactors.^[4][5]

Working with Oregon State University (OSU), NuScale Power developed the first Nuclear Regulatory Commission approved model for the US market in 2022.^[6]