Characteristics and advantages of Small Modular Reactors

At the beginning of the 2010's, the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) Program from the International Atomic Energy Agency (IAEA) launched the development of an new family of nuclear reactors known as Small Modular Reactors (SMR). These reactors have a 300 MWe capacity and could start their operation at the end of the 2020's or beginning of the 2030's.

The interest in this type of design–focused on producing electricity and/or industrial processed steam with cogeneration–stems from the desire to reduce direct investment costs, simplify the licensing process, shorten construction periods and make it possible to locate nuclear power plants far away from the large electricity transport networks.

One essential characteristic is that –thanks to its small unitary potencies and modular characteristics– it is possible to produce these reactors in a factory, which has multiple advantages regarding better manufacturing quality, easier standardization and easier transport of the reactors to their location after they are complete and ready to reach the desired power by adding modular units and assembling the output of steam or another active fluid to the generator-turbine cycle.

Generally speaking, the advantages of SMRs are simple design, economy of scale associated to factory production and reduction in costs, time of execution and errors and changes during their installation in their location. 

They also present a high level of inherent safety, since they use passive safety factors based on natural phenomena such as circulating the coolant using gravity or heat transmission with convection. This facilitates indefinite refrigeration without the need for any action from the operator, and without depending on external feeding or external water replacement. 

The great potential of these reactors can be summarized by the following factors: 

• Low power and modular characteristics, which make it possible to build the reactor almost completely inside the controlled environment of a factory, as well as install it at its location, module by module. This improves the quality level and efficiency of the project. 
• Power flexibility, so that they can easily be adapted to countries with smaller and weaker grids. 
• The modules can be independently managed.Maintenance and refueling outage can be done while the other modules are still in operation. 
• Lower need for cooling water. 

• The possibility to partially or totally bury the modules to improve their safety, especially their resistance to air strikes, as well as to improve their integration in their environment. 
• They allow other uses, for example in seawater desalination plants or remote locations. 

Over 50 small modular reactor designs are currently going through the various licensing stages in Canada, China, United States, Finland, France, United Kingdom and Russia. 

An example of a small modular reactor in operation is the world’s first floating nuclear power plant, Akademik Lomonosov. It first produced electricity in December 2019 for the independent network at the autonomous district of Chukotka in Eastern Russia. In June 2019 the Russian nuclear regulatory organization (Rostekhnadzor) issued a 10-year authorization to Rosenergoatom, the plant’s operator. 

In September 2019, the vessel carrying Akademik Lomonosov docked at its destination base in the Artic port of Pevek (Chukotka), after a 18-day, 9,000 km journey from its original base in Múrmansk, where the fuel was loaded. With two KLT-40S Russian designed reactors –35 MWe small modular reactors– the floating plant will be used to replace the lost generation capacity when the Bilibino nuclear power plant is permanently shut down at the beginning of the 2030’s.