TerraPower has been working with GE Hitachi Nuclear Energy, Ltd. (GEH) on the development of a small sodium-cooled fast reactor named Natrium (345MWe), aiming to begin operating a demonstration reactor in the latter 2020s. In June 2021, TerraPower and the governor of Wyoming agreed on a plan to build a plant in the state.

Among next-generation nuclear concepts, sodium-cooled fast reactors represent a technology with a high level of maturity, and their development is accelerating globally. Given the high thermal conductivity of sodium, heat removal by natural-type circulation would be possible even in the event of loss of all power sources at Natrium.

In combination with a system known as a molten salt energy storage loop, Natrium’s output can be flexibly adjusted in response to output fluctuations from renewable energies, which is expected to contribute to improving overall economic efficiency.

According to releases by JAEA and others, TerraPower highly regards the Japanese fast-reactor know-how and test facilities already obtained through the experimental reactor Joyo and the prototype fast breeder reactor (FBR) Monju, as well as the designing and manufacturing capabilities of Japanese equipment companies generally.

Databases were accumulated through the operation and maintenance of the Joyo and Monju reactors, and those, too, will be highly valuable for development overseas, as will the knowledge and expertise of manufacturers engaged in the construction of both reactors.

With the conclusion of the memorandum, the four parties—JAEA, MHI, MFBR and TerraPower—will exchange technological information and proceed with consultation on cooperation in fast reactor development, including technologies particular to sodium-cooled reactors, such as fuel handling machinery and a damaged-fuel detection apparatus.