The US Nuclear Regulatory Commission announced on Wednesday that it has granted its first construction approval in almost a decade, paving the way for the development of a novel nuclear reactor design by TerraPower in Kemmerer, Wyoming. TerraPower, a company largely funded by Bill Gates, is known for its pioneering work in nuclear technology and is pursuing a radically new reactor that incorporates sodium cooling and energy storage.
While this approval is a significant milestone, it does not guarantee operational approval for the reactor. The TerraPower design, known as Natrium and developed in collaboration with GE Hitachi, introduces several innovative features. One of the most notable is the use of liquid sodium as a cooling and heat transfer medium. This choice allows the primary coolant to remain liquid, bypassing the challenges associated with high-pressure steam in water-cooled reactors. However, it also presents the risk due to sodium's highly reactive nature when exposed to air or water. The Natrium reactor is a fast-neutron reactor, capable of consuming certain isotopes that would typically become radioactive waste in conventional reactor models.
The reactor's relatively small size, producing 345 megawatts compared to the standard one gigawatt of current nuclear plants, is complemented by an integrated energy storage system. Instead of directly using the heat from sodium to generate steam, the reactor stores this heat in a salt-based material. This stored heat can generate electricity on demand or be held for later use. Such a system allows the reactor to adjust its operation around renewable energy sources, which could otherwise have a cost advantage. The energy storage also enables the reactor to temporarily increase its electricity output to 500 MW.