TerraPower is a nuclear reactor design company headquartered in Bellevue, Washington, United States. TerraPower is developing a class of nuclear fast reactors called the traveling wave reactor. The TWR concept places a small core of enriched fuel in the center of a much larger mass of non-fissile material, in this case depleted uranium. Neutrons from fission in the core "breeds" new fissile material in the surrounding mass, producing Pu239. Over time, enough fuel is bred in the area surrounding the core that it begins to undergo fission as well, sending neutrons further into the mass and continuing the process while the original core burns out. Over a period of decades, the reaction moves from the core of the reactor to the outside, thus giving the name "travelling wave". In September 2015, TerraPower signed an agreement with the state-owned China National Nuclear Corporation to build a prototype 600 MWe reactor unit at Xiapu in Fujian province, China from 2018 to 2025. Commercial power plants, generating about 1150 MWe, were planned for the late 2020s. However, in January 2019 it was announced that the project had been abandoned due to technology transfer limitations placed by the Trump administration.
Traveling wave reactor
TerraPower has chosen traveling wave reactors as its primary technology. The major benefit of such reactors is high fuel utilization in a manner that does not require nuclear reprocessing and could eventually eliminate the need toenrich uranium. TWRs are designed to convert typically non-fissile fertile nuclides such as U-238 into fissile nuclides like Pu-239 in-situ and then shift the power from the highly burned region to the freshly bred region, as an integrated breeder reactor. This allows the benefits of a closed fuel cycle without the expense and proliferation-risk of enrichment and reprocessing plants typically required to get them. Enough fuel for between 40 and 60 years of operation could be in the reactor from the beginning. The reactor could be buried below ground, where it could run for an estimated 100 years. TerraPower described the concept of its main reactor design as a "Generation IV, liquid sodium-cooled fast reactor".
Environmental effects
By using depleted uranium as fuel, the new reactor type could reduce stockpiles from uranium enrichment. TerraPower notes that the US hosts 700,000 metric tons of depleted uranium and that 8 metric tons could power 2.5 million homes for a year. Some reports claim that the high fuel efficiency of TWRs, combined with the ability to use uranium recovered from river or sea water, means enough fuel is available to generate electricity for 10 billion people at US per capita consumption levels for million-year time-scales.
Research and development
The TWR design is still in the research and development phase. The conceptual framework of the TWR operations was simulated by supercomputers with an empirical evidence for theoretical feasibility. US regulators postponed the construction of the experimental reactor for a decade over extended documentation for its certification process. On November 6, 2009, TerraPower executives and major investor Bill Gates visited Toshiba's Yokohama and Keihin Factories in Japan, and concluded a non-disclosure agreement with them on December 1. Toshiba had already developed an ultracompact reactor, the 4S, that can operate continuously for 30 years without fuel handling and generates 10 megawatts. Some of the technologies used in 4S are considered to be transferable to TWRs.
