Traveling wave reactor

Traveling Wave Reactor (TWR) is a type of nuclear reactor that can convert fertile material into usable fuel through nuclear transmutation, in tandem with the burnup of fissile material. TWRs differ from other kinds of fast-neutron and breeder reactors in their ability to use fuel efficiently without uranium enrichment or reprocessing, instead using depleted uranium, natural uranium, thorium, spent fuel removed from light water reactors, or some combination of these materials.

History

The concept of a reactor that could breed its own fuel was first proposed by Leo Szilard in 1958. However, it was not until the 21st century that the concept was further developed by TerraPower, a company founded by Bill Gates and former Microsoft CTO Nathan Myhrvold.

Design and Operation

The TWR's design is based on the principle of a "wave" of nuclear fission that moves through the reactor core over time. The wave slowly converts fertile material into fissile fuel, which is then consumed in place. This allows the reactor to operate for decades without refueling.

The core of a TWR is filled with a mixture of fuel and fertile material. The fuel, typically a small amount of enriched uranium or plutonium, initiates a wave of fission that moves through the core. As the wave passes, it converts the fertile material (typically depleted uranium or thorium) into additional fuel. This newly created fuel is then consumed in place, allowing the wave to continue moving through the core.

Advantages and Challenges

One of the main advantages of TWRs is their ability to use depleted uranium and other waste products as fuel. This not only reduces the amount of nuclear waste, but also provides a potential source of cheap and abundant fuel.

However, TWRs also present several technical challenges. These include the need for advanced materials to withstand the high temperatures and radiation levels inside the reactor, and the need for precise control of the fission wave.

Future Development

TerraPower is currently developing a prototype TWR, known as the TWR-P. The company plans to build the reactor in China, with operation expected to begin in the mid-2020s.

See Also

• Breeder reactor
• Fast-neutron reactor
• Nuclear transmutation
• TerraPower