Very-high-temperature reactor

Very-high-temperature reactor (VHTR), also known as High-temperature gas-cooled reactor (HTGR), is a type of nuclear reactor that is designed to operate at extremely high temperatures, typically in the range of 700 to 1000 degrees Celsius. The VHTR is a type of Generation IV reactor, which are advanced nuclear reactor designs currently being researched for commercial applications.

Design and Operation

The VHTR uses a graphite moderator and a gas coolant, typically helium. The fuel used in a VHTR is usually in the form of TRISO particles, which are tiny spheres of uranium, plutonium, or thorium fuel encapsulated in layers of graphite and silicon carbide. These particles are then embedded in graphite to form fuel elements.

The high operating temperatures of the VHTR make it possible to achieve higher thermal efficiencies than conventional nuclear reactors, typically around 40% to 50%. In addition, the high temperatures can be used for industrial processes that require heat, such as the production of hydrogen.

Safety Features

One of the key safety features of the VHTR is the TRISO fuel particles. The multiple layers of the particles provide a strong barrier against the release of radioactive materials, even under severe accident conditions. In addition, the use of helium as a coolant reduces the risk of chemical reactions that could lead to a release of radioactivity.

Applications

The main application of the VHTR is for electricity generation. However, due to its high operating temperatures, it can also be used for other applications such as hydrogen production, process heat for industrial applications, and even for desalination of seawater.

Future Development

The VHTR is one of the six reactor technologies selected for further research and development by the Generation IV International Forum (GIF). Several countries, including the United States, Japan, and China, are currently conducting research on VHTR technology.