Homogeneous Reactor

a nuclear reactor in which the active core consists of a homogeneous mixture of nuclear fuel and a moderator.

The distinguishing feature of the homogeneous reactor is the absence of fuel elements; the nuclear fuel and the raw material for breeding (uranium, thorium, or plutonium) may be placed into the active core as a salt solution with ordinary or heavy water, or as a dispersion in a solid moderator (for example, graphite). Possible modifications of the homogeneous reactor contain the fuel in gaseous form, such as gaseous compounds of uranium or a suspension of uranium dust in a gas. The heat released in the core may be conducted away by a heat transfer agent (water, gas, or other materials), which is circulated through pipelines that pass through the core, or else the homogeneous mixture of fuel and moderator is conducted out of the core directly.

Because of considerable difficulties of engineering and design, homogeneous reactors are not widely used and are applied only for experimental purposes. There are only isolated examples of projects using homogeneous reactors as heat sources in the industrial production of electrical power.