Hydrogen-moderated self-regulating nuclear power module
The hydrogen-moderated self-regulating nuclear power module (HPM), also referred to as the compact self-regulating transportable reactor (ComStar), is a new type of nuclear power reactor using hydride as a neutron moderator. The design is inherently safe, as the fuel and the neutron moderator is uranium hydride UH3, which is reduced at high temperatures (500–800 °C) to uranium and hydrogen. The gaseous hydrogen exits the core, being absorbed by hydrogen absorbing material such as depleted uranium, thus making it less critical. This means that with rising temperature the neutron moderation drops and the nuclear fission reaction in the core is dampened, leading to a lower core temperature. This means as more energy is taken out of the core the moderation rises and the fission process is stoked to produce more heat.
The concept for this type of nuclear reactor was developed by the scientists Otis Peterson and Robert Kimpland of the Los Alamos National Laboratory (LANL) in New Mexico. Dr. Otis G. Peterson received a Federal Laboratory Consortium Award in the notable technology development category for this reactor concept in 2002. This technology has since been licensed exclusively to Hyperion Power Generation, under a technology-transfer program and a co-operative research and development agreement (CRADA) with the Los Alamos National Laboratory.
The reactor shares some characteristics with the TRIGA research reactors, which are operated by research laboratories and universities around the world, as well as the SNAP-10A reactor, which was developed for space applications.
According to the patent application the reactor design has some notable characteristics, that sets it apart from other reactor designs. It uses uranium hydride (UH3) "low-enriched" to 5% uranium-235—the remainder is uranium-238—as the nuclear fuel, rather than the usual metallic uranium or uranium dioxide that composes the fuel rods of contemporary light-water reactors. In fact, within the application, the contemporary "rod" based design with fuel rods and control rods is completely omitted from the proposed reactor design in favor of a "tub" design with passive heat pipes conducting heat to the heat exchanger running through the "tub" of granulated uranium hydride. The likely coolant to be used is potassium.
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