UHTREX

The Ultra-High Temperature Reactor Experiment (UHTREX) was an experimental gas-cooled nuclear reactor run at Los Alamos Scientific Laboratory between 1959 and 1971as part of research into reducing the cost of nuclear power.Its purpose was to test and compare the advantages of using a simple fuel against the disadvantages of a contaminated cooling loop.It first achieved full power in 1969.

The experiment was a spin-off from the technology developed by the earlier ROVER project.

Reactor core design

The UHTREX core was composed of a vertical hollow rotating cylinder (turret) constructed of solid graphite.

The cylinder was 70 in. OD x 23 in. ID x 39 in. high. The core had 312 fuel channels. The channels were equally spaced radially around the core at 15 degree intervals arranged in 13 separate layers of 24 channels each. Each channel held up to 4 fuel elements and extended completely through to the inside of the cylinder. The core could be refueled remotely while at full power. Refueling involved rotating the core to the channel containing the element requiring replacement and pushing in a new element. The used element would be pushed out into the center and fall to the base of the reactor to be collected. At full power the reactor used up 1 to 6 fuel elements per day depending on enrichment and porosity of the fuel element. It produced 3MW of thermal energy.