UHTREX

[3] Its purpose was to test and compare the advantages of using a simple fuel against the disadvantages of a contaminated cooling loop.

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

Some of these products poison the reaction ultimately leading to poor efficiency well before a significant portion of the fuel is used up.

For example, the metal tubing required to do so cannot be operated at temperatures above its melting point which is generally significantly lower than the fuel pellet.

The UHTREX used un-clad porous carbon extruded fuel elements each shaped like a long hollow cylinder.

[4] The fuel elements were manufactured by vacuum impregnating the porous carbon cylinders with aqueous uranyl nitrate solution then air drying and baking them in a furnace ultimately producing a uranium oxide coating tightly held in a porous graphite matrix.

[4] The major disadvantage to porous reactor fuel is that the entire primary cooling loop including all the pumps, compressors and heat exchangers would become highly contaminated with fission products.