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. This fuel was expected to be substantially less expensive to manufacture than other types of fuel at the time. The primary advantages of this type of fuel was that the porosity of the pellet in addition to the high temperatures achievable would allow most of the poisons created by the fission products to migrate out of the fuel. The poisons would then be carried away by the coolant stream for eventual filtering out and removal. This allows a higher percentage of fuel to be burned up before the pellet needed replacement (up to 50%). Disadvantages 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. Contamination caused by a potential contaminated coolant leak would pose a significant danger to personnel and the environment. The high contamination level precludes being able to open the reactor vessel for the eventual refueling. Therefore, the reactor was designed for remote online refuelling. Specifications UHTREX had following specifications: Fuel - highly enriched uranium Rated power - 3 MW (thermal) Core construction material - graphite Moderator - graphite Reactor vessel - carbon steel sphere 13 ft. 2 in. diameter 1.75 inches thickness. Fuel channels - 312 channels. Each one is 1.1 in. ID, 23.5 in. long and holds up to 4 fuel elements. Fuel element - 1 in. OD, 0.5 in. ID and 5.5 in. long (25.4 mm x 12.7 mm x 139.7 mm). Core power density - 1.3 W/cc Fuel utilization - up to 50%. Coolant - helium at 500 psi (3.45 MPa) Coolant temperature - inlet 1600 °F, Outlet 2400 °F (871 °C and 1316 °C). Coolant flow rate - 10,250 pounds per hour (1.294 kg/s) where ID and OD are the inner and outer diameter, respectively. See also Omega West Reactor Clementine reactor References Nuclear reactors