The Depleted Uranium Getter bed (Ubed) is a doubly contained pressure vessel filled with depleted uranium (DU) which acts as a hydrogen isotope getter material. Tritium gas is easily absorbed onto the DU to very low partial pressures above the material. This means that most of the tritium gas is absorbed into the material with very little inventory remaining in the vessel volume or piping, thereby minimizing accidental tritium release when opening the Ubed.
The primary vessel supports heaters and thermocouples to allow for the heating of the DU material and the desorption of the tritium gas at modest temperatures below 430 ˚C. The primary vessel and heaters are enclosed in a secondary vessel that is evacuated to provide both thermal insulation and to minimize any tritium permeation from the primary vessel.
The pyrophoricity for DU is passively protected by designed flow conductance and thermal management to restrict the temperature excursion below 250oC in the event of an air ingress into the Ubed.
The Ubed is designed for robustness. The ability to operate at high temperatures ensures that multiple absorption/desorption cycles will not damage the bed. The stainless steel welded vessels, rugged band heater and sheathed thermocouples ensure a clean package that can operate continuously at temperatures up to 500oC without damage.
The Ubed comes standard with metal bellows isolation hand valves fitted with copper stem tips and VCR-8 or 4 female nuts. The unit is helium leak tight to 1×10-9 scc/sec at the operating temperature which is suitable for tritium service.