Pyrophoricity of Tritium-Storage Bed Materials^a

Experiments were conducted on samples of depleted uranium and on intermetallic compounds of zirconium-cobalt and lanthanum-nickel-aluminide to evaluate the pyrophoricity of the activated materials and their hydrides and deuterides on exposure to air. None of the materials spontaneously ignited when exposed to room temperature air, but the uranium and the zirconium-cobalt both ignited in air at moderately elevated temperatures. Activated (dehydrided) materials ignited at essentially the same temperatures. Deuterides showed effectively the same characteristics as the hydrides except the ignition temperature of zirconium-cobalt deuteride was reduced by 20–50 K from that of the hydride. The pyrophoricity of these materials raises concern about the possibility of fires in tritium-storage beds with attendant damage to the bed and dispersal of tritiated debris, but fires may not occur until the bed is heated.