IMPROVEMENTS IN ZRCO BASED TRITIUM STORAGE MEDIA

Behavior and improvement of the ZrCo based intermetallic materials for tritium recovery, storage and supply are studied. Compound ZrCo was f ound to be subject to disproportionation at high temperature under hig h hydrogen pressure to form ZrCo2 and ZrH2. This process is completely reversed by vacuum treatment at temperature above 500 degrees C for s everal hours. Kinetics of the disproportionation was described to be s imilar to phase transition that have apparent incuvation time to take place. The logarithmic reaction rate constant was related to the recip rocal temperature. With some precautions drawn from the results, this reaction is not a problem in practice. For the application that needs prolonged supply of relatively high-pressure tritium, solid solution o f ZrCo and HfCo was developed as an improvement of the material. Mater ials otained by are melting with compoistion of Zr-(1-x)HfxCo (0<x<0.5 ) exhibits single plateaus in pressure - composition isotherms when hy drogenated. Repeated hydrogenation - dehydrogenation cycles did not ge nerate separate ZrCo and HfCo phases. The equilibrium hydrogen pressur e in the plateau regions are expressed as a functio of reciprocal temp erature and increases with increasing HfCo contents. This material pro vides controlled equilibrium hydrogen pressure required for specific a pplications of tritium storage nad supply.