MODIFICATION OF THE HYDRIDING KINETICS OF U-0.2WT.PERCENT V-ALLOY USING ION IMPLANTATIONS

Uranium metal and U-0.2wt.%V alloy are very sensitive to hydrogen cont amination. Prevention of hydride formation, a basic problem, can be ap proached by modifying the surface characteristics. Implantations of ox ygen, nitrogen, carbon and sulphur ions have been tested as a function of dose from 2 x 10(16) to 2 x 10(18) ions cm-2. The main results are an increase in the induction time, which is multiplied by factors of 20-80 depending on the implanted species, and a change in the nucleati on and growth mechanism from instantaneous nucleation (3 x 10(5) nucle i cm-2, 125-degrees-C, P(H-2) = 5 kPa) to a pitting attack (from 300 t o less than 10 pits cm-2) according to the species. Characteristics of the implanted shells have been determined by secondary ion mass spect rometry and X-ray diffraction.