Influence of thermal treatment on beryllium/carbon formation and fuel retention

Since the operation conditions for the nuclear fuel removal in a fusion power plant like ITER involves wall baking at high temperatures of the plasma facing components – i.e. 515 K for the first wall and 623 K for the divertor area – it is important to know how this thermal treatment procedures will affect the materials’ properties. It was observed that by heating at 623 K, the carbon from the graphite substrate diffuses into the deposited beryllium film forming a mixed layer of Be, BeO and Be2C at the interface, while the oxygen present at the Be–C interface diffuses to the surface of the film. Comparing the results obtained by Nuclear Reaction Analysis it was observed that the deuterium implanted after annealing was retained in deeper layers in the case of thermally treated samples due to the structural changes induced in the films by the Be/C mixed layer formation and the effects of the oxygen diffusion into the thermal treated films.