In order to understand the mechanisms related to He migration in nuclear oxide fuels, 3He was implanted to a level of 2 x 1016/cm2 in UO2 sintered disks. The samples were then annealed at 800C to 1300C. Changes in He concentrations were investigated by using 2 nuclear reaction analysis techniques based upon the 3He(d,α)1H reaction. The first technique used a macrobeam to measure He depth profiles averaged over a 500 x 500μm2 area. The second technique used a microbeam and provided a quantitative 2-dimensional He concentration cartography, in which each pixel corresponded to a depth-integrated He signal. The analyzed zones were optically characterized, permitting a detailed analysis to be made of the effect of the microstructure upon He release; with the emphasis being placed on grain-boundary effects.

A Quantitative μNRA Study of Helium Intergranular and Volume Diffusion in Sintered UO2. G.Martin, P.Desgardin, T.Sauvage, P.Garcia, G.Carlot, H.Khodja, M.F.Barthe: Nuclear Instruments and Methods in Physics Research Section B, 2006, 249[1-2], 509-12