The effects of radiation on helium migration were investigated through the analysis of polycrystalline uranium dioxide samples irradiated at fluences up to 5 x 1015at/cm2 with 8MeV iodine ions. Following irradiation, samples were implanted with 500keV 3He+ ions at fluences in the range of 1016 at/cm2. Three nuclear reaction analysis techniques were subsequently implemented using the 3He(2H,1H)4He reaction. The influence of temperature using nuclear reaction analysis was first studied based upon 3He depth profile changes and the on-line monitoring of helium release. The effect of the sample microstructure was also investigated at the grain scale by performing analyses of the helium spatial distribution with a nuclear microprobe. Neither substantial helium release nor depth profile changes were observed at temperatures below 900C in irradiated samples. Following annealing at temperatures above 1000C, a substantial proportion of the implanted helium was released from the samples. From this temperature upwards, the two dimensional He cartographies reveal that the gas was preferentially released in the vicinity of grain boundaries. These results can be interpreted in the light of previous studies in terms of gas precipitation and re-solution. Helium precipitation was enhanced in irradiated samples up to 900C because of the presence of irradiation induced defects. At temperatures in excess of 1000C, the precipitated helium was partly returned to the matrix hence it was preferentially released in regions adjacent to grain boundaries, which appear to act as defect sinks.Irradiation Damage Effects on Helium Migration in Sintered Uranium Dioxide. G.Martin, C.Sabathier, G.Carlot, P.Desgardin, C.Raepsaet, T.Sauvage, H.Khodja, P.Garcia: Nuclear Instruments and Methods in Physics Research B, 2012, 273, 122-6