Irradiation-Assisted Stress Corrosion Cracking of austenitic stainless steels in primary water is arguably the instance of environment-assisted fracture where metallurgy and microstructure, micro-mechanics of deformation, environment chemistry and surface reactivity effects are most tightly interweaved. Beyond the cost and difficulty of testing irradiated materials, separating each contribution is complex because they are all affected simultaneously by irradiation, yet it is necessary for a physically-based modelling of this damage phenomenon. We propose two complementary approaches aimed at isolating and assessing the effects of dislocation channelling on intergranular crack propagation. We developed a two-dimensional discrete dislocation dynamics simulation aimed at 1) reproducing the tensile behaviour of irradiated materials in uniform tension, including obstacle sweeping and dislocation channelling, and 2) studying the effect of channelling on the local criterion for the propagation of a micro-crack along a grain boundary. The principles of the simulation method and first results are be presented. A precipitation-hardened stainless steel whose matrix composition is close to that of the grain boundary region in irradiated austenitic stainless steels is heat-treated to obtain a uniform distribution of coherent g' precipitates with a size and density comparable to those of irradiation-induced faulted loops after a few dpa. Cyclic pre-straining of these samples causes the formation of precipitates-free channels due to the repeated shearing of precipitates. The pre-cycled samples are then tested in slow strain rate tension in primary water. The extent of intergranular cracking is seen to be significantly increased when compared to channel-free specimens with the same yield strength tested in the same environment.