We investigate the dynamics of nucleation and the growth of voids in an irradiated material in the presence of a spatially heterogeneous dislocation microstructure. We find that, due to the sensitivity of the void nucleation rate to the local vacancy supersaturation, voids nucleate and grow almost exclusively in the regions where the density of dislocations is low. Numerical simulations show that the relatively high void growth rates observed experimentally in the regions of low dislocation density, leading to segregated evolution of dislocations and voids, can be naturally described by solutions of a spatially heterogeneous reaction-diffusion model that takes continuous nucleation of voids into account but does not assume the occurrence of long-range one-dimensional transport of clusters of self-interstitial atoms through the material.
