Modeling Defect Evolution in Irradiated 800H using Cluster Dynamics

A reaction-diffusion reaction rate theory based cluster dynamics was used to model the microstructure evolution of Alloy 800H under conditions similar to that of current and proposed nuclear reactors. The predicted interstitial and vacancy faulted loop densities grew orders of magnitude larger than experimentally measured in similar environments. The large calculated densities were determined to result from the over-nucleation of faulted loops directly generated by irradiation. In order to reduce the number densities, an additional reaction term is proposed that would approximate the enhanced recombination and reduced damage production caused by the damage cascade volume overlapping with the physical volume of defect clusters. To correctly parameterize the modified recombination and production terms, molecular dynamics simulations need to be performed to provide a computational database on the effects of a cascade overlapping with pre-existing defects.