Radiation-induced swelling and microcracking in SiC cladding for LWRs

After the Fukushima accident in 2011, SiC has attracted considerable attention as a potential material for fuel cladding that can offer increased accident tolerance in light water reactors (LWRs) compared to zircaloy cladding. Existing measurements on nuclear grade SiC/SiC composites made of high-purity, stoichiometric SiC have already shown very good radiation tolerance in various harsh environments. However, there are a number of challenges that need to be addressed before SiC composites can be successfully used in LWR technologies. One of them is irradiation-induced swelling, which can lead to development of significant stresses in the matrix, followed by microcracking and subsequent release of fission products. Up to this point, models of irradiation-induced swelling have been largely empirical, so they cannot be used to predict the microstructural dependence of microcracking. The models are empirical because we lack understanding of defects that form due to irradiation in the range of temperatures relevant to fuel cladding in LWRs (