Coupling nuclear predictions into damage simulations with SPECTRA-PKA
Modern nuclear physics software is well-validated, providing advanced capabilities to support the engineering of the future generations of fission and fusion reactors. Transport simulators can model the transport of neutrons through reactor geometries and inventory codes can accurately predict transmutation and activation. Meanwhile, material modelling is applying a variety of techniques to understand how the structural damage and composition changes will alter the properties of materials, ultimately limiting their useable lifetime in a reactor.
Bridging the gap between nuclear simulation tools and materials modelling is a necessary step if these lifetimes are to be accurately predicted, which, for fusion in particular, is critical to provide the necessary assurance of commercial viability.
SPECTRA-PKA is a tool developed to compute the rates of structural damage source events — the primary knock-on atoms or PKAs — using the same nuclear data as used by transport and inventory simulations. Now, it has been interfaced with a binary collision approximation (BCA) code SDTrimSP, allowing those PKA events, distributed spatially and temporally in an atomic system, to be converted into damage cascades. This computational infrastructure provides insight into the variation in damage distributions between different materials under the same nuclear environment, and also gives estimates for fundamental metrics of radiation damage, such as cascade overlap thresholds. Example simulations in Fe and W under harsh fusion reactor conditions demonstrate how the rich detail of the nuclear environment can be applied directly to modelling, without the need to resort to integrated measures such as displacement per atom (DPA).