Xian-Ming Bai

Development of a grain boundary pinning model that considers particle size distribution using the phase field method

In this work, we expand a grain boundary (GB) pinning model that considers a range of different spatial distributions of particles to also account for a distribution of particle sizes. We begin by developing a phase field model that describes GB and pore interactions and verify it by comparing to molecular dynamics simulations. We then develop an analytical pinning model that considers the impact of the particle size distribution, in terms of the mean and standard deviation of the particle radius. The analytical model is verified by comparing to simulation results of our phase field model and those of a simple Monte Carlo model. A significant finding from the model is that the mean value of the resistive pressure decreases with increasing standard deviation of the particle radius.

Irradiation effects in Generation IV nuclear reactor materials

Generation IV reactor structural materials will be exposed to high doses and temperatures during reactor operation that may lead to irradiation-induced degradation. This degradation will differ from that seen in light water reactors and therefore understanding mechanisms controlling material performance during irradiation is critical for evaluating the viability of Generation IV nuclear reactor concepts. This chapter discusses irradiation effects and microstructural changes that affect mechanical properties and dimensional stability of Generation IV reactor materials.

NEAMS-ATF M3 Milestone Report: Literature Review of Modeling of Radiation-Induced Swelling in Fe-Cr-Al Steels

Fe-Cr-Al steels are proposed as accident-tolerant-fuel (ATF) cladding materials in light water reactors due to their excellent oxidation resistance at high temperatures. Currently, the understanding of their performance in reactor environment is still limited. In this review, firstly we reviewed the experimental studies of Fe-Cr-Al based alloys with particular focus on the radiation effects in these alloys. Although limited data are available in literature, several previous and recent experimental studies have shown that Fe-Cr-Al based alloys have very good void swelling resistance at low and moderate irradiation doses but the growth of dislocation loops is very active. Overall, the behavior of radiation damage evolution is similar to that in Fe-Cr ferritic/martensitic alloys. Secondly, we reviewed the rate theory-based modeling methods for modeling the coevolution of voids and dislocation loops in materials under irradiation such as Frenkel pair three-dimensional diffusion model (FP3DM) and cluster dynamics. Finally, we summarized and discussed our review and proposed our future plans for modeling radiation damage in Fe-Cr-Al based alloys.

NEAMS FPL M2 Milestone Report: Development of a UO₂ Grain Size Model using Multicale Modeling and Simulation

This report summarizes development work funded by the Nuclear Energy Advanced Modeling Simulation programs Fuels Product Line (FPL) to develop a mechanistic model for the average grain size in UO₂ fuel. The model is developed using a multiscale modeling and simulation approach involving atomistic simulations, as well as mesoscale simulations using INLs MARMOT code.