A new spatially resolved model for defects and fission gas bubbles interaction at the mesoscale

Abstract

Fission gases, especially Xenon, produced during irradiation in a nuclear fuel, have very low solubility in the U O 2 fuel matrix and precipitate into bubbles. These gas bubbles interact with point defects of the fuel (vacancies, selfinterstitials, etc.) causing significant microstructural evolution which may eventually affect the overall performance of the fuel. Spatially resolved models are developed to predict and model the microstructural change at the mesoscale. We present a new model, which focuses on modeling the interaction between point defects and xenon gas bubbles. This new model overcomes the limitation of the existing cluster dynamics models as it can account for spatialization as well as the limitation of the spatially resolved phase-field models as it can also account for very small defect clusters, even below the individual grid spacing. The modeling of the phenomena of coalescence of two bubbles in a vacancy supersaturation and the vanishing of a small bubble in the presence of a larger bubble (Ostwald ripening) prove the credibility of the new model. 2-D analysis of a case depicting the movement and growth of bubbles in a vacancy concentration gradient is presented and is in good agreement with the associated physics.

Accelerating cluster dynamics simulation of fission gas behavior in nuclear fuel on deep computing unit–based heterogeneous architecture supercomputer

“…It is an effective model to describe the evolution of fission gas bubbles (gas atomic clusters). It has been applied to the study of fission gas diffusion, bubble nucleation, and release of fission gas under high burnup structure (Pizzocri et al, 2016; Miao et al, 2017, Miao et al, 2018; Verma et al, 2019; Matthews et al, 2020; Gamble et al, 2021).…”