Design parameters sensitivity analysis of dispersed plate-type nuclear fuel in Reactivity Insertion Accident

For dispersed plate-type nuclear fuel, the Reactivity Insertion Accident (RIA) is a kind of design basis accident that poses a range of challenges to the safety of nuclear fuel, such as fuel element melting, fuel meat cracking, etc. However, the effect of fuel design parameters on fuel performance during RIA has not been adequately investigated. In this paper, a two-dimensional geometric model which is composed of Zr-4 cladding, Zr-4 matrix and UO₂ fuel particles was established to simulate the thermal–mechanical behaviors of dispersed plate-type nuclear fuel under RIA. The simulation employs the finite element method, integrating numerical models for thermal/mechanical properties, mechanical behaviors, and irradiation effects of fuel into ABAQUS through subroutines. In order to analyze design parameters sensitivity of dispersed plate-type nuclear fuel, the variation trends of fuel performance parameters with different design parameters were analyzed, with emphasis on temperature, von Mises stress and strain. The results indicate that the accident tolerant capacity of dispersed plate-type nuclear fuel under RIA can be improved by increasing fuel particle volume fraction, decreasing fuel particle radius and increasing BeO volume fraction. In particular, changing the fuel particle volume fraction from 4.3 % to 19.3 % can reduce the peak temperature by about 50 K and the vonMises stress by about 100 MPa during RIA.