A new method to simulate dispersion plate-type fuel assembly in a multi-physics coupled way.

• 3D thermo-mechanical modeling of JRR-3M plate-type fuel assembly under irradiation condition with BEEs-Plates. • 1D simulation of coolant channels, considering the flow distribution. • Verification and utilization of 3D solid domain-1D fluid domain coupling method. • Analysis of the effect of burnup and uneven power distribution on temperature, stress profile of the assembly, and the flow distribution. The plate-type fuel has an excellent thermal–mechanical behavior as a type of nuclear fuel. To simulate and analyze the behavior of plate-type fuel assembly under irradiation conditions, a fuel performance analysis code BEEs-Plates was developed based on MOOSE (Multiphysics Object-oriented Simulation Environment). The properties, mechanical behavior, and irradiation effects of dispersion fuel meat were simulated by using the equivalent property models, and a one-dimensional Petrov-Galerkin stability model was used to solve the governing equations of coolant. The coupling between the three-dimensional solid domain and the one-dimensional fluid domain was also realized. The JRR-3 research reactor fuel assembly model was then used to perform the coupling simulation, and the assembly's temperature, stress, strain distribution, and coolant temperature, the size of the channels, flow distribution were analyzed. The results under the boundary conditions and input parameters applied herein show that the burnup effect has limited effects on the thermohydraulic performance of the assembly, with the variation of maximum temperature below 1 K and the change of channel width below 3.9%. However, its mechanical behavior is greatly affected by burnup, with the maximum stress of 396.2 MPa at the meat-cladding interface. The uneven power distribution causes the assembly to bend to one side, but its effect on the coolant flow distribution is negligible. [ABSTRACT FROM AUTHOR]