Calculation Simulation of Equivalent Thermomechanical Properties of Dispersion Nuclear Fuel

The equivalent performance parameters of dispersion fuels are critical indicators for reactor safety analysis and fuel element evaluation. This study develops a numerical method to simulate the thermomechanical coupling behavior of metal matrix dispersion fuel rods at the mesoscopic scale and to calculate their macroscopic equivalent properties. Based on a fission gas migration model and considering irradiation effects, a thermomechanical-fission gas migration coupling method is established for metal matrix dispersion fuels. The effects of particle volume fraction, particle size, temperature, and burnup on the equivalent performance parameters are systematically analyzed and fitting formulas for the equivalent properties are provided. The results show the following: (1) The equivalent elastic modulus and shear modulus increase with particle volume fraction but decrease with temperature, and they exhibit a decreasing-then-increasing trend with burnup. (2) The equivalent thermal expansion coefficient increases with both particle volume fraction and temperature, while particle size has little effect. This study provides a theoretical basis for the optimization of dispersion fuel design and contributes to enhancing reactor core safety.