A mesoscale stress model for irradiated U 10Mo monolithic fuels based on evolution of volume fraction/radius/internal pressure of bubbles

Effects of U-Mo Irradiation Creep Performance on the Thermo-Mechanical Coupling Behavior in U-Mo/Al Monolithic Fuel Assemblies

“…where k(T) is the thermal conductivity; _ q is the heat generation rate. It is noted that the porosity-related thermal conductivity models (Jian et al, 2019b) are adopted for the nuclear fuel foils, and the porosity varies with burnup due to the fission-induced bubbles (Jian et al, 2019a). The heat generation rate for nuclear fuel foils is location dependent, which can be obtained with Eq.…”

“…The mechanistic fission gas swelling model has been used. The grain crystallization effect has been involved, and the bubble radius correlates with the grain-scale fission gas atom diffusion, detailed in Jian et al (2019a); Jian et al, 2019b. For the Al alloy, the total deformation rate is composed of elasticity, creep and plasticity parts, with the models of Lame constants and creep the same as those in Jian et al (2019b), with the plasticity model adopted from Jian et al (2019a).…”

“…Complicated in-pile thermo-mechanical behavior appears in U-Mo/Al monolithic fuel assemblies (Miller et al, 2010;Kim et al, 2012;Deng et al, 2017), which mainly depends on the following contributions: 1) the deformations (Miller et al, 2010;Kim and Hofman, 2011;Kim et al, 2013;Meyer et al, 2014;Zhao et al, 2015) induced by irradiation swelling and creep of fuel foil (Kim et al, 2013;Kim and Hofman, 2011); 2) the plasticity and thermal creep performances of cladding (Yan et al, 2017;Jian et al, 2019a); 3) formation of porous fuel structure due to the fission-gas-resulted bubbles (Rest, 2010;Meyer et al, 2014); 4) the acceleration of fission gas swelling driven by grain recrystallization (Rest, 2010); 5) the degradations of thermo-mechanical properties and macroscale strength owing to the formed porous structure, pore pressure and the possible creep damage in the fuel foil (Rest, 2010;Robinson et al, 2008;Iltis et al, 2016;Yan et al, 2017;Salvato et al, 2018;Jian et al, 2019a;Schulthess et al, 2019); 6) the complex mechanical interactions across all the parts, including the fuel plates, the outside Al plates and the side plates (Deng et al, 2017). On one hand, the irradiation creep strains will relax the stresses in the fuel foils or the other parts.…”

“…On one hand, the irradiation creep strains will relax the stresses in the fuel foils or the other parts. On the other hand, the high creep strains will result in creep damage and degradation of fuel strength (Iltis et al, 2016;Jian et al, 2019a). It is necessary to examine the effects of fuel creep performance on the thermal-mechanical behavior in U-Mo/Al fuel assemblies, which will supply a basis for advanced fuel design.…”

“…The thermo-mechanical behavior analysis for monolithic U-Mo/Al fuel plates can be found in the previous works (Kim et al, 2012;Kim et al, 2013;Jian et al, 2019a). A linear relation of equivalent creep strain rate with fission rate and Von Mises stress was generally adopted, namely _ ε cr ∝ σ • _ f (Dienst, 1977;Ghoshal et al, 2013;Yan et al, 2019).…”