Swelling and gas release in UO2 and comparisons with FASTGRASS and OGRES code predictions

摘要: Abstract The results of experiments on the swelling UO2 under known pressure driving forces are reviewed. High-pressure argon was entrapped during sintering which then caused when ambient reduced. strains rates before interconnection could be expressed as V = AF n exp(−Q/RT) , where A is a structural constant, F net force for swelling, ≈ 1.5, and Q 200 kJ/mol. consistent with models growth pores controlled by diffusion atoms along grain boundaries from pore surfaces. For conditions investigated, begins at ~ 91% TD associated decrease in strain concurrent gas release. Interconnection occurs first edges corners. Pores maintain equilibrium shape prior to interconnection, but not able do so after interconnection. Resintering densification follows Under rapid microstructural change coalescing “pinching-off”, subsequent show considerable scatter. more stable structures, also become reproducible same conditions. relevant portions FASTGRASS OGRES codes were benchmarked against experimental mathematical model diffusive growth. Both required adjustments using measured parameters approximate data. Since based models, they describe almost linear dependence low pressures expected higher pressures, deformation mechanisms may control. relaxation time approach appears inappropriate large transients. resintering accurately.