Fuel Performance Modeling at High Burn-Up by FEMAXI-6 Code

The scope of the current research in the field of fuel performance is primarily aimed at an improvement of the operating reliability, safety, and cost-effectiveness of the reactors in operation. The current requirement of nuclear industry is to have fuel suitable for load follow operation. Fission gas release, pellet-cladding mechanical interaction, and stress corrosion cracking are the main phenomena that limit the variability of reactor operation from a safety perspective. To reasonably predict the fuel performance limits, it is necessary to benchmark the computational tools against high-quality experimental data. This work is devoted to the calculation of fuel performance using the code FEMAXI-6 based on the longest irradiation experiment in the Halden reactor. The fuel burn-up was approaching 90 MWd/kgUO₂ in three selected rods, which were equipped with the pressure sensors and were subjected to extensive postirradiation examination. During the experiment, the rods were exposed to several periods of power cycling. The rods were manufactured with different fuel grain size and fuel-to-clad gap size.