Comparative evaluation of the steady state fuel rod thermal behaviour code GAPCON-THERMAL-2 and the integral fuel rod performance code URANUS

A comparison between the steady state fuel rod thermal behaviour code GAPCON-THERMAL-2 and the integral fuel rod performance code URANUS was made by analyzing with both codes a few sample data cases representing idealized LWR fuel conditions. The results reveal certain discrepancies in the thermal submodels of the codes, but quite consistent fuel maximum temperature predictions are achieved. Capabilities of the GAPCON-THERMAL-2 for mechanical performance analyses appear very limited, but as far as the calculation of thermal behaviour is concerned the mechanical parts of the code seem to be quite acceptable. The URANUS results for mechanical phenomena seem very plausible. Yet, no reference to experimental findings was made at this stage of the evaluation. The running times of URANUS appear very short, especially if demands for detail are optimized. After refining certain submodels and sufficient verification against experimental data URANUS is potentially a most valuable tool for a wide variety of practical LWR fuel applications. (author)