Comparisons of light water reactor pellet transient thermal response with FRAP-T4 predictions during reactor shutdown events under normal cooling conditions. [PWR; BWR]

Thermal response calculations performed with the transient fuel rod analysis program, FRAP-T4, are independently evaluated. FRAP-T4 predictions of fuel centerline initial temperature, thermal decay constant, and equilibrium temperature are compared with fuel pellet temperature data taken during reactor shutdown events. The contributions of fuel pellet effective conductivity and stored energy to the error in calculated thermal conditions is discussed. Conclusions are reached regarding existing model capabilities and further model development requirements.