Comparison of measured and calculated LWR fuel behavior during a hypothetical reactivity initiated accident

Comparisons of measured and calculated LWR fuel rod responses during a reactivity initiated accident test are presented. The results indicate that the computer code, FRAP-T5, adequately calculates the fuel rod behavior up to the time at which the gap closes and provides a good thermal solution up to the time of gross fuel and cladding relocation. Three areas have been identified for further model development: (a) development of a fuel swelling model for near molten fuel temperatures; (b) incorporation of a deformable fuel pellet model that is applicable for the closed gap, high strain rate regime; and (c) expansion of the failure stress data base to include heat-up rates of up to 5000 K/s