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Fuel swelling due to retained fission gas in molten fuel during high temperature transients

Technical Report ·
DOI:https://doi.org/10.2172/5670590· OSTI ID:5670590
Fuel swelling, which caused cladding plastic strain, occurred within the film boiling region of previously irradiated pressurized-water-reactor-type fuel rods tested under power-cooling-mismatch conditions in the Power Burst Facility. Mechanisms contributing to the observed swelling are assessed and the applicability of an analytical fission gas behavior computer code, GRASS-SST, is evaluated. Fuel melting and expansion, expansion of the solid fuel, fission gas bubble coalescence, fission gas diffusion to grain boundaries, and decrease in surface tension of fuel upon melting were found to be the major contributors to the fuel swelling. In addition, the contribution to fuel swelling of solid fission products and the effects of cladding contraction and wall thinning on rod swelling were included in the fuel swelling calculations. The overall empiricallly calculated fuel swelling values and the GRASS-SST code calculated values were compared with measured values.
Research Organization:
Idaho National Engineering Lab., Idaho Falls (USA)
DOE Contract Number:
EY-76-C-07-1570
OSTI ID:
5670590
Report Number(s):
NUREG/CR-1236; EGG-2014
Country of Publication:
United States
Language:
English