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Power-Cooling-Mismatch Test Series: Test PCM-3 postirradiation examination. [PWR]

Technical Report ·
OSTI ID:5287158

The results are presented of the postirradiation examination of four previously unirradiated pressurized water reactor (PWR) type fuel rods tested in-pile in pre- and post-DNB (departure from nucleate boiling) operation. All four rods remained intact during the DNB testing and subsequent reactor shutdown. Two of the tested fuel rods showed evidence of surface damage, characterized by cladding collapse and oxide spalling. Metallographic examination of the cladding microstructure of the two fuel rods which exhibited extensive collapse in the film boiling zone indicated that those rods operated at temperatures above the ..cap alpha.. + ..beta.. to ..beta..-phase transformation temperature of 1245/sup 0/K for the zircaloy cladding. The other two fuel rods, which exhibited less extensive collapse, operated at temperatures below the ..cap alpha.. + ..beta.. phase transformation temperature of 1105/sup 0/K. Rod A-0021 failed during remote handling following the test. Prior beta grain boundary embrittlement is postulated as the failure mechanism.

Research Organization:
Idaho National Engineering Lab., Idaho Falls (USA)
DOE Contract Number:
EY-76-C-07-1570
OSTI ID:
5287158
Report Number(s):
TREE-NUREG-1187
Country of Publication:
United States
Language:
English