CRACKING AND BULK MOVEMENT IN IRRADIATED URANIUM OXIDE FUEL ELEMENTS
UO/sub 2/ pellets were fabricated with simulated circumferential or diametral cracks, and with voids formed by drilling axial or radial holes. Under irradiation the cracks healed in a region extending out slightly beyond the area of discernible grain growth. Cracks in the cooler outer annulus formed early and remained during the irradiation. Similarly voids in the outer annulus were unchanged, whereas those in the grain-growth region closed. Tungsten wire markers stayed in their original positions, demonstrating that the surrounding columnar grains in the UO/sub 2/ had not formed during the solidification of a melt. Decreases in diameter of 1 mm thick Zircaloy-2 sheathing assembled with large fuel/sheath diametral clearances were due to multi-axial stresses arising from axial elongation and the lack of diametral restraint. (auth)
- Research Organization:
- Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)
- NSA Number:
- NSA-18-002292
- OSTI ID:
- 4142502
- Report Number(s):
- CRFD-1156; AECL-1827
- Country of Publication:
- Canada
- Language:
- English
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