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Title: Low-temperature rupture behavior of Zircaloy-clad pressurized water reactor spent fuel rods under dry storage conditions

Journal Article · · Nucl. Technol.; (United States)
OSTI ID:5944989

Creep rupture studies on five well-characterized Zircaloy-clad pressurized water reactor spent fuel rods, which were pressurized to a hoop stress of about145 MPa, were conducted for up to 2101 h at 323/sup 0/C. The conditions were chosen for limited annealing of in-reactor irradiation hardening. No cladding breaches occurred, although significant hydride agglomeration and reorientation took place in rods that cooled under stress. Observations are interpreted in terms of a conservatively modified Larson-Miller curve to provide a lower bound on permissible maximum dry-storage temperatures, assuming creep rupture as the life-limiting mechanism. If hydride reorientation can be ruled out during dry storage, 305/sup 0/C is a conservative lower bound, based on the creep-rupture mechanism, for the maximum storage temperature of rods with irradiation-hardened cladding to ensure a 100-yr cladding lifetime in an inert atmosphere. An oxidizing atmosphere reduced the lower bound on the maximum permissible storage temperature by about5/sup 0/C. While this lower bound is based on whole-rod data, other types of data on spent fuel behavior in dry storage might support a higher limit. This isothermal temperature limit does not take credit for the decreasing rod temperature during dry storage. High-temperature tests based on creep rupture as the limiting mechanism indicate that storage at temperatures between 400 and 440/sup 0/C may be feasible for rods that are annealed.

Research Organization:
Westinghouse Hanford Company, P.O. Box 1970, Mail Stop W/A-40, Richland, Washington 99352
OSTI ID:
5944989
Journal Information:
Nucl. Technol.; (United States), Vol. 67:1
Country of Publication:
United States
Language:
English