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U.S. Department of Energy
Office of Scientific and Technical Information

Cladding deformation into pellet end voids

Technical Report ·
OSTI ID:6083392

Inherent in the fabrication of ceramic fuel pellets for use in fuel elements of nuclear reactors is the propensity to form small chip voids in the pellets, generally at end edges. Those voids having their major exposure on the pellet lateral surfaces can, in light water reactors, provide unsupported regions leading to local cladding deformation into the voids. This deformation is undesirable because of additional cladding strain and because of a potential reduction in fuel rod lateral support as the cladding moves away from grid springs. This report presents a model for predicting cladding deformation depths over unsupported regions of fuel pellet voids. The proposed model is semi-theoretical; it employs empirical coefficients derived from both ex-reactor and in-reactor tests. Data from these tests is presented and analyzed. Based on observed cladding deformation in an irradiation test rod, a local cladding deformation is predicted for a pressurized water reactor core rod having typical pellet void sizes.

Research Organization:
Bettis Atomic Power Lab., West Mifflin, PA (USA)
DOE Contract Number:
AC11-76PN00014
OSTI ID:
6083392
Report Number(s):
WAPD-TM-1338; ON: DE82003886
Country of Publication:
United States
Language:
English