U02 SWAGED POWDER FUEL ROD FAILURES AT HIGH THERMAL PERFORMANCE CONDITIONS

摘要

The initial two irradiations of Euratom Program fuel assemblies containing compacted powder fuel rods have resulted in fuel rod failures during GETR startup. The first failure occurred on December 20, 1962, when the reactor power rise from 20 to 25 MW was initiated. The failure was found to be a longitudinal split in the cladding of the maximum power rod in the assembly, approximately 3/4 of an inch long and five inches from the bottom end of the rod. The calculated peak surface heat flux in this rod--four inches above the point of failure--was 720,000 Btu/hr-ft. These initial four rods in the assembly were all Zircaloy-2 clad, arc-fused UO2, vibrated and swaged to a density of 90.5％.