Use of plutonium fuel in boiling water reactors. Destructive examination of PuO2--UO2 fuel rods irradiated in Big Rock Point to 30,000 MWd/t. Final report

The results obtained from the destructive examination of three mixed-oxide fuel rods, which were irradiated to a peak burnup of approximately 25,000 MWd/t, are presented. These rods were selected from a group of 11 that were non-destructively examined earlier. The results from the non-destructive examination (NDE) were used for the selection of these three fuel rods. The examinations performed include pulsed eddy current (PEC) inspection for cladding flaws, rod internal fission-gas collection and analysis, isotopic and burnup analyses, metallography of the fuel and cladding, and microprobe examination for migration of plutonium and fission products. Two of the fuel rods examined contained annular fuel pellets. The third fuel rod contained solid fuel pellets. The original enrichments for the three rods varied from 1.22 to 5.53% Pu/(Pu + U). No unusual features were observed. These fuel rods were found to be in very satisfactory condition at the high burnups achieved