Post irradiation examination of high burnup PWR fuel

Abstract

Post irradiation examination (PIE) of a high burnt lead fuel assembly was carried out before the start of the full batch loading of high burnup fuel of 48 GWd/t optimum fuel assembly burnup. The lead fuel assembly was 17 × 17 B-type PWR fuel. Twelve fuel rods obtained from the lead fuel assembly at the reactor site were studied as well. Visually, the fuel rods seemed in good condition although some spallings were noted at the second span from the top where oxide film was relatively thicker than other spans. The optimum oxide film thickness was lower than 50 μm. Fission gas release was less than 1%, which rendered only a small increase in fuel rod internal pressure. Mechanical characteristics of the fuel cladding were assessed by tensile tests. These PIE results were within the range of other PIE data obtained earlier from domestic and foreign PWR fuel rods. The data verified that the integrity of B-type fuel would be retained at least up to 48 GWd/t.