Investigation of Zircaloy-fuel interaction in failed spent PWR fuel using EPMA

A failed spent fuel rod with 53,000/tU from a nuclear power plant was characterized and the fission products and oxygen layer in the fuel-clad gap region were observed using an EPMA (Electron Probe Micro-Analyzer, CAMECA SX-50 R). EPMA techniques offer the possibility of identifying and analyzing phases and segregations in spent PWR fuel. Although phases and segregations are small in terms of the amount expected to be present in background radiation, they nevertheless present a significant analytical challenge. In the fuel-clad gap of the failed fuel, an oxide layer with a thickness of about 10 μm and a composition of ZrO and Zr2O3 was observed. This report presents the results of the EPMA examination of a spent fuel specimen and a technique to analyze fission products in the fuel-clad gap region.