Characteristics of Radial Distribution of Key Nuclides in Spent Fuel Rod and Effect on Measurement Accuracy of Leached Hull

Leached hull is the most important high-level radioactive solid waste in spent fuel PUREX process. Non-destructive assay technique and instruments are widely used for uranium and plutonium and other nuclides content analysis in leached hull. Average burnup of spent fuel assembly is quoted as initial parameter in traditional algorithm. According to reactor operation experience, spent fuel assembly burnup and fission product in spent fuel rods are inhomogeneity. So it contributes uncertainty to non-destructive analysis results of leached hull. Based on simulated reconstruction techniques, the key nuclides distribution along radius of spent fuel rods was got. The results show that the key nuclides concentration deviation between leached hull and fuel rod can be up to 100%. Several correction factors were added to establish fitting curves for correcting inhomogeneity affects.