Burnup determination of dry process refabrication fuel by using neodymium isotope monitors

One of the important parameters required for studies of irradiated nuclear fuel is burnup, which is the number of fission per 100 heavy nuclide atoms initially present in the fuel. Destructive method, which is based on the determination of specific nuclides by chemical analysis after appropriate separation procedures, is widely used as a reference method to measure the burnup of irradiated fuel. The isotope 148Nd was selected mainly because its fission yield is independent of the fissioning actinide, and because of its low thermal neutron capture cross section. An approach is to use another monitor such as the sum of 145Nd and 146Nd because it appears invariant with neutron flux and fluence. In order to check the consistency of post-irradiation analysis results, correlations between parameters of irradiated nuclear fuels such as concentration of heavy elements and fission products, ratios of their isotopes and burnup were established. These correlations can be used to identify reactor fuels and to estimate the burnup and Pu production. Some of these correlations may also be useful for safeguards purposes. The aim of this work is to determine the total burnup by using various Nd monitors on the same sample from SIMFUEL and dry process refabrication fuels irradiated in Hanaro reactor and to compare the results for the validity of the methods. In addition, the dependences of U, Pu and Nd isotope composition on burnup values, and correlations between U and Pu and their isotopes for these fuel samples were characterized experimentally