Development of Inverse Distance Weighting Method to Estimate Pin-by-Pin Burnup Distribution of PWR Spent Fuel Assemblies using Measurement Data

A method to estimate pin-by-pin burnup distribution of PWR spent fuel assemblies has been developed using spent fuel measurement data. The type of target spent fuel assembly is Westinghouse 14x14 type. The detector for spent fuel measurement converts spent fuel gamma radiation into electric current and records the amount of generated current. The detector measures spent fuel gamma intensity inside 16 guide tubes. The effect of single fuel pin on detector signal, as a function of pin-detector distance, has been simulated using the SCALE and MCNPX code. The normalized single pin effect are defined as weighting factors. This study applies inverse distance weighting method to estimate burnup distribution of 179 pins using detector signals at each guide tube and the weighting factors. The results of burnup estimation are then compared to the results in literature.