Development of a practical fuel management system for PSBR based on advanced three-dimensional Monte Carlo coupled depletion methodology

by 1978- Tippayakul, Chanatip

iii The main objective of this research is to develop a practical fuel management system for the Pennsylvania State University Breazeale research reactor (PSBR) based on several advanced Monte Carlo coupled depletion methodologies. Primarily, this research involved two major activities: model and method developments and analyses and validations of the developed models and methods. The starting point of this research was the utilization of the earlier developed fuel management tool, TRIGSIM, to create the Monte Carlo model of core loading 51 (end of the core loading). It was found when comparing the normalized power results of the Monte Carlo model to those of the current fuel management system (using HELIOS/ADMARC-H) that they agreed reasonably well (within 2% – 3 % differences on average). Moreover, the reactivity of some fuel elements was calculated by the Monte Carlo model and it was compared with measured data. It was also found that the fuel element reactivity results of the Monte Carlo model were in good agreement with the measured data. However, the subsequent task of analyzing the conversion from the core loading 51 to the core loading 52 using TRIGSIM showed quite significant difference of each control rod worth between the Monte Carlo model and the current methodology model. The differences were mainly caused by inconsistent absorber atomic number densities between the two models. Hence, the model of the first operating core (core loading 2) was revised in light of new information about the absorber atomic densities to validate the Monte Carlo model with the measured data. With the revised Monte Carlo model, the results agreed better to the measured data. iv Although TRIGSIM showed good modeling and capabilities, the accuracy of