Three-dimensional neutronic calculations for reactor desing optimizations

In this thesis study, the modeling of a three-dimensional boiling water reactor (BWR) was designed using the Monte Carlo method by dividing the reactor core into 8×8 type square lattices. Square are divided into four small square zones, and each square zone is divided into small square lattices of 7×7 type. In the BWR designed in this study, NpO2 and NpF4 fuel rods were used as fuel, Zr-2 and SiC as fuel clad and water as coolant. NpO2 and NpF4 fuel rods at the rate of 0.2-1% in the designed BWR modeling, Zr-2 and SiC fuel clads keff, fission energy and stored heat energy neutronic values were calculated. Three dimensional modeling of the BWR system was designed using MCNPX-2.7.0 Monte Carlo method and ENDF/B-VII.0 nuclear data library. In the designed BWR modeling, it was seen that as the fuel percentages increased, the neutronic values increased. As a result of the neutronic calculations, it was concluded that the SiC clad NpO2 fuel rod is more suitable for the BWR reactor. Keywords: BWR, Neutronic Values, MCNPX-2.7.0, ENDF/B-VII.0