Design of an MCNPX model to simulate the performance of BWRs using thorium as fuel and its validation with HELIOS code

The main target of this research was to estimate the possibility for improving the performance of Boiling Water Reactor (BWR) cores by using uranium thorium dioxide fuels instead of the commonly used oxide fuel. MCNPX (Monte Carlo N-Particle eXtend) computer code based on Mont Carlo method, is used to design two models for a BWR fuel bundle in a typical operating temperature and pressure conditions, the first is the oxide fuel bundle model and the second is the blanket-seed (BS) bundle model. A test case was compared with a previously published data calculated by HELIOS code and good agreement was found. The two models are used to determine the multiplication factor, pin-by-pin power distribution and thermal neutron flux distribution for both UO2 and (UZr/ThO2) fuels. BS bundle model improves the performance of BWR in different ways: (a) by increasing the energy extracted per fuel assembly, (b) by reducing the uranium ore, (c) reducing the plutonium accumulated in BWR through burn-up and continues to grow throughout the world, and (d) by increasing fuel burn-up and reactor lifetime. The spent fuel in the reactor can be recycled, and the plutonium and its isotopes can be extracted. The extracted plutonium can be used as a Mixed Oxide (MOX) fuel.