Monte Carlo Simulation of BN-600 LMFR Hybrid Core

MCNPX code is used to design a three dimensional model to simulate and study the whole hybrid core of the BN-600 prototype LMFR. In the model, the core is composed of eight radial zones and eight axial zones. The spectrum of neutron flux is divided into 23 energy groups. Results from this model were verified using published results of benchmark problems that utilized diffusion or transport theories in calculation and found acceptable. The maximum difference was about 4% for multiplication factor, 1% for control rod worth, and 2.6% for radial power distribution. The model is used to calculate power distributions at different zones of the reactor core. Partial insertion of control rods is simulated and analyzed. The effect of burnup on reactivity is also determined in typical operating conditions of the reactor core. Burnup reactivity loss is about 2.7%.