ICNPAA 2010: Mathematical Problems in
Engineering, Aerospace and Sciences

Deterministic and stochastic nuclear codes have been used to simulate several reactor types around the world. The deterministic code spent short time in the simulations but have the disadvantageous of the simplification in the geometry. In the statistical codes, the geometry can be configured very detailed but it spent very time in the simulations. In this work, the deterministic code WIMSD-5B and the stochastic code MCNPX 2.6.0 were used to simulate a representative core of a Modular Helium Reactor (MHR). Two geometries (cell and cluster) were evaluated in both codes to a qualitative study. In this way, the effective multiplication factor (keff) during steady state and burnup were evaluated.