A Study On Application Of A Three-Dimensional Monte Carlo Code To Deep Penetration Analysis In Reactor Shielding Design Of An Lmfbr

A three-dimensional Monte Calro (SD-MC) code has been utilized for the reactor shielding analysis of a liquid metal fast breeder reactor (LMFBR). Calculations involve sodium deep penetration in a reactor vessel, requiring several bias techniques and often causing a still prohibitively long CPU time. This study has been performed to investigate the effective use of bias techniques for the deep penetration analysis of neutrons to make a CPU time shorter than acceptable limit. This study has shown that the 3D-MC calculations can be employed for sodium deep penetration configuration in a large LMFBR by using proper bias parameters determined by neutron flux distributions of preceding core-centered two-dimensional discrete ordinates (2D-Sn) calculations.