The Multigroup and Cylindrical Geometry Formulation of the Fully Coupled S_n/Monte Carlo Method

A hybrid method that iteratively couples S_n and Monte Carlo regions of the same problem has been developed. The method results in a general and relatively efficient method of coupling the two regions and avoids many of the restrictions and limitations of previous attempts, since no assumption is made about geometric separation or decoupling. The hybrid method has been extended from monoenergetic x-y geometries to r-z geometries and multigroup problems, with good results and no significant increases in memory requirements. The reformulation of the hybrid method for multigroup and r-z problems is described, along with the results of several test problems.