Space and angular dependence of interface currents in the multiband-CCCP method

The present pal,cr discusses the effect on accuracy of eigenvalue by the de gree of discretization at the cell boundary within the framework of the mul tiband-CCCP, a combination of the multiband method and the CCCP method. A s tudy oil sensitivity of discretization has been done concerning the depende nce of surface flux distribution in space and angular domain, or interface currents. It is found that appropriate discretization with more than five f or both uf segments and sectors is required to accurately calculate effecti ve cross sections and eigenvalue in the multiband-CCCP method. However, in practice, discretization schemes with one segment and several sectors can b e employed with some biases on eigenvalue. The distribution of surface flux at the boundary of a typical PWR-MOX cell has been studied. It is found that discontinuity and strong angular depende nce in the distribution of surface flux on the off-centered segments have l arge influence in the multiband-CCCP method. An improved scheme of angular discretization has been examined for the feasibility to retain calculation accuracy with less degree of discretization in angular domain.