| Abstract: | The present paper discusses the effect on accuracy of eigenvalue by the degree of discretization at the cell boundary within the framework of the multiband-CCCP, a combination of the multiband method and the CCCP method. A study on sensitivity of discretization has been done concerning the dependence of surface flux distribution in space and angular domain, or interface currents. It is found that appropriate discretization with more than five for both of segments and sectors is required to accurately calculate effective cross sections and eigenvalue in the multiband-CCCP method. However, in practice, discretization schemes with one segment and several sectors can be 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 dependence in the distribution of surface flux on the off-centered segments have large 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. |
