(A) study on pin power reconstruction with APEC-corrected NEM nodal analysis

Abstract

In this study, pin power reconstruction is performed using the APEC-corrected NEM (Nodal Expansion Method) nodal calculation results. The form function method which is widely used in commercial core analysis is used for pin power reconstruction. The form function method is to obtain the heterogeneous flux distribution by multiplying homogeneous flux distribution in the fuel assembly with the form function determined in a single fuel assembly calculation. To obtain the homogeneous flux distribution in the fuel assembly, an analytic function expansion method is used in this work. The constant term is added to analytic solution to preserve the reaction rate of the fuel assembly. To determine the coefficients of the analytic solution, homogeneous corner point fluxes are calculated using the MSS (method of successive smoothing) method. In addition, a new method using discontinuity factors corrected by the APEC method is proposed to convert homogeneous corner point fluxes into heterogeneous corner point fluxes.