Two-Dimensional Baffle/Reflector Constants for Nodal Code in PWR Core Design

概要

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Currently nodal codes are widely used in three-dimensional core calculation. For nodal calculations, in addition to fuel assembly homogenization constants, baffle/reflector homogenization constants (B/R constants) have to be generated. Due to the complexity of its geometrical structure, the baffle/reflector region is usually represented by the two regions, which are called flat edges and corner edges. B/R constants are generated using an equivalent one-dimensional model for each region. However, errors of 3–4% appear for fuel assemblies along core corner when one-dimensional B/R constants are used. Therefore, in order to improve the accuracy of power distribution calculation based on the nodal method, B/R constants need to be calculated by modeling the geometrical configuration of the baffle/reflector region in greater detail. For this purpose, a method of calculating two-dimensional B/R constants that reflects the geometrical configuration has been developed, in which the geometrical configuration ouside the core is treated explicitly using a two-group fine-mesh diffusion code. The two-dimensional B/R constants thus obtained have reproduced assembly power from heterogeneous calculation within 0.5%, error regardless of fuel loading patterns.
一般社団法人日本原子力学会の論文
2000-11-25