Advanced PWR Core Calculation Based on Multi-group Nodal-transport Method in Three-dimensional Pin-by-Pin Geometry

A parallel production code, SCOPE2, has been developed for advanced calculations in the reactor core design of PWRs. In SCOPE2, the multi-group diffusion and/or SP3 transport equations are solved by the Red/Black iterative method within the framework of the finite difference method or the advanced nodal method without non-linear iterations. The effects due to pin-cell homogenization are taken into account by using the SPH factors. In this paper, calculation methods needed for fast computation are derived including efficient response matrix formulation of the nodal-SP3 method, an analytic solution of the flux moments in the nodal-SP3 transport equations, and coarse-group coarse-mesh diffusion acceleration method. It was found that the present pin-by-pin nodal-SP3 method was more accurate than the finite difference SP3 method with a small additional computational cost in the same meshing scheme. Tracking calculations of a commercial PWR plant by SCOPE2 revealed that the present model accurately predicted the power distribution and critical boron concentration. A set of depletion calculations in a typical design scheme can be completed within a few hours running on a PC-cluster (16 processors) for the full-core geometry of a 3-loop PWR with 340×3407times;26 meshes based on the 9-group pin-by-pin nodal-SP3 method.

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