Development of axially simplified method of characteristics in three-dimensional geometry

Axially simplified method of characteristics in three-dimensional geometry (ASMOC3D) has been proposed, and the 3D neutron transport calculation code based on this method, SHIKOKU, has been developed. Since ASMOC3D handles 3D problems by a two-dimensional (2D) neutron track set and simplified treatment in axial direction, the required memory and the computational time are expected to be less than those required by a direct 3D characteristics calculation scheme. SHIKOKU is applied to two problems of 3D geometry and the results of these problems show good agreements with the reference solutions obtained by a Monte-Carlo code. SHIKOKU is also applied to an actual three-loop-type PWR core. The prediction error of the radial power distribution is satisfactory and it is shown that the computational time and the required memory for a whole-core calculation by ASMOC3D are not prohibitive for presently available PCs. (author)