A method of generating directional diffusion coefficients using the TWODANT code

Various studies have been made to generate the broad group cell averaged directional diffusion coefficients. Benoist and Gelbard showed the typical methods of generating them. Benoist used directional first-flight collision probability to get the directional diffusion coefficients of fuel assemblies and Gelbard used homogenized neutron paths calculated with Monte Carlo method. In this study we produced directional diffusion coefficients by adjusting the diffusion coefficients so that the diffusion leakage terms are same as the calculated ones from the transport theory code TWODANT to avoid cell calculations which were used in the previous methods. The purpose of this paper is to present a method of generating directional diffusion coefficients using the TWODANT code and to show the effects of directional diffusion coefficients in the DIF3D code. The result showed that the effective multiplication factors of the DIF3D code using directional diffusion coefficients are more accurate than those of using conventional diffusion coefficients