Research on Ray Effect of Multi-dimensional S_N Method Based on First Collision Source Theory

The uncollision neutron source was calculated from isolated source by semi-analytic method, and distribution of first collision source for the models was achieved. In this way, the theory to mitigate ray effect of S_N theory by distributing the isolated source into range area was established, and the corresponding code REM3D for three-dimensional discrete ordinate code CTDOS was also developed. The results on Kobayashi benchmark indicate that this theory is appropriate and this program is correct.