Direct Integration Method for Numerical Solution of the Radiation Transport Equation in Axisymmetric Toroidal Geometry

A numerical analysis program for radiation transport in axisymmetric toroidal geometry AIDA is developed using the method of direct integration (method of characteristics). The shape of the torus cross section is represented by coupled ellipses with different elongations. Several new techniques, such as a ray-tracing technique in the core plasma region and subdivision of angular mesh cells, are introduced to make the method well adapted to the neutronics analysis of a tokamak. These improvements are illustrated by sample toroidal geometry calculations. To verify the validity of the present program, results of analysis for two sample problems are compared with results of DOT-3.5 as well as those of Monte Carlo calculations. Agreement between the results of AIDA and those of DOT-3.5 becomes better as the quadrature approximation used in DOT-3.5 becomes higher. For the same accuracy, the AIDA code requires only about half as much running time as the DOT-3.5 code for a practical natural lithium blanket system.