Direct-coupled-ray method for three-dimensional shielding analysis

A fast, three-dimensional design-oriented transport method has been developed for the solution of both neutron and gamma shielding problems. It combines a nodal approach with analytic integral transport to achieve relative speed and accuracy. An analytic solution is obtained for each of 14 angular fluxes in each mesh block of a three-dimensional assembly. The directions are such that the outgoing angular flux components in one mesh block become the incoming angular flux components in the adjacent mesh blocks. The approach is therefore described as the Direct-Coupled-Ray (DCR) method. The DCR method with full anisotropic scattering capability, variable mesh capability, and generalized boundary conditions, has been implemented in the TRANS3 code. Several benchmark calculations and numerous scoping calculations were performed using problems representative of LMFBR shielding configurations. These included a 1-D deep penetration configuration and one-, two-, and three-dimensional representations of the lower axial shield of the Clinch River Breeder Reactor