The DC_N-S_N Hybrid Method for Neutron Transport Calculations in (r-z) Geometry

A hybrid method for two-dimensional neutron transport calculations in (r-z) geometry has been developed. In this method the equation in void regions is solved by the discrete cones (DC_N) method, whereas the equation in nonvoid regions is solved by the standard discrete ordinates (S_N) method. The two methods are incorporated in one computer program so that a user does not see the difference from a program applying only the S_N method. This DC_N-S_N hybrid method significantly mitigates the ray effects in a void compared with a solution by the same order S_N. The method, however, requires a little more computing effort and it is difficult for the method to yield a sufficiently accurate solution for narrow duct streaming problems.