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 non-void 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.