Application of three-dimensional discrete ordinates transport codes in (X, Y, Z) and (R, O, Z) geometries to shielding analysis

A discrete ordinates transport code, ENSEMBLE, has been developed for use in (X,Y,Z) geometry and its applicability to practical shielding analyses has been shown by the analysis of a bent duct streaming experiment. As a further improvement ENSEMBLE-RTZ has been developed for (R,theta,Z) geometry, and the validity of the calculational algorithm of ENSEMBLE-RTZ has been assured by numerical checks. In this paper we have applied the ENSEMBLE-RTZ code to a three-dimensional analysis of neutron streaming through a complicated inlet pipe cutout in the graphite shield of an experimental fast reactor, JOYO. By this analysis it has been shown that three-dimensional effects are significant and ENSEMBLE-RTZ has potential for useful application in many three-dimensional transport problems. (author)