H. Brockmann, Narrow-duct-streaming calculations using generalized configuration factorswithin the discrete ordinates method, NUCL SCI EN, 132(1), 1999, pp. 127-134
In calculating neutral particle transport through elongated voids with the
discrete ordinates method, the problem of ray effect may occur if standard
angular quadrature sets are used. To mitigate this ray effect, the configur
ation-factor concept developed in the theory of thermal radiation for calcu
lating the radiation exchange among surfaces is applied here. The common co
nfiguration;factor concept is extended in such a way that the angular depen
dence of the radiation emitted from the surfaces can be considered. The met
hod is applied to regular and annular cylinders with r-z geometry and incor
porated into a two-dimensional discrete ordinates transport code. Calculati
ons on a narrow-duct-streaming problem show that the ray effect is strongly
reduced by this method. The new method gives results equivalent to or even
better than a standard discrete ordinates calculation using a biased angul
ar quadrature set with 166 directions at computing times for one inner iter
ation that are about a factor of 2 less.