A closure for stochastic transport equations

The problem of particle transport through a stochastic mixture of two immiscible materials is considered. The material mixing process is assumed to obey Markovian statistics. An ensemble average of this stochastic transport equations leads to two equations containing four different ensemble-averaged intensities. To close these equations to a set of two equations in two unknowns, certain rod geometry problems are considered. In this geometry, two distinct exact analyses are possible, namely a small correlation length analysis, and a non stochastic mean number of secondaries per collision analysis. The closure philosophy is to demand that the closed set of two equations reproduces these exact limiting behaviors. Numerical results are given which compare the predictions of this new closure with exact benchmark results as well as with the standard closure available in literature. (authors). 12 refs., 2 figs