Bounded Estimators for Flux at a Point in Monte Carlo

Methods are given for obtaining bounded estimators for radiation flux at a point detector in a Monte Carlo calculation. In essence, the procedure is to so bias the collision density in the neighborhood of the detector that the usually singular last-flight estimator gives bounded results. The change with respect to usual Monte Carlo procedures is “local” in that only collisions within a fixed neighborhood of the detector are affected. A reselection procedure is used to implement the local requirement.