An automated deterministic variance reduction generator for Monte Carlo shielding applications

As part of a larger project to upgrade the shielding capabilities in the SCALE code system, efforts have been initiated to independently develop and demonstrate generalized automated variance reduction. Initial efforts have developed a prototypic utility code for automated variance reduction based on existing Monte Carlo and discrete ordinates codes and proven methodologies. This prototypic utility code represents the first step in this effort and will be used for testing and refining the implementation of existing methodologies and investigating alternative methodologies, before attempting to integrate an automated variance reduction capability into SCALE. This paper describes the utility code and a demonstration of its effectiveness on a standard nuclear well-logging problem. The computational efficiencies achieved are very encouraging when compared to both stochastic and manual approaches for developing variance reduction, and the process seems to be well-suited for automation in a future SCALE shielding analysis sequence.