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AMNESIA RADIUS VERSIONS OF CONDITIONAL POINT SAMPLING FOR RADIATION TRANSPORT IN 1D STOCHASTIC MEDIA

Vu, Emily V.; Olson, Aaron J.

Conditional Point Sampling (CoPS) is a newly developed Monte Carlo method for computing radiation transport quantities in stochastic media. The algorithm involves a growing list of point-wise material designations during simulation that causes potentially unbounded increases in memory and runtime, making the calculation of probability density functions (PDFs) computationally expensive. In this work, we adapt CoPS by omitting material points used in the computation from being stored in persisting memory if they are within a user-defined “amnesia radius” from neighboring material points already defined within a realization. We conduct numerical studies to investigate trade-offs between accuracy, required computer memory, and computation time. We demonstrate CoPS's ability to produce accurate mean leakage results and PDFs of leakage results while improving memory and runtime through use of an amnesia radius. We show that a limit on required computer memory per cohort of histories and average runtime per history is imposed as a function of a non-zero amnesia radius. We find that, for the benchmark set investigated, using an amnesia radius of ra = 0.01 introduces minimal error (a 0.006 increase in CoPS3PO root mean squared relative error) in results while improving memory and runtime by an order of magnitude for a cohort size of 100.