Transport Test Problems for Radiation Detection Scenarios

Modeling forms an important component of radiation detection development, allowing for testing of new detector designs, evaluation of existing equipment against a wide variety of potential threat sources, and assessing operation performance of radiation detection systems.This can, however, result in large and complex scenarios which are time consuming to model.A variety of approaches to radiation transport modeling exist with complementary strengths and weaknesses for different problems.This variety of approaches, and the development of promising new tools (such as ORNL's ADVANTG) which combine benefits of multiple approaches, illustrates the need for a means of evaluating or comparing different techniques for radiation detection problems.This report presents a set of 9 test problems for comparing different types of radiation transport calculations, identifying appropriate tools for classes of problems, and testing and guiding the development of new methods.Cases are drawn primarily from existing or previous calculations with a preference for cases which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22.From a technical perspective, cases are chosen to span a range of difficulty and to include gamma transport, neutron transport, or both and represent different important physical processes and a range of sensitivity to angular or energy fidelity.Following test case identification, existing information about geometry, measurements, and previous calculations were assembled.Monte Carlo results (MCNP decks) were reviewed or created and re-run in order to attain accurate computational times and to verify agreement with experimental data, when present.Test case information was then conveyed to ORNL in order to guide testing and development of hybrid calculations.The results of those ADVANTG calculations were then sent to PNNL for compilation.This is a report describing the details of the selected test cases and results from available transport codes.Additional results from other transport codes will be added during the next year, along with additional cases if needed for software testing.Future work will extend the test problems to include more extensive crosscode comparisons as well as more refined metrics for evaluating the tradeoffs between operator time, computational time, and solution accuracy, to assemble a formalized benchmark set.vThe test problems summarized in this report represent a substantial effort in both radiation detection methods and transport model development by a number of staff from both PNNL and elsewhere.While the original work is referenced in this report,