The recently developed open source FREAR tool improves nuclear event analysis by using Bayesian inference principles to estimate key source term parameters using measurements from distant radionuclide monitoring equipment in combination with Atmospheric Transport and Dispersion Models (ATDM). Trials on real world reconstructions have demonstrated clear and dramatic improvements over standard correlation techniques, such as the Possible Source Region (PSR) algorithm. The improvements in source characterization are a result of implementing a statistical non-detection model that accurately represents the performance of the radionuclide detection equipment and by using a full ATDM uncertainty model in the reconstruction process. To further test the performance and capabilities of this tool, two blind tests are conducted with synthetic source terms with short- and long-range transport. The test scenarios and the results of the reconstruction are described and assessed to further demonstrate the compelling benefits of using the FREAR statistical tool in event analysis.
The Forensic Radionuclide Event Analysis and Reconstruction Tool is a new method to improve nuclear test monitoring and verification by applying statistical inference methods to reconstruct the emission source by fusion of radionuclide data and atmospheric transport modelling.