Analysis of radionuclide detection events on the International Monitoring System

The United Kingdom (UK) National Data Centre (NDC) operates a series of custom-developed software tools for the automatic processing, analysis, archiving and interpretation of radionuclide (RN) data from the International Monitoring System (IMS) - the primary instrument for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The software in-use at the NDC includes an RN Pipeline for the retrieval, analysis, categorisation and archiving of noble gas and particulate radionuclide data. On the identification of a treaty-relevant radionuclide detection or plume of radioxenon, a 'radionuclide detection event' is formed. A series of atmospheric transport and dispersion simulations are activated, and the data is added to the 'RN Event' database where the detection is compared with forward simulations from known or suspected radionuclide emitters. The field of regard for a radionuclide detection event is cross-checked with others to identify possible associated detections, and finally a source reconstruction tool (known as FREAR) is used to determine the source parameters - location, magnitude, emission start time and emission stop time.