Reducing Uncertainty in Nuclear Test Detection: An Analysis of Multiple IMS Detections

The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) relies on its International Monitoring System (IMS) to detect radionuclide releases, which can indicate potential nuclear tests. By using atmospheric transport modelling (ATM), the CTBTO aims to establish links between detecting stations and corresponding source locations. When detection is limited to a single event within a narrow time window or between neighbouring stations, operational analysis typically generates large possible source regions that require further refinement. Multiple detections offer a unique opportunity for a more detailed analysis, allowing advanced methods to be applied for more accurate identification of the source location.

Recently, elevated levels of radioxenon were detected at multiple IMS locations in and around the Japanese region, including Takasaki, Wake Island, and the non-IMS system at Horonobe. These detections exceeded historical levels, emphasizing the need for a more detailed analysis. The dense network of measurement stations in this area presents an opportunity to explore advanced methods for source localization, reducing the uncertainty, and to discuss the implications of these findings on the monitoring of radioxenon isotopes.