CTBT: Science and Technology Conference 2025 - SnT2025

Tuning alarm levels for Xenon isotope detection

P3.6-625

10 Sept 2025, 11:00

1h

Zeremoniensaal

Board: 37

E-poster T3.6 Analysis of Radionuclide Monitoring Data P3.6 Analysis of Radionuclide Monitoring Data

Speaker

Peter Kimstrand (Swedish Defense Research Agency (FOI))

Description

Radioxenon detection is one of the key methods used in the International Monitoring System (IMS) of CTBTO for detecting a nuclear explosion event. However, since there are numerous civilian sources of radioxenon, such as isotope production facilities and nuclear power plants, any detection of radioxenon must be carefully analysed in order to determine if the source could be a nuclear explosion.
In this work we utilize published discrimination methods based on the isotopic activity ratios of the four relevant isotopes (^131mXe, ¹³³Xe, ^133mXe and ¹³⁵Xe) in combination with historical IMS data and simulated nuclear explosion events to tune alarm levels for different types of radioxenon detections. The in-house software framework NEMOS (Nuclear Event Monitoring Simulator) is used to simulate the full chain of nuclear explosion events, from explosion, via atmospheric transport, to detection. The goal of the tuning is to find a good trade-off that minimizes the amount of false alarms (and thus the burden of manual analysis) while still capturing true events.