Projected network performance for next-generation xenon monitoring systems

Next-generation radioxenon monitoring systems are reaching maturity and are expected to improve certain aspects of performance in verifying the absence of nuclear tests. To predict the improvement in detecting and locating nuclear test releases, thousands of releases all over the globe were simulated and the global detection probability was calculated for the single xenon isotope ¹³³Xe. This was done for the International Monitoring System network of noble gas samplers as it currently exists (25 certified stations), and how it would be for potential future network sizes of 39 and 79 stations. The probability of detection was calculated for releases ranging from 10¹⁰ Bq to 10¹⁶ Bq of ¹³³Xe using 10 d of atmospheric transport and presented as coverage maps and global integrals for both current and next-generation monitoring systems. Similarly, the number of detecting stations and the number of detecting samples were tabulated to elucidate the possibilities for enhanced location capability. Improvements in global detection coverage are maximized at different release sizes in a way that depends on the station density. For example, for releases of 3 × 10¹⁴ Bq and 39 stations, the detection probability would rise from 60% to 70% with next-generation systems, while for releases of 10¹³ Bq and 79 stations, it would rise from 37% to 52%. Achieving an average of two detecting stations would require a 10¹⁵ Bq release for a 39-station network and a 10¹⁴ Bq release for a 79-station network. The largest impact of using next-generation systems may be the confidence, detection redundancy, and location capability that arise from obtaining multiple samples associated with a single release event.