PNNL

Abstract

In 1995, the development of a global radioactive xenon monitoring network was discussed in the Conference on Disarmament as part of a nuclear explosion verification regime. Discussions considered different network densities and different possible source magnitudes. The Comprehensive Nuclear Test Ban Treaty was subsequently written to initially include 40 xenon stations, and to consider a total of 80 xenon stations in its International Monitoring System (IMS) after the treaty enters into force. Since 2000, a global network of xenon monitoring stations has been built as part of the IMS. This network, currently at 31 stations, is of sufficient sensitivity to discover that the Earth’s atmosphere contains a complex anthropogenic radioactive xenon background. In this work, the impact of calculated xenon backgrounds on IMS radionuclide stations is determined by atmospheric transport modeling for multiple years. Rather than simple binary xenon detections, coverage is based on a proposed method for finding anomalies amongst frequent background signals. Despite the addition of background and a conservative anomaly-based approach, this work shows various network configurations, even for much smaller source terms than originally discussed, exceed the WP.224 xenon coverage estimates. While these global xenon coverage figures are surprisingly good, the regional impact of background is large, especially for smaller source magnitudes, and in some cases the xenon background vastly reduces the value of individual stations. The results show the detection capability and most optimal installation order of stations, e.g. from 40 to 80, after the treaty enters into force.