Investigation on atmospheric radioactivity sample association using consistency with isotopic ratio decay over time at IMS radionuclide stations.

For the enhancement of the International Data Centre's products, specifically the Standard Screened Radionuclide Event Bulletin, an important step is to establish methods to associate the detections of the Comprehensive Nuclear-Test-Ban Treaty-relevant nuclides in different atmospheric radioactivity samples with the same radionuclide release to characterize its source for the purpose of nuclear explosion monitoring. Episodes of anomalously high activity concentrations in samples at the International Monitoring System radionuclide stations are used as the primary assumption for being related to the same release. For multiple isotope observations, the consistency of their isotopic ratios in subsequent samples with radioactive decay is another plausible hint for one unique release.

Characterisation of Xe-133 background at the IMS stations in the East Asian region: Insights based on known sources and atmospheric transport modelling.

Radioxenon can be produced with a high fission yield during a nuclear explosion, making it an important tracer to demonstrate the nuclear origin of an explosion. For this reason, it is continuously monitored by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) as part of the verification regime. Radioxenon is emitted by civil nuclear facilities, like nuclear power plants (NPPs) or isotope production facilities (IPFs), providing significant but variable contribution to the noble gas background.