G. Le Petit¹ , A. Axelsson² , K. Ungar³ , P. Achim¹ , P. Gross¹ , S. Generoso¹ , M. Morin¹ , A. Ringbom²

¹Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CENTRE Île-de-France, France
²Swedish Defence Research Agency (FOI), Stockholm, Sweden
³Health Canada, Ottawa, ON, Canada

Abstract:

Releases from industrial facilities, due mainly to medical isotope production facilities (MIPs) and to a lesser extend to nuclear power plants (NPPs), are at the origin of the worldwide radioxenon background, and lead to specific activity concentration levels at most noble gas stations of the IMS network. In parallel, owing to the tremendous atmospheric dilution, the signature of an underground nuclear test in case of a prompt or/and delayed release into the atmosphere is likely to be detected at the IMS station at the background level. NDCs follow up over years of detecting time series at each IMS noble gas station and the assessment of the worldwide radioxenon background from the atmospheric transport modelling calculations can be of a great help to screen out numerous events. However, only a radioxenon isotopic ratio will give a clear event discrimination. Analysis and validation by NDCs of isotopic ratios involving three radioxenons (135, 133m and 133Xe), measured by the IMS noble gas stations over the last decade, allows efficient enhancement of the current IDC event characterization scheme.