Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia

The verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT) relies amongst other things on the continuous and worldwide monitoring of radioxenon. The characterization of the existing and legitimate background, which is produced mainly by nuclear power plants and isotope production facilities, is of high interest to improve the capabilities of the monitoring network. However, the emissions from legitimate sources can usually only be estimated. For this paper historic source terms of 133Xe emissions from the isotope production facility at ANSTO, Sydney, Australia, have been made available in a daily resolution. Based on these high resolution data, different source term sets with weekly, monthly and yearly time resolution have been compiled. These different sets are then applied together with atmospheric transport modelling (ATM) to predict the concentration time series at two radioxenon monitoring stations. The results are compared with each other in order to examine the improvement of the prediction capability depending on the used time resolution of the most dominant source term in the region. -- Highlights: • Atmospheric transport modelling of Xe-133 emissions from an isotope facility. • Emission data sets with different time resolutions are compared. • The correlation between simulation and detections is analysed. • An underestimation of the Xe-133 concentrations is found and discussed