Xenon and radon time series analysis: A new methodological approach for characterising the local scale effects at CTBT radionuclide network

A new methodology of time series analysis has been tested on 133Xe and estimated 220Rn activity concentrations in order to characterise the site response of four different CTBT/IMS monitoring stations. Seasonal variability of 133Xe and 220Rn at these IMS stations and the role played by different meteorological parameters on such variability have been quantified. As xenon and radon are both noble gases with similar physical characteristics but very different source terms, the methodology adopted in this comparative study, once coupled to analysis of radioxenon emission time series sampled at nearby NPPs or IPFs and to direct measurements of 220Rn at IMS sites location, might help assess relative influence of near and far field air on IMS radioxenon detections. Possible applications of the adopted methodology to radioxenon categorisation schemes are also discussed.