A Method for Identification and Assessment of Radioxenon Plumes by Absorption in Polycarbonates.

A method for the retrospective evaluation of the integrated activity concentration of Xe during radioxenon plumes and the moment of the plume's center is proposed and explored by computer modeling. The concept is to use a specimen of polycarbonate material (a stack of Makrofol N foils of thickness 120 µm and 40 µm in 1 L non-hermetic Marinelly beaker) that is placed in the environment or in a controlled nuclear or radiopharmaceutical facility. On a regular basis or incidentally, the specimen may be retrieved and gamma spectrometry in two consecutive time intervals with durations of 8 h and 16 h is performed. To assess the performance of the method, Xe plumes of various integrated activity concentrations and with a duration of up to 10 h are simulated and analyzed, assuming that the measurement starts with a delay of up to one day after the moment of the plume center. It is found that the deviation between the estimates by the method and their true values are within a few percent. Depending on the delay, events of integrated Xe activity concentration 250-1000 Bq h m might be qualitatively identified. At levels >10,000 Bq h m, the uncertainty of the quantitative estimates might be ≤10%.