An innovative atmospheric gradient approach for monitoring radon-222 exhalation from uranium mining tailings

An innovative atmospheric gradient approach for monitoring radon-222 exhalation from uranium mining tailings disposal sites is developed and evaluated within the FLURAD project (2024–2027). Radon-222, a major contributor to natural radiation exposure, is both a radiological concern and a powerful tracer of surface–atmosphere exchanges. On former uranium mining sites, conventional accumulation chamber techniques provide direct but spatially limited surface exhalation flux measurements and require site accessibility. The proposed approach adapts the atmospheric gradient method to radon by combining vertical profiles of atmospheric radon concentration with a detailed characterization of turbulent transport. Atmospheric concentrations are obtained from short-lived radon progeny produced inside dedicated decay chambers supplied with filtered air, ensuring that only gaseous radon enters the system and avoiding uncertainties related to outdoor disequilibrium between radon and its progeny. An exploratory field campaign conducted on a former uranium tailings disposal site demonstrates the operational feasibility of this indirect, spatially integrated monitoring strategy. Results were compared with simultaneous accumulation chamber measurements to assess methodological consistency, applicability limits and uncertainty sources, contributing to the advancement of innovative environmental radioactivity monitoring approaches.