An indoor radon mitigation method by heterogeneous nucleation of H2O vapor on Rn favored by Peltier cooling

This work presents a novel method for mitigating indoor radon, which consists of four steps:  a) nucleation of water vapor around Rn atoms and Rn progenies, b) condensation of the mentioned clusters favored by a Peltier cooling process, c) accumulation of the resulting liquid, and d) discharging of the liquid outside. This system was proved in an underground cave with microclimate conditions (80 % relative humidity, 798-800 mbar atmospheric pressure, 20 ± 1 0C temperature, and an almost constant indoor Rn activity of  890 Bq/m3), in México City. The proposed method takes advantage of the natural formation of a system of Radon-Water (Rn-H2O) complexes, by van der Waals interactions. We have observed that by reducing the relative humidity by Peltier cooling, from 80 to 52%, a removal of radon is produced, from 607 to 165 Bq/m3, which is a very remarkable mitigation effect. Experimentally, the operation of the mitigation system in relative humidity environments between 30 and 80%, and between 40 and 1500 Bq/m3, is certified, always obtaining control of the desired intramural radon activity (100 Bq/m3), in less than 12 hours. This surpasses most of today’s commercial radon mitigation methods in efficiency, cost, time and ease, specifically in conditions where ventilation is not a reliable option.