Objective:To establish an evaluation model for the radon reduction effect of activated carbon adsorption in localized underground spaces, to guide the rational application of the activated carbon adsorption method for radon reduction in localized underground spaces.Methods:For both intermittent and continuous adsorption-based radon reduction method in localized underground spaces, a theoretical model was constructed for evaluating the of radon reduction effec. By means of this modle, the influence factors on the radon reduction effect were analyzed such as radon concentration, space volume, and air exchange rate with the external environment. Experimental validation of the theoretical model was conducted under typical conditions.Results:The radon exhalation rate from concrete surface in localized underground spaces was inversely linear relationship with the indoor radon concentration. However, the slope of this relationship was very small: when the radon concentration decreased from 2 018 Bq/m 3 to 0, the exhalation rate only increased slightly from 4.20 to 4.46 Bq·m -2·h -1, indicating a minimal change. At the same air exchange rate and in the same space volume, the initial radon concentration had little impact on the adsorption-based radon reduction effect, thus suggesting that the radon generation rate from the enclosure surface could be negligible in the evaluation. In contrast, the adsorption flow rate of a radon reduction device and the air exchange rate between the localized spaces and surrounding environment had significant fluence on radon reduction effect. In the same sealed space and at the same adsorption flow rate, the difference in effect between intermittent and continuous adsorption method was of insignificance. However, in localized spaces with connectivity to surrounding environment, the continuous adsorption significantly outperforms intermittent adsorption, achieving faster radon reduction and better suitability for larger spaces. Simulated experiments validated that the theoretical model for evaluating adsorption-based radon reduction effect was reliable. Conclusions:The research findings provide theoretical guidance on selecting appropriate adsorption-based radon reduction devices for localized underground spaces of different volumes and varing connectivity conditions, in order to reduce the radon concentration within localized spaces to expected levels.

Objective:To establish an evaluation model for the radon reduction effect of activated carbon adsorption in localized underground spaces, to guide the rational application of the activated carbon adsorption method for radon reduction in localized underground spaces.Methods:For both intermittent and continuous adsorption-based radon reduction method in localized underground spaces, a theoretical model was constructed for evaluating the of radon reduction effec. By means of this modle, the influence factors on the radon reduction effect were analyzed such as radon concentration, space volume, and air exchange rate with the external environment. Experimental validation of the theoretical model was conducted under typical conditions.Results:The radon exhalation rate from concrete surface in localized underground spaces was inversely linear relationship with the indoor radon concentration. However, the slope of this relationship was very small: when the radon concentration decreased from 2 018 Bq/m 3 to 0, the exhalation rate only increased slightly from 4.20 to 4.46 Bq·m -2·h -1, indicating a minimal change. At the same air exchange rate and in the same space volume, the initial radon concentration had little impact on the adsorption-based radon reduction effect, thus suggesting that the radon generation rate from the enclosure surface could be negligible in the evaluation. In contrast, the adsorption flow rate of a radon reduction device and the air exchange rate between the localized spaces and surrounding environment had significant fluence on radon reduction effect. In the same sealed space and at the same adsorption flow rate, the difference in effect between intermittent and continuous adsorption method was of insignificance. However, in localized spaces with connectivity to surrounding environment, the continuous adsorption significantly outperforms intermittent adsorption, achieving faster radon reduction and better suitability for larger spaces. Simulated experiments validated that the theoretical model for evaluating adsorption-based radon reduction effect was reliable. Conclusions:The research findings provide theoretical guidance on selecting appropriate adsorption-based radon reduction devices for localized underground spaces of different volumes and varing connectivity conditions, in order to reduce the radon concentration within localized spaces to expected levels.