Study of the influencing factors of measuring radon exhalation rate by the method of the activated charcoal absorption

The influencing factor of measuring radon exhalation rate is studied with the method of the activated charcoal absorption. The sampling time is 24 hours, and water sponge is used to simulate the medium with different water. The authors use 100g activated charcoal to measure different materials. It is found that when we measure concrete surface, activated charcoal absorbs more than 1 g water, educing the measured value by about 1%. When we measure plaster surfaces, activated charcoal absorbs more than 1 g water, educing the measured value by about 1.85%. In normal condition, measured value of the radon exhalation rate from plaster surface reduces by about 12% and 25% respectively, when we lengthen the sampling time from 24 hours to 48 hours and 72 hours. The anti-diffusion effects are not obvious to the medium which is biggish in density such as concrete. (authors)