Improving the quality of the 'ventilation chamber' technique for surveying the radon exhalation rate continuously

摘要

The "ventilation chamber" technique is unreplaceable when the radon exhalation rate is surveyed continuously. The air pressure difference between the chamber and the environment that leads the increase of radon exhalation rate can be reduced by increasing the diameter of the air input tube. A sufficient condition for a standard measurement is the air change rate has to be far larger than the effective decay constant in the measurement. When the sufficient condition is false, the measured value of the radon exhalation rate from the custom model is incorrect and it decreases with the air change rate. A new model is proposed to obtain the effective decay constant and the real radon exhalation rate. The influence of thoron on the radon monitor without discrimination ability of the thoron increases with the flow rate. Finally, another sufficient condition is proposed to obtain the radon exhalation rate when the radon distribution in the chamber is inhomogeneous but steady.