On the calibration of a radon exhalation monitor based on the electrostatic collection method and accumulation chamber

•The radon flux can be obtained by the radon monitor based on electrostatic collection.•The difference between radon and 218Po is the main system error for measuring radon flux.•The difference changes vs. time and effective decay constant.•The calibration of the radon flux monitor is useful to reduce the measurement error.•The calibration factor obtained is impossible to completely correct the system error.

The radon exhalation rate can be obtained quickly and easily from the evolution of radon concentration over time in the accumulation chamber. Radon monitoring based on the electrostatic collection method is not interfered with by 220Rn. In this paper, we propose that the difference between radon and 218Po concentrations in the measurement cell of this kind of radon exhalation monitor is the main system error, and it changes with time and different effective decay constants. Based on the results of simulation experiments, we propose that the calibration factor obtained from the suitable experiment cannot completely correct the system error, even if it is useful to reduce the measurement error. The better way for reducing measurement error is to use the new measurement model which we have proposed in recent years.