Method for continuously measuring radon exhalation rate in close-loop mode

Abstract

Disclosed is a method for continuously measuring a radon exhalation rate in a close-loop mode. The method comprises the steps that in the measurement process, a radon collection cover with an opening in on face in a close-loop type measuring device is buckled on the surface of a medium to be measured, due to the fact that radon atoms in the medium to be measured overflow out of the surface and enter the radon collection cover under the action of diffusion and seepage, the radon concentration in the radon collection cover is changed, radon in the radon collection cover is pumped into a measurement cavity of a radon measuring instrument by a pump at the constant flow speed of 0.5-10 L / minute and returns to the radon collection cover, and the radon concentration of the measurement cavity in the radon measuring instrument and the radon concentration in the radon collection cover are balanced; then time T is used as the measurement period, the radon concentration in the radon collection cover is continuously measured and monitored, if the radon concentration is basically unchanged after the ith measurement period, nonlinear data fitting is carried out through the measurement values of the first i measurement periods and the relation of the radon concentration and the time of the i measurement periods to obtain the radon exhalation rate and the effective decay constant within the first i periods, and then the radon exhalation rate in all the periods is obtained by combining the effective decay constant previously obtained and later measurement data.

Description

technical field [0001] The invention relates to nuclear radiation detection technology, in particular to a closed-loop method for continuously measuring radon exhalation rate. Background technique [0002] Radon in the air environment mainly comes from the precipitation on the surface of the medium. Measuring the change of the radon precipitation rate can reflect the change of the radon concentration faster. In studies of earthquakes, geology, volcanoes, etc., the cracking of underground rocks will cause a large change in the exhalation rate of radon. Continuously monitoring the change of radon exhalation rate can quickly obtain the changing state of underground rocks. The traditional open-loop radon exhalation rate measurement method can continuously measure the radon exhalation rate, but the introduction of external air will reduce the radon concentration in the radon collection hood, resulting in large statistical fluctuations and low measurement accuracy. In the tradit...

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Problems solved by technology

The traditional open-loop radon exhalation rate measurement method can continuously measure the radon exhalation rate, but the introduction of external air will reduce the radon concentration in the radon collection hood, resulting in large statistical fluctuations and low measurement accuracy

In the traditional closed-loop measurement of radon exhalation rate, because the air is not actively exchanged with the outside world, the radon concentration in the radon collecting hood is high, and the measurement accuracy is high. Cannot continuously monitor changes in radon exhalation rate

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