Method for continuously measuring radon exhalation rate based on change of leakage coefficient and back-diffusion coefficient

Abstract

According to a method for continuously measuring the radon exhalation rate according to the change of a leakage coefficient and a back-diffusion coefficient, before the leakage coefficient and the back-diffusion coefficient are not changed, the effective decay constant is firstly measured, and the radon exhalation rate is directly calculated through the effective decay constant. When rainfall or geological conditions are changed, and the leakage coefficient and the back-diffusion coefficient are changed, each measurement period is set to be 2 to 60 minutes, n measurement periods are set as one group, m groups are continuously measured, m is an even number, the flow rate of the pump is L1 when the first, third, fifth,... and (m-1) th groups are measured, the flow rate of the pump is L2 when the second, fourth, sixth,... and m th groups are measured, and the difference between L1 and L2 is more than 20%; and the radon exhalation rate and the effective decay constant are calculated through a formula by using the data of the first and second groups, the data of the third and fourth groups,..., and the data of the m-1 and m groups. According to the method, after the leakage coefficient and the back-diffusion coefficient are changed, the accurate radon exhalation rate and the effective decay constant can still be obtained, and the calculation precision of the radon exhalation rate is improved.

Description

technical field [0001] The invention relates to a nuclear radiation detection technology, in particular to a method for measuring the exhalation rate of radon by the change of leakage coefficient and back diffusion coefficient. 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 the research of earthquake, geology, volcano, etc., the cracking of underground rocks will lead to a large change in the exhalation rate of radon. Continuous monitoring of changes in the exudation rate of radon 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. However, in the traditional open-loop radon exhalation rate measurement method, the excessive ventilation flow rate will reduce the ...

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Problems solved by technology

[0004] However, in the process of on-site measurement, the actual measurement situation is very complicated, and the leakage coefficient and back-diffusion system cannot be maintained at all times. For example, if there is rainfall or geological conditions change, it is very likely that Leakage coefficient and back-diffusion coefficient will also change. At this time, the Chinese patent CN 103777222 B "Method for Continuously Measuring Radon Exhalation Rate Using Effective Decay Constant Open-loop" is used in the measurement process, and the effective decay constant obtained by the initial measurement is used in the measurement process. When rainfall or geological conditions change, the obtained effective decay constant will not be applicable to subsequent measurements

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