Study On The Influence Of Air Flow Rate On The Radon Exhalation Rate Measuring

Entered into force on June 1, 2011 GB the indoor environmental pollution control of civil building engineering specifications?2010Edition?,-GB50325-2010, stricter provisions of building materials surface and soil radon exhalation rate limit, set out in the national standard of radon exhalation rate measuring method or traditional Gamma activated carbon adsorption method. Traditional Gamma activated carbon adsorption measurement method of sampling and measurement time too long, under the influence of Thoron, under the influence of factors such as leaks and a counter-proliferation, in measuring radon exhalation rate values timeliness and accuracy of great impact. In order to reduce or even eliminate these factors build radon exhalation rate measuring method for fast and reliable. In the sampling methods for optimization, it is necessary to improve efficiency and timeliness.The paper has carried out double room open-loop continuous measuring method of radon exhalation rate optimization study, paper key to open-loop continuous sampling method for measuring radon exhalation rate research. Main contents include the following two aspects:?1? study on effect of sampling method for measuring radon exhalation rateAccording to analysis of parameters of continuous sampling method for measuring radon exhalation rate results, theoretical calculations of sa mpling methods for measuring radon exhalation rate best sampling metho ds, sampling rate, sampling time and other parameters.?2? study on sampling method for measuring radon exhalation rateIn radon precipitation rate reference standard device Shang for corresponding experiment: select continuous sampling continuous count measurement and used, time interval sampling, different measurement mode carried out experiment measurement and analysis data,optimization select measurement different object radon precipitation rate of sampling method; change sampling flow and sampling time,experiment analysis optimization get based on electrostatic collection radon precipitation rate continuous measurement of best sampling flow,and sampling time and cycle way.Through the open loop optimum design of radon exhalation rate measuring devices, and using MATLAB software and FLUENT simulation software to model the theoretical value calculation, collection of fluid motion model simulation of indoor radon; get the corresponding theoretical conclusions. Hunan provincial key laboratory of radon radon exhalation rate reference device verified this on the experiment andmeasurement device experiment; the following conclusions: in open-loop radon exhalation rate measuring device increase the external design of the pump, you can control the size of gas flow rate to control the set balance of indoor radon concentrations of radon. External pump introduction balance of indoor radon concentrations of radon over a set time also affects the balance of radon concentration increases with the increase of the flow rate and shorten the time.Through a large number of experiments are: 1) the reference standard equipment of radon exhalation rate from soil and tailings, radon P=1.62 0.05 Bq ? m^-2 ? s^-1. Suitable for measuring the flow rate as 2.5-4 L? min^-1, measurement period is 30 min, balance of radon concentration is709^-1127 Bq·m-3. 2) made of low grade uranium ore powder and cement mixing radon exhalation rate as the reference standard, the radon exhalation rate stable at 0.39 ± 0.03 Bq ? m^-2 ? s^-1. Suitable for measuring the flow rate for 1^-2L ? min^-1 is the best, period 30 min, balance of radon concentration is 466-749 Bq·m-3.