Measuring radon exhalation rate through three cycles

Tan, Yanliang; Xiao, Detao

doi:10.1088/1748-0221/7/08/t08004

Cited by 6 publications

(4 citation statements)

References 20 publications

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“…The radon concentration in the ventilation-type chamber can be determined by the following differential equation: where C V (t) is the radon concentration in the ventilation-type chamber; C E is the radon concentration of outdoor air; J is the radon exhalation rate; S is the area of the bottom of the chamber; V is the volume of the ventilation-type chamber and it equals 4 liter; L is the ow rate of the pump; and l eff is the effective decay constant (the summation of decay constant, back-diffusion coefficient, and chamber leakage coefficient) of radon. [9][10][11][12][13] Given the decay constant of radon is only 2.1 Â 10 À6 s À1 , the leakage and back diffusion greatly inuence the equilibrium radon concentration. Fig.…”

Section: Methodsmentioning

confidence: 99%

A novel method to measure the radon exhalation rate in only one measurement cycle

Tan

Xiao

2013

Anal. Methods

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A novel method was proposed to measure the radon exhalation rate in only one measurement cycle. We obtain the radon concentration variety regulation in the internal cell of the RAD7 by analyzing the work principle of RAD7 and the radon concentration variety regulation in the ventilation-type accumulation chamber when the effects of leakage and back diffusion are neglected. This method uses the measured value before the radon concentration in the ventilation-type accumulation chamber reaches a steady state. Several radon exhalation rate measurements of the medium surface have been performed in the Radon Laboratory of the University of South China. The radon exhalation rates obtained by verification experiments are in good agreement with the reference value. This simple, accurate and fast method can be applied to develop and improve the instruments for measuring radon exhalation rates.

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Section: Methodsmentioning

confidence: 99%

A novel method to measure the radon exhalation rate in only one measurement cycle

Tan

Xiao

2013

Anal. Methods

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“…Then, this measurement was conducted on 3 different days that the letter is intended to after number. In conducting short-term continuous sampling, time intervals that have been used by other researchers were 10, 12, 15, 20, 40, 60-minute or 2 hours [4,5,7,[11][12][13][14]. 2) In this study, radon data were collected with 5 and 15-minute periods during total measurement time of 4 hours.…”

Section: Soil Exhalation Rate Measurementmentioning

confidence: 99%

“…Equation 10 is suitable for exponential fitting. (10) where and k= λ+λl+λb (11) The following form of E is adopted to explain Equation 12 for the uncertainty propagation of E. (12) Also, the contributions to relative uncertainty of each parameter are summed to 1.…”

Section: ) Exponential Fittingmentioning

confidence: 99%

Standard Measurement Procedure for Soil Radon Exhalation Rate and Its Uncertainty

et al. 2018

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Background: Radon contributing about 42% of annual average dose, mainly comes from soil. In this paper, standard measurement procedures for soil radon exhalation rate are suggested and their measurement uncertainties are analyzed. Materials and Methods: We used accumulation method for estimating surface exhalation rate. The closed-loop measurement system was made up with a RAD7 detector and a surface chamber. Radon activity concentrations in the system were observed as a function of time, with data collection of 5 and 15-minute and the measurement time of 4 hours. Linear and exponential fittings were used to obtain radon exhalation rates from observed data. Standard deviations of measurement uncertainties for two approaches were estimated using usual propagation rules. Results and Discussion: The exhalation rates (E) from linear approach, with 30 minutes measurement time were 44.8-48.6 mBq• m-2 • s-1 or 2.14-2.32 atom• cm-2 • s-1 with relative measurement uncertainty of about 10%. The contributions of fitting parameter A, volume (V) and surface (S) to the estimated measurement uncertainty of E were 59.8%, 30.1% and 10.1%, in average respectively. In exponential fitting, at 3-hour measurement we had E ranged of 51.6-69.2 mBq• m-2 • s-1 or 2.46-3.30 atom•cm-2 • s-1 with about 15% relative uncertainty. Fitting with 4-hour measurement resulted E about 51.3-68.2 mBq • m-2 • s-1 or 2.45-3.25 atom • cm-2 • s-1 with 10% relative uncertainty. The uncertainty contributions in exponential approach were 75.1%, 13.4%, 8.7%, and 2.9% for total decay constant k, fitting parameter B, V, and S, respectively. Conclusion: In obtaining exhalation rates, the linear approach is easy to apply, but by saturation feature of radon concentrations, the slope tends to decrease away from the expected slope for extended measurement time. For linear approach, measurement time of 1-hour or less was suggested. For exponential approach, the obtained exhalation rates showed similar values for any measurement time, but measurement time of 3-hour or more was suggested for about 10% relative uncertainty.

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“…RAD7 (Durridge Company) counts only the 218 Po decays in sniff mode; it means that radon measurements are not interfered with by 220 Rn daughters. Because sufficient delay time is needed for the 218 Po concentration in the internal cell of the RAD7 to become equal to the Radon concentration of the environment [11][12][13], RAD7 can not trace the change of radon concentration quickly. We propose a novel method for quickly measuring the radon exhalation rate in the open loop by RAD7.…”

Section: Introductionmentioning

confidence: 99%

Revision for measuring radon exhalation rate in open loop

et al. 2013

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We propose a novel method for quickly measuring the radon exhalation rate in open loop. We first obtain the temporal variation of radon concentration in the internal cell of the RAD7 by analyzing the work principle of RAD7. We then obtain the temporal variation of radon concentration in the ventilation-type accumulation chamber when the effects of leakage and back diffusion are neglected. This method uses the measured value before the radon concentration in the ventilation-type accumulation chamber reaches a steady state. The diameter of the air input tube to the ventilation-type accumulation is large enough to keep the differential pressure in the accumulation chamber and outdoors negligible. Short cycle time and large flow rate will be appropriate for reducing measurement error. Several radon exhalation rate measurements of the medium surface have been performed in the Radon Laboratory of the University of South China. The radon exhalation rates obtained by verification experiments are in good agreement with the reference value. This method can be applied to develop and improve the instruments for measuring radon exhalation rate.

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Measuring radon exhalation rate through three cycles

Cited by 6 publications

References 20 publications

A novel method to measure the radon exhalation rate in only one measurement cycle

A novel method to measure the radon exhalation rate in only one measurement cycle

Standard Measurement Procedure for Soil Radon Exhalation Rate and Its Uncertainty

Revision for measuring radon exhalation rate in open loop

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