Development of a novel low-pressure scintillation cell with ZnS(Ag)-coated clapboard for Rn-220 measurement.

The high-precision measurement of Rn-220 is essential for assessing and preventing thoron radiological hazards. Prior research has revealed that employing a scintillation cell without a clapboard improves the detection efficiency for both Rn-222 and Rn-220 by reducing air pressure, and the Rn-220 calibration factor is established at an atmospheric pressure of 0.4.

A new model to accurately measure the radon exhalation rate from soil using AlphaGUARD.

Radon exhalation rate from soil is a critical factor in evaluating environmental radon levels. However, AlphaGUARD PQ2000PRO may have some sensitivity towards thoron, which can have a significant impact on radon measurement. The traditional radon exhalation models generally ignore the presence of thoron, leading to an overestimation of the radon exhalation rate from soil.

Design of intermittent continuous measurement of radon concentration in water.

The U.S. Environmental Protection Agency established the maximum contaminant level limit for radon concentration in drinking water as 11.

COMPARISON OF RADON EXHALATION RATE MEASUREMENTS ON REFERENCE DEVICE IN OPEN AND CLOSED LOOP BY ALPHAGUARD IN FLOW-THROUGH MODE.

Radon-222 (Rn-222) exhalation rate is vital for estimating radiation risk from many kinds of materials. AlphaGUARD measures the radon concentration based on the ionization chamber principle, which is currently recognized as a reference instrument to measure radon. In China, measurements of radon exhalation rate are performed by AlphaGUARD operated in flow-through mode on a reference device to verify measurement accuracy.

OPTIMIZING THE INTERNAL CELL STRUCTURE OF THE RADON MONITOR BASED ON ELECTROSTATIC COLLECTION METHOD.

As Rn-222 decays, an alpha particle is emitted and the residual polonium nucleus recoils in the opposite direction. At the end of the recoil path, 88% of the polonium atoms have a positive charge and 12% are neutral. The electric potential distribution in the 60 ml hemispherical internal cell of the radon monitor based on electrostatic collection is studied for reducing the combined probability of the positively charged Po-218 and the OH- produced by the ionization of water vapour in the air.

A model comparison of diffusion-controlled radon exhalation from solid and cavity walls with application to high background radiation areas.

Radon exhaled from building material surfaces is an important source of indoor radon. Yangjiang, located in the southern part of mainland China, is well-known as a high background radiation area (HBRA). Rather, high levels of radon and thoron concentration have been observed in adobe and brick houses.

No flow meter method for measuring radon exhalation from the medium surface with a ventilation chamber.

The method for measuring radon exhalation rate from the medium surface with a ventilation chamber is un-replaceable when surveying the radon exhalation rate continuously. Generally, the pump flow rate is an important parameter to obtain the radon exhalation rate from the measurement model. Our previous research indicated that the results of those measurements are inaccurate when the air change rate is not far larger than the effective decay constant.

Design of Interrogation Protocols for Radiation Dose Measurements Using Optically-Stimulated Luminescent Dosimeters.

Optically-stimulated luminescent dosimeters are capable of being interrogated multiple times post-irradiation. Each interrogation removes a fraction of the signal stored within the optically-stimulated luminescent dosimeter. This signal loss must be corrected to avoid systematic errors in estimating the average signal of a series of optically-stimulated luminescent dosimeter interrogations and requires a minimum number of consecutive readings to determine an average signal that is within a desired accuracy of the true signal with a desired statistical confidence.

Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident.

The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available.

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

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 (220)Rn. In this paper, we propose that the difference between radon and (218)Po 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.

Analysis of the saturation phenomena of the neutralization rate of positively charged 218Po in water vapor.

Generally, 88% of the freshly generated 218Po ions decayed from 222Rn are positively charged. These positive ions become neutralized by recombination with negative ions, and the main source of the negative ions is the OH- ions formed by radiolysis of water vapor. However, the neutralization rate of positively charged 218Po versus the square root of the concentration of H2O will be a constant when the concentration of H2O is sufficiently high.

A method to simultaneously and continuously measure the 222Rn and 220Rn exhalation rates of soil in an open loop.

This paper presents a process in which a radon monitor based on the electrostatic collection method is used to measure the (222)Rn and (220)Rn exhalation rates simultaneously and continuously employing a ventilation-type accumulation chamber. Generally, the radon exhalation rate can be measured by accumulation technique, but cannot be measured continuously. The advantage of this method using a ventilation-type accumulation chamber is that the radon exhalation rates can be measured continuously.

Measuring radon exhalation rate in two cycles avoiding the effects of back-diffusion and chamber leakage.

This paper will present a simple method for measuring the radon exhalation rate from the medium surface in two cycles and also avoiding the effects of back-diffusion and chamber leakage. The method is based on a combination of the "accumulation chamber" technique and a radon monitor. The radon monitor performs the measurement of the radon concentration inside the accumulation chamber, and then the radon exhalation rate can be obtained by simple calculation.

A novel algorithm for quick and continuous tracing the change of radon concentration in environment.

Several measurements of the radon concentration are performed by RAD7 in the University of South China. We find that 30-40 min is needed for RAD7 for tracing the concentration of the standard radon chamber. There are two reasons.