• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2013-2017
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• 2019

The radon concentrations in soil air were measured before and after a rainfall. ²²⁶Ra concentration, porosity, moisture content and temperature in soil were measured at Kyungpook National University in Daegu. As the results of measurement and analysis, the arithmetic mean of measured ²²²Rn concentration increased from 12100 ± 500 Bq/㎥ to 16200 ± 600 Bq/㎥ after the rainfall. And the measured ²²⁶Ra concentration was 61.4 ± 5.7 Bq/kg and the measured porosity was 0.5 in soil. The estimated values of ²²⁶Ra concentration and porosity using diffusion model of ²²²Rn in soil were 60.3 Bq/kg and 0.509, respectively. The estimated values were similar to the measured values. ²²²Rn concentration in soil increased with depth and moisture content. The estimations were obtained through fitting based on the diffusion model of ²²²Rn using the measurement values. The measured depth profiles of ²²²Rn were similar to the calculated depth profiles of ²²²Rn in soil. We hope that the results of this study will be useful for environmental radiation analysis.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1289-1296
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• 2020

The estimation of radioactivity level is vital for population health risk assessment and geological point of view and can be evaluated as rate of exhalation and source concentration (²²⁶Ra, ²³²Th and ⁴⁰K). The present study deals with the soil samples for investigation of radionuclides content and exhalation rates of radon -thoron gas from different sites in northern Haryana, India. Absorbed dose and associated index estimated in the present study are the measures of environmental radioactivity to inhalation dose. Effective doses received by different tissues and organs by considering different occupancy and conditions are also measured. Exhalation rates of radon and thoron are measured with active scintillation monitors based on alpha spectroscopy namely scintillation radon (SRM) and thoron (STM) monitors respectively. Sample height was optimized before measurement of thoron exhalation rate using STM. Average values of radon and thoron exhalation are found 16.6 ± 0.7 mBqkg^-1h^-1 and 132.1 ± 2.6 mBqm^-2s^-1 respectively. Also, a simple approach was also adopted, to evaluate the thoron exhalation which accomplished a lot of challenges, the results are compared with the data obtained experimentally. The study is useful in the nationwide mapping of radon and thoron exhalation rates for understanding the environmental radioactivity status.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.57-66
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• 1988

A series of experiments is performed to measure radon concentration in the near-surface soil gas at the four locations (Cheju-Si, Seoguipo-Si, Taejeong-eup, Seongsan-eup) in Cheju Island, using CR-39 detectors placed inside radon cups. Two types of radon cups are installed in shallow holes of about 15 cm in diameter and 50cm in depth. The optimum etching conditions, i.e., the concentration of NaOH solution, etchant temperature and etching time, are found to be 625N, $70^{\circ}C$ and 5.5 hours for CR-39 detectors. A typical conversion factor of radon cup is calculated as $$1track/mm^3{\cdot}30day=0.059Bq/{\ell}$$. Average radon concentrations over 30 days measured in Cheju Island from May 1, 1987 to April 23, 1988 are $3.1{\pm}0.3Bq/{\ell}$ for open radon cups and $1.7{\pm}0.2Bq/{\ell}$ for closed radon cups.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.881-889
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• 2020

The objective of this study was to quantitatively measure the changes in radon concentration due to ventilation and air purification plants in the lower and upper floors of a building. This study measured and compared radon concentration in the lower and upper floors of the building by using a radon meter when the room was closed, it was ventilated, and air purification plants were installed at a specific time. One-way ANOVA was conducted to evaluate the effect of treatment (i.e., closure, ventilation, and air purification plants) on radon concentration. The results of this study showed that ventilation and air purification plants significantly decreased radon concentration in the lower and upper floors of the building, but the effect of ventilation and that of air purification plants were not significantly different. Therefore, it will be possible to reduce radon concentration effectively when ventilation and air purification plants are used appropriately.

• Journal of Radiation Protection and Research
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• v.14 no.2
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• pp.18-22
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• 1989

In order to calibrate the CR-39 Solid State Nuclear Track Detector (SSNTD), a closed -circulation type SSNTD-Calibration-System containing a radon-cup with the Millipore filter has been set-up, and the tracks produced on the SSNTD were measured for the known amount of radon concentration. Calibration factor for the time integrated radon concentration as a function of the track density on CR-39 was estimated to be $0.24{\pm}0.09(pCi/l)\;day/(Tr/cm^2)$.

• Journal of radiological science and technology
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• v.44 no.6
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• pp.671-677
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• 2021

Interest in the everyday hazards of radon has recently increased as such, this study attempted to examine the dangers of radon in spilled groundwater by comparing the radon concentrations of the drained groundwater and tap water used in recirculating systems in Incheon Subway restrooms. At five stations of Incheon Subway Line 1 and three stations of Line 2, drained groundwater is recirculated and used in restrooms for toilet flushing. Stations restroom tap water for hand washing that used as a control and the measured values of each were compared. With the cooperation of Incheon Transportation Corporation, samples of spilled groundwater and tap water were collected sealed to prevent contact with the air, and a DURRIDGE RAD7 was used as the experimental equipment. The collected samples were subjected to radial equilibration for approximately 3.5 h, at which the radon concentration reached its maximum, and then calculated as 10 measurements using the RAD7 underwater radon measurement mode. In all eight stations, the radon concentration in tap water was lower than the recommended amount. However, in an average of 7 out of the eight stations, the radon concentration in the effluent groundwater was 100 times higher than that in tap water. Since high radon concentrations in groundwater runoff can be harmful to humans, and there is no accurate standard for radon concentrations in domestic water, it is necessary to continuously monitor radon in water and prepare a guidance of recommended values.

• Journal of Environmental Impact Assessment
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• v.31 no.5
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• pp.286-295
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• 2022

In this study, the concentration distribution of indoor radon in Daejeon Metropolitan City was investigated and the reduction efficiency was evaluated by applying the radon reduction methods. Based on the results of the National Institute of Environmental Research, indoor radon measurements were conducted on 24 selected houses, and the average value of District A was 261 Bq/m3, far exceeding the standard, and even in the same house, indoor radon concentration was affected by measurement point and time. In the case of eight houses that applied the soil venting method to reduce radon, the indoorradon level was significantly lowerthan the standard value, and the average reduction efficiency was also around 55%, indicating a good reduction effect. In addition, the average reduction efficiency was around 90% in the two houses that carried out the shielding method, showing the very excellent effect of the indoorradon reduction. Even if the same reduction method is applied when reducing radon, the reduction efficiency may vary depending on various factors such as the structure of the building, the frequency of ventilation, and the season, so it is necessary to accurately evaluate the effectiveness of the reduction method in the future. Based on this, it is necessary to establish indoor radon management measures in Daejeon Metropolitan City to reduce human harm caused by radon exposure.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.31-36
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• 2013

The radioactive gas radon ($^{222}Rn$), which is generated from the decay process of uranium ($^{238}U$) originating from the soil of more than 85 percent higher the porosity of the soil, the soil can radiate out the possibility that many isotopes. In order to protect the human body from radon, above all, the development of accurate measurement techniques to formulate appropriate measures should be followed. This study Gamma-ray spectrometry using a high purity germanium (HPGe) detector, if you want to measure radon unstable the nature radiation of the background problems can be reduced, radium and radon daughter nuclides after radioactive equilibrium leads to Radon concentration was measured, the soil samples from the Gamma-ray emitting nuclides, and the energy spectrum is analyzed.

• Journal of Environmental Health Sciences
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• v.47 no.4
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• pp.330-338
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• 2021

Background: This study was conducted to provide background information for the proper management of radon contamination in apartments using mechanical ventilation facilities in residential environments. Objectives: To this end, this study compared and evaluated changes in radon concentrations based on different operating intensities of mechanical ventilation with or without natural ventilation. Methods: For the continuous measurement of radon concentrations, an RAD7 instrument was installed in four apartments equipped with a ventilation system. The measurements were done for comparison of ventilation types and different ventilation intensities ("high", "middle", "low"). Results: The results confirmed that both mechanical and natural ventilation sufficiently reduced the radon concentration in the apartments. In particular, mechanical ventilation at "high" intensity was the most effective. Natural ventilation combined with mechanical ventilation and then natural ventilation alone were the second and the third most effective, respectively. Conclusions: When using ventilation to reduce indoor radon concentrations, it is most effective to operate mechanical ventilation ("high") or natural ventilation and mechanical ventilation at the same time. In cases where mechanical ventilation is available alone, it is recommended to operate it at a minimum of "middle" intensity.

• Journal of Radiation Protection and Research
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• v.7 no.1
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• pp.17-22
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• 1982

Measurement of the radon concentration close to the ground surface can be used in search of environmental radiation for human safety, exploration for uranium, premonitory signals from earthquakes. We can detect radons in soil gas by alpha particle track method using the plastic track detectors, cellulose nitrate (LR115-Type 2 and CA80-15, Kodak $Path\'{e}$) and CR-39. For present works, radon cups having these detectors were made in our laboratory and their conversion factor was determined. A typical conversion factor was $1tr/cm^2{\cdot}30days=1.2{\times}10^{-2}pCi/l$. In the radon cups, some of $CaSO_4$ were used as desiccant for reducing the moisture effects on plastic track detectors. With these radon cups, underground radon concentrations of Kyungpook area were measured. Average radon concentration in Daegu from Jan. 1981 to Feb. 1982 was 39.7pCi/l. From Aug. 1981 to Feb. 1982, average radon concentrations of Daegu, Angang, Kyungju, Pohang, Chungha, and Andong were 31.8pCi/l, 124.5pCi/l, 127.0pCi/l, 79.1pCi/l, 144.4pCi/l, and 70.9pCi/l, respectively. The results were compared with the environmental radiation measured by TLD method.