• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.337-339
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• 2000

저준위 환경 방사능 측정에서 가장 문제가 되는 것은 주변의 백그라운드에 의한 영향이다. 백그라운드로는 우주선, 지각 방사선, 그리고 대기중의 방사선 둥이 있다. 이러한 백그라운드를 감소시킬 수 있다면 저준위 방사능 측정의 감도향상은 물론 정확성을 향상시킬 수 있다. 이러한 백그라운드 중에서 대기중의 방사선은 주로 지각으로부터의 라돈 방출에 의하여 기인하게 된다(Eisenbud, 1987 : Thomas, 1972). 방출된 라돈 및 딸핵종들은 대기 중의 먼지에 흡착되어 부유하게 되는데, 부유 먼지에 흡착된 백그라운드의 주요 원인이 된다. (중략)

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.589-593
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• 1998

활성탄 검출기를 이용하여 실내 라돈농도를 측정하였다. 라돈농도 측정을 위한 활성탄 검출기의 노출기간은 4일, 5.8일, 5일이었다. 측정결과 사무실내 라돈농도는 각각 1.63 pCi/$\ell$, 1.23 pCi/$\ell$, 1.76 pCi/$\ell$였으며, 측정기간 동안 평균 1.54 pCi/$\ell$였다. 이 결과는 미국 환경보호청에서 제시한 조치준위의 최저치인 4 pCi/$\ell$ 이하였다. 같은 장소에서 WL Meter를 이용하여 라돈 딸핵종의 농도를 축정한 결과, 각각 5. 64 mWL, 4.88 mWL, 6.43 mWL이었다. 라돈과 라돈 딸핵종 농도로부터 라돈평형인자 값을 산출한 결과 각각 0.34, 0.39, 0.36으로, 이 결과는 다른 방법에 의해 타 연구자가 측정한 기존의 사무실내 라돈농도 및 라돈평형인자 산출결과와 비교적 유사했다. 따라서 활성탄 검출기를 이용한 라돈농도 측정법은 매우 유용한 방법임을 확인할 수 있었다.

• Journal of Radiation Protection and Research
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• v.17 no.1
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• pp.1-10
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• 1992

A number of investigators have reported the formation of the radiolytic ultrafine particles produced by the interaction of ionizing radiation with water vapor. Previous studies have suggested that a very high localized concentration of the OH radical produced by the radiolysis of water can react with trace gas like organic vapors and produce lower vapor pressure compounds that can then nucleate. In order to determine water vapor dependence of the active, positively charged, first radon daughter(Po-218), an experiment was conducted using a well-controlled radon chamber. The activity size distribution of the radon daughter in the range of 0.5-100nm was measured using the parallel graded wire screens system. Measurements were taken for different relative humidity. The resultant activity size distributions were analyzed. The addition of water vapor to the radon carrier gases resulted in the formation of ultrafine particles by OH radicals formed by radon radiolysis. It may be due to the neutralization of charged Po-218 ion with water vapor through the radio lysis.

• Analytical Science and Technology
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• v.13 no.6
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• pp.743-750
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• 2000

For the ${\gamma}$-ray spectrometry analysis of radium and radon in environmental samples, plastic Marinelli beakers have been usually used. But, there are two problems; one is the increment of background by adsorption of airborne radon daughters on the plastic beaker, and other is the incompleteness of radioactive equilibrium by the loss of gaseous radon produced during the radioactive equilibrium process. In order to solve these problems, we made aluminium counting container, and investigated its characteristics. We investigated radioactive equilibrium process using the aluminium container. We found that both solid and liquid samples reached at radioactive equilibrium state in the aluminium container without loss of gaseous radon. By the use of the aluminium container, we established radon and radium analysis method of solid and liquid samples using gamma-ray spectrometry.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.357-357
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• 1999

• Analytical Science and Technology
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• v.16 no.1
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• pp.39-47
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• 2003

The measurement of radium ($^{226}Ra$) in the groundwater was established using ${\gamma}$-ray spectroscopy without sample preparation. The background interference by air borne radon daughter nuclides was reduced by $N_2$ gas flow into the counting chamber. Leakage of radon gas produced in the radioactive equilibrium with radium and its daughter nuclides was prevented by use of the air-tighted aluminium container. We investigated the effect of air layer in the counting container. Radioactivity variation due to emanation of radon into the air layer was within the counting error range 5%. When the nitrogen gas was flowed around the detector, peak counts of ${\gamma}$-rays from the daughters of airborne radon was decreased and detection limit was decreased to 0.02 Bq/L. The detection limit of detector was lower than 0.74 Bq/L, the $^{226}Ra$ Maximum Contaminant Level (MCL) in the groundwater proposed by US Environmental Protection Agency (EPA). It was confirmed that $^{226}Ra$ radioactivity in the groundwater could be determined by the ${\gamma}$-ray spectroscopy.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.79-83
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• 1995

A number of investigators have reported formation of radiolytic ultrafine particles produced by the interaction of ionizing radiation with atmospheric trace gases. Previous studies have suggested that a very high localized concentration of the hydroxyl radical produced by the radiolysis of water can react with atmospheric trace gases such as $SO_2$ and produce lower vapor pressure compounds that can subsequently nucleate. To determine the trace gas and water vapor concentration dependence of the active, positively charged, first decayt product of radon (Po-218), a well-controlled radon chamber was used in this research. The mobility spectrum of the decay products in the range of $0.07-5.0cm^2/V\;sec$ from the radon chamber was measured using alpha track detector installed inside a specially-designed electrostatic spectrometer. Measurements were taken for different concentrations (0.5ppm to 5ppm) of $SO_2$ in Purified, Compressed air. A kinetics Study following the clustering of $SO_2$ around the $PoO_x^+$ ion in an excess of $SO_2$ for interpretation of the reaction processes was performed.

• Analytical Science and Technology
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• v.14 no.3
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• pp.212-220
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• 2001

This study was performed to establish the analytical method of radium and radon in various environmental samples with the ${\gamma}$-ray spectrometry. The major problem in the measurements of low level ${\gamma}$-ray, such as environmental radioactivity, is the fluctuation of ${\gamma}$-ray background spectrum. To overcome this problem, a nitrogen gas was filled up in the detector chamber to reduce the background counts due to airborne radioactivities, i.e., $^{214}Pb$ and $^{214}Bi$, the daughters of $^{222}Rn$ in air. When nitrogen gas flowed around the detector, peak counts of ${\gamma}$-rays from the daughters of $^{222}Rn$ decreased about 80% below 1 MeV and about 20~50% above 1 MeV. The use of nitrogen purging results in approximately tenfold increment of sensitivity.

• Journal of Radiation Protection and Research
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• v.18 no.1
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• pp.25-35
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• 1993

To develop a technique of theoretical alpha track density calculation for comparison with measured track density, an electrostatic ion spectrometer was specially designed and fabricated. The mobility spectrum of first radon daughter(Po-218) in the range of $0.07{\sim}5.0cm^2/V\;s$ from the radon chamber was measured using-the electrostatic ion spectrometer. Measurement was taken in a radon chamber operated using dry particle free air passed through silica gel, activated charcoal and molecular sieve filters. The mobility of a new-born Po-218 ion measured by the electrostatic ion spectrometer was determined to be $1.92cm^2/V\;s$. A comparison of the theoretical and measured alpha track densities was completed and uncertainties concerning the shape of the spectrum were analyzed. It was found that the discrepancies in track densities are primarily Que to the neglect of wall loss of ions in the theoretical track density calculation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.299-300
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• 2002

현재 우리가 살고 있는 지구에는 인공적 또는 자연적으로 생성된 많은 방사성 핵종이 혼재하고 있으며 인간은 이러한 자연환경에 항상 노출되어 있다. 우라늄(U)과 토륨(Th)은 자연계에 존재하는 $\alpha$입자를 방출하는 방사성 원소이며 이들의 연속적인 $\alpha$ 및 $\beta$붕괴에 의하여 많은 방사성 핵종이 생성된다. 특히 대기중이나 토양, 암석에 함유되어 있는 U-238은 자발 붕괴하여 라돈(Rn-222)이 되고 라돈에 의하여 생성된 딸 핵종들이 호흡을 통하여 흡수되어 방사선 피폭을 유발한다고 알려져 있다. (중략)