• Title, Summary, Keyword: $^{222}Rn$

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Analysis and radiation dose assessment of 222Rn in indoor air at schools: Case study at Ulju County, Korea

  • Lee, ChoongWie;Choi, Sungyeol;Kim, Hee Reyoung
    • Nuclear Engineering and Technology
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    • v.50 no.5
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    • pp.806-813
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    • 2018
  • $^{222}Rn$ exists in nature in the form of a rare radioactive gas. In terms of environmental radiation, issues regarding $^{222}Rn$ have persisted because of its radiological hazardousness. Ulju County is one of the regions of Ulsan metropolitan city, with a population of 227,699. Ulju County has the highest density of industrial complexes in Korea. In this study, $^{222}Rn$ radioactivity concentration was measured and analyzed in 57 schools in Ulju County using 114 passive LR-115 type detectors to secure radiological safety and confirm basic information for reduction of resident exposure to $^{222}Rn$. The effective dose of $^{222}Rn$ was assessed to find the actual risk of the concentration surveyed in schools to human beings. The dose depended on four factors: subjects, $^{222}Rn$ concentration, dose coefficient, and time. The individuals subjected to dose estimation were classified into three types: students, teachers, and office workers. The subjects had different dwelling locations and times. The findings demonstrate that the radiological hazard to students and workers at schools in Ulju County owing to $^{222}Rn$ is negligible in terms of $^{222}Rn$ activity recommendation level.

A Study on Harmful Radioactive Gas(Rn$_222$)-Concentration in Soils, Taejeon City (대전지역 토양에서 유해 방사성가스인 라돈 농집에 대한 연구)

  • 김승오;김해경
    • Journal of Environmental Science International
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    • v.6 no.5
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    • pp.489-496
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    • 1997
  • The arm of this study is to determine harmful radioactive gas($Rn^{222}$)-concentrations in soils and to suggest the anormalous regions of $Rn^{222}$-concentration in Taejeon area. The range of $Rn^{222}$-concentration in the soils (45 samples) of the survey area is 100 to 2, 475 (pCi/L) and mean$\pm$$\sigma$ of those values is 489$\pm$ 505 (pCi/L). The 2% (4 samples) of soil-gas samples (45 ones) collected In the survey area is corresponded to high rusk level, 53% (24 samples) to medium one and 43% (19 samples) to low one. Especially. The $Rn^{222}$-concentration is relatively higher in schistose granite region than in other rock Mts (two-mica granite and biotite ganite) in the survey area. The $Rn^{222}$-concentration is propotional to the uranium contents in the soils. The soil hardness among the various factors is correlative with $Rn^{222}$-concentrations. To prevent the damage from $Rn^{222}$-concentrations, It is necessary to close the cracks of underground structure and to consider methods reducing $Rn^{222}$-concentration for the anormalous regions.

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A Rapid Method for the Measurement of $^{222}Rn$ in Groundwater and Hot Spring Water using Ultra Low-Level Liquid Scintillation Counter and Pulse Shape Analysis (극저준위 액체섬광계수기와 파형분석법을 이용한 지하수 및 온천수중 $^{222}Rn$의 신속측정법)

  • Kim, Chang-Kyu;Kim, Cheol-Su
    • Journal of Radiation Protection and Research
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    • v.20 no.2
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    • pp.103-115
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    • 1995
  • For the determination of $^{222}Rn$ in water by a very simple and time saving liquid scintillation counting method that does not require any chemical separation, an optimum analytical condition has been investigated. The optimum pulse shape analysis(PSA) level for the measurement of $^{222}Rn$ using LKB 1220 Quantulus liquid scintillation counter was 110 for Optiphase HiSafe3 cocktail and 90 for toluene-based cocktail. The counting efficiencies of $^{222}Rn$ in the window covering u spectra using Optiphase HiSafe3 cocktail were 282.2% for glass vial and 271.6% for Teflon vial, whereas the counting efficiencies in toluene-based cocktail were 262.3% and 247.5% for glass and Teflon vials, respectively. The minimum detectable activity(MDA) in the u window for a 60-min measurement with a Teflon vial using Optiphase HiSafe3 cocktail was $0.30Bq/{\iota}$. The analytical method studied from this work was also applied to the determination of $^{222}Rn$ in some groundwater and hot spring water samples.

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Investigation on the petroleum contamination by using Rn-222 tracer (라돈 추적자를 이용한 유류오염에 대한 연구)

  • Yoon, Yoon-Yeol;Koh, Dong-Chan;Lee, Kil-Yong;Cho, Soo-Young;Ko, Kyung-Seok
    • Analytical Science and Technology
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    • v.25 no.1
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    • pp.14-18
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    • 2012
  • Rn-222 was used as a natural radioactive isotope tracer to evaluate non-aqueous phase liquid(NAPL) contaminated soil and aquifer. In the case of soil sample, Rn-222 concentration was inversely decreased with diesel concentration in the granite soil sample and it was decreased about 30% at the 13% diesel contaminated soil. For evaluating trichloroethylene (TCE) contaminated aquifer, the natural radioisotope Rn-222 was used as naturally occurring partitioning tracer for the approximate localization and semiquantitative assessment of the TCE source zone. Rn-222 was analyzed for the estimation of TCE contamination ranges of the acquifer in the contaminated site at Wonju in Korea.

Estimation of 222Rn Concentration in the Lower Troposphere during Precipitation Using Wet Scavenging Model for its Decay Products

  • Takeyasu, Masanori;Takeishi, Minoru
    • Asian Journal of Atmospheric Environment
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    • v.4 no.1
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    • pp.20-25
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    • 2010
  • The gaseous $^{222}Rn$ concentration at the level of clouds was estimated by using the wet scavenging model of its decay products with the observed data of environmental radiation at the ground. And the origin of the $^{222}Rn$ was also discussed. The estimation was done for a precipitation event on Dec. 26-27, 2003, when a large increase of the radiation was observed in Tokai-mura in Ibaraki, Japan. From a backward trajectory analysis, the origin of $^{222}Rn$ atoms for that event was traced back to the northeastern part of China, and it was expected that the large amount of $^{222}Rn$ emitted in the northeastern part of China was transported to Tokai-mura by the Eurasian continental air mass.

Study on the Assessment of Dose Equivalent due to the Inhalation of $^{222}Rn$ and Its Daughters in Indoor Air (실내 $^{222}Rn$$^{222}Rn$ 딸핵종에 의한 피폭선량 해석연구)

  • Jun, Jae-Shik;Chai, Ha-Seok;Yi, Chul-Young;Cho, Hyuck;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.20 no.1
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    • pp.16-24
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    • 1995
  • Assesment of dose equivalent given by inhaled $^{222}Rn$ and its progeny has been carried out based on the concentrations of $^{222}Rn$ and its daughters in indoor air, and equilibrium factor between them measured by charcoal canister method and alpha spectrometry. Assuming the occupancy factor to be 0.8, and breathing rate to be $0.75m^3\;h^{-1}$ for public and $1.2m^3\;h^{-1}$ for occupational exposure, respectively, the regional lung dose 대valent and the resulting annual effective dose equivalent due to the inhalation of $^{222}Rn$ and its daughters in indoor air were evaluated by use of three different lung models, namely, Jacobi-Eisfeld, James-Birchall and ICRP model.

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A Study of $^{222}Rn\;and\;^{226}Ra$ Analysis in the Groundwater by LSC (액체섬광계수기에 의한 지하수중의 $^{222}Rn$$^{226}Ra$ 분석법 연구)

  • Woo, Hyung-Joo;Yoon, Yoon-Yeol;Cho, Soo-Young;Chun, Sang-Ki
    • Journal of Radiation Protection and Research
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    • v.20 no.4
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    • pp.275-283
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    • 1995
  • PERALS(Photon Electron Rejecting Alpha Liquid Scintillation) spectrometry coupled with solvent extraction method has been set up for the analysis of $^{222}Rn\;and\;^{226}Ra$ in the groundwater. This analytical method offers low background, better energy resolution and lower quenching problem than the other techniques. By the analysis of NIST SRM 4966 $^{226}Ra$ standard, the analytical accuracy and precision were found to be 3% and 1%, respectively, and the relative standard deviation of the recovery of Rn extraction between pH2 and pH10 was 7%. Detection limits of $^{222}Rn$ and $^{226}Ra$ for 10 hours counting were counted to be $0.42 pCi/{\iota}\;and\;0.016 pCi/{\iota}$, respectively. For the test analysis of $^{222}Rn\;and\;^{226}Ra$ in the graundwater, hot spring water samples of 17 regions were analyzed. The concentration of $^{222}Rn$ were in the range of $90{\sim}5200pCi/{\iota}$ and average value was $1470pCi/{\iota}\;^{226}Ra$ concentration showed a peak value of $97.9pCi/{\iota}$ in a Kangwon region, but the average value was $1.14pCi/{\iota}$ except that region.

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Comparison of the Quantulus 1220 and 300SL Liquid Scintillation Counters for the Analysis of 222Rn in Groundwater

  • Kim, Hyuncheol;Jung, Yoonhee;Lee, Wanno;Choi, Guen-Sik;Chung, Kun Ho;Kang, Mun Ja
    • Journal of Radiation Protection and Research
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    • v.41 no.4
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    • pp.395-401
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    • 2016
  • Background: Liquid scintillation counters (LSCs) are commonly used as an analytical method for detecting $^{222}Rn$ in groundwater because they involve a simple sample pretreatment and allow high throughout with an autosampler. The Quantulus 1220 is the best-selling LSC in Korea, but its production was stopped. Recently, a new type of LSC, the 300SL, was introduced. In this study, the 300SL was compared with the Quantulus 1220 in order to evaluate the ability of each apparatus to detect $^{222}Rn$ in groundwater. Materials and Methods: The Quantulus 1220 and 300SL were used to detect the presence of $^{222}Rn$. Radon gas was extracted from a groundwater sample using a water-immiscible cocktail in a LSC vial. The optimal analytical conditions for each LSC were determined using a $^{222}Rn$ calibration source prepared with a $^{226}Ra$ source. Results and Discussion: The optimal pulse shape analysis level for alpha and beta separation was 80 for the Quantulus 1220, and the corresponding pulse length index was 12 in the 300SL. The counting efficiency of the Quantulus 1220 for alpha emissions was similar to that of the 300SL, but the background count rate of the Quantulus 1220 was 10 times lower than that of the 300SL. The minimum detectable activity of the Quantulus 1220 was $0.08Bq{\cdot}L^{-1}$, while that of the 300SL was $0.20Bq{\cdot}L^{-1}$. The analytical results regarding $^{222}Rn$ in groundwater were less than 10% different between these LSCs. Conclusion: The 300SL is an LSC that is comparable to the Quantulus 1220 for detecting $^{222}Rn$ in groundwater. Both LSCs can be applied to determine the levels of $^{222}Rn$ in groundwater under the management of the Ministry of Environment.

A Study of the Rn-222 and Ra-226 Analysis in Aqueous Samples with a Low-Level Liquid Scintillation Counter and Pulse-Shape Analysis (저준위 액체섬광계수기와 파형분석법을 이용한 수용액 중 라돈-222 및 라듐-226의 분석법 연구)

  • Shin, Hyun-Sang;Lee, Chang-Woo;Lee, Myung-Ho;Cho, Yung-Hyun;Hong, Kwang-Hee;Choi, Geun-Sik
    • Analytical Science and Technology
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    • v.12 no.5
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    • pp.428-435
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    • 1999
  • A method for measuring Rn-222 and Ra-226 in aqueous sample using liquid scintillation counting technique has been studied. The Rn-222 was extracted easily from the water sample (10 mL) by 12 mL of xylene based organic scintillant. After radioactive equilibrium between Rn-222 and its alpha emitting decay products for three hours, the alpha activity from Rn-222 and its decay products were measured in a scintillation vial using the Wallae $1220^{TM}$ Quantulus liquid scintillation counter. Ra-226 concentration in aqueous sample was determined, after isolation of Ra-226 from the sample matrix, by extraction the ingrowth of the Rn-222 and its alpha emitting decay products with xylene based organic scintillant. The optimum pulse-shape analysis (PSA) value was evaluated by the figure of merit (FM) criterion. Minimum detectable activity (MDA) is about 0.14 Bq/L (3.78 pCi) for the region of Rn-222 and its alpha emitting decay products and 0.06 Bq/L (1.63 pCi) for the region of Po-214 respectively, with 200 min, counting time at PSA level 100 in the low-diffusion polyethylene vial and xylene based cocktail solution. Experiment on the optimum sample-cocktail volume ratio, the influence of agitation and the diffusion of radon from vial were carried out.

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Study on Concentration Variation of 222Rn for Various Scintillators Using Low-Level Liquid Scintillation Counter (저 준위 액체섬광계수기를 이용한 섬광체 종류에 따른 222Rn 농도 변화 연구)

  • Jeon, JaeWan;Lee, Deuk-Hee;Kim, Jin-Seop
    • Journal of the Korean Society of Radiology
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    • v.13 no.6
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    • pp.847-856
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    • 2019
  • The various environmental issues arose with the development of today's economy. naturally, people were increased interest in environment and the importance of research on drinking water and contamination are emerging especially. A number of country areas, uranium and 222Rn in ground water have been detected to people using as drinking water. So this study evaluated the way for more accurate measurements than when measuring 222Rn concentrations in the ground water containing. the experiment was performed using the low-level liquid scintillation counter with an alpha, beta analysis easy PSA function of pulse. the scintillator as the preparation of the ground water samples are mixed, the measure value detection is lowered over prepare period and expiration date. Energy spectrum was also moved to a lower side channel. As a long time to buy the scintillator and over time after opening, it was confirmed that detection is lowered. if the purpose is to use a different scintillator can see the energy through the channel change.