• Journal of Radiation Protection and Research
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• 제18권1호
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• pp.37-51
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• 1993

본 연구에서는 환기장치로 제어하는 환경인 라돈 표준실 및 라돈 발생기로부터 이론적으로는 Jacobi모델 이론을 사용하여 라돈 자핵종의 농도를 계산하였으며, 실험적으로는 두 발생 조건으로부터 채취된 시료를 알파스펙트럼 분석법에 의해 측정 분석하여 그 농도를 결정하였다. 이론적인 계산치와 실험적인 측정결과를 비교해 본 결과 매우 잘 일치되는 좋은 결과를 얻게 되었다. 따라서 이러한 연구는 실내 라돈환경에서 라돈 자핵종의 알파방출체에 의한 내부피폭선량을 보다 정확히 평가하고, 라돈 자핵종의 개별 농도를 신속히 결정하는 데 크게 기여할 것이라 사료된다.

• Journal of Radiation Protection and Research
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• 제45권3호
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• pp.95-100
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• 2020

Background: Compared with reported data of radon concentration, data of radon progeny concentration is limited in general, especially in outdoor environment. Materials and Methods: To know both the level and the variation of radon progeny concentration in outdoor environment in Beijing area, one-year continuous measurement with a cycle of 60 minutes was carried out by a step-advanced filter (SAF) monitor for radon progeny measurement. The observation site was located in a park in Eastern Beijing area, and the observation period was from October 17, 2018 to September 29, 2019. Results and Discussion: The equivalent equilibrium concentration (EEC) of radon progeny varies from 0.7 to 19.1 Bq·m^-3, with an annual average of 4.9 ± 2.7 Bq·m^-3. A clear diurnal variation of EEC, higher in the early morning and lower in the late afternoon, is observed due to the high sensitivity of the SAF monitor. Conclusion: Vertical convection of atmospheric boundary layer is thought to be the main reason of this phenomenon. For annual variation, the lowest monthly average EEC appeared in April, while the highest appeared in November, which might attribute to the atmospheric stability in different seasons.

• Journal of Radiation Protection and Research
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• 제17권1호
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• pp.31-41
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• 1992

라돈 자핵종의 알파 측정용 여과지 매질에 대한 평가를 위한 연구는 물리적 특성조사로 여과지의 정전하 충전과 역학적 강도가 조사된 후, 시료채취 전과 후 여과지에 부가되는 압력차로 여과지의 성질을 시험하였으며, 알파 스팩트럼분석으로 여과지내 부착된 라돈 자핵종의 에너지스펙트럼을 분석하여 성능지수를 계산한 후 여과지의 특성을 비교 평가하였다. 평가의 결과 새로운 여과지 매질은 과거의 표준인 Millipore AA보다 크게 유리한 점은 없었으나, 정전하가 문제되는 곳에서는 Metricel DM-800을 권고하였다. 또한 평가방법은 새로 개발될 여과지들의 물리적 특성과 매질의 수집효율을 고려하여 라돈 자핵종의 알파 측정용 여과지 매질 평가를 위해 유용하게 사용될 수 있을 것이다.

• Journal of Radiation Protection and Research
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• 제26권4호
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• pp.399-408
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• 2001

일반가옥 및 실험실에서 라돈농도, 평형등가농도 및 평형인자의 농도 변화를 검토하였으며, 환기조건에 따른 평형인자, 비흡착 라돈자손 비율의 변통 특성을 검토하였다. 가옥 7개 지점에서의 평균 라돈농도, 평형등가농도 및 평형인자는 각각 $30\;Bq\;m^{-3},\;19.6\;Bq\;m^{-3}$, 0.65였다. 한편, 실험실 3개 지점에서의 평균 라돈농도, 평형등가농도 및 평형인자는 각각 $55.0\;Bq\;m^{-3},\;31.9\;Bq\;m^{-3}$, 0.58였다 실내에서의 라돈농도, 평형등가농도 및 평형인자는 새벽 및 아침시간에 높고 오후 4시부터 밤 10시 사이에 낮아지는 주기적인 특성을 나타내었다 환기상태가 좋은 경우가 환기상태가 나쁜 경우에 비해 평형인자는 낮아지는 반면, 비 흡착 라돈자손 비율이 증가하는 경향을 나타내었으며, 평형인자는 기압, 습도에 비례하는 반면, 온도에는 반비례하는 관계를 나타내었다.

• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.237-245
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• 2022

Background: The current study reports measurements of activity concentrations of radon (²²⁰Rn) and thoron (²²⁰Rn) in dwellings, followed by inhalation dose assessment of the public, and then by the development of regulation and the national radon action plan (NRAP) in Cameroon. Materials and Methods: Radon, thoron, and thoron progeny measurements were carried out from 2014 to 2017 using radon-thoron discriminative detectors (commercially RADUET) in 450 dwellings and thoron progeny monitors in 350 dwellings. From 2019 to 2020, radon track detectors (commercially RADTRAK) were deployed in 1,400 dwellings. It was found that activity concentrations of radon range in 1,850 houses from 10 to 2,620 Bq/㎥ with a geometric mean of 76 Bq/㎥. Results and Discussion: Activity concentrations of thoron range from 20 to 700 Bq/㎥ with a geometric mean of 107 Bq/㎥. Thoron equilibrium factor ranges from 0.01 to 0.6, with an arithmetic mean of 0.09 that is higher than the default value of 0.02 given by UNSCEAR. On average, 49%, 9%, and 2% of all surveyed houses have radon concentrations above 100, 200, and 300 Bq/㎥, respectively. The average contribution of thoron to the inhalation dose due to radon and thoron exposure is about 40%. Thus, thoron cannot be neglected in dose assessment to avoid biased results in radio-epidemiological studies. Only radon was considered in the drafted regulation and in the NRAP adopted in October 2020. Reference levels of 300 Bq/㎥ and 1,000 Bq/㎥ were recommended for dwellings and workplaces. Conclusion: Priority actions for the coming years include the following: radon risk mapping, promotion of a protection policy against radon in buildings, integration of the radon prevention and mitigation into the training of construction specialists, mitigation of dwellings and workplaces with high radon levels, increased public awareness of the health risks associated with radon, and development of programs on the scientific and technical aspects.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2222-2229
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• 2023

Radon and radon progeny being natural radioactive pollutants, seriously affect the health of uranium miners. Radon reduction by ventilation is an essential means to improve the working environment. Firstly, the relational model is built between the radon exhalation rate of the loose body and the ventilation parameters in the stope with radon percolation-diffusion migration dynamics. Secondly, the model parameters of radon exhalation dynamics are uncertain and described by triangular membership functions. The objective functions of the left and right equations of the radon exhalation model are constructed according to different possibility levels, and their extreme value intervals are obtained by the immune particle swarm optimization algorithm (IPSO). The fuzzy target and fuzzy constraint models of radon exhalation are constructed, respectively. Lastly, the fuzzy aggregation function is reconstructed according to the importance of the fuzzy target and fuzzy constraint models. The optimal control decision with different possibility levels and importance can be obtained using the swarm intelligence algorithm. The case study indicates that the fuzzy aggregation function of radon exhalation has an upward trend with the increase of the cut set, and fuzzy optimization provides the optimal decision-making database of radon treatment and prevention under different decision-making criteria.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 1999년도 Japanese Journal of Medical Physics
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• pp.407-408
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• 1999

• KIEAE Journal
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• 제1권2호
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• pp.21-28
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• 2001

Naturally-ocurring short-lived decay products of radon gas in indoor air are the dominant source of ionizing radiation exposure to the general public. It is written in BEIR VI Report(l999l the radon progeny were identified as the second cause of lung cancer next to cigarette or 10 % to 14 %(15,400 to 21,800 persons p.a.) of all lung cancer deaths in USA. Indoor radon concentrations in houses typically result from radon gaining access to houses mainly from the underlying soil. In the States, they have "Indoor Radon Abatement Act" which was converted from "Toxic Substance Control Act" in 1988 to establish the national long-term goal that indoor air should be as free of radon as the ambient air outside of buildings. To review and study techniques for controlling radon, two test cells were constructed for a series of tests and are under measuring indoor and soil gas (underneath of floor slab)radon concentrations according to EPA's measurement protocol. In this paper, important theoretical studies are previewed and the following paper will explain the test results and confirm the theories reviewed to find out suitable coefficients. On the basis of test analysis, it will be described and evaluated various techniques that can be used to mitigate elevated indoor concentration of radon including the control of radon and its decay products.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.950-956
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• 2018

For complete assessment of inhalation doses of radon and its progeny inside the three main ancient Egyptian tombs in Saqqara, seasonal radon concentrations have been measured by using a new electronic device that allows for measurement of real-time-resolved radon concentrations. Measurements were complemented by very fast measurements of thoron concentrations, which turned out to be low. Based on these measurements, annual residence time inside these tombs and the newest International Commission on Radiological Protection-recommended radon dose conversion coefficients or seasonal effective doses were calculated. The results indicate that workers receive highest annual effective doses of up to 140 mSv, which exceeds the annual limit of 20 mSv, whereas lower values up to 15 mSv are received by guides. In contrast, much lower doses were obtained for one-time visitors of the investigated tombs. The obtained results are somewhat different but still consistent with those previously obtained by means of fixed passive dose meters at some of the investigated places. This indicates that reasonable estimates of the effective dose of radon can be also obtained from short-term radon measurements carried out only twice a year (summer and winter season). Increasing the ventilation, minimizing the working times, etc., are highly recommended to reduce the annual effective dose.

• Nuclear Engineering and Technology
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• 제37권4호
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• pp.395-400
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• 2005

An environmental radon monitoring system, comprising a radon-cup, an etching system, and a track counting system, was constructed. The radon cup is a cylindrical chamber with a radius of 2.2 cm and a height of 3.2 cm in combination with a CR-39 detector. Carbon is impregnated in the bodies of the detector chamber to avoid problem of an electrostatic charge. The optimized etching condition for the CR-39 exposed to a radon environment turned out to be a 6 N NaOH solution at 70^{\circ}$ over a 7hour period. The bulk etch rate under the optimized condition was $1.14{\pm}0.03\;{\mu}m\;h^{-1}$. The diameter of the tracks caused by radon and its progeny were found to be in the range of $10\~25\;{\mu}m$ under the optimized condition. The track images were observed with a track counting system, which consisted of an optical microscope, a color charged couple device (CCD) camera, and an image processor. The calibration factor of this system is obtained to be $0.105{\pm}0.006$ tracks $cm^2$ per Bq $m^{-3}$ d.