• 한국지하수토양환경학회지:지하수토양환경
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• 제14권5호
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• pp.51-61
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• 2009

본 연구에서는 부산지역 지하수수질측정망 80개소를 대상으로 방사성물질의 특성을 연구하였다. 우라늄의 전체 평균 농도는 $4.33\;{\mu}g/L$이였고, 최대 평균농도는 $171.55\;{\mu}g/L$이였다. 미국 먹는물기준인 $30\;{\mu}g/L$을 초과한 곳은 1곳, WHO 권고기준인 $15\;{\mu}g/L$을 초과한 곳은 4곳으로 나타났다. 라돈의 전체 평균농도는 169 pCi/L이였고, 최대 평균농도는 1,850 pCi/L이였다. 미국 먹는물기준인 4,000 pCi/L WHO 권고기준인 2,700 pCi/L을 초과한 곳은 단 한곳도 없었다. 전알파의 전체 평균농도는 0.3pCi/L이였고 최대 평균농도는 6.9 pCi/L로 다른 방사성물질에 비하여 미미한 수준으로 나타났다. 지하수중에서 방사성물질의 평균 농도는 낮은 편이지만 미량이나마 검출되는 바 국민건강상 위해를 예방하기 위하여 먹는물 수질기준 둥 관리대책 마련의 필요성이 요구된다. 또한 우라늄이 고농도로 검출되는 일부 지점에 대해서는 정밀한 검토를 거쳐 폐공 조치 등 적절한 조치가 필요할 것으로 판단된다.

• 센서학회지
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• 제6권5호
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• pp.362-368
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• 1997

질소레이저, optode 및 광증배관을 사용하여 우라늄 농도를 원격 실시간으로 측정할 수 있는 방법을 연구하였다. 원격 측정에서 보다 효과적으로 우라늄 형광을 집광할 수 있는 optode를 설계하였으며, optode를 이용하여 우라늄 이온으로부터 나온 형광을 광섬유로 전송하여 광증배관으로 검출하였다. 신호처리에서는 온도 변화와 quencher들의 방해효과가 거의 없는 형광의 초기치를 유도하여 사용하므로 보다 정확한 우라늄 농도를 측정할 수 있었다. 측정 결과 우라늄 농도 변화에 따른 형광 강도의 변화를 쉽게 감지할 수 있었으며, 검출한계는 0.06ppm을 얻었고, $0.1{\sim}2ppm$ 범위에서 직선성이 우수하였다.

• 한국환경보건학회지
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• 제48권2호
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• pp.86-95
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• 2022

Background: As high concentrations of uranium and radon have been detected in some areas in Korea, it is considered necessary to investigate natural radioactive materials in the Gwangju area. Objectives: This study aimed to identify the hydrochemical characteristics of groundwater in Gwangju and investigate the distribution characteristics of uranium and radon, which are naturally radioactive substances. Methods: To determine the uranium and radon concentrations in groundwater according to the geology of the Gwangju area, we measured 62 groundwater wells. A geological distribution map of uranium and radon content was prepared for this study. Results: The groundwater type, defined using a Piper diagram, was mainly Ca-HCO₃. The concentration of uranium in the groundwater ranged from 0 to 29.3 ㎍/L, with a mean of 3.3 ㎍/L and a median of 0.9 ㎍/L. The median concentration of uranium in groundwater was highest in alluvium, granitic gneiss, and biotite granite (classified by geological unit), in that order. The concentration of radon in the groundwater ranged from 4.8 to 313.2 Bq/L, with a mean of 75.6 Bq/L and a median of 59.6 Bq/L. The median concentration of radon in groundwater was highest in biotite granite, alluvium, and granitic gneiss, in that order. As a result of the correlation analysis of groundwater in the study area, there was no significant correlation between uranium and radon. Conclusions: In this study area, uranium was shown to be far below the concentrations allowed by drinking water quality standards, but radon concentrations exceeded drinking water quality monitoring standards in 11% of the samples. It was judged that appropriate measures, such as the installation of radon reduction facilities, will be required after a thorough review of high-concentration radon detection sites of in the research area.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권6호
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• pp.37-48
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• 2014

Lab scale rhizofiltration by using four plants was performed to investigate the uranium removal efficiency from groundwater. Lettuce (Lactuca sativa L.), Chinese cabbage (Brassica campestris L.), radish sprouts (Raphanus sativus L.) and buttercup (Oenanthe javanica) were cultivated during 3 weeks in the phytotron. Glass jar ($12cm{\times}12cm{\times}8cm$ for each), containing 350 ml of the artificially uranium contaminated solution was used for 72 hours of the rhizofiltration. In experiments with different initial uranium concentration ($18.00{\mu}g/L$, $31.00{\mu}g/L$, $84.00{\mu}g/L$ and $116.00{\mu}g/L$) in solution, more than 70% of the initial uranium were removed by using lettuce, Chinese cabbage and radish sprouts and the residual uranium concentration in solution maintained lower than USEPA water tolerance limit ($30{\mu}g/L$). From the rhizofiltration experiments at various pH conditions, the highest uranium removal for all four plants was acquired at pH 3 in solution. Rhizofiltration experiments testing two field samples of groundwaters having high uranium concentrations ($86.00{\mu}g/L$ and $173.00{\mu}g/L$) were duplicated and more than 83% of the initial uranium were removed from the groundwater within 72 hours of rhizofiltration by using radish sprouts, which, suggests that the rhizofiltration can be a useful process to remediate uranium contaminated groundwater in the field. After the rhizofiltration experiment, the SEM and EDS analyses for the root surface of the radish sprouts were conducted, suggesting that the main mechanism of the rhizofiltration for the removal of uranium from groundwater would be surface precipitation on the root surface of the plant.

• Carbon letters
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• 제4권2호
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• pp.64-68
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• 2003

A study on the electrosorption of uranium ions onto a porous activated carbon fiber (ACF) was performed to treat uraniumcontaining lagoon sludge. The result of the continuous flow-through cell electrosorption experiments showed that the applied negative potential increased the adsorption kinetics and capacity in comparison to the open-circuit potential (OCP) adsorption for uranium ions. Effective U(VI) removal is accomplished when a negative potential is applied to the activated carbon fiber (ACF) electrode. For a feed concentration of 100 mg/L, the concentration of U(VI) in the cell effluent is reduced to less than 1 mg/L. The selective removal of uranium ions from electrolyte was possible by the electrosorption process.

• Nuclear Engineering and Technology
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• 제33권2호
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• pp.166-174
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• 2001

An apparatus for detecting remote real-time uranium concentration using an optrode was developed. An optrode to detect uranium fluorescence as remote real-time control was designed. Fluorescence intensity at time 2ero was derived by the fluorescence signal processing and the algorithm to exclude the quenching effect of various quenchers and temperature fluctuations. This apparatus employing the above deriving method and the optrode has an error range within 6% in spite of serious fluorescence lifetime changes due to the quenching effect and temperature fluctuations. The detection limit is 0.06 ppm and the linearity is excellent between 0.06 ppm and 2 ppm on the aqueous uranium solution.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.43-52
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• 2015

The uranium removal capacity of radish sprouts (Raphanus sativus L.) in groundwater was calculated on the basis of the amount of uranium accumulated in the radish sprouts rather than the concentration in solution, of which process was very limited in previous studies. Continuous rhizofiltration clean-up system was designed to investigate the feasibility of radish sprouts, applying for uranium contaminated groundwater (U concentration: 110 μg/L) taken at Bugogdong, Busan. Six acrylic boxes (10 cm × 30 cm × 10 cm) were connected in a direct series for the continuous rhizofiltration system and 200 g of radish sprouts cultivars was placed in each box. The groundwater was flushed through the system for 48 hours at the constant rate of 5 mL/min. The rhizofiltration system was operated in the phytotron, of which conditions were at 25℃ temperature, 70% of relative humidity, 4,000 Lux illumination (16 hours/day) and 600 mg/L of CO₂ concentration. While 14.4 L of contaminated groundwater was treated, the uranium removal efficiency of the radish sprouts (1,200 g in wet weight) was 77.2% and their removal capacities ranged at 152.1 μg/g-239.7 μg/g (the average: 210.8 μg/g), suggesting that the radish sprouts belong to the group of hyper-accumulation species. After the experiment, the sum of U amounts accumulated in radish sprouts and remained in groundwater was 1,472.2 μg and the uranium recovery ratio of this rhizofiltration experiment was 92.9%. From the results, it was investigated that the radish sprouts can remove large amounts of uranium from contaminated groundwater in a short time (few days) because the fast growth rate and the high U accumulation adsorption capacity.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.119-120
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• 2004

A study on the selective adsorption of uranium(VI) from a high concentration of chemical salts has tern peformed to investigate the uranium removal mechanisms and the application conditions of the electrosorption technique using the activated carbon fiber(ACF) as a good conductive electrosorption adsorbent. Electrosorption test were carried out using an electrochemical cell.(omitted)

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1471-1480
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• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.453-461
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• 2018

Shaft stations of underground uranium mines in China are not only utilized as waiting space for loaded mine-cars queuing to be hoisted but also as the principal channel for fresh air taken to working places. Therefore, assessment of how mine-car queuing processes affect shaft station radon concentration was carried out. Queuing network of mine-cars has been analyzed in an underground uranium mine, located in Quzhou, Zhejiang province of Eastern China. On the basis of mathematical analysis of the queue network, a MATLAB-based quasi-random number generating program utilizing Monte-Carlo methods was worked out. Extensive simulations were then implemented via MATALB operating on a DELL PC. Thereafter, theoretical calculations and field measurements of shaft station radon concentrations for several working conditions were performed. The queuing performance measures of interest, like average queuing length and waiting time, were found to be significantly affected by the utilization rate (positively correlated). However, even with respect to the "worst case", the shaft station radon concentration was always lower than $200Bq/m^3$. The model predictions were compared with the measuring results, and a satisfactory agreement was noted. Under current working conditions, queuing-induced variations of shaft station radon concentration of the study mine are not remarkable.