• Nuclear Engineering and Technology
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• 제52권3호
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• pp.581-588
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• 2020

The membrane fouling is an important problem for FO applied to the radioactive wastewater treatment. The FO fouling characteristics for simulated radioactive wastewater treatment was investigated. On-line cleaning by deionized (DI) water and external cleaning by ultrasound and HCl were applied for the fouled membrane. The effectiveness and foulant removing amount by each-step cleaning were evaluated. The membrane fouling was divided into three stages. Co(II), Sr(II), Cs(I), Na(I) were all found deposited on both active and support layers of the membrane surface, resulting in membrane surface became rougher and more hydrophobic, which increased membrane resistance. On-line cleaning by DI water recovered the water flux to 69%. HCl removed more foulants than ultrasound.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.886-889
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• 2018

This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid waste was 2264, 17, and 9 Bq/L for Cs-137, Cs-134 and Co-60, respectively. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8-10 according to the laboratory jar tests. After the process, radioactivity was precipitated as sludge at the bottom of the tank and decontaminated clean liquid was evaluated depending on discharge limits. By this precipitation method decontamination factors were determined as 66.5, 8.6, and 9 for Cs-137, Cs-134, and Co-60, respectively. By using the potassium ferrocyanide, about 98% of the Cs-137 was removed at pH 9. At the bottom of the tank, radioactive sludge amount from both stages was totally $0.98m^3$. It was transferred by sludge pumps to cementation unit for solidification. By chemical processing, 97.2% of volume reduction was achieved. The potassium ferrocyanide in two-staged precipitation method could be used successfully in large-scale applications for removal of Cs-137, Cs-134, and Co-60.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.738-745
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• 2019

Coprecipitation using hydrous ferric oxide (HFO) has been effectively used for the removal of radionuclides from radioactive wastewater. This work studied the dynamic behavior of HFO floc formation during the neutralization of acidic ferric iron in the presence of several radionuclides by using a photometric dispersion analyzer (PDA). Then the coagulation-flocculation system using HFO-anionic poly acrylamide (PAM) composite floc system was evaluated and compared in seawater and distilled water to find the effective condition to remove the target nuclides (Co-60, Mn-54, Sb-125, and Ru-106) present in wastewater generated in the severe accident of nuclear power plant like Fukushima Daiichi case. A ferric iron dosage of 10 ppm for the formation of HFO was suitable in terms of fast formation of HFO flocs without induction time, and maximum total removal yield of radioactivity from the wastewater. The settling time of HFO flocs was reduced by changing them to HFO-PAM composite floc. The optimal dosage of anionic PAM for HFO-anionic PAM floc system was approximately 1-10 ppm. The total removal yield of Mn-54, Co-60, Sb-125, Ru-106 radionuclides by the HFO-anionic PAM coagulation-flocculation system was higher in distilled water than in seawater and was more than 99%.

• 공업화학
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• 제17권4호
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• pp.391-396
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• 2006

방사성 폐기물을 시멘트로 고화처리는 농축 폐액 내의 붕산으로 인해 시멘트의 양생을 지연시키며 감용비가 낮아지는 현상을 나타낸다. 본 연구에서는 이러한 단점을 보완하기 위하여 파라핀 왁스로 처리하여 감용 효과를 높이는 연구를 수행하였다. 파라핀 왁스는 소수성이 커서 무기물과의 혼합특성이 좋지 않아 층 분리 현상이 일어날 수 있다. 왁스의 양이 적은 경우 고화체의 압축강도가 낮아짐을 알 수 있었다. 따라서 먼저 폐기물의 붕산성분을 알칼리염으로 처리하고 이것을 stearic acid로 코팅처리 하였다. 파라핀 왁스로 고화처리 시 왁스의 함량을 일정이상 유지하면 시멘트로 처리한 고화체의 압축강도로 향상되었고 파라핀 고화체의 침출특성에서 파라핀 왁스를 20% 및 25% 함유한 고화체는 CFL (cumulative fraction leached), PR (penetration rate), 유효확산계수 등이 비숫한 값을 지닌다.

• 해양안보
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• 제2권1호
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• pp.125-149
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• 2021

후쿠시마 원전 사고가 일어난 지 10년이 지난 지금까지도 일본은 매일 생성되는 원전 오염수 문제를 해결하지 못하고 있다. 그들은 오염수 저장탱크가 한계에 다다를 것으로 예상되자, 안전성에 관한 한국의 우려에도 일방적으로 원전 오염수를 해양에 방출하기로 했다. 문제는 한국의 대응에도 불구하고, 여전히 일본이 『유엔해양법협약』상 의무를 성실히 이행하지 않은 채 해양 방출을 준비하고 있다는 데 있다. 원전 오염수의 방사성물질로 인한 해양오염은 물론, 한국의 해양주권 침탈까지도 우려되는 상황이다. 특히 한번 환경이 오염되기 시작하면 본래의 상태로 되돌리기 어렵기에, 당장 안전성이 보장되지 않는 한 원전 오염수의 해양 방출은 반드시 막아야 한다. 본 논문은 일본과 한국이 원전 오염수 해양 방출 사안으로 빚은 갈등을 해결하기 위한 한국의 대응 전략을 제안한다. 한국은 일본과의 협력, 잠정조치, 주변국과의 공조를 통해 다양한 측면에서 일본의 원전 오염수 해양 방출에 대응해야 할 것이다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.399-400
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• 2018

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.516-522
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• 2023

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (¹³³Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (¹³⁷Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of ¹³⁷Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of ¹³³Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of ¹³⁷Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4441-4448
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• 2022

The electrochemical oxidation process has been widely studied in the field of wastewater treatment for the decomposition of organic materials through oxidation using ·OH generated on the anode. Pt anode electrodes with high durability and long-term operability have a low oxygen evolution potential, making them unsuitable for electrochemical oxidation processes. Therefore, to apply Pt electrodes that are suitable for long-term operation and large-scale processes, it is necessary to develop a new method for improving the decomposition rate of organic materials. This study introduces a method to improve the decomposition rate of organic materials when using a Pt anode electrode in the electrochemical oxidation process for the treatment of organic decontamination liquid waste. Electrochemical decomposition tests were performed using sodium dodecylbenzenesulfonate (SDBS) as a representative organic material and a Pt mesh as the anode electrode. Y₂O₃ particles were introduced into the electrolytic cell to improve the decomposition rate. The decomposition rate significantly improved from 21% to 99%, and the current efficiency also improved. These results can be applied to the electrochemical oxidation process without additional system modification to enhance the decomposition rate and current efficiency.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.482-483
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• 2018

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.355-356
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• 2018