• 대한방사선기술학회지:방사선기술과학
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• 제44권5호
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• pp.481-487
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• 2021

This study was conducted for the purpose of efficient radioactive waste disposal and management. Experiment was evaluated the decontamination efficiencies of the four types decontamination materials(Water, Alcohol, Decontamination Water, Decontamination Gel) with radioactive wastes generated during radio-pharmaceutical production process at Korea Institute Radiological and Medical Sciences(KIRAMS). The radioactive waste sample used in experiment is a lead plate of the fume hood that was disposed in April, 2019. In the experimental method, radioactive waste was measured before and after decontamination using a HPGe semiconductor detector and Gamma survey meter. The measured values before and after decontamination were evaluated for decontamination efficiency as a percentage. As a result, it was confirmed that a lot of specific activity and surface dose rate was removed from the radioactive wastes. In particular, when decontamination water was used, most of the radioactivity of radioactive wastes was removed. Considering these results, if decontamination water is used in decontamination of radioactive waste, decontamination efficiency equivalent to the disposition criteria can be expected with just one decontamination treatment. In addition, in the case of water and alcohol, only on decontamination was effective in approximately 75% and 95%. Otherwise, when decontamination gel was used, it was confirmed that the largest deviation occurred among all experimental results.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.12-24
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• 2023

With the improvement of laser technology, the strategic needs of efficient and precise decontamination of various components in nuclear application units can be fulfilled by laser decontamination. The surface contaminants of nuclear facilities mainly exist both as loose contaminated layer and fixed oxide layer. The types of radionuclides and contamination layer thickness are closely related to the operation status of nuclear facilities, which have an important influence on the laser decontamination process. This study reviewed the mechanism of laser surface treatment and the influence of laser process parameters on the decontamination thickness, decontamination factor, decontamination efficiency and the distribution of aerosol particle. Although multiple studies have been performed on the mechanism of laser processing and laser decontamination process, there are few studies on the microscopic process mechanism of laser decontamination and the influence of laser decontamination on surface properties. In particular, the interaction between laser and radioactive contaminants needs more research in the future.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2918-2925
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• 2021

The efficiency of decontamination of model spent ion exchange resins, contaminated with magnetite and hematite, with mineral acid solutions, and using electro-decontamination, was evaluated. It has been shown that effective hematite dissolution occurs in concentrated mineral acid solutions. However, the use of direct current increases the decontamination efficiency of spent ion exchange resins contaminated with hematite. It is determined that with increasing voltage and acid concentration, the dissolution efficiency of hematite deposits increases and can exceed 99%. It has been shown that hematite dissolution is accompanied by secondary adsorption of radionuclides due to ion exchange, which can be removed with sodium nitrate solutions.

• 방사성폐기물학회지
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• 제14권1호
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• pp.45-55
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• 2016

Decontamination is one of the most important technologies for the decommissioning of NPP. The purpose of decontamination is to reduce the Risk of exposure of the decommissioning workers, and to recycle parts of the plant components. Currently, there is a lack of data on the efficiency of the decontamination technologies for decommissioning. In most cases, the local radiation level can be lowered below a regulatory limitation by decontamination. Therefore, more efficient decontamination technology must be continuously developed. This work describes the practical experiences in the United States and the European countries for NPP decommissioning using these decontamination technologies. When the decommissioning of domestic nuclear power plant is planned and implemented, this work will be helpful as a reference of previous cases.

• 방사선산업학회지
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• 제9권4호
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• pp.217-221
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• 2015

When reactor coolant leaks occur due to cracks of a steam generator's tube, radioactive materials contained in the primary cooling water in nuclear power plant are forced out toward the secondary systems. At this time the secondary water purification resin in the ion exchange resin tower of the steam generator blowdown system is contaminated by the radioactivity of the leaked radioactive materials, so we pack this in special containers and store temporarily because we could not dispose it by ourselves. If steam generator tube leakage occurs, it produces contaminated spent resins annually about 5,000~7,000 liters. This may increase the amount of nuclear waste productions, a disposal working cost and a unit price of generating electricity in the plant. For this reasons, it is required to develop a decontamination process technique for reducing the radioactive level of these resins enough to handle by the self-disposal method. In this research, First, Investigated the structure and properties of the ion exchange resin used in a steam generator blowdown system. Second, Checked for a occurrence status of contaminated spent resin and a disposal technology. Third, identified the chemical characteristics of the waste radionuclides of the spent resin, and examined ionic bonding and separation mechanism of radioactive nuclear species and a spent resin. Finally, we carried out the decontamination experiment using chemicals, ultrasound, microbubbles, supercritical carbon dioxide to process these spent resin. In the case of the spent resin decontamination method using chemicals, the higher the concentration of the drug decontamination efficiency was higher. In the ultrasound method, foreign matter of the spent resin was removed and was found that the level of radioactivity is below of the MDA. In the microbubbles method, we found that the concentration of the radioactivity decreased after the experiment, so it can be used to the decontamination process of the spent resin. In supercritical carbon dioxide method, we found that it also had a high decontamination efficiency. According to the results of these experiments, almost all decontamination method had a high efficiency, but considering the amounts of the secondary waste productions and work environment of the nuclear power plant, we judged the ultrasound and supercritical carbon dioxide method are suitable for application to the plant and we established the plant applicable decontamination process system on the basis of these two methods.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.207-209
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• 2002

A fraction of TRIGA contaminated soil whose decontamination is practicable by soil washing was about 34.2 %. It appeared from results of first decontamination experiment that decontamination efficiency using (NH$_4$)$_2$SO$_4$, H$_2$C$_2$O$_4$, and NaOH solution were high. Meanwhile, the most suitable ratio of contaminated soil mass(g) to decontamination solution volume(ml) appeared to be 1:10 according to experiment results. And the most suitable concentration of oxalic acid used as a decontamination solution appeared to be 0.5 M.

• 환경위생공학
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• 제19권2호
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• pp.30-36
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• 2004

Dry decontamination technique is required for maintaining nuclear material handling equipment contaminated with highly radioactive material in a hot cell. In order to determine the optimum blasting conditions of dry ice pellet blasting device, the basic experiments have been conducted on the simulated test specimens of four types of metals. The removal efficiency of test piece was evaluated by the XRF analysis and the change of the surface condition before and after blasting. The removal efficiency of cesium on loose contamination was 100% under blasting pressure; 3 kg/$cm^2$, blasting distance; 10 cm, blasting time: 10 sec. In case of fixed contamination, the removal efficiency of cesium was almost 96% under blasting pressure; 4kg/$cm^2$, blasting distance; 10 cm, blasting time; 30 sec.

• 방사성폐기물학회지
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• 제13권1호
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• pp.35-43
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• 2015

선행핵연료 주기관련 시설의 해체/복원 시 방사능으로 오염된 다량의 자갈폐기물이 발생할 수 있다. 하지만 현재 방사성 오염 자갈을 제염하기 위한 기초자료가 부족하므로, 본 연구에서는 토양세척법을 응용하여 방사능 오염 자갈을 제염하는데 필요한 기초실험을 수행하였다. 효율적인 제염을 위하여 제염제를 비교하여 선정하였는데, 우라늄으로 오염된 자갈의 제염제로는 증류수나 계면활성제보다 0.1 M의 질산을 사용하였을 때 제염이 잘 되었다. 또한, 제염효율을 높이고 제염시간을 단축하기 위하여 우라늄 오염 자갈을 파쇄/분쇄한 후 세척한 결과, 입자의 크기가 작으면 작을수록 제염효율이 높고 자체처분허용농도를 만족하는 것으로 나타났다.

• Korean Chemical Engineering Research
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• 제52권3호
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• pp.360-365
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• 2014

과산화수소 증기는 기존 염소계열의 멸균제에 비해 부식성이 낮아 제약 및 의료 분야의 실내멸균제로 사용되며, 암모니아 가스 추가 시 화학작용제의 제독성능이 있다고 알려져 있다. 본 연구에서는 과산화수소 증기를 이용하여 HD, GD, VX의 유사작용제인 CEPS, DFP, dimethoate 등에 대한 제독효율을 확인하였다. 이를 위해 자체 구성한 과산화수소 기화장치에서 발생시킨 증기를 제독챔버에 주입하여 반응시간을 유지하였다. 제독 후 잔류물을 GC/MS로 분석한 후 제독효율을 계산하였고, 각각의 유사작용제에 대한 반응 생성물을 통해서 화학작용제의 반응 메카니즘과 유사함을 확인하였다. 실험결과 CEPS는 30%의 상대습도에서 60분의 반응시간에 완전제독 되었고, 암모니아 가스 주입의 동반하에서 DFP는 30분, dimethoate는 150분의 반응시간에 완전제독되었다.

• 방사성폐기물학회지
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• 제2권4호
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• pp.245-251
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• 2004

원전의 정상운전이나 해체시 발생될 수 있는 토양의 제염을 위한 토양제염장치를 개발하였으며 실증 실험을 수행하였다. 제염장치를 이용한 제염실험을 종합해본 결과 제염조건에 큰 상관없이 $80{\%}$이상의 제염율을 얻을 수 있었다. 방사능 준위 및 토양입도에 의한 실험결과를 보면 낮은 방사능 농도 및 고입도의 제염율이 다소 높음을 알 수 있었다. 제염용액과 토양질량의 비에 따른 제염율은 제염제 부피를 두배로 높였을 경우 방사능 농도가 높은 경우에 큰 것으로 나타났다. 반복 제염은 $0.5{\sim}2.0mm$의 다소 작은 입자에 더욱 효과적으로, 제염이 어려운 작은 입자의 반복제염시 방사능 저감 효과가 비교적 크게 나타났다. 본 오염토양 제염장치를 활용하면 원전에서 발생되는 오염토양의 방사능 농도를 줄일 뿐 아니라 처분양을 줄여 저장공간의 확보에 기여할 뿐만 아니라 향후 원전의 해체시에도 유용하게 활용될 수 있으리라 생각된다.