• 공업화학
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• 제9권4호
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• pp.475-480
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• 1998

본 연구에서는 고밀집 glassy carbon (GC) 섬유 다발체 전극 전해계를 사용하여 우라늄 (VI)를 함유한 유기상과 질산 수용상의 혼합상에서 전해 역추출시 우라늄 (VI) 환원 전해특성 연구가 수행되었고, 이에 관한 전해 역추출 모델을 제시하였다 우라늄 (VI) 전해환원 반응은 혼합상 내의 수용상에서 보다 혼합상 내의 유기상에서 빨리 일어났다. 유기상의 유속이 증가하는 경우 역추출 과정에서 유기상 내 우라늄 이온의 확산 저항 증가에 의해서 수용상으로의 역추출은 증가하다 일정하게 되었으며, 수용상 유속 변화는 총 우라늄 (VI) 환원전류에는 영향을 주지 않았다. 전해반응이 없는 경우보다 전해 반응이 동반되는 경우 우라늄 역추출이 보다 효과적으로 이루어 짐을 알 수 있었다.

• 방사성폐기물학회지
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• 제8권1호
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• pp.85-89
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• 2010

사용후핵연료 파이로프로세싱 공정 생성물인 우라늄 전착물을 잉곳 형태로 주조하는 공정이 있다. 이 논문에서는 실험실 규모의 우라늄 전착물 잉곳 주조 장치에 대한 설계 개념을 소개하고, 이에 따라 제작된 장치의 성능 시험 결과 및 우라늄을 사용한 잉곳 주조 시험 결과를 소개한다. 이 장치는 도가니를 경동시켜 우라늄 용탕을 주형에 주입하여 우라늄 잉곳을 제조하며, 우라늄 전착물을 연속으로 주입할 수 있는 컵 형태의 원료 장입장치를 장착하였다. 이러한 장치를 사용하면 우라늄 전착물의 잉곳 생산성을 높일 수 있다. 실험 결과 우라늄 원료를 장입하여 주조한 결과 수축공이 적은 양호한 주물을 제조하는데 성공하였으며, 이러한 실험실 규모의 장치를 개발한 경험을 활용하여 공학규모의 장치를 설계하는데 활용하였다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.83-83
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• 2017

Electrorefining is a key step in pyroprocessing. The electrorefining process is generally composed of two recovery steps - the deposit of uranium onto a solid cathode and the recovery of the remaining uranium and TRU elements simultaneously by a liquid cadmium cathode. The solid cathode processing is necessary to separate the salt from the cathode since the uranium deposit in a solid cathode contains electrolyte salt. Distillation process was employed for the cathode processing. It is very important to increase the throughput of the salt separation system due to the high uranium content of spent nuclear fuel and high salt fraction of uranium dendrites. In this study, a mesh-covered crucible was investigated for the sat distillation of electrorefiner uranium deposits. A liquid salt separation step and a vacuum distillation step were combined for salt separation. The adhered salt in uranium deposits was efficiently removed in the mesh-covered crucible. The salt distiller was operated simply since repeated cooling - heating step was not necessary for the change of the crucible. The operation time could be reduced by the use of the mesh-covered crucible and the combined operation of the two steps. A method to preserve a vacuum level was proposed by double O-rings during the operation of the distiller with the mesh-covered crucible. After the salt distillation, the salt content was measured and was below 0.1wt% after the salt distillation. The residual salt after the salt distillation can be removed further during melting of uranium metal.

• 자원환경지질
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• 제56권5호
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• pp.547-555
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• 2023

분석 기기의 발달과 더불어 자연 우라늄 동위원소 비(²³⁸U/²³⁵U)와 분별작용에 대한 연구가 점차 증가하고 있다. MC-ICP-MS을 이용한 우라늄 동위원소의 정밀한 분석이 가능해지면서 137.88의 고정된 값으로 여겨졌던 자연 물질의 ²³⁸U/²³⁵U 비가 우라늄 동위원소 분별작용에 의해 최대 수 퍼밀까지 변화할 수 있다는 것이 밝혀졌다. 본 고찰에서는 우라늄 동위원소의 분석과 표기에 대해 간략하게 설명한 후, 지구 상 주요 물질들의 우라늄 동위원소 값(δ²³⁸U)의 변화와 지구화학적 특징을 살펴본다. 특히, 우라늄 광상의 유형과 특징에 따른 우라늄 동위원소 조성 연구 사례를 소개하고, 상대적으로 큰 δ²³⁸U 범위를 야기하는 우라늄 동위원소 분별작용에 대해 논의한다. 이를 바탕으로 고준위 방사성 폐기물 처분장의 모의 실험을 위한 자연 유사 모델로서 우라늄 광상이 갖는 연구 의의에 대해 고찰한다.

• 자원환경지질
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• 제56권5호
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• pp.565-580
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• 2023

본 연구에서는 고준위방사성폐기물 처분안전성 입증 및 신뢰성 향상을 위한 처분자연유사연구의 역할과 중요성을 개괄적으로 조사하였다. 아울러 지하 처분환경에서 복잡하고 다양한 핵종거동을 규명하고 해석하기 위한 우라늄광상을 이용한 국내외 자연유사연구 동향을 고찰하였다. 또한 국내 옥천변성대 우라늄광상을 포함하는 우라늄광상 지하수와 암석에서의 우라늄의 거동특성과 지질환경에서의 우라늄의 생지화학적 상호작용을 조사하였다. 비록 우라늄광상에서 획득한 우라늄 거동 특성 자료들은 처분안전성평가에 직접적으로 활용하는 데는 많은 제약과 불확실성을 내포하고 있지만, 우라늄광상을 통해 획득한 자료와 정보들은 처분안전성평가와 Safety Case 구축에 정성적으로 또는 일부 정량적으로 활용될 수 있을 것이다.

• 자원환경지질
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• 제19권spc호
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• pp.163-173
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• 1986

Black and graphite slates from the Okcheon metamorphic belt contain enriched values of uranium (average 200~250ppm) and molybdenum (average 150~200ppm). Uranium mineralization is closely associated with quartz and sulfide veinlets which are formed diagenetically in graphite slate. The uranium minerals were concentrated in outer part of graphite nodules. The ${\delta}^{13}C$ values of organic carbon from the metasediments including uranium bearing graphite slate range from -15.2 to -26.1‰ with a mean of -23.5‰. Meanwhile, ${\delta}^{13}C$ values of coal and coaly shale from some Paleozoic coal fields of South Korea vary from -19.4 to -23.9‰ with an average of -22.5‰. Isotopic compositions of vein calcite in uranium bearing slate range from -13.4 to -15.4‰ in ${\delta}^{13}C$ and +11.3 to +15.1‰ in ${\delta}^{18}O$ could indicate a reduced organic carbon source isotopically exchanged with a graphite of biogenic origin. Metamorphic temperature determined by a calcite-graphite isotope geothermometer was 383~$433^{\circ}C$ which corresponded to greenschist facies by Miyashiro (1973) and is consistent with metamorphic facies estimated by mineral assemblages (Lee, et al., 1981, and Kim, 1971). The fixation of uranyl species by carbonaceous matter in marine epicontinental environment, and remobilization of organouranium by diagenetic processes have attributed to the enrichment of uranium and heavy metals in the graphite slate of Okcheon metamorphic belt.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권1호
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• pp.33-40
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• 2017

Identification of radon in soil provides information on the areas at risk for high radon exposure. In this study, we measured uranium-238 and radon-222 concentrations in soil to assess their approximate levels in Seoul. A total of 246 soil samples were taken to analyze uranium with ICP-MS, and 120 measurements of radon in soil were conducted with an in-situ radon detector, Rad7 at a depth of 1-1.5 m. The data were statistically analyzed and mapped, layered with geological classification. The range of uranium in soil was from 0.0 to 8.5 mg/kg with a mean value of 2.2 mg/kg, and the range of radon in soil was from 1,887 to $87,320Bq/m^3$ with a mean value of $18,271Bq/m^3$. The geology had a distinctive relationship to the uranium and radon levels in soil, with the uranium and radon concentrations in soils overlying granite more than double those of soils overlying metamorphic rocks.

• Mass Spectrometry Letters
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• 제7권2호
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• pp.41-44
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• 2016

Secondary ion mass spectrometry (SIMS) is a promising tool to measure isotope ratios of individual uranium particles in environmental samples for nuclear safeguards. However, the analysis requires prior identification of a small number of uranium particles that coexist with a large number of other particles without uranium. In the present study, this identification was performed by scanning electron microscopy - energy dispersive X-ray analysis with automated particle search mode. The analytical results for an environmental sample taken at a nuclear facility indicated that the observation of backscattered electron images with × 1000 magnification was appropriate to efficiently identify uranium particles. Lower magnification (less than × 500) made it difficult to detect smaller particles of approximately 1 μm diameter. After identification, each particle was manipulated and transferred for subsequent isotope ratio analysis by SIMS. Consequently, the isotope ratios of individual uranium particles were successfully determined without any molecular ion interference. It was demonstrated that the proposed technique provides a powerful tool to measure individual particles not only for nuclear safeguards but also for environmental sciences.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.751-757
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• 2016

The present work discusses two different models of boiling water reactor (BWR) bundle to compare the neutronic characteristics of uranium dioxide ($UO_2$) and uranium zirconium hydride ($UZrH_{1.6}$) fuel. Each bundle consists of four assemblies. The BWR assembly fueled with $UO_2$ contains $8{\times}8$ fuel rods while that fueled with $UZrH_{1.6}$ contains $9{\times}9$ fuel rods. The Monte Carlo N-Particle Transport code, based on the Mont Carlo method, is used to design three dimensional models for BWR fuel bundles at typical operating temperatures and pressure conditions. These models are used to determine the multiplication factor, pin-by-pin power distribution, axial power distribution, thermal neutron flux distribution, and axial thermal neutron flux. The moderator and coolant (water) are permitted to boil within the BWR core forming steam bubbles, so it is important to calculate the reactivity effect of voiding at different values. It is found that the hydride fuel bundle design can be simplified by eliminating water rods and replacing the control blade with control rods. $UZrH_{1.6}$ fuel improves the performance of the BWR in different ways such as increasing the energy extracted per fuel assembly, reducing the uranium ore, and reducing the plutonium accumulated in the BWR through burnup.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.143-149
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• 2011

In order to figure out the characteristics of radionuclides concentrations of nine provinces, we analyzed uranium and radon in 681 samples of groundwater. Most of uranium concentrations in each province were less than $10{\mu}g/L$, and Gyeongnam, Jeonnam, Jeju provinces did not have groundwaters exceeding the US EPA drinking water MCL ($30{\mu}g/L$) of uranium. The ratio of radon values exceeding US EPA drinking water AMCL (4,000 pCi/L) was 22.6% (154/681) and Gyeongnam and Jeju provinces had no groundwaters exceeding the AMCL (alternative maximum contaminant level). Uranium and radon concentrations in groundwaters of Gyeonggi, Chungbuk, Jeonbuk, Chungnam mainly composed of the Mesozoic granite and the Precambrian gneiss were relatively high, but the concentrations of Gyeongnam and Jeju widely comprised of the sedimentary rock and the volcanic rock were relatively low. A week correlation between uranium and radon values showed in Gangwon, Chungbuk, Gyeonggi provinces.