• 방사성폐기물학회지
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• 제16권3호
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• pp.309-313
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• 2018

Li-Cd 합금을 이용한 환원추출방식을 LiCl-KCl 기반의 drawdown 공정에 적용하게 되면, LiCl-KCl 공융염의 조성이 파괴되므로 공정온도를 높여야 하며, 전해정련 및 전해제련과 같은 공정에 LiCl-KCl 용융염을 재사용할 수 없게 된다. 따라서, 본 연구에서는 공융염 조성에 적합한 Li-K-Cd 합금을 제조하였으며, 이를 이용하여 U와 Nd가 포함된 LiCl-KCl 염에 투입하여 용융염 내 $UCl_3$의 제거가 가능한지 평가하였다.

• 시스템엔지니어링학술지
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• 제9권1호
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• pp.33-45
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• 2013

Systems Engineering Approach was applied to the development of operator-support core management system based on the on-site operation experience and document of core management procedures, which is for enhancing operability and safety in PHWR (Pressurized Heavy Water Reactor) operation. The dissertation and definition of the system were given on th basis of investigating and analyzing the core management procedures. Fuel management, detector calibration, safety management, core power distribution monitoring, and integrated data management were defined as main user's requirements. From the requirements, 11 upper functional requirements were extracted by considering the on-site operation experience and investigating documents of core management procedures. Detailed requirements of the system which were produced by analyzing the upper functional requirements were identified by interviewing members who have responsibility of the core management procedures, which were written in SRS (Software Requirement Specification) document by using IEEE 830 template. The system was designed on the basis of the SRS and analysis in terms of nuclear engineering, and then tested by simulation using on-site data as a example. A model of core power monitoring related to the core management was suggested and a standard process for the core management was also suggested. And extraction, analysis, and documentation of the requirements were suggested as a case in terms of systems engineering.

• 소음진동
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• 제6권2호
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• pp.163-177
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• 1996

An investigation on thermohydraulic stability of flow oscillations in the CANada Deuterium Uranium-600(CANDU-6) heat transport system has been conducted. Flow oscillations in reactor coolant loops, comprising two heat sources and two heat sinks in series, are possibly caused by the response of the pressure to extraction of fluid in two-phase region. This response consists of two contributions, one arising from mass and another from enthalpy change in the two-phase region. The system computer code used in the investigation os SOPHT, which is capable of simulating steady states as well as transients with varying boundary conditions. The model was derived by linearizing and solving one-dimensional, homogeneous single- and two-phase flow conservation equations. The mass, energy and momentum equations with boundary conditions are set up throughout the system in matrix form based on a node-link structure. Loop stability was studied under full power conditions with interconnecting the two compressible two phase regions in the figure-of-eight circuit. The dominant function of the interconnecting pipe is the transfer of mass between the two-phase regions. Parametric survey of loop stability characteristics, i. e., damping ratio and period, has been made as a function of geometrical parameters of the interconnection line such as diameter, length, height and orifice flow coefficient. The stability characteristics with interconnection line has been clarified to provide a simple criterion to be used as a guide in scaling of the pipe.

• 한국분말재료학회지
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• 제1권1호
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• pp.72-78
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• 1994

Two kinds of $U_3Si$ powders and $U_3Si$ dispersed nuclear fuel meats have been prepared by conventional comminution process and a newly developed rotating disk atomization process. In contrast to angular shape and broad size distribution of the conventionally processed powder, the atomized powder was spherical and showed narrow size distribution. For the atomized powder, the heat treatment time for the formation of $U_3Si$ by a peritectoid reaction was reduced to about one tenth, thanks to microstructure refinement by rapid cooling of about 5$\times$104 K/s. The extruding pressure of atomized $U_3Si$ powder and Al powder mixture was lower than that of comminuted $U_3Si$ and Al powder mixture. The elongation of the atomization processed fuel meats was much higher than that of the comminution processed fuel meats and remained over 10% up to 80wt.% of $U_3Si$ powder fraction in the fuel meats. It appears therefore that the loading density of $U_3Si$ in fuel meat can be increased by using atomized $U_3Si$ powder. The atomized spherical particles were randomly distributed, while the comminuted particles with angular and longish shape were considerably aligned along the extrusion direction. Along the transverse direction of the extraction the electrical conductivity of the atomization processed fuel meats was appreciably higher than that of comminution processed fuel meats. This tendency became pronounced as $U_3Si$ content increased. Because the thermal conduction which is believed to be proportioned to the electrical conduction in the nuclear fuel meats occurs in radial direction, the atomization processed fuel can be better used in research reactors where high thermal conductivity is required.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.351-357
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• 2003

원전발생 방사성폐기물 시료 중 TRU를 정량하기위해 모의 사용 후 핵연료 시료 용액 중 Pu, Am 및 Cm 을 이온교환수지 및 HDEHP 추출크로마토그래피로 분리한 다음 알파분광분석법으로 각 핵종의 함량을 정량하였다. Dowex AG1 음이온수지 에서 12M HC1-0.lMHI 용리액으로 Pu를 분리하고 이차분리관인 HDEHP 흡착 분리 관에서 DTPA-Lactic Acid 용리액으로 Am과 Cm을 군분리하였다. 분리된 Pu, Am 및 Cm은 0.1M $NaHSO_4$-0.53M $Na_2SO_4$ 매질에서 전착한 다음 알파분광분석법으로 $^{239}Pu$, $^{241}Am$및 $^{244}Cm$의 알파에너지의 방사능을 측정하여 회수율을 추하였다. 비방사성 금속원소 및 우라늄을 포함하는 합성용액 시료중 $^{239}Pu$, $^{241}Am$및 $^{244}Cm$ 을 측정한 결과 각각 83.8%, 85.2% 및 86.3% 의 회수율을 나타내었다.

• 자원환경지질
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• 제29권4호
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• pp.495-508
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• 1996

This study had three purposes: (1) to investigate dispersion and enrichment level of potentially toxic elements; (2) to identify uranium-bearing minerals in black shales; and (3) to assess the chemical speciation of heavy metals in soils and sediments. Rock, surface soil and stream sediment samples were collected in the Chungjoo area covered with black shales in Korea. These samples were analyzed for multi-elements using INAA and ICP-AES. The maximum abundance of U in black shales is 56 ppm and radioactivity counts up to 240CPM. Molybdenum, V, Ba, Cu, and Pb are enriched in black shales and most of soils show high concentrations of U, Mo, Ba, Cu, Pb and Zn. Concentrations of potentially toxic elements decrease in the order of mountain soil > farmland soil > paddy soil. Enrichment index of soils and sediments are calculated and higher than 1.0 in the black shale area with the highest value of 6.1. In order to identify U-bearing minerals, electron probe micro analysis was applied, and uraninite and brannerite in black shale were found. Uraninite grains are closely associated with monazite or pyrite with the size of $2{\mu}m$ to $10{\mu}m$ in diameter whereas brannerite occurs as $50{\mu}m$ euhedral grains. With the results of sequential extraction scheme, residual fractions of Cu, Pb and Zn in soils are mainly derived from weathering of black shale but Cu, Pb and Zn in sediments are present as non-residual fractions. Lead is predominantly present as oxidizable phase in soils whereas Zn is in exchageable/water-acid soluble phase in sediments.

• 분석과학
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• 제17권4호
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• pp.302-307
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• 2004

환경시료중의 극미량의 악티늄계 동위원소들을 분석하기는 무척 어렵다. 이들 원소들은 개별 분리하는 작업이 필요하며, 알파분광법으로 분석한 어떤 핵종들은 검출감도도 높은 편이다. 이런 극미량의 악티늄계 동위원소들을 분석하기 위해 용매추출법이 결합된 TRU-Spec 이온교환수지와 음이온 교환수지를 사용하여 악티늄계 원소들을 분리한 후 알파분광법으로 검출하였다. 그리고 U과 Th의 검출한계를 낮추기 위해 중성자방사화분석법을 적용하였다. 중성자방사화분석법을 적용하기 위한 바탕물질로 고순도 V foil을 사용하여 검출감도를 10배 향상시킬 수 있었으며, 이 분석법을 표준시료인 NIST-4354, IAEA-368 퇴적물 시료에 적용한 결과 표준값과 10% 이내에서 잘 일치하였다.

• 대한화학회지
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• 제45권4호
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• pp.304-311
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• 2001

경수로 사용후 핵 연료에 미량 함유되어 있는 핵분열생성물을 유도 결합 플라스마 원자방출분광법(ICP-AES)으로 분석하기 위하여 우라늄으로부터 학분열생성물을 추출 크로마토그래피로 분리, 회수하는 방법을 검토하였다. 우라늄 분리 분야에서 잘 알려져 있는 tri-n-butyl phosphate(TBP)를 추출제로 사용하여 몇 가지 Amberlite XAD 다공성 수지들에 대한 침윤능을 비교한 후 TPB침윤양이 가장 큰 Amberlite XAD-16을 지지체로 선택하였다. 사용후핵연료 용해용액과 화학조성이 유사한 모의 사용후핵연료 용해용액을 사용하여 TBP 침윤수지에 대한 핵분열생성물 원소들의 흡착거동을 조사하고, 분리에 미치는 여러 변수들을 최적화 하였다. Pd 및 Ru을 제외한 대부분의 핵분열생성물 원소들을 정밀도 3.1% 이하의 범위에서 정량적으로 회수할 수 있었다.

• 자원환경지질
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• 제30권6호
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• pp.567-586
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• 1997

Concentrations of several heavy metals in soils derived from black shale and slate have been reported to be higher than the average concentrations in non-polluted soils. This study describes and characterizes soil minerals, and investigates the distribution of heavy metals in soils, and then examines their relationship. Soils in the study area are mainly consist of guartz and feldspars with minor amount of kaolin, illite, vermiculite, chlorite and illite-vermiculite interstratified minerals. Mineral compositions are similar in mountain-, farmland-, and paddy-soils. The residual soils derived from sandy phyllites contain less illites than those from black shale and black slate. Heavy metals appear to be more concentrated in soils than in rocks. The concentrate ratios in soils to rocks ranges 1.1 times for Cr, 2 for Cu, 1.4 for Ni. The contour maps of Cd, Zn, Pb, Cu contents using 0.43N $HNO_3$-extraction imply that these elements are highly concentrated in the soils near the past uranium exploration region, coal seams, black slate beds and tailings than other parts of the study area. The proportions of the day in most soils are less than 10%. In spite of small proportions of the clay, the concentrations of heavy metals from clay fractions to the total concentrations are high: 1~2.4 times for Co, 1.4~2.5 for Cu, 1.2~2.6 for Ni, 1~5 for Pb, 1~2.7 for Zn and 1.6~1.8 for Cr and V. The contents of organic carbons in clay fractions are also 1.5~3.9 times higher than in silt and sand fractions. Cu, Pb and organic carbons show positive relationship in all size fractions. In the size-fractionated soil profile samples, the contents of heavy metals and organic carbons show analogous trends with depth. For the clay fractions of soil profile samples, the contents of heavy metals with depth have analogous trends to abundances of vermiculites, which have the high CEC in main clay minerals.

• 방사성폐기물학회지
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• 제18권2_spc호
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• pp.227-235
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• 2020

우리는 실험과 MCNP 시뮬레이션을 통해 전알파 분석법의 한계를 설명하였다. 국내에서 중·저준위 방사성폐기물 인도 규정 관련, 전알파 분석법은 방사성폐기물을 처분하기 위해 반드시 규명해야 할 방사성 특성평가 인자이다. 전알파 분석법은 시료 준비 절차가 간단하고 신속한 분석 결과를 제공하지만, 정량분석 인자로 사용하는 것은 적절하지 않다. KCl과 ²⁴¹Am을 이용하여 시편 건조고형물 무게에 따른 전알파 계측효율을 평가하였다. 동일한 무게의 시편일지라도 계측효율의 차이가 20% 나는 것을 확인하였고, 이는 시편의 물리적 형태가 서로 다르기 때문인 것으로 보인다. 토양 중 우라늄을 화학분리 한 후, ICP-MS로 우라늄을 직접 측정한 결과와 전알파 농도를 비교하였다. 전알파는 실제 우라늄 농도에 비해 50% 과소평가되었다. 알파핵종별 전알파 계측효율이 최대 3배 차이 나기 때문에, 전알파 분석결과는 개별 알파핵종의 합과 비교하기 보다는 스크리닝 개념으로 사용하는 것이 적절하다.