Spin-off pyroprocessing technology and inert anode materials to replace the conventional carbon-based smelting process for critical materials were introduced. Efforts to select inert anode materials through numerical analysis and selected experimental results were devised for the high-throughput reduction of oxide feedstocks. The electrochemical properties of the inert anode material were evaluated, and stable electrolysis behavior and CaCu generation were observed during molten salt recycling. Thereafter, CuTi was prepared by reacting rutile (TiO2) with CaCu in a Ti crucible. The formation of CuTi was confirmed when the concentration of CaO in the molten salt was controlled at 7.5mol%. A laboratory-scale electrorefining study was conducted using CuTi(Zr, Hf) alloys as the anodes, with a Ti electrodeposit conforming to the ASTM B299 standard recovered using a pilot-scale electrorefining device.

The domestic CANDU nuclear power plants have been operated for a long time and various unforeseen spent fuel defects have been discovered. As the spent fuel defects are important factors in the safety of the nuclear power plant, a study on the analysis of the spent fuel defects to prevent their recurrence is necessary. However, in cases where the fuel rods inside the fuel assembly are defected, it is difficult to dismantle the fuel assembly owing to their welded structure and the facility conditions of the plant. Therefore, it is impossible to analyze the spent fuel defect because it is difficult to visually check the shape of the fuel defect. To resolve these problems, an analysis technology that can predict the number of defected fuel rods and defect size was developed. In this study, we developed a methodology for investigating the root cause of spent fuel defects using a database of the earlier fuel defects in the plants. It is anticipated that in the future this analysis technology will be applied when spent fuel defects occur.

Strontium lanthanum vanadate La1-xSrxVO3 (LSVO) is a promising anode material for electrochemical devices, especially for solid oxide fuel cells, thanks to its irregular electrical conductivity. However, the known synthesis methods are incapable of producing well-dispersed LSVO nanoparticles (NPs) with homogeneous size distribution, which partly impedes the applicability of the material. Thus, a new approach to synthesize LSVO NPs with such characteristics is of paramount importance. In the present work, we successfully prepare LSVO NPs with a high dispersion degree and homogeneous size distribution via a modified co-precipitation pathway, followed by hydrogen reduction at a temperature as low as 700 oC. The prepared LSVO NPs display uniform sizes in the range of 50 ~ 100 nm and do not contain any secondary phases, according to XRD analysis. The chemical mechanism of reactions that occur to form the LSVO is thoroughly highlighted. The work functions of NPs measured by the UPS analysis are in the 2.13 ~ 3.62 eV range, making the LSVO powders promising for use in thermionic devices. An explanation of the role of Sr substitution in work function values of LSVO is also proposed.

The high-temperature stability of YSZ specimens fabricated by die pressure and cold isostatic press (CIP) is investigated in CaCl2-CaF2-CaO molten salt at 1,150 °C. The experimental results are as follows: green density 46.7 % and 50.9 %; sintering density 93.3 % and 99.3 % for die press and CIP, respectively. YSZ foremd by CIP exhibits higher stability than YSZ formed by die press due to denseness dependency after high-temperature stability test. YSZ shows peaks mainly attributed to CaZrO3, with a small t-ZrO2 peak, unlike the high-intensity tetragonal-ZrO2 (t-ZrO2) peak observed for the asreceived specimen. The t-ZrO2 phase of YSZ is likely stabilized by Y2O3, and the leaching of Y2O3 results in phase transformation from t-ZrO2 to m-ZrO2. CaZrO3 likely forms from the reaction between CaO and m-ZrO2. As the exposure time increases, more CaZrO3 is observed in the internal region of YSZ, which could be attributed to the inward diffusion of molten salt and outward diffusion of the stabilizer (Y2O3) through the pores. This results in greater susceptibility to phase transformation and CaZrO3 formation. To use SOM anodes for the electroreduction of various metals, YSZ stability must be improved by adjusting the high-density in the forming process.

삼불화알루미늄(AlF3)이 포함된 염화물-불화물 혼합 용융염에서 ZIRLO 튜브를 이용한 지르코늄 전해정련공정을 실증하였다. 순환 전압전류실험 결과, AlF3의 농도가 증가함에 따라 금속환원의 개시 전위가 일정하게 증가하고 지르코늄-알루미늄 합금형성과 관련된 추가적인 peak의 크기가 점차 증가하는 것으로 나타났다. 전류조절 전착법과 달리, −1.2 V의 일정전위 에서 수행한 지르코늄 전해정련에서 방사형 판 구조의 지르코늄 성장이 염의 상단 표면에서 확연하게 나타났으며, 전착물 지름의 크기는 AlF3의 농도에 따라 점차 증가하는 것으로 나타났다. 주사전자현미경(SEM)과 에너지 분산 X선 분광기(EDX) 와 X선 광전자 분광기(XPS)를 이용하여 판 구조의 지르코늄 전착물을 분석한 결과, 극미량의 알루미늄이 지르코늄-알루미늄 합금 형태로 존재하며, 전착물의 상단과 하단 간에 서로 다른 화학성분구조를 갖는 것으로 나타났다. AlF3의 첨가는 전착물 내 잔류염 양을 줄이고, 지르코늄 회수를 위한 전류효율을 향상시키는 데 효과적인 것으로 나타났다.

Nd-Fe-B permanent magnets have been used in a wide variety of applications because of their high magnetic flux density. So, demand for neodymium has been increasing in worldwide. In this study, an electrowinning process was performed in LiF-NdF3-Nd2O3 high temperature molten salts. However, a corrosion resistant material for use in the molten salt must be found for stable operation because of the harsh corrosion environment of the electrowinning process. Therefore, for this paper, boron nitride(BN), aluminum nitride(AlN), and silicon nitride(Si3N4) were selected as protective and structural materials in the high temperature electrolyte. To investigate the characteristics of BN, AlN, and Si3N4, in molten salts, materials were immersed in the molten salts for 24, 72, 120, and 192 hours. Also, surface condition and stability were investigated by SEM and EDS and corrosion products were calculated by HSC chemistry. As a result, among BN, AlN, and Si3N4, AlN was found to show the best protective material properties.

The purpose of this experiment is to measure the change in the growth rate and the amount of bioactive compounds when additives are added to mushrooms. According to the additive content, Ganoderma lucidum ASI7004, Ganoderma lucidum ASI7071, Ganoderma. meredithae KACC42868 and Ganoderma lucidum ASI7013 mycelial growth rate variation analysis, oriental raisin tree, Siberian ginseng, chestnut shell, apple pomace, and Korean cabbage additive increased mycelial growth by approximately 2.5 times when compared to the control group(MCM medium). The results of analyzing the total amount of polyphenol in mycelia of G. lucidum based on different kinds of additives have shown that the amount of polyphenol increased only in G. lucidum ASI7004 with 2% Korean cabbage additive. However, when other additives are added, the amount of polyphenol turned out to be lower than original G. lucidum and other individual additives. The results of analyzing the total amount of triterpenoid in mycelia of G. lucidum based on different kinds of additives have shown that the amount of triterpenoid increased in G. lucidum mycelia with apple pomace and Korean cabbage additives. Siberian ginseng additive was effective in increasing the amount of triterpenoid only when 4% Siberian ginseng was added to G. lucidum ASI7004, yet the increased amount was not significant. Although the addition of additives turned out to be effective to the growth rate, it was not effective enough towards the amount of bioactive compounds. Further experiments are required.

The effects of Nb and Cr addition on the microstructure, corrosion and oxide characteristics of Zr based alloys wereinvestigated. The corrosion tests were performed in a pressurized water reactor simulated-loop system at 360oC. Themicrostructures were examined using OM and TEM, and the oxide properties were characterized by low-angle X-ray diffractionand TEM. The corrosion test results up to 360 days revealed that the corrosion rates were considerably affected by Cr contentbut not Nb content. The corrosion resistance of the Zr-xNb-0.1Sn-yCr quaternary alloys was improved by an increasing Nb/Cr ratio. The crystal structure of the precipitates was affected by a variation of the Nb/Cr ratio. The Zr-Nb beta-enrichedprecipitates were mainly formed in the high Nb/Cr ratio alloy while Zr(NbCr)2 precipitates were frequently observed in the lowNb/Cr ratio alloy. The studies of oxide characteristics revealed that the corrosion resistance was related to the crystal structureof the precipitate.

핵연료는 원자로 운전 중 예기치 못한 상황에서 연료 결함을 초래할 수 있다. 핵연료 결함은 연료봉의 수소화나 이물질에 의한 금속 마모, 그리고 펠렛과 피복관의 상호작용에 의해 피복관이 손상된다. 이렇게 손상된 핵연료의 결함원인을 규명하는 것은 원자력발전의 안전운전에 중요하다고 사료된다. 핵연료가 손상되면 원자로 냉각재가 오염되어 원자로 출력을 낮추거나, 발전소를 정지할 수도 있다. 모든 사용후연료는 건식저장고로 이동 보관되어야 하나, 결함연료는 이동할 수 없으므로 이 연구의 목적은 중수로형 원자로에서 연료가 인출된 후 사용후연료 저장조에서 보관된 연료에 대하여 결함 여부를 판단할 수 있 는 기술을 개발하고자 하였다. 이 연구를 통하여 핵종 누설 검출 기술을 이용한 사용후연료 검사기술을 개발하였으며, 이 기술을 월성발전소에 적용함으로써, 검사기술 및 검사시스템에 대한 성능을 입증하였다.

경제적이고 우수한 핵확산저항성을 갖는 파이로공정의 핵심 단위공정인 전해제련 공정에서 U와 TRU를 동시에 회수하기 위해 환원전극으로써 LCC가 사용된다. 한가지 원소만을 회수하는 금속음극과는 달리 LCC는 전기화학적으로 U와 TRU의 선택적 분리가 어려워 핵확산저항성을 높이는 기술의 핵심이라고 할 수 있다. LCC를 담아놓는 LCC 도가니는 U나 TRU로만 전착되어야하기 때문에 도가니는 전기적으로 절연되어야 한다. LCC와의 안정성과 회수된 TRU 및 용융염과의 화학적 안전성은 물론 공정 중 전착될 수 있는 금속 Li과의 반응성도 고려되어야하므로 LCC 도가니의 소재 특성은 매우 중요하다. 본 연구에서는 Al2O3, MgO, Y2O3, BeO 네 가지 대체 세라믹 소재의 화학적 안정성을 500℃에서 모의 LCC로 열역학적 및 실험적으로 평가하였다. 세라믹 기판 위의 LCC 접촉각은 화학적 반응성을 예측하기 위해 시간에 따라 측정하였다. Al2O3는 가장 낮은 화학적 안정성 갖고 BeO는 재료 내에 존재하는 기공은 접촉각감소에 영향을 주었다. MgO, Y2O3는 우수한 화학적 안정성을 나타내었다.

본 연구에서는 사용후 TRISO 연료 처리를 위한 보다 효과적인 공정개발을 위하여 기존 전처리 기술에 대한 검토를 수행하였다. TRISO 연료 처리에 있어서 가장 중요한 사항은 연료입자에 포함되어 있는 탄소와 SiC성분을 효과적으로 분리하는데 있다. 공정개발 초기에 고려되었던 분쇄 후 배소공정의 경우 처리공정에서 발생되는 2차 폐기물로 인하여 분쇄 후 침출공정으로 대체 되었으나 여전히 해결해야 될 근본적인 문제점이 존재하고 있다. 따라서 본 논문에서는 TRISO 입자의 피복층 제거를 위한 새로운 개념의 열적 파쇄와 용융염 전해반응에 의한 피복층 제거 공정을 제안하였으며 각 공정에 대한 원리를 자세하게 기술하였다.