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고압 수증기에 따른 Low-Sn Zircaloy-4의 고온 산화 거동
양성우(Sungwoo Yang),박광헌(Kwangheon Park) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4
A new zirconium alloy, low-Sn Zircaloy-4 was investigated to see the effects of high pressure steam on the oxidation at high temperatures. High pressure steam turned out to enhance the oxidation at high temperatures below 1000℃. The oxide layer growed to deviate from the uniform layer under high steam pressures, and usually cracks were found at the thicker parts in the oxide layer. High pressure steam seems to destabilize the tetragonal oxides near the metal layer, and the monoclinic oxides transformed from the destabilized tetragonal oxides are structurally not sound, resulting in enhanced oxidation under high pressure steam.
정윤목(Yunmock Jung),정성기(Seonggi Jeong),박광헌(Kwangheon Park),노선호(Seonho Noh) 한국표면공학회 2014 한국표면공학회지 Vol.47 No.1
The characteristics of oxidation for the Zry-4 was measured in the 800℃ and high steam pressure (50 bar, 75 bar, 100 bar) conditions, using an apparatus for high pressure steam oxidation. The effect of accelerated oxidation by high-pressure steam was increased more than 60% in hydrogen-charged cladding than normal cladding. This difference between hydrogen charged claddings and normal claddings tends to be larger as the higher pressure. The accelerated oxidation effect of hydrogen charging cladding is regarded as the hydrogen on the metal layer affects the formation of the protective oxide layer. The creation of the sound monoclinic phase in Zry-4 oxidation influences reinforcement of corrosion-resistance of the oxide layer. The oxidation is estimated to be accelerated due to the creation of equiaxial type oxide film with lower corrosion resistance than that of columnar type oxide film. When tetragonal oxide film transformed into the monoclinic oxide film, surface energy of the new monoclinic phase reduced by hydrogen in the metal layer.
정윤목(Yunmock Jung),하성우(Sungwoo Ha),박광헌(Kwangheon Park) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.4
The operation method of nuclear power plants is currently changing to high burn-up and long period that can enhance economics and efficiency of the plant. Since nuclear plant operation environment has been becoming severe, the amount of absorbed hydrogen also has increased. Absorbed hydrogen can be fatal securing safety of nuclear fuel cladding in case of Loss of Coolant Accidents(LOCA). In order to examine the impact of hydride on high-temperature oxidation, high-temperature oxidation experiment was performed on normal Zry-4 cladding and on Zry-4 cladding where hydrogen is charged in air pressure·steam atmosphere under the 950℃ and 1000℃. According to the results, while oxidation acceleration due to charged hydrogen was not observed prior to breakaway oxidation creation, oxidation began to accelerate in cladding where hydrogens charged as soon as the breakaway oxidation started. If so much hydrogen are charged in the cladding, equiaxial monoclinic phase to unstable of stress is formed and it is presumed that oxidation is accelerated because nearby stress caused a crack in equiaxial phase, and that makes corrosion resistance decline sharply.
SiC 복합체 보호막 금속 피복관의 개발 및 고온산화 특성 분석
노선호(Seonho Noh),이동희(Dong-hee Lee),박광헌(Kwangheon Park) 한국표면공학회 2015 한국표면공학회지 Vol.48 No.5
The goal of this study is to investigate a metal cladding that contains SiC composites as a protective layer and analysis the characteristics of the specimens on high temperature oxidation To make SiC composites, the current process needs a high temperature (about 1100℃) for the infiltration of fixing materials such as SiC. To improve this situation, we need a low temperature process. In this study, we developed a low temperature process for making SiC composites on the metal layer, and we have made two kinds: cladding with protective SiC composites made by polycarbosilane(PCS), and a PCS filling method using supercritical carbon dioxide. A corrosion test at 1200℃ in a mixed steam and Ar atmosphere was performed on these specimens. The result show that the cladding with protective SiC composites have excellent oxidation suprression rates. This study can be said to have developed new metal cladding with enhanced durability by using SiC composite as protective films of metal cladding instead of simple coating film.
초임계이산화탄소 하에서 QCM을 이용한 I-TEDA의 제거특성 측정
유재룡(Jaeryong Yoo),고문성(Moonsung Koh),성진현(Jinhyun Sung),이정근(Jeongken Lee),박광헌(Kwangheon Park) 한국청정기술학회 2008 청정기술 Vol.14 No.2
원자력산업이 발생하는 방사성폐기물은 고체, 액체 그리고 기체상으로 구분된다. 특히 기체상 방사성폐기물인 방사성 메틸요오드는 활성탄을 이용하여 흡착된다. 이때 활성탄에는 방사성 메틸요오드를 보다 효율적으로 포집하기 위해 5 wt%의 트리에틸렌다이아민 (Trietylenediamine; 1,4-diazania-bicyclo[2.2.2]octane, TEDA)이 첨착되어 있다. 일반적으로 대기중에서 TEDA와 메틸요오드(CH₃I)는 I-TEDA(TEDA와 메틸요오드 결합물)를 형성하게 된다. 방사성 요오드를 포집한 방사성 폐 활성탄을 재사용하기 위해서는, 이러한 형태의 I-TEDA를 제거해야 하는데, 현재는 아세토나이트릴을 이용한 습식재활용법이 개발되었다. 그러나 이러한 습식재활용법은 다량의 2차폐기물을 발생하는 문제점이 있기 때문에, 본 연구에서는 I-TEDA를 제거하기 위한 방법으로 초임계이산화탄소를 기본용매로써 사용하였으며, 수정미량저울(Quartz Crystal Microbalance, QCM)을 이용하여 I-TEDA의 제거율을 측정하였다. 실험결과 I-TEDA를 제거하기 위해 추출을 위한 첨가용액으로 메탄올이 가장 적합하였고, 최적화된 온도, 압력 및 추출용매의 유량조건을 찾아내었다. 이러한 결과를 바탕으로 하여 방사성 폐활성탄으로부터 I-TEDA를 제거할 수 있는 가능성에 대한 검토를 하였다. The radioactive wastes generated from the nuclear industry can be divided into the forms of solid, liquid, or gas. Radioactive methyl iodide, a gaseous radioactive waste, is absorbed by activated carbon with 5 wt% of Trietylenediamine (1,4-diazania-bicyclo[2.2.2]octane, TEDA) impregnated on the surface. Methyl Iodide (CH₃I) is combined chemically with TEDA (the final product: I-TEDA). To recycle radioactive activated carbon, removal of I-TEDA from activated carbon is needed. A wet method for recycling impregnated active carbon was developed to remove radioactive I-TEDA using an acetonitrile solution, which produces lots of secondary wastes. We suggest the removal of I-TEDA by supercritical carbon dioxide with co-solvents. In this experiment, we used a quartz crystal microbalance (QCM) for measuring the removal rate of the I-TEDA. From the experimental results, methanol was found to be the optimum co-solvent, and the optimum conditions such as temperature, pressure, and co-solvent flow rate were obtained. Possibility of using supercritical fluid in the removal of I-TEDA from radioactive activated carbon was also discussed.
박광헌,양명승,박현수 慶熙大學校 材料科學技術硏究所 1994 材料科學技術硏究論集 Vol.7 No.-
The oxygen potential of urania with soluble fission products is modeled based on the point defect chemistry. This model explains well the measured values. The oxygen potential of the UO_(2) fuel is also calculated with the assumption of the closed system. The calculated oxygen potential is within the error of the experimental values. This model can be used for the analyses of physical and chemical properties of high bumup fuels.
Oxygen Diffusion in Polycrystalline Zirconia
Park, Kwangheon 慶熙大學校 材料科學技術硏究所 1991 材料科學技術硏究論集 Vol.4 No.-
지르코늄 금속을 산화시켜 얻어진 산화지르코늄 다결정의 산소 확산계수를 기체-고체 동위원소 교환 방법으로 구하였다. 다결정 산화지르코늄의 결정립은 원주형의 형태를 띄었고, 원주의 반경은 표면에서 내부로 갈수록 깊이에 비례하여 증가하였다. 단결정과 다결정의 전체 산소 확산계수를 비교하여 주로 산소의 이동은 결정립계를 따라 이루어짐을 알게 되었다. 결정립계 산소확산 계수를 다결정시편의 단위 결정립을 반경이 일정한 원주로 가정하여 구하였다. 립계 산소확산계수와 분리인자의 곱한 값이 약 10^(-11)∼10^(-10)㎤/s가 되었고, 이 값은 다른 산화물에서 얻어진 값과 비교하면 매우 적절한 값이다.
金明鎭,朴光憲 慶熙大學校 材料科學技術硏究所 1992 材料科學技術硏究論集 Vol.5 No.-
The transient-oxidation behaviors of zircaloy in steam are studied by measuring the temperature change of a specimen during oxidation. The parabolic rate law applied to high-temperature zircaloy oxidation was used in the analysis of the temperature change. The parabolic rate law satisfactorily explains the transient behaviors of zircaloy in the temperature-change rate less than 3℃/sec.