• 한국압력기기공학회 논문집
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• 제4권2호
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• pp.1-6
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4159-4166
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• 2023

Laser decontamination of radioactive surfaces is an innovative technology. Our contribution to improving this technology includes studies on laser beam decontamination with a pulsed laser of an average power of 150 W, equipped with a hand guided working head. Our investigations are focused on metallic surfaces typical in nuclear power plants, such as stainless steel, bright and rusted mild steel, galvanized steel, and painted steel. As typical nuclides of contaminated surfaces we chose Co-60 and Cs-137, the most frequently occurring nuclides in many nuclear plant components; Sr-85 as a representative of Sr-90, the potentially most harmful fission nuclide; and Am-241 as a representative of the minor alpha-radiation emitting actinides. Here, we present our results of decontamination and recovery ratios. Decontamination ratios of 90-100% were achieved on different surfaces.

• 에너지공학
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• 제15권2호
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• pp.127-137
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• 2006

화학연료 사용으로 야기된 환경문제, 경제문제를 해결하기 위한 방안으로 수소경제가 추진되고 있다. 원자력을 이용한 대량수소생산은 수소경제를 뒷받침하기 위한 현실적인 방안이다. 본 논문에서는 원자력수소 생산에 사용할 초고온가스로의 특징과 개발현황, 초고온가스로로부터 발생하는 고온의 열을 이용한 수소생산방법 중 유력시 되는 기술로서 요오드-황 열화학법, 황산하이브리드법, 고온전기분해법의 기술개발 현황과 방향을 소개한다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.495-500
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• 1997

For hydrogen management in severe accidents with degraded nuclear core of PWR's, several experiments have been performed in the SNU hydrogen mixing facility. The objectives are understanding the extent of hydrogen mixing and analyzing the effects of factors which dominate uniform or non-uniform mixing at compartments in the containment building. The facility represents on a 1/11th linearly scaled model of the YGN unit 3&4, hydrogen was simulated by helium. Because there are the gaps between safety injection tank and compartment layers in the containment, the test facility was constructed in three dimentinal mode for analyzing of mixture behavior through the gaps. From the experimental results we could conclude that overall hydrogen concentration distributed uniformly in the free volume of the test compartment, but fluctuated in the gaps. This paper is focused on experimental result from several experiment.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1748-1751
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• 2017

Reduced activation ferritic/martensitic (RAFM) steels are widely applied as structural materials in the nuclear industry. To investigate hydrogen's effect on RAFM steels' elastic properties and the mechanism of that effect, a procedure of first principles simulation combined with experiment was designed. Density functional theory models were established to simulate RAFM steels' elastic status before and after hydrogen's insertion. Also, experiment was designed to measure the Young's modulus of RAFM steel samples with and without hydrogen charging. Both simulation and experiment showed that the solubility of hydrogen in RAFM steels would decrease the Young's modulus. The effect of hydrogen on RAFM steels' Young's modulus was more significant in water-quenched steels than it was in tempering steels. This indicated that defects inside martensite, considered to be hydrogen traps, could decrease the cohesive energy of the matrix and lead to a decrease of the Young's modulus after hydrogen insertion.

• 분석과학
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• 제16권4호
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• pp.261-268
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• 2003

불활성기체용해-열전도도검출법에 의한 수소분석시 매질효과를 조사하기 위해 티타늄 및 지르코늄-2.5니오븀 매질의 수소 표준물질 및 수소기체 주입에 의한 교정계수를 측정하였다. 또한 주석 조연제를 사용하지 않고 티타늄 및 지르코늄-2.5니오븀 매질 수소 표준물질의 수소 추출효율을 조사하였다. 수소기체 주입에 의한 수소분석기의 보정에 대해 지르코늄-2.5니오븀 매질 수소표준물질의 그것은 2~3% 높았으며, 티타늄 매질의 수소 표준물질은 약 14% 높은 값을 주었다. 교정계수 측정결과에 의하면 티타늄 매질 시료의 수소추출 효율이 지르코늄-2.5니오븀 매질 시료에 비해 약 12% 낮을 것으로 예상된다. 주석을 사용하지 않았을 때 티타늄 및 지르코늄-2.5니오븀매질 수소 표준물질의 수소 회수율은 약 70% 이었으며, 티타늄의 수소 회수율이 지르코늄-2.5니오븀 보다 낮았다.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.26-32
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• 2015

During the course of a severe accident in a light water nuclear reactor, large amounts of hydrogen can be generated and released into the containment during reactor core degradation. Additional burnable gases [hydrogen ($H_2$) and carbon monoxide (CO)] may be released into the containment in the corium/concrete interaction. This could subsequently raise a combustion hazard. As the Fukushima accidents revealed, hydrogen combustion can cause high pressure spikes that could challenge the reactor buildings and lead to failure of the surrounding buildings. To prevent the gas explosion hazard, most mitigation strategies adopted by European countries are based on the implementation of passive autocatalytic recombiners (PARs). Studies of representative accident sequences indicate that, despite the installation of PARs, it is difficult to prevent at all times and locations, the formation of a combustible mixture that potentially leads to local flame acceleration. Complementary research and development (R&D) projects were recently launched to understand better the phenomena associated with the combustion hazard and to address the issues highlighted after the Fukushima Daiichi events such as explosion hazard in the venting system and the potential flammable mixture migration into spaces beyond the primary containment. The expected results will be used to improve the modeling tools and methodology for hydrogen risk assessment and severe accident management guidelines. The present paper aims to present the methodology adopted by Institut de Radioprotection et de $S{\hat{u}}ret{\acute{e}}$ $Nucl{\acute{e}}aire$ to assess hydrogen risk in nuclear power plants, in particular French nuclear power plants, the open issues, and the ongoing R&D programs related to hydrogen distribution, mitigation, and combustion.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.9-20
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• 2007

Design study on the Gas Turbine High Temperature Reactor 300-Cogeneration (GTHTR300C) aiming at producing both electricity by a gas turbine and hydrogen by a thermochemical water splitting method (IS process method) has been conducted. It is expected to be one of the most attractive systems to provide hydrogen for fuel cell vehicles after 2030. The GTHTR300C employs a block type Very High Temperature Reactor (VHTR) with thermal power of 600MW and outlet coolant temperature of $950^{\circ}C$. The intermediate heat exchanger (IHX) and the gas turbine are arranged in series in the primary circuit. The IHX transfers the heat of 170MW to the secondary system used for hydrogen production. The balance of the reactor thermal power is used for electricity generation. The GTHTR300C is designed based on the existing technologies of the High Temperature Engineering Test Reactor (HTTR) and helium turbine power conversion and on the technologies whose development have been well under way for IS hydrogen production process so as to minimize cost and risk of deployment. This paper describes the original design features focusing on the plant layout and plant cycle of the GTHTR300C together with present development status of the GTHTR300, IHX, etc. Also, the advantage of the GTHTR300C is presented.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3659-3664
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• 2023

The electrochemical behavior of dissolved hydrogen (H₂) was investigated at a Pt electrode in a high temperature LiOH-H₃BO₃ solution. The diffusion current of the H₂ oxidation was proportional to the concentration of the dissolved H₂ as well as the reciprocal of the temperature. In the polarization curve, a potential region in which the oxidation current decreases despite an increase in the applied potential between the H₂ oxidation and the water oxidation regions was observed. This potential region was interpreted as being caused by the formation of a Pt oxide layer. Using the properties of the Cl^- ion that reduces the growth rate of the Pt oxide layer, it was confirmed that there is a correlation between the Cl^- ion concentration and the transient current of the H₂ oxidation.

• Carbon letters
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• 제11권1호
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• pp.41-47
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• 2010