• Nuclear Engineering and Technology
• /
• v.37 no.6
• /
• pp.537-556
• /
• 2005

A primary-pipe rupture accident is one of the design-basis accidents of a High-Temperature Gas-cooled Reactor (HTGR). When the primary-pipe rupture accident occurs, air is expected to enter the reactor core from the breach and oxidize in-core graphite structures. This paper describes an experiment and analysis of the air ingress phenomena and the method fur the prevention of air ingress into the reactor during the primary-pipe rupture accident. The numerical results are in good agreement with the experimental ones regarding the density of the gas mixture, the concentration of each gas species produced by the graphite oxidation reaction and the onset time of the natural circulation of air. A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) Is being designed to be able to produce hydrogen by themo-chemical iodine-Sulfur process, using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world; hence a permeation test of hydrogen isotopes through heat exchanger is carried out to obtain detailed data for safety review and development of analytical codes. This paper also describes an overview of the hydrogen permeation test and permeability of hydrogen and deuterium of Hastelloy XR.

• Nuclear Engineering and Technology
• /
• v.54 no.1
• /
• pp.177-185
• /
• 2022

Hydrogen risk in the containment filtered venting system (CFVS) vessel was analyzed, considering operation pressure and modes with the effect of PAR and accident scenarios. The CFVS is to depressurize the containment by venting the containment atmosphere through the filtering system. The CFVS could be subject to hydrogen risk due to the change of atmospheric conditions while the containment atmosphere passes through the CFVS. It was found that hydrogen risk increased as the CFVS opening pressure was set higher because more combustible gases generated by Molten Core Concrete Interaction flowed into the CFVS. Hydrogen risk was independent of operation modes and found only at the early phase of venting both for continuous and cyclic operation modes. With PAR, hydrogen risk appeared only at the 0.9 MPa opening pressure for Station Black-Out accidents. Without PAR, however, hydrogen risk appeared even with the CFVS opening set-point of 0.5 MPa. In a slow accident like SBO, hydrogen risk was more threatening than a fast accident like Large Break Loss-of-Coolant Accident. Through this study, it is recommended to set the CFVS opening pressure lower than 0.9 MPa and to operate it in the cyclic mode to keep the CFVS available as long as possible.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.3
• /
• pp.88-95
• /
• 2019

The hydrogen torch ignition system has been widely used to ignite a pure aluminum for aluminum powder combustion system because of its simple ignition method. However, the conventional hydrogen torch ignition system has a disadvantage that requires a high-pressure tank to supply hydrogen, which leads to the increase of the weight. In order to solve this problem, a hydrogen ignition system using $NaBH_4$, a solid chemical hydride, was designed in this study. The thermal decomposition of $NaBH_4$ was initiated approximately at $500^{\circ}C$ and hydrogen was generated. The parameters affecting the thermal decomposition characteristics of $NaBH_4$ were analyzed and the aluminum combustion test was carried out using $NaBH_4$-based hydrogen ignition system to study the applicability to a practical aluminum-combustion propulsion system.

• Transactions of the KSME C: Technology and Education
• /
• v.3 no.4
• /
• pp.299-305
• /
• 2015

Nuclear hydrogen production technology is being developed for the future energy supply system. The sulfur-iodine thermo-chemical hydrogen production process directly splits water by using of the heat generated from very high temperature gas-cooled reactor, a typical Generation IV nuclear system. Nuclear hydrogen key technologies are composed of VHTR simulation technology at elevated temperature, computational tools, TRISO fuel, and sulfur iodine hydrogen production technology. Key technology for nuclear hydrogen production system were developed and demonstrated in a laboratory scale test facility. Technical challenges for the commercial hydrogen production system were discussed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.2
• /
• pp.150-156
• /
• 2022

This study proposes a design method of fuel cell DC/DC converter using in 5-ton forklift. For efficient hydrogen usage, targeted fuel cell system recirculates discarded hydrogen after fuel cell reaction. Recirculating hydrogen contains much impurities that reduces output power, increasing pressure that can damage the internal fuel cell reaction system. The proposed DC/DC converter effectively converts fuel cell power considering the voltage drop rate to reflect the recirculating hydrogen. Then, frequency control method is used to regulate the current ripple amount for battery and fuel cell hybrid configuration. Proposed power converter system design and control methods are verified in a practical fuel cell system that implements recirculating hydrogen.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.3
• /
• pp.235-245
• /
• 2023

Techno-economic analyses on a 5-MW water electrolysis system for hydrogen production, operated in Jeju Island where the portion of renewable energy in the power grid is the highest in Korea, have been performed. The cost of hydrogen production and the economic feasibility of the hydrogen production system have been mainly analyzed based on the levelized-cost-of-hydrogen model. The effects of carbon emission trading and renewable power purchase method have been considered to reduce the cost of green hydrogen production in the case studies. This economic analysis model is expected to be used to derive a business model for green hydrogen production.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.4
• /
• pp.159-165
• /
• 2014

For the hydrogen economy system being tried starting with the 21st century, the fields that was not dealt with so far, such as the safety measure for large leakage accidents, the safety problem at infrastructures like a hydrogen station, the safety problem in terms of automobiles depending on introduction of hydrogen cars, the safety problem in a supply for homes like fuel cells, etc., are being deeply reviewed. In order to establish a safety control system, an essential prerequisite in using and commercializing hydrogen gas as an efficient energy source, it is necessary to conduct an analysis, such as analysis of hydrogen accident examples, clarification of physical mechanisms, qualitative and quantitative evaluation of safety, development of accident interception technologies, etc. This study prepared scenarios of hydrogen gas leakage that can happen at hydrogen stations, and predicted damage when hydrogen leaks by using PHAST for this.

• YAKHAK HOEJI
• /
• v.46 no.5
• /
• pp.324-330
• /
• 2002

This experiment was carried out to determine non-destructively the hydrogen peroxide concentration of 3％ antiseptic hydrogen peroxide solutions by portable near-infrared (NIR) system. Hydrogen peroxide standards were prepared ranging from 0 to 25.6 w/w％ and the NIR spectra of hydrogen peroxide standard solutions were collected by using a quartz cell in 1 mm pathlength. We found the variation of absorbance band due to OH vibration of hydrogen peroxide depending on the concentration around 1400 nm in the second derivatives spectra. Partial least square regression (PLSR) and multilinear regression (MLR) were explored to develop a calibration model over the spectral range 1100-1720 nm. The model using PLSR was better than that using MLR. The calibration showed good results with a standard error of prediction (SEP) of 0.16％. In order to validate the developed calibration model, routine analyses were performed using commercial antiseptic hydrogen peroxide solutions. The hydrogen peroxide values from the NIR calibration model were compared with the values from a redox titration method. The NIR routine analyses results showed good correlation with those of the redox titration method. This study showed that the rapid and non-destructive determination of hydrogen peroxide in the antiseptic solution was successfully performed by portable NIR system without very harmful solvents.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.1
• /
• pp.1-7
• /
• 2023

A fuel handling process combined with a pressure swing adsorption system (PSA) was simulated to produce pure hydrogen with a purity greater than 99.97%. The simulation consists of two parts. The fuel processing part consisting of reformer and water-gas shift reaction was simulated with Aspen plus^®, and the hydrogen purification part consisting of PSA was simulated with Aspen Adsorption^®. In this study, the effect of reformer temperature and pressure on the total hydrogen production yield was investigated. Simulations were performed over a temperature range of 700 to 1,000℃ and a pressure range of 1 to 10 bar. The total hydrogen production yield increased with increasing temperature and decreasing pressure. The maximum hydrogen yield was less than 50% in the simulation and will be lower in the real process.

• Transactions of the Korean hydrogen and new energy society
• /
• v.35 no.2
• /
• pp.175-184
• /
• 2024

This study focuses on investigating the importance of managing greenhouse gas emissions from global energy consumption, specifically examining domestic targets for clean hydrogen production. Using life cycle assessment, we evaluated reductions in global warming potential and assessed the carbon neutrality contribution of the domestic hydrogen sector. Transitioning from brown or grey hydrogen to blue or green hydrogen can significantly reduce emissions, potentially lowering CO₂ equivalent levels by 2030 and 2050. These research findings underscore the effectiveness of clean hydrogen as an energy management strategy and offer valuable insights for technology development.