• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4266-4273
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• 2023

In a severe reactor accident, a crust will form on the surface of the molten material during the core melting process. The crust will have a contact melting with the internal components of the reactor. In this paper, the contact melting process of the molten material on the austenitic stainless steel plate bundles is studied. The contact melting model of parabolic molten material on the plate bundles is proposed, and the rule and main effect factors of the contact melting are analyzed. The results show that the melting velocity is proportional to the slope of the paraboloid, the heat flux and the distance between two plates D. The influence of melt gravity and the plate width on melting velocity is negligible. The thickness of the molten liquid film is proportional to the heat flux and plate width, and it is inversely proportional to the gravity. With the increase of D, the liquid film thickness decreases at first and then increases gradually. The liquid film thickness has a minimum against D. When the width of the plate is small, the width of the plate is the main factor affecting the thickness of the liquid film. The parameters are coupled with each other. In a severe reactor accident, the wider internal components of reactor, which can increase the thickness of the melting liquid film and reduce the net input heat flux from the molten material to the components, are the effective measures to delay the melting process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.648-652
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• 2008

Corona discharge and ozone generation characteristics of a wire-plate plasma reactor, with a biased third electrode, have been investigated with an emphasis on the role of the bias voltage and frequency applied on the third electrode. It was found that the wire-plate plasma reactor, with the biased third electrode, had a switching characteristic on its I-V characteristics for negative and positive discharges, which is very different from that of a conventional wire-plate plasma reactor without the third electrode. As a result, the corona discharge and ozone generation characteristics of the proposed plasma reactor could be controlled by adjusting the bias voltage and frequency of the third electrode. The corona onset and breakdown voltages, and ozone generation and yield, were increased compared with those of without the third electrode. These, however, reveal the effectiveness of the biased third electrode.

• Transactions on Electrical and Electronic Materials
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• v.4 no.4
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• pp.30-35
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• 2003

In this paper, the $CF_4$ decomposition efficiency is investigated for three simulated plasma reactors that are needle plate reactor, metal particle reactor, and dielectric barrier reactor with hole (DBH). The$CF_4$ decomposition efficiency by DBH is much better than that by needle plate reactor or metal particle reactor. When applied voltage is increased up to the critical voltage for spark formation in the all reactors, the $CF_4$ decomposition efficiency is increased. The $CF_4$ decomposition efficiency in needle plate reactor and metal particle reactor is about $12\%$ and $22\%$ respectively at applied voltage of 23 kV (consumption power: 110 W) and $CF_4$ concentration of 500 ppm, however, the $CF_4$ decomposition efficiency is more than $95\%$ in case of DBH. DBH should be much better than two reactors investigated for $CF_4$ decomposition.

• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.529-540
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• 2014

In this research, a drop impact analysis of a fuel assembly in a research reactor is carried out to determine whether the fuel plate integrity is maintained in a drop accident. A fuel assembly drop accident is classified based on where the accident occurs, i.e., inside or outside the reactor, since each occasion results in a different impact load on the fuel assembly. An analysis procedure suitable for each drop situation is systematically established. For an accident occurring outside the reactor, the direct impact of a fuel assembly on the pool bottom is analyzed using implicit and explicit approaches. The effects of the key parameters, such as the impact velocity and structural damping ratios, are also studied. For an accident occurring inside the reactor, the falling fuel assembly may first hit the fixing bar at the upper part of the standing fuel assembly. To confirm the fuel plate integrity, a fracture of the fixing bar should be investigated, since the fixing bar plays a role in protecting the fuel plate from the external impact force. Through such an analysis, the suitability of an impact analysis procedure associated with the drop situation in the research reactor is shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.734-738
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• 2012

A comprehensive vibration assessment program for the Advanced Power Reactor 1400 reactor vessel internals is established in accordance with the United States Nuclear Regulatory Commission Regulatory Guide 1.20 Revision 3. This paper is related to instruments and measurement locations based on the vibration and stress response analysis results at the inner barrel assembly top plate in the reactor. The analysis results of the inner barrel assembly top plate in the reactor show that the deterministic stress and deformation due to the reactor coolant pump induced pressure pulsations are larger than the random stress and deformation induced by the flow turbulence. The selection of the instruments and measurement locations at Inner barrel assembly top plate in the reactor is essential requirements and very important study process for the vibration and stress measurement program in comprehensive vibration assessment program for the Advanced Power Reactor 1400 reactor vessel internals.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.407-411
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• 2003

The purpose of this paper is to study the removal of nitrogen oxide(NOx) using a wire-plate type plasma reactor with magnet attached for indoor air purification. In order to produce a more effective reactor, we conducted magnetic field simulations. The results of the magnetic field simulations show that NOx can be removed more effectively. The results from the magnetic field simulation show that when 7 magnets were applied to the reactor, the magnetic flux density was at its highest amount than when using 0, 3, or 5 magnets. From the data obtained by the simulation results a plasma reactor was made and thus, several experiments were conducted. The best removal efficiency was obtained with 14 W AC power to the reactor with 5 magnets.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.99-106
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• 2001

A laboratory experiment was performed to investigate phosphorus and nitrogen removal from synthetic wastewater by intermittently activated sludge process packed with aluminium plate. Three continuous experimental systems, I. e. an intermittently activated sludge process(Run A), an intermittently activated sludge process with an aluminium plate packed into the reactor(Run B), and a reactor post stage(Run C) were compared. In the batch experiments, the phosphorus removal time in the reactor packed with copper and aluminium plate simultaneously was faster than that of the reactor packed with only an aluminium plates. However, the reactor packed with only an aluminium plate could be used for phosphorus removal. Move phosphorus was removed with an increase of surface area of aluminium plate and electrolysis(NaCl) concentration. The efficiency of COD and nitrogen removal was not affected in Run B. However, the phosphrus removal efficiency decreased because of reaction products and activated sludge which gradually covered gradually the surface of the aluminium plate. The efficiency of phosphorus removal in Run C was 86.3% at the HRT of 3.2 hours. Especially, the efficiency of phosphorus removal in Run C was higher than that in Run B.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.745-753
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• 2016

The objective of this study was to investigate design factors of the electrolysis reactor through the CFD(computational fluid dynamics) simulation technique. Analyses of velocity vector, streamline, chloride ion concentration distribution showed differences in flow characteristics between the plate type electrode and the porous plate type electrode. In case of the porous plate type electrode, chlorine gas bubbles generated from the anode made upward density flow with relatively constant velocity vectors. Electrolysis effect was more expected with the porous plate type electrode from the distribution of chloride ion concentration. The upper part of the electrolysis reactor with the porous plate type electrode had comparatively low chloride concentration because chloride was converted to the chlorine gas formation. Decreasing the size and increasing total area of rectifying holes in the upper part of cathodes, and widening the area of the rectifying holes in the lower part of cathodes could improve the circulation flow and the efficiency of electrolysis reactor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.933-937
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• 2007

A point plate type nonthermal plasma reactor, with a grounded cylindrical third electrode which closely- encompasses the needle point, have been investigated with an emphasis on the role of the third electrode. It was found that the point plate airgap, with the grounded third electrode, had a switching characteristic on its I V characteristics for negative and positive discharges, which is very different from that of a conventional point plate airgap without a third electrode. The corona discharge and ozone generation characteristics of the plasma reactor with the grounded cylindrical third electrode, such as the corona onset voltage. the breakdown voltage. the corona current. and the amount of output ozone, were influenced significantly by the height of the third electrode. and these characteristics can be controlled by adjusting the height of the third electrode.

• Journal of computational fluids engineering
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• v.13 no.3
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• pp.21-27
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• 2008

The reactor head of a sodium-cooled fast reactor KALIMER-600 should be cooled during the reactor operation in order to maintain the integrity of sealing material and to prevent a creep fatigue. Analyzing turbulent natural convection flow in the cover gas region of reactor vessel with the commercial CFD code CFX10.0, the cooling requirement for the reactor head and the performance of the insulation plate were assessed. The results showed that the high temperature region around reactor vessel was caused by the convective heat transfer of Helium gas flow ascending the gap between the insulation plate and the reactor vessel inner wall. The insulation plate was shown to sufficiently block the radiative heat transfer from pool surface to reactor head to a satisfactory degree. More than $32.5m^3$/sec of cooling air flow rate was predicted to maintain the required temperature of reactor head.