• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1577-1579
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• 1994

200-MW pulse modulators(total 11units) for the PLS linac employ the SCR phase control circuit. It controls 3-phase AC line voltage for the high-voltage DC power supply (DCPS, maximum of 25kVDC, 4.2A) which charges the pulse forming network(PFN). The PFN delivers 400kV, 500A, ESW $7.5{\mu}s$ pulse power to the 80-MW klystron amplifier tube. The SCR regulates 3-phase AC power and feeds to the high voltage transformer. Two different types of the transformer configurations namely ${\Delta}-{\Delta}$ and ${\Delta}-Y$, are alternatively installed to 11 modulator units for the suppression of harmonic noises. RC filters and reactors are also installed. Currently, approximately 110-kW of average AC power per unit is consumed at the normal operation level of the modulator with 30pps. This paper presents the operational characteristics of the high power pulse modulator, especially the experimental results of the AC line harmonic components generated by the operation of the high power pulse modulator to suppress the switching noises from the SCR and rectifying diode arrays.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1131-1136
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• 2020

Xenon behaves differently in molten salt reactors (MSRs) compared to solid fuel reactors. This behavior needs exploring due to the large reactivity effect of the ¹³⁵Xe isotope, given the current interest in MSR power plant development for commercial deployment. This paper focuses on select topics in xenon transport, reviews relevant past works, and proposes specific research questions to advance the state of the art in each of the focus areas. Specifically, the paper discusses the issue of xenon solubility in MSRs, the behavior of particulates circulating in MSR fuel salt and its influence on the xenon transport, the possibility of ionization of xenon atoms which changes its effective size and thus affects its mass transport, and finally the issue of circulating void fraction and how it is measured. This work presents specific recommendations for MSR designers to research the limits of Henry's law validity, circulating particulate scrubbers, validity of mass transport coefficients in high radiation fields, and the effects of pump speed on circulating void fraction.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.161-166
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• 2003

It is the common features of the integral reactors that the main components of the RCS are installed within the reactor vessel, and so there are no any flow pipes connecting the coolant pumps or steam generators. Due to no any flow pipes, it is impossible to measure the differential pressure at the RCS of the integral reactors, and it also makes impossible measure the flow-rate of the reactor coolant. As a alternative method, the method by the measurement of coolant pump power has been introduced in this study. Up to now, we did not found out a precedent which the coolant pump power is used for the real-time flow-rate calculation at normal operation of the commercial nuclear power plants. The objective of the study is to embody the real-time flow-rate calculation method by the measurement of coolant pump power in an integral reactor. As a result of the study, we could theoretically reason that the capacity-head curve and capacity-shaft power curve around the rated capacity with the high specific-speeded axial flow pumps have each diagonally steep incline but show the similar shape. Also, we could confirm the above theoretical reasoning from the measured result of the pump motor inputs, So, it has been concluded that it is possible to calculate the real-time flow-rate by the measurement of pump motor inputs. In addition, the compensation for a above new method can be made by HBM being now used in the commercial nuclear power plants.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.86-92
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• 2004

In this paper miniaturized disposable micro/nanofluidic components applicable to bio chip, chemical analyzer and biomedical monitoring system, such as blood analysis, micro dosing system and cell experiment, etc are reported. This system includes various microfluidic components including a micropump, micromixer, DNA purification chip and single-cell assay chip. For low voltage and low power operation, a surface tension-driven micropump is presented, as well as a micromixer, which was implemented using MEMS technology, for efficient liquid mixing is also introduced. As bio-reactors, DNA purification and single-cell assay devices, for the extraction of pure DNA from liquid mixture or blood and for cellular engineering or high-throughput screening, respectively, are presented.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.414-422
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• 2021

The aim of this work considers a second order point reactor kinetics model based on the P1 approximation of transport theory, called in this work as P1 point reactor model. The P1 point reactor model implicitly considers the time derivative of the neutron source which has not been thus considered previously. The inverse method to calculate the reactivity in nuclear reactors -chosen because its high accuracy- Matrix Formulation. The numerical results shown that the Matrix Formulation for the reactivity estimation constitutes a method with insignificant calculation errors.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1874-1879
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• 2024

Owing to strict radiation safety management in Korean nuclear power plants (NPPs), most radiation workers receive very low radiation doses, even lower than the annual dose limit for the general public. However, the occupational dose distribution indicates that some Korean NPP workers receive a relatively higher dose than the average dose. This inequity in radiation exposure could be reduced by providing customized radiation protection measures, such as dose constraints, to workers receiving relatively higher doses. In this study, dose normalization was performed to identify the highest radiation exposure work in Korean pressurized water reactors (PWRs). The results show that most of the occupational exposure in Korean PWRs occurs during the planned maintenance period. Finally, the three highest radiation exposure tasks in Korean PWRs were identified: nozzle dam installation and removal, eddy current testing, and man-way opening and closing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.227-231
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• 2004

It is the common features of the integral reactors that the main components of the RCS are installed within the reactor vessel, and so there are no any flow pipes connecting the steam generator or the pump whose type is the axial flow. Due to no any flow pipes, it is impossible to measure the differential pressure at the RCS of the integral reactors, and it also makes impossible measure the flow-rate of the reactor coolant. As a alternative method, the method by the measurement of the pump power of the axial flow pump has been introduced in this study. Up to now, we did not found out a precedent which the pump power is used for the flow-rate calculation at normal operation of the commercial nuclear power plants. The objective of the study is to embody the flow-rate calculation method by the measurement of the pump power in an integral reactor. As a result of the study, we could theoretically reason that the capacity-head curve and capacity-shaft power curve around the rated capacity with the high specific-speeded axial flow pumps have each diagonally steep incline but show the similar shape. Also, we could confirm the above theoretical reasoning from the measured result of the pump motor inputs. So, it has been concluded that it is possible to calculate the flow-rate by the measurement of the pump motor inputs.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.65-71
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• 2015

A solar thermal simulator is suitable for indoor experiments of solar receivers and reactors when solar insolation and weather conditions are not favorable. Moreover, due to the easy control of electric power input, the solar thermal simulator allows the adjustment of power input incident on solar receivers and reactors and thus the implementation of accurate experiments. We manufactured a solar simulator, which is comprised of three sets of a xenon lamp and an elliptical reflector. In order to serve as a test facility, optical characterization of the solar simulator via radiation heat flux measurement is a critical prerequisite. We applied the flux mapping method to measuring the heat flux distribution of the three lamps. We presented the measurement results in terms of the heat flux distribution, the peak heat flux, the power distribution, the maximum power, and the efficiency for electric power conversion into radiation power. Characterization results show that our solar simulator provides the peak heat flux of $3,019kW/m^2$, the maximum power of 16.9 kW, and the conversion efficiency of 45%, additionally with a 10% operation margin for output increase.

• Corrosion Science and Technology
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• v.15 no.3
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• pp.113-119
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• 2016

Corrosion science faces new challenges in various nuclear environments. Three main areas may be identified where increases of knowledge and understanding have been done and are still needed to face the technical needs: (i) the extension of the service time of nuclear power plants from 40 years, as initially planned, to 60 years and probably more as expected now, (ii) the prediction of long term behaviour of metallic materials in nuclear waste disposal where the corrosion processes have to be predicted over large periods of time, some thousands years and more, (iii) the choice of materials for use at very high temperatures as expected in Generation IV power plants in environments like gas (helium), supercritical water, liquid metals or salts. Service time extension, deep geological waste repositories and high temperature reactors sustain researches and developments to model corrosion phenomena at various scales, from atoms to components.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.640-648
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• 2002

This study is to develop electromagnetic-catalyst application plasma reactors for indoor air purification. Nitrogen Oxide(NOx) removal characteristics are measured in the electromagnetic catalyst application plasma reactors with various parameters and the effect of catalyst or/and magnetic field are investigated on the NOx removal. And AC or DC high voltage is applied for corona discharge, flow rates are 150~1500 $\ell/min$ and NO initial concentration is about 10 ppm. $Mn0_2$ and $TiO_2$ catalysts to increase NOx removal rate are used. In the results, NOx removal rate by AC power is about 10 % higher than that by DC power under the experimental condition of 700 $\ell/min$, 5 magnets, $MnO_2$ and $Ti)_2$ catalysts. When magnet is applied to the reactor, NOx removal rate increased. Also, the reactor with $MnO_2$ and $Ti)_2$ catalyst and magnet have the best removal rate.