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Numerical analysis on spatial universality of similarity technique inside molten salt reactor system
Seo, Seok Bin,Shin, Yukyung,Bang, In Cheol Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.116 No.-
<P><B>Abstract</B></P> <P>To compensate the difficulties in the study on a thermal-hydraulic system in a full scale, a similarity technique has been developed to predict the thermal characteristics of fluid in the full-scale system under smaller and simpler conditions. Then the feasibility of using simulant fluid for various MSR systems are numerically tested based on the similarity technique in this study. The utilization of thermal-hydraulic code with the simulant fluid, DOWTHERM RP, reproduces the system design values and the Nusselt numbers for the representative MSR systems including MSFR, MOSART, and MSBR. The steady state results confirm the applicability of similarity technique using DOWTHERM RP to simulate the thermal-hydraulic phenomena in MSR systems. The evaluated Nusselt numbers from the analysis results well agrees with the theoretical Nusselt numbers for all the MSR systems. Thus, it is concluded that the numerical analysis using the similarity technique well reproduces the steady-state heat transfer performance of the molten salts regardless of system configuration and specifications. In addition, the spatial consistency between global characteristics and local characteristics evaluated from the similarity techniques is tested. From the transient analyses results under the loss of flow accident, it is found that the local characteristics of molten salt evaluated by the similarity technique can well reproduce the global thermal-hydraulics of molten salt in existing MSR systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The feasibility of using simulant fluid for various MSR systems are numerically tested based on the similarity technique. </LI> <LI> The spatial consistency between global characteristics and local characteristics evaluated from the similarity techniques is tested. </LI> <LI> It is found that the local characteristics of molten salt evaluated by the similarity technique can well reproduce the global thermal-hydraulics of molten salt in existing MSR systems. </LI> </UL> </P>
Risk mitigation strategy by Passive IN-core Cooling system for advanced nuclear reactors
Seo, Seok Bin,Kim, In Guk,Kim, Kyung Mo,Jeong, Yeong Shin,Bang, In Cheol Elsevier 2018 Annals of nuclear energy Vol.111 No.-
<P><B>Abstract</B></P> <P>After the Fukushima accident, the installation of passive safety systems for nuclear power plants becomes necessary as protection against external power failures. Recently, an innovative safety system was introduced by employing a hybrid heat-pipe concept asa Passive IN-core Cooling system (PINCs). The hybrid heat-pipe concept employs the combination of a control rod and a heat pipe to passively shutdown a reactor in an accident condition and simultaneously remove decay heat from the core. As a result, a PINCs can handle the entire accident sequence in a single system, leading to significant enhancement in nuclear reactor safety. In this study, the safety enhancement of various nuclear reactors has been quantitatively evaluated by using the probabilistic safety assessment method (PSA). PSA models of the APR1400, PGSFR, and SMART nuclear reactors developed in Korea, are developed, and a PINCs model has been applied to each reactor. The PSA model of the PINCs has been developed based on the systematic design and configuration of each reactor. In addition, postulated accident sequences where the PINCs operates have been developed in the PSA model. Finally, the consequence of each accident sequence has been quantitatively evaluated in the form of core damage frequency (CDF) and minimal cut set (MCS) for each nuclear reactor. Based on the PSA results, it is confirmed that the application of the PINCs effectively reduces the overall CDF of all nuclear reactors. In addition, the failure paths causing the core damage are restricted for APR1400 and PGSFR. In conclusion, the employment of the PINCs significantly improved the overall safety degrees of various nuclear reactors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PINCs combines a control rod and a heat pipe to enhance safety of advanced reactors. </LI> <LI> PSA models of advanced reactors are developed including PINCs. </LI> <LI> The consequences of the accident aided by PINCs are quantitatively evaluated. </LI> <LI> PINCs significantly reduces the overall CDFs of all nuclear reactors. </LI> </UL> </P>
Seo, Seok Bin,Bang, In Cheol Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.131 No.-
<P><B>Abstract</B></P> <P>In this study, the feasibility of identifying boiling regimes through acoustic emission (AE) measurement is tested, and the relationship between AE features and boiling dynamics is investigated. Conventional pool quenching experiments are performed using a spherical test section to investigate the entire boiling regime from film boiling to nucleate boiling. The AE measurements and accompanying optical visualization enable analyses of the AE features of each boiling regime, which are characterized by statistical and spectral parameters. The recorded boiling dynamics provide the history of vapor–liquid interface motion to verify the characteristics of AE features. The present work analyzes different acoustic features generated from different boiling regimes including nucleate boiling, transition boiling, boiling crisis, and film boiling. Each boiling regime is characterized by its measured AE signal with respect to various parameters. At the same time, optical visualization of the boiling process accompanies the AE measurements. A comparison of the wave information in vapor–liquid interface motion with AE features proves the feasibility of AE measurement for clear identification of boiling regimes and offers an insight into understanding boiling dynamics with respect to vapor behaviors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigation of wave information in acoustic emission features. </LI> <LI> Investigation of wave information in vapor-liquid interface motion. </LI> <LI> Identification of boiling regimes using AE measurement. </LI> <LI> Understanding boiling dynamics with respect to vapor behaviors. </LI> </UL> </P>
Analysis of the combustion oscillation in a silo-type gas turbine combustor and its suppression
Seok Bin Seo,Dal Hong Ahn,Jong Ho Park,차동진 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4
The characteristics of combustion oscillation of a silo-type 79.5 MW gas turbine combustor in commercial operation and its suppression have been investigated. The oscillation of the lean premixed gas turbine combustor resulting from the combustion instability occurred at near full load operation. An FFT analysis of the combustion dynamics showed that the dominant frequency of the oscillation would be that of the 1st longitudinal acoustic resonance mode of the combustor. To suppress the combustion oscillation, a passive control technique for reducing the combustion instability was employed; that is, the fuel to the combustor was redistributed by adjusting the operational schedule of one of six fuel control valves, which would lead the increase of the local operational equivalence ratio near the central recirculation zone of the combustor. By doing so, the oscillation was successfully reduced to the permissible level while the amount of NOx emission met proper regulatory level set by the local government.
발전용 가스터빈에서 발생하는 연소진동 특성 및 이상연소진동의 저감
서석빈(Seo Seok-Bin),안달홍(Ahn Dal-Hong),정재화(Chung Jae-Hwa) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Gas Turbine combustors for power plant can be reduced NOx emissions using lean premixed combustion technology. But the combustors are likely to occur combustion oscillations which damage operation reliability and mechanical life of the gas turbines. In this paper, characterizations of oscillation in a gas turbine combustor for power plant are presented. Combustion dynamics occur 1~1.5 psi in amplitude with low frequency less than 140Hz during normal operation. An abnormal high level dynamics, 2.0 psi amplitude occur at 125 Hz frequency. Abnormal combustion oscillation is reduced by modulation of fuel supply valve control schedule.
Silo형 가스터빈 연소기에서 발생하는 연소진동 분석 및 저감
서석빈(Seo Seok-Bin),안달홍(Ahn Dal-Hong),차동진(Cha Dong-Jin),박종호(Park Jong-Ho) 대한설비공학회 2009 설비공학 논문집 Vol.21 No.2
The present study describes an investigation into the characteristics of combustion oscillation and its suppression instability of a silo type gas turbine combustor in commercial power plant. Combustion oscillation is occurred the combustor in near full load during operation. As a result of FFT analysis of the combustion dynamics, the frequency of the oscillation is analyzed as the 1'st longitudinal mode of acoustic resonance of the combustor. For suppress of the instability, combustion tuning with adjust of fuel valve schedule is carried out, which changes equivalent ratio of each burners. As the result, the oscillation is successfully reduced with meeting the level of NOx emission regulation.
서석빈(Seo Seok-Bin),안달홍(Ahn Dal-Hong),정재화(Chung Jae-hwa),김종진(Kim Jong-Jin) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Gas Turbine combustors for power plants can be reduced NOx emissions using lean premixed combustion technology. But The combustors are likely to occur combustion oscillations which damage operation reliability and mechanical life of the gas turbines. In this paper, characterizations of oscillation in a gas turbine combustor for power plants are presented. Combustion dynamics occurs 1 ~ 1.5 psi in amplitude with low frequency less than 170㎐ during premixed mode in the combustor. A abnormal high level dynamics, 4 ~ 9 psi amplitude occurs in during combustion mode changes. Tests of pre-filling transfer fuel during the mode change result in reduction of combustion oscillations.