• Nuclear Engineering and Technology
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• 제26권4호
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• pp.516-525
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• 1994

TMI 및 Chernobyl 사고이후 향후 원전에 대한 안전성 향상을 강화하기위해 개량형 원전에 대해 여러가지 피동형 안전설비가 제안되고 있다. 피동냉각계통의 타당성을 검증하고 상세 설계자료를 제공하기 위해, 본 연구는 웨스팅하우스사의 AP-600 피동격납용기와 같은 한쪽 가열면을 갖는 폐쇄유로에 대한 공기 유입구 위치 및 외부영향이 자연순환 공기유량에 미치는 영향과 자연 및 강제대류하에서 대류열전달계수를 조사하였다. 본 실험은 AP-600 격납용기를 1/26로 축소한 segment 유형의 실험장치를 토대로 수행되었다. 자연 및 강제대류 조건하의 공기유로내 특정 위치에서 공기의 속도 및 온도를 측정하였다. 실험결과는 일차원 단순 모델과 비교하였으며, 좋은 일치점을 보였다.

• 한국안전학회지
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• 제35권4호
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• pp.84-91
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• 2020

The Korean nuclear industry developed the SPACE (Safety and Performance Analysis Code for nuclear power plants) code and this code adpots two-phase flows, two-fluid, three-field models which are comprised of gas, continuous liquid and droplet fields and has a capability to simulate three-dimensional model. According to the revised law by the Nuclear Safety and Security Commission (NSSC) in Korea, the multiple failure accidents that must be considered for accident management plan of nuclear power plant was determined based on the lessons learned from the Fukushima accident. Generally, to improve the reliability of the calculation results of a safety analysis code, verification work for separate and integral effect experiments is required. In this reason, the goal of this work is to verify calculation capability of SPACE code for multiple failure accident. For this purpose, it was selected the experiment which was conducted to simulate a Multiple Steam Generator Tube Rupture(MSGTR) accident with Passive Auxiliary Feedwater System(PAFS) operation by Korea Atomic Energy Research Institute (KAERI) and focused that the comparison between the experiment results and code calculation results to verify the performance of the SPACE code. The MSGR accident has a unique feature of the penetration of the barrier between the Reactor Coolant System (RCS) and the secondary system resulting from multiple failure of steam generator U-tubes. The PAFS is one of the advanced safety features with passive cooling system to replace a conventional active auxiliary feedwater system. This system is passively capable of condensing steam generated in steam generator and feeding the condensed water to the steam generator by gravity. As the results of overall system transient response using SPACE code showed similar trends with the experimental results such as the system pressure, mass flow rate, and collapsed water level in component. In conclusion, it could be concluded that the SPACE code has sufficient capability to simulate a MSGTR accident.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.53-62
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• 2009

A set of experiments has been conducted on the performance sensitivity of the passive residual heat removal system (PRHRS) for an advanced integral type reactor, SMART, by using a high temperature and high pressure thermal-hydraulic test facility, the VISTA facility. In this paper the effects of the opening delay of the PRHRS bypass valves and the closing delay of the secondary system isolation valves, and the initial water level and the initial pressure of the compensating tank (CT) are investigated. During the reference test a stable flow occurs in a natural circulation loop that is composed of a steam generator secondary side, a secondary system, and a PRHRS; this is ascertained by a repetition test. When the PRHRS bypass valves are operated 10 seconds later than the secondary system isolation valves, the primary system is not properly cooled. When the secondary system isolation valves are operated 10 or 30 seconds later than the PRHRS bypass valves, the primary system is effectively cooled but the inventory of the PRHRS CT is drained earlier. As the initial water level of the CT is lowered to 16% of the full water level, the water is quickly drained and then nitrogen gas is introduced into the PRHRS, resulting in the deterioration of the PRHRS performance. When the initial pressure of the PRHRS is at 0.1MPa, the natural circulation is not performed properly. When the initial pressures of the PRHRS are 2.5 or 3.5 MPa, they show better performance than did the reference test.

• 국제초고층학회논문집
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• 제11권3호
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• pp.227-240
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• 2022

Under the Korean Enforcement Decree of the Building Act, all high story apartment houses more than 5 stories high are mandated to install a fire evacuation system to ensure safe evacuation from fire accidents and providing quick and easy bidirectional escape route when main entrance is blocked by flame or toxic smoke. However, the current fire evacuation system shows a lack of understanding from residents and thus is widely ignored for having insufficient safety functions, especially vis-à-vis fire emergencies. Studies have found that an alternative evacuation method, the escapable fire evacuation system, has been analyzed for safety evaluation compared with the conventional passive fire escape system and can bring efficient and safer solutions, providing high rise residents escape from fire accidents. Evaluation for safety evacuation has been performed by the Fire Dynamics Simulation and applying Pathfinder simulation. This resulted in providing appropriate escape routes within the safety escape time and allowed for people in high rise building fires to get to safety.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.89-91
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• 1999

The use of electronic power unit essentially result in serious problems by harmonics. To reduce the effect by harmonics, we propose passive filter system which can control each harmonic filters individually. So, additional devices to detect and analyze harmonics were installed to filter system. According to measured data in the field, we calculated the values of filter components and verified them by computer simulation. After installation of filter system in the field, we could reduce harmonics and improve power factor.

• 조명전기설비학회논문지
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• 제23권6호
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• pp.31-39
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• 2009

본 논문은 기존의 자동문시스템의 단점을 개선하여 보다 지능적인 기능을 추가함으로써 통행자에게 편의를 제공하고, 전격손실을 낮추는 보다 효율적인 초음파센서 기반의 지능형 자동문 시스템을 제안한다. 기존의 자동문시스템에서는 물체 및 인체 감지 기능 센서로서 원적외선 열선 감지센서와 근적외선 반사식 감지센서를 사용해 왔나. 기존의 방식은 상황에 맞지 않는 문닫힘에 의한 전력손실, 빠르게 다가오는 물체에 대한 적응 부족, 그리고 안전에 대한 문제점이 있었다. 제안된 초음파센서를 이용한 지능형자동문 시스템은 기존의 자동문시스템에 비교하여 필요없는 문닫힘 방지에 의한 전력손실 방지와 빠르게 접근하는 물체에 적응적으로 자동문이 빠르게 열릴 수 있게 하며, 안전도를 높여 기존 방식의 자동문보다 운용적, 경제적, 안정 면에서 성능을 개선하였다.

• 시스템엔지니어링학술지
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• 제15권2호
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• pp.39-46
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• 2019

The purpose of this paper is to present the results of the study, applying Systems Engineering(SE) method, on the feasibility of developing a Melt-down Proof Modular Micro Reactor(MDP-MMR) for its future deployment in Korea. The reactor is being developed by NCSU (North Carolina State University) due to its advantage of melt-down proof nature of the reactor core. For this paper, the characteristics of the MDP-MMR has been studied in terms of fuel characteristics, inherent safety features and passive safety system. The NCSU's development process has been reviewed applying the SE method, and further research is recommended for the feasibility study on deploying such a modular micro reactor in Korea.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.953-967
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• 2017

In this paper, a complete station blackout (SBO) or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR). The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank), safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal-hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

• 한국압력기기공학회 논문집
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• 제7권1호
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• pp.1-8
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• 2011

Advanced SITs of the evolutionary PWRs have the advantage that they can passively control the ECC water discharge flow rate. Thus, the LPSI pumps can be eliminated from the safety injection system owing to the benefit of the advanced SITs. In the present study, a passive sealing plate was designed in order to overcome the shortcoming of the advanced SITs, i.e., the early nitrogen discharge through the stand pipe. The operating principle of the sealing plate depends only on the natural phenomena of buoyancy and gravity. The performance of the sealing plate was evaluated using the VAPER test facility, equipped with a full-scale SIT. It was verified that the passive sealing plate effectively prevented the air discharge during the entire duration of the ECC water discharge. Also, the major performance parameters of the advanced SIT were not changed with the installation of the sealing plate.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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• pp.514-519
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• 1997

The MRX is an integral type ship reactor with 100 MWt power, which is designed by Japan Atomic Energy Research Institute. It is characterized by integral type PWR, in-vessel type control roe drive mechanism, water-filled containment vessel and passive decay heat removal system. Marine reactor should have high passive safety. Therefore, in this study, we simulated the loss of flow accident to verify the passive decay heat removal by natural circulation using RETRAN-03 code. auxiliary feed water systems are used for decay heat removal mechanism and results are compared with the loss of flow accident analysis using emergency decay heat removal system by JAERI. Results are very similar to case of EDRS 1 loop operation in JAERI analysis and decay heat is successfully removed by natural circulation.