• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1667-1668
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• 2008

There are three main devices such as boiler producing steam, turbine driving generator and generator producing electricity. An electrical generator in power plant is driven and maintained its speed at rated by steam turbine which is coupled into generator directly. Turbine auxiliary devices such as condenser, deaerator, feed water heater, gland steam condenser, pump recirculation equipment, feed water pump, and so on should be operated well so that the steam turbine exert its maximum efficiency. There are many control loop such as hot well level and condenser recirculation, deaerator level, pegging steam pressure, feed water heater level, feed water pump recirculation. In this paper condenser level control and deaerator level control are going to be described.

• 한국기계가공학회지
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• 제13권3호
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• pp.42-48
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• 2014

The auxiliary-feed-water pump (AFWP) used to supply water during a station black out situation at nuclear power plants should meet the seismic qualification regulations stipulated in IEEE Std 323 and 344, so as to withstand earthquakes or dangerous situations. Here, we establish a model for the estimation of the structural integrity of this type of pump. If the natural frequency that results from a modal analysis is less than 33 Hz, we adopt a dynamic analysis, instead of a static analysis. A dynamic analysis was carried out taking into consideration seismic conditions such as the floor response spectra (FRS), an operation-base earthquake (OBE), and a safe-shutdown earthquake (SSE). Finally, an analytical estimation of the structural integrity of an AFWP is made through a comparison of calculated values and allowable values. If the result is less than the allowable stress, the pump is deemed to have good structural integrity. In addition, future studies will involve a stability check for rotor accidents that may occur during the operation of the pump.

• 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.

• 대한기계학회논문집B
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• 제36권5호
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• pp.553-562
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• 2012

난방, 환기 및 공기조절(HVAC) 기능이 상실된 사고의 경우, 보조급수를 위한 모터-구동 펌프격실의 온도상승을 전산유체역학 분석을 통해 평가하였다. 닫힌 펌프격실의 과도 계산결과, 8 시간 동안 공간-평균된 공기온도는 $60^{\circ}C$ 정도의 상승이 예상된다. 외기 온도 및 외부 온도는 이전 계산결과로부터 초기 $35^{\circ}C$에서 시작하여 서서히 증가한다고 가정하였다. 격실 문이 사고발생 후 약 2, 4, 그리고 6시간 경과 시점에서 열릴 경우, 체적-평균 격실 내가 온도는 약 $4^{\circ}C$의 즉각적인 하강이 나타나며 이후 서서히 온도가 상승하는 장기 거동을 보인다. 전산유체역학을 적용한 현재의 상세 해석결과는 이전의 집중(lumped) 모델을 사용한 보수적인 계산결과에 비해 낮은 격실온도 상승률을 예측한다.

• 한국연소학회지
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• 제19권3호
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• pp.8-17
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• 2014

The aims of this research were to evaluate effects of biomass co-firing to pulverized coal power plants and the variation of co-firing ratios on the plant efficiency related to power consumption of auxiliary system and flue gas characteristics such as production and component by process simulation based on the existing pulverized coal power plant. In this study, four kinds of biomass are selected as renewable fuel candidates for co-firing: wood pellet(WP), palm kernel shell(PKS), empty fruit bunch(EFB) and walnut shell(WS). Process simulation for various biomass fuels and co-firing ratios was performed using a commercial software. Gas side including combustion system and flue gas treatment system was considering with combination of water and steam side which contains turbines, condenser, feed water heaters and pumps. As a result, walnut shell might be the most suitable as co-firing fuel among four biomass since when 10% of walnut shell was co-fired with 90% of coal on thermal basis, flue gas production and power consumption of auxiliary systems were the smallest than those of other biomass co-firing while net plant efficiency was relatively higher than those of other biomass co-firing. However, with increasing walnut shell co-firing ratios, boiler efficiency and net plant efficiency were expected to decrease rather than coal combustion without biomass co-firing.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1603-1618
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• 2024

Emergency operation plans are indispensable elements for effective process safety management especially when unanticipated events occur under extreme situations. In the paper, a synthesis framework is proposed for the integration success path planning and performance analysis. Within the synthesis framework, success path planning is implemented through flow-directed signal tracing, renaming and reconstruction from a complete collection of Minimal Path Sets (MPSs) that are obtained using graph traversal search on GO-FLOW model diagram. The performance of success paths is then evaluated and prioritized according to the task complexity and probability calculation of MPSs for optimum action plans identification. Finally, an Auxiliary Feed Water System of Pressurized Water Reactor (PWR-AFWS) is taken as an example system to demonstrate the flow-directed MPSs search method for success path planning and performance analysis. It is concluded that the synthesis framework is capable of providing procedural guidance for emergency response and safety management with optimal success path planning under extreme situations.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.60-72
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• 2019

The air-cooled passive decay heat removal system (APDHR) was proposed to provide the ultimate heat sink for non-LOCA accidents. The APDHR is a modified one of Passive Auxiliary Feed-water system (PAFS) installed in APR+. The PAFS has a heat exchanger in the Passive Condensate Cooling Tank (PCCT) and can remove decay heat for 8 h. After that, the heat transfer rate through the PAFS drastically decreases because the heat transfer condition changes from water to air. The APDHR with a vertical heat exchanger in PCCT will be able to remove the decay heat by air if it has sufficient natural convection in PCCT. We conducted the thermal-hydraulic simulation by the MARS code to investigate the behavior of the APR + selected as a reference plant for the simulation. The simulation contains two phases based on water depletion: the early phase and the late phase. In the early phase, the volume of water in PCCT was determined to avoid the water depletion in three days after shutdown. In the late phase, when the number of the HXs is greater than 4089 per PCCT, the MARS simulation confirmed the long-term cooling by air is possible under extended Station Blackout (SBO).

• Nuclear Engineering and Technology
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• 제37권1호
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• pp.109-117
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• 2005

Limiting conditions for operations (LCOs) are evaluated dynamically using the tool of system dynamics. The LCOs de-fine the allowed outage times (AOTs) and the actions to be taken if the repair cannot be completed within the AOT. System dynamics has been developed to analyze the dynamic reliability of a complicated system. System dynamics using Vensim software have been applied to LCOs assessment for an example system, the auxiliary feed water system of a reference nuclear power plant. Analysis results of both full power operation and shutdown operation have been compared for a measure of core damage frequency. The framework developed in this study has been shown to be very flexible in that it can be applied to assess LCOs quantitatively under any operational context of the TS in FSAR.

• 한국화재소방학회논문지
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• 제19권3호
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• pp.20-27
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• 2005

본 논문에서는 화재 모델 CFAST를 사용하여 원자력발전소에 있는 8개 펌프실의 화재 안전 수준을 평가해 보고, 그 결과를 조건부 노심손상확률에 반영하여 분석해 보았다. 분석 대상 구역은 원자력발전소 일차보조건물에 위치한 고압안전주입 펌프실 A/B,저압안전주입 펌프실 A/B, 격납건물 살수 펌프실 A/B 및 모터구동 보조급수 펌프실 A/B 총 8곳이었다. 각 화재구역의 상부층 가스 온도를 분석하였으며, 분석 결과를 바탕으로 상부층에 위치한 케이블의 손상 유무를 파악하였다. 분석 결과에 의하면 총 8개 화재구역의 상부층 케이블은 건전성을 유지하는 것으로 확인되었다. 케이블의 건전성 평가 결과를 바탕으로 각 화재구역의 조건부 노심손상확률을 평가한 결과, 기존의 보수적인 가정 하에 수행된 화재위험도분석 결과보다 약 2배정도 감소하는 보다 현실적이고 불확실성이 감소한 결과를 도출할 수 있었다.