• Title/Summary/Keyword: primary cooling system

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SAFETY ANALYSIS OF INCREASE IN HEAT REMOVAL FROM REACTOR COOLANT SYSTEM WITH INADVERTENT OPERATION OF PASSIVE RESIDUAL HEAT REMOVAL AT NO-LOAD CONDITIONS

  • SHAO, GE;CAO, XUEWU
    • Nuclear Engineering and Technology
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    • v.47 no.4
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    • pp.434-442
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    • 2015
  • The advanced passive pressurized water reactor (PWR) is being constructed in China and the passive residual heat removal (PRHR) system was designed to remove the decay heat. During accident scenarios with increase of heat removal from the primary coolant system, the actuation of the PRHR will enhance the cooldown of the primary coolant system. There is a risk of power excursion during the cooldown of the primary coolant system. Therefore, it is necessary to analyze the thermal hydraulic behavior of the reactor coolant system (RCS) at this condition. The advanced passive PWR model, including major components in the RCS, is built by SCDAP/RELAP5 code. The thermal hydraulic behavior of the core is studied for two typical accident sequences with PRHR actuation to investigate the core cooling capability with conservative assumptions, a main steam line break (MSLB) event and inadvertent opening of a steam generator (SG) safety valve event. The results show that the core is ultimately shut down by the boric acid solution delivered by Core Makeup Tank (CMT) injections. The effects of CMT boric acid concentration and the activation delay time on accident consequences are analyzed for MSLB, which shows that there is no consequential damage to the fuel or reactor coolant system in the selected conditions.

Numerical Analysis of Single Phase Thermal Stratification in both Cold Legs and Downcomer by Emergency Core Cooling System Injection : A Study on the Necessity to Consider Buoyancy Force Term (비상노심냉각계통 주입에 따른 저온관 및 강수관에서 단상 열성층 수치해석 : 부력항 고려 필요성에 관한 연구)

  • Lee, Gong Hee;Cheong, Ae Ju
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.12
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    • pp.654-662
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    • 2017
  • When emergency core cooling system (ECCS) is operated during loss of coolant accident (LOCA) in a pressurized water reactor (PWR), pressurized thermal shock (PTS) phenomenon can occur as cooling water is injected into a cold leg, mixed with hot primary coolant, and then entrained into a reactor vessel. Insufficient flow mixing may cause temperature stratification and steam condensation. In addition, flow vibration may cause thermal stresses in surrounding structures. This will reduce the life of the reactor vessel. Due to the importance of PTS phenomenon, in this study, calculation was performed for Test 1 among six types of OECD/NEA ROSA tests with ANSYS CFX R.17. Predicted results were then compared to measured data. Additionally, because temperature difference between the hot coolant at the inlet of the cold leg and the cold cooling water at the inlet of the ECCS injection line is 200 K or more, buoyancy force due to density difference might have significant effect on thermal-hydraulic characteristics of flow. Therefore, in this study, the necessity to include buoyancy force term in governing equations for accurate prediction of single phase thermal stratification in both cold legs and downcomer by ECCS injection was numerically studied.

Theoretical Heat Flow Analysis and Vibration Characteristics During Transportation of PCS(Power Conversion System) for Reliability (전력변환장치 캐비넷에서의 내부발열 개선을 위한 열유동 분석 및 유통안전성 향상을 위한 진동특성 분석)

  • Joo, Minjung;Suh, Sang Uk;Oh, Jae Young;Jung, Hyun-Mo;Park, Jong-Min
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.28 no.2
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    • pp.143-149
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    • 2022
  • PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.

Fouling Analyses of Heat Exchangers for PSR (주기적안전성평가를 위한 원전 열교환기 Fouling 평가)

  • Hwang, K.M.;Jin, T.E.;Han, S.G.;Kim, B.S.
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1467-1472
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    • 2003
  • Fouling of heat exchangers is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. This fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. This paper focuses on fouling analyses for six heat exchangers of two primary systems in two nuclear power plants; the regenerative heat exchangers of the chemical and volume control system and the component cooling water heat exchangers of the component cooling water system. To analyze the fouling for heat exchangers, fouling factor was introduced based on the ASME O&M codes and TEMA standards. Based on the results of the fouling analyses, the present thermal performances and fouling levels for the six heat exchangers were predicted.

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Study on operation characteristics of the cold air distribution systems with an ice storage tank (빙축열을 이용한 저온공조시스템 운전 특성 연구)

  • 염한길;박병규;고득용
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.3
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    • pp.301-312
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    • 1999
  • Experiments were carried out to evaluate performance of the cold air distribution systems with an ice storage tank in test room. Cold air distribution systems provide primary air for comfort conditioning or process cooling at coil discharge temperatures$4^{\circ}C$ to$11^{\circ}C$. The application of a cold air distribution system allows for the downsizing of air distribution equipment and central plant equipment when ice storage tank is used. The benefit of a cold air distribution system include a decrease in the floor-to-floor height, increase floor space, reduced building capital costs, reduced energy use and demand. The use of cold air distribution can result in the most cost effective system and is currently being implemented world wise as the new standard in air conditioning systems. In this study, the cold air distribution system is compared with the general ice storage system. Under the same cooling load conditions, experimental results show that the supply air volume of cold air distribution system decrease 38%, and decrease 45% flow rate of brine for the general ice storage system.

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Analysis of Catalytic Cracking and Steam Reforming Technologies for Improving Endothermic Reaction Performance of Hydrocarbon Aviation Fuels (탄화수소 항공유의 흡열반응 성능향상을 위한 촉매 분해 및 수증기 개질 기술분석)

  • Lee, Hyung Ju
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.2
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    • pp.98-109
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    • 2021
  • Fundamental parameters describing overall operational characteristics of active cooling systems of a hypersonic flight vehicle are mainly classified into endothermic hydrocarbon fuels, regenerative cooling channels, and materials and system structures. Of primary importance is the improvement of endothermic performance of hydrocarbon aviation fuels in a series of studies developing efficient regenerative cooling systems. In a previous study, therefore, an extensive technical analysis has been carried out on thermal decomposition characteristics of liquid hydrocarbon fuels. As a subsequent study, catalytic cracking and steam reforming technologies have been reviewed to find a way for the improvement of endothermic reaction performance of hydrocarbon aviation fuels.

Design and Test of ASME Strainer for Coolant System of Research Reactor (연구용 원자로 냉각계통의 ASME 스트레이너 설계 및 성능시험)

  • Park, Yong-Chul;Park, Jong-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.3 s.4
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    • pp.24-29
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    • 1999
  • The ASME strainers have been newly installed at the suction side of each reactor coolant pump to get rid of the foreign materials which may damage the pump impeller or interfere with the coolant path of fuel flow tube or primary plate type heat exchanger. The strainer was designed in accordance with ASME SEC. III, DIV. 1, Class 3 and the structural integrity was verified by seismic analysis. The screen was designed in accordance with the effective void area from the result of flow analysis for T-type strainer. After installation of the strainer, it was confirmed through the field test that the flow characteristics of primary cooling system were not adversely affected. The pressure loss coefficient was calculated by Darcy equation using the pressure difference through each strainer and the flow rate measured during the strainer performance test. And these are useful data to predict flow variations by the pressure difference.

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Evaluation on Cooling Performance of Ground Source Heat Pump System Equipped with Steel-pipe Civil Structures (강관 토목구조물이 설치된 지열 히트펌프 시스템의 냉방 성능 평가)

  • Seokjae Lee;Jeonghun Yang;Hangseok Choi
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.19 no.3
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    • pp.14-22
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    • 2023
  • Steel-pipe civil structures, including steel-pipe energy piles and cast-in-place piles (CIPs), utilize steel pipes as their primary reinforcements. These steel pipes facilitate the circulation of a working fluid through their annular crosssection, enabling heat exchange with the surrounding ground formation. In this study, the cooling performance of a ground source heat pump (GSHP) system that incorporated steel-pipe civil structures was investigated to assess their applicability. First of all, the thermal performance test was conducted with steel-pipe CIPs to evaluate the average heat exchange amount. Subsequently, a GSHP system was designed and implemented within an office container, considering the various types of steel-pipe civil structures. During the performance evaluation tests, parameters such as the coefficient of performance (COP) and entering water temperature (EWT) were closely monitored. The outcomes indicated an average COP of 3.74 for the GSHP system and the EWT remained relatively stable throughout the tests. Consequently, the GSPH system demonstrated its capability to consistently provide a sufficient heat source, even during periods of high cooling thermal demand, by utilzing the steel-pipe civil structures.

Coolant Options and Critical Heat Flux Issues in Fusion Reactor Divertor Design

  • Baek, Won-Pil;Chang, Soon-Heung
    • Nuclear Engineering and Technology
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    • v.29 no.4
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    • pp.348-359
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    • 1997
  • This paper reviews cooling aspects of the diverter system in Tokamak fusion devices with primary emphasis on the critical heat flux (CHF) issues for oater-cooled designs. General characteristics of four (4) coolant options for diverter cooling gases, oater, liquid metal, and organic liquid - are discussed first, focusing on the comparison of advantages and disadvantages of those options. Then results of recent studies on the high-heat-flux CHF of water at subcooled high-velocity conditions are reviewed to provide a general idea on the feasibility of the water-cooled diverter concept for future Tokamak fusion reactors. Water is assessed to be the most viable and practical coolant option for diverters of future experimental Tokamaks.

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A Study of Cooldown Performance of Shutdown Cooling System of Korea Next Generation Reactor (차세대 원자로 정지냉각계통의 냉각 성능에 대한 연구)

  • 유성연;이상섭
    • Journal of Energy Engineering
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    • v.8 no.4
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    • pp.525-532
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    • 1999
  • The standardized Korea Next Generation Reactor (KNGR) NSSS has developed in the basis of the ABB-CE System 80+ design concept. In this study, several regulatory requirements for the KNGR shutdown cooling system (SCS) operation are investigated. The purpose of this study is to establish the technical self-reliance for SCS design by supporting fundamental data such as SDCHX effective area and reactor CCW flow rate. Thermal power of KNGR would be increased to about 4,000 $MW_{th}$ in comparison with thermal power 2.825 $MW_{th}$ of UCN 3&4, therefore, SCS design data shall b recalculated by using the KDESCENT Code, which could evaluate cooling capability of SCS. It is found that SCS minimum flow rate is able to remove the primary sensible heat. Reviewing the major components such as heat exchanger, pump, value, and operating procedure, it is concluded as follows.

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