AP1000 Passive Residual Heat Removal Heat Exchanger Confirmatory Analysis

2006 ◽  
Author(s):  
Richard F. Wright ◽  
James R. Schwall ◽  
Creed Taylor ◽  
Naeem U. Karim ◽  
Jivan G. Thakkar ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Cooling System ◽  
Heat Removal ◽  
Passive Safety ◽  
Tube Heat Exchanger ◽  
Removal Capacity ◽  
Safety Margins ◽  
Final Design ◽  
Safety Features ◽  
Residual Heat

The AP1000 is an 1100 MWe advanced nuclear power plant that uses passive safety features to enhance plant safety and to provide significant and measurable improvements in plant simplification, reliability, investment protection and plant costs. The AP1000 received final design approval from the US-NRC in 2004. The AP1000 design is based on the AP600 design that received final design approval in 1999. Wherever possible, the AP1000 plant configuration and layout was kept the same as AP600 to take advantage of the maturity of the design and to minimize new design efforts. As a result, the two-loop configuration was maintained for AP1000, and the containment vessel diameter was kept the same. It was determined that this significant power uprate was well within the capability of the passive safety features, and that the safety margins for AP1000 were greater than those of operating PWRs. A key feature of the passive core cooling system is the passive residual heat removal heat exchanger (PRHR HX) that provides decay heat removal for postulated LOCA and non-LOCA events. The PRHR HX is a C-tube heat exchanger located in the in-containment refueling water storage tank (IRWST) above the core promoting natural circulation heat removal between the reactor cooling system and the tank. Component testing was performed for the AP600 PRHR HX to determine the heat transfer characteristics and to develop correlations to be used for the AP1000 safety analysis codes. The data from these tests were confirmed by subsequent integral tests at three separate facilities including the ROSA facility in Japan. Owing to the importance of this component, an independent analysis has been performed using the ATHOS-based computational fluid dynamics computer code PRHRCFD. Two separate models of the PRHR HX and IRWST have been developed representing the ROSA test geometry and the AP1000 plant geometry. Confirmation of the ROSA test results were used to validate PRHRCFD, and the AP1000 plant model was used to confirm the heat removal capacity for the full-sized heat exchanger. The results of these simulations show that the heat removal capacity of the PRHR HX is conservatively represented in the AP1000 safety analyses.

Passive Safety Features in Sodium Cooled Super-Safe, Small and Simple Reactor

2002 ◽  
Author(s):  
N. Ueda ◽  
I. Kinoshita ◽  
Y. Nishi ◽  
A. Minato ◽  
H. Matsumiya ◽  
...  
Keyword(s):  
Cooling System ◽  
Heat Removal ◽  
Reactor Vessel ◽  
Passive Safety ◽  
Primary Coolant ◽  
Decay Heat ◽  
The Core ◽  
Design Requirements ◽  
Safety Features ◽  
Dynamics Analyses

This paper describes the passive safety features utilized in the updated sodium cooled Super-Safe, Small and Simple fast reactor, which is the improved 4S reactor. This reactor can operate up to ten years without refueling and neutron reflector regulates the reactivity. One of the design requirements is to secure the core against all anticipated transients without reactor scram. Therefore, the reactor concept is to design to enhance the passive safety features. All temperature reactivity feedback coefficients including whole core sodium void worth are negative. Also, introducing of RVACS (Reactor Vessel Auxiliary Cooling System) can enhance the passive decay heat removal capability. Safety analyses are carried out to simulate various transient sequences, which are loss of flow events, transient overpower events and loss of heat sink events, in order to evaluate the passive safety capabilities. A calculation tool for plant dynamics analyses for fast reactors has been modified to model the 4S including the unique plant system, which are reflector control system, circulation pumps and RVACS. The analytical results predict that the designed passive features improve the safety in which temperature variation in transients are satisfied with the safety criteria for the fuel element and the structure of the primary coolant boundary.

A Simulation of Small Break Loss of Coolant Accident in Nuclear Heating Reactor Based on RELAP5

2018 ◽  
Author(s):  
Meng Lu ◽  
Heng Xie
Keyword(s):  
Thermal Power ◽  
Heat Removal ◽  
Injection System ◽  
Water Volume ◽  
Nuclear Heating Reactor ◽  
Removal Capacity ◽  
Loss Of Coolant ◽  
Nuclear Heating ◽  
Residual Heat

Nuclear heating reactor is integrated designed without main pump and safety injection system. The loss of coolant accidents are mainly in the form of small break LOCA. As no safety injection system is designed for coolant makeup, the water volume in the reactor vessel is critical since it determines whether the reactor will be submerged during the whole scenario. Therefore, the study on coolant loss in this pool system is indispensable. The RELAP5 code has been developed for best-estimate transient simulation of light water reactor coolant systems during postulated accidents. The long term effect in nuclear heating reactor is important. In this paper we investigated the influential factors on SBLOCA scenario and found the long term residual heat removal capacity is decisive in determining the loss of coolant. The residual heat removal capacity should be greater than 2% of reactor thermal power if ensuring the core submerged in the long run.

scholarly journals Heat Transfer Analysis of Passive Residual Heat Removal Heat Exchanger under Natural Convection Condition in Tank

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qiming Men ◽  
Xuesheng Wang ◽  
Xiang Zhou ◽  
Xiangyu Meng
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Stratification ◽  
Heat Removal ◽  
Heat Transfer Analysis ◽  
Average Error ◽  
Water Tank ◽  
Shaped Tube ◽  
Heat Transfer Calculation ◽  
Residual Heat

Aiming at the heat transfer calculation of the Passive Residual Heat Removal Heat Exchanger (PRHR HX), experiments on the heat transfer of C-shaped tube immerged in a water tank were performed. Comparisons of different correlation in literatures with the experimental data were carried out. It can be concluded that the Dittus-Boelter correlation provides a best-estimate fit with the experimental results. The average error is about 0.35%. For the tube outside, the McAdams correlations for both horizontal and vertical regions are best-estimated. The average errors are about 0.55% for horizontal region and about 3.28% for vertical region. The tank mixing characteristics were also investigated in present work. It can be concluded that the tank fluid rose gradually which leads to a thermal stratification phenomenon.

Experimental Study on Natural Convection Heat Transfer Outside Tube Bundle in Space Under Low Temperature Difference

2020 ◽  
Author(s):  
Junxiu Xu ◽  
Ming Ding ◽  
Changqi Yan ◽  
Guangming Fan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Tube Bundle ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Reactor Pool ◽  
Residual Heat

Abstract The Passive Residual Heat Removal System (PRHRS) is very important for the safety of the heating reactor after shutdown. PRHRS is a natural circulation system driven by density difference, therefore, the heat transfer performance of the Passive Residual Heat Removal Heat Exchanger (PRHR HX) has a great impact to the heat transfer efficiency of PRHRS. However, the most research object of PRHR HX is the C-shape heat exchanger at present, which located in In-containment Refueling Water Storage Tank (IRWST). This heat exchanger is mainly used for the PRHRS of nuclear power plants. In the swimming pool-type low-temperature heating reactor (SPLTHR), the PRHR HX is placed in the reactor pool, which the pressure and temperature of the reactor pool are relatively low, and the outside heat transfer mode of tube bundle is mainly natural convection heat transfer. In this study, a miniaturized single-phase pool water cooling system was built to investigate the natural convective heat transfer coefficient of the heat exchanger under the large space and low temperature conditions. The experimental data had been compared with several correlations. The results show that the predicted value of Yang correlation is the closest to the experimental data, which the maximum deviation is about 11%.

Analysis of Heat Transfer and Flow Characteristics of AP1000 Passive Residual Heat Removal Heat Exchanger

2014 ◽  
Author(s):  
Xu Xie ◽  
Changhua Nie ◽  
Li Zhan ◽  
Hua Zheng ◽  
Pengzhou Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Tube Bundle ◽  
Natural Circulation ◽  
Heat Removal ◽  
Large Temperature ◽  
Water Tank ◽  
Secondary Side ◽  
Residual Heat

In this paper, the computational fluid dynamics (CFD) method is applied to the thermal-hydraulic analysis, while the porous media model is used to simplify AP1000 passive residual heat removal heat exchanger tube. The temperature as well as flow distribution in the secondary side of the heat exchanger are obtained, aiming at analysis of natural circulation ability. It can be noted that the fluid in the secondary side of heat exchanger moves driven by the effect of thermal buoyancy, forming the natural cycle, which takes away heat in tube bundle region. The heat transfer in water tank is mainly enhanced by vortex and turbulent flow, caused by the large resistance of tube bundle region as well as large temperature difference. This phenomenon is obvious especially for the recirculation of flow near the tube bundle. The enduring change of flow rate and direction enhance the heat transfer. Besides, the big temperature difference helps to increase the driving effect of natural circulation. Consequently, the heat transfer of the tank is enhanced by above mechanism. The results of this study contribute to the capacity analysis of passive residual heat removal of natural circulation system, providing valuable information for safe operation of AP1000.

A Numerical Study of Flow and Temperature Maldistribution in a Parallel Microchannel System for Heat Removal in Microelectronic Devices

2012 ◽  
Author(s):  
Manoj Siva ◽  
Arvind Pattamatta ◽  
Sarit Kumar Das
Keyword(s):  
Heat Exchanger ◽  
Cross Section ◽  
Design Theory ◽  
Cooling System ◽  
Search Algorithm ◽  
Numerical Study ◽  
Heat Removal ◽  
Flow Distribution ◽  
Microchannel Cooling ◽  
Flow Maldistribution

A common assumption in basic heat exchanger design theory is that fluid is distributed uniformly at the inlet of the exchanger on each fluid side and throughout the core. However in reality, uniform flow distribution is never achieved in a heat exchanger and is referred to as flow maldistribution. Flow maldistribution is generally well understood for the macrochannel system. But it is still unclear whether the assumptions underlying the flow distribution in conventional macrochannel heat exchangers hold good for microchannel system. In this regard, extensive numerical simulations are carried out in a ‘U’ type parallel micro-channel system in order to study flow and heat transfer maldistribution and validated with in-house experimental data. A detailed parametric analysis is carried out to characterize flow maldistribution in a microchannel system and to study the effect of geometrical factors such as number of channels, n, Area of cross section of the channel Ac, manifold cross section area Ap, and flow parameter such as Reynolds number, Re, on the pressure and temperature distribution. In order to minimize the variation in pressure and to reduce temperature hot spots in the microchannel, a Response surface based surrogate approximation (RSA) and a gradient based search algorithm are used to arrive at the best configuration of microchannel cooling system. A three level factorial design involving three parameters namely Ac/Ap, Re, n are considered. The results from the optimization indicate that the case of n = 5, Ac/Ap = 0.12, and Re = 100 is the best possible configuration to alleviate flow maldistribution and hotspot formation in microchannel cooling system.

Research of Combined Heating and Cooling by Solar Ground-Source Heat Pump and PCM Thermal Storage

Solar Energy ◽  
2005 ◽  
Author(s):  
Li-Xia Wu ◽  
Mao-Yu Zheng
Keyword(s):  
Heat Exchanger ◽  
Solar Energy ◽  
Cooling System ◽  
Storage System ◽  
Thermal Storage ◽  
Cold Climate ◽  
Coefficient Of Performance ◽  
Tube Heat Exchanger ◽  
Heating And Cooling ◽  
Ground Source

In severely cold climate, significant amount of energy is used to heat buildings. Both the theoretical computation and experiments show that it is difficult and uneconomical to use solar energy collected merely in winter. A new method has been developed to store solar energy during summer, fall, and spring for winter heating. This paper presents in details the combined heating and cooling system by solar ground-source heat pump (GSHP) and short-term phase change material (PCM) thermal storage. The hybrid system and season-shift mode can make the sustainable use of solar energy possible. As for the above system, the solar energy collected is stored into soil through the U-tube heat exchanger. In winter, the thermal energy is taken out for heating using the GSHP. At the end of the heat supply season, the underground soil temperature may drop below 0°C. Then some heat exchangers begin to store the heat into soil while others stop. In summer, the U-tube heat exchanger is used to produce low temperature water without compressor to cool the room. The project was supported by the Energy Conservation Laboratory at Harbin Institute of Technology (HIT). The whole systems, which have run for over two years, consist of a flat plate solar hot water system installed on the roof, a soil thermal storage system, a GSHP system, a PCM thermal storage system and heating-cooling system. The measured results show an average heating coefficient of performance (COP) of 3.2 in winter and the cooling coefficient of performance (COP) of 18.0 in summer. The PCM thermal storage system has been investigated by numerical simulation and experiments in the cold climate. In most time of winter, the PCM thermal storage system was used to supply heat, while solar GSHP was also used during continuous cloudy days and severely cold days. The result shows that above method is feasible. The most advantage of this system is that it does not need the usual energy equipment. The numerical analysis has been used to investigate the thermal energy balance of the underground soil. The variation of the soil temperature field around the U-tube heat exchanger has also been studied, not only for the single exchanger but also for multiple exchangers. The underground soil makes the yearly thermal balance possible because the solar energy supplies the heat that is extracted from the soil for heating in winter. Then this system can operate for a long period.

A Numerical Study of Flow and Temperature Maldistribution in a Parallel Microchannel System for Heat Removal in Microelectronic Devices

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
V. Manoj Siva ◽  
Arvind Pattamatta ◽  
Sarit Kumar Das
Keyword(s):  
Heat Exchanger ◽  
Cross Section ◽  
Design Theory ◽  
Cooling System ◽  
Search Algorithm ◽  
Numerical Study ◽  
Heat Removal ◽  
Flow Distribution ◽  
Microchannel Cooling ◽  
Flow Maldistribution

A common assumption in basic heat exchanger design theory is that fluid is distributed uniformly at the inlet of the exchanger on each fluid side and throughout the core. However, in reality, uniform flow distribution is never achieved in a heat exchanger and is referred to as flow maldistribution. Flow maldistribution is generally well understood for the macrochannel system. But it is still unclear whether the assumptions underlying the flow distribution in conventional macrochannel heat exchangers hold good for microchannel system. In this regard, extensive numerical simulations are carried out in a “U” type parallel microchannel system in order to study flow and heat transfer maldistribution and validated with in-house experimental data. A detailed parametric analysis is carried out to characterize flow maldistribution in a microchannel system and to study the effect of geometrical factors such as number of channels, n, Area of cross section of the channel Ac, manifold cross section area Ap, and flow parameter such as Reynolds number, Re, on the pressure and temperature distribution. In order to minimize the variation in pressure and to reduce temperature hot spots in the microchannel, a response surface based surrogate approximation and a gradient based search algorithm are used to arrive at the best configuration of microchannel cooling system. A three level factorial design involving three parameters namely Ac/Ap, Re, n are considered. The results from the optimization indicate that the case of n = 7, Ac/Ap = 0.69, and Re = 100 is the best possible configuration to alleviate flow maldistribution and hotspot formation in microchannel cooling system.

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