小型堆非能动安全壳冷却系统传热特性实验研究
发布时间：2018-10-13 11:02
【摘要】：小型反应堆所具有的安全设计理念、结构简化等特点,以及在特殊领域的应用优势,推动了其快速发展。安全壳作为小型反应堆中防止放射性物质扩散的最后一道屏障,在LOCA\MSLB事故后必须保证其完整性以尽可能的降低核事故的危害。目前,部分小型反应堆采用钢制结构的安全壳,例如Nuscale、ACP100。除了作为最后一道屏障外,钢制安全壳在破口事故后还具有导出壳内热量的作用,能有效降低事故后安全壳内的温度和压力。随着小型堆的全面发展,研究小型堆的安全性,尤其是破口事故后安全壳的非能动冷却能力,对小型堆的推广有着尤为重要的意义。本文主要研究破口事故下小型堆安全壳内的温度分布和安全壳的传热特性,希望对小型堆的结构设计和安全分析提供一定的参考。为研究小型安全壳破口事故后由强迫射流、浮力射流引起的热分层现象及安全壳传热特性,本文进行了实验和数值计算两方面的工作。实验以蒸汽为工质,通过测量安全壳内空间和壁面温度以及内壁面凝结水量,研究破口喷射流量、破口直径、破口高度和外部喷淋流量四个因素对安全壳内部热分层现象和安全壳壳壁传热的影响。数值计算工作利用FLUENT软件进行,采用欧拉多相流模型,引入软件自带的蒸发-冷凝模型,研究不同条件下安全壳内的温度分布、气体组分和气体流动,以补充实验测量的不足,并验证计算模型的准确性,为以后的实验和反应堆专有程序的开发提供一些参考。通过分析实验数据发现,破口事故后安全壳内普遍存在热分层现象,安全壳上部的温度搅混均匀,存在明显的等温区,下部则是有一定温度梯度的低温区。喷射流量、破口直径、破口高度对热分层的影响主要表现为改变了等温区厚度,喷淋流量则是整体性改变了安全壳的空间温度,安全壳的热流密度则受到了等温区厚度和温度的影响。在模拟计算结果中也出现了安全壳热分层现象,结合壳内流场发现气体速度对热分层现象的影响较大,但是计算结果中安全壳空间温度偏高,且下部温度梯度不明显。
[Abstract]:The small reactor has the characteristics of safety design, structural simplification and its application in special fields, which promote its rapid development. Containment, as the last barrier against the spread of radioactive material in small reactors, must be kept intact after the LOCA\ MSLB accident in order to minimize the damage caused by nuclear accidents. At present, some small reactors use steel containment, such as Nuscale,ACP100. In addition to being the last barrier, the steel containment has the function of deriving the heat in the shell after the break accident, which can effectively reduce the temperature and pressure in the containment after the accident. With the overall development of the small reactor, it is of great significance to study the safety of the small reactor, especially the passive cooling ability of the containment after the break accident. In this paper, the temperature distribution and heat transfer characteristics in the containment of small reactor are studied in order to provide some reference for the structural design and safety analysis of the small reactor. In order to study the thermal stratification phenomenon caused by forced jet and buoyant jet and the heat transfer characteristics of containment after a small containment break accident, two aspects of experiment and numerical calculation have been carried out in this paper. In this experiment, steam was used as working medium. By measuring the space and wall temperature of containment and the amount of condensate on the inner wall, the jet flow rate and the diameter of the break were studied. The influence of four factors such as break height and external spray flow rate on the thermal stratification phenomenon and heat transfer in the containment wall. The numerical calculation is carried out by FLUENT software. The Euler multiphase flow model is used to study the temperature distribution, gas composition and gas flow in containment under different conditions. The accuracy of the calculation model is verified and some references are provided for future experiments and the development of reactor proprietary procedures. By analyzing the experimental data, it is found that thermal stratification is common in the containment after the break accident, the temperature in the upper part of the containment is mixed uniformly, there is an obvious isothermal zone, and the lower part is the low temperature zone with a certain temperature gradient. The influence of jet flow rate, break diameter and break height on thermal delamination mainly shows that the thickness of isothermal zone is changed, while the spray flow rate changes the space temperature of containment as a whole. The heat flux of containment is influenced by the thickness and temperature of isothermal zone. The phenomenon of thermal stratification of containment was also found in the simulation results. Combined with the flow field in the shell, it was found that the gas velocity had a great influence on the thermal stratification, but the temperature of the containment space was higher and the temperature gradient of the lower part was not obvious.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TK124;TM623.2
本文编号：2268377
[Abstract]:The small reactor has the characteristics of safety design, structural simplification and its application in special fields, which promote its rapid development. Containment, as the last barrier against the spread of radioactive material in small reactors, must be kept intact after the LOCA\ MSLB accident in order to minimize the damage caused by nuclear accidents. At present, some small reactors use steel containment, such as Nuscale,ACP100. In addition to being the last barrier, the steel containment has the function of deriving the heat in the shell after the break accident, which can effectively reduce the temperature and pressure in the containment after the accident. With the overall development of the small reactor, it is of great significance to study the safety of the small reactor, especially the passive cooling ability of the containment after the break accident. In this paper, the temperature distribution and heat transfer characteristics in the containment of small reactor are studied in order to provide some reference for the structural design and safety analysis of the small reactor. In order to study the thermal stratification phenomenon caused by forced jet and buoyant jet and the heat transfer characteristics of containment after a small containment break accident, two aspects of experiment and numerical calculation have been carried out in this paper. In this experiment, steam was used as working medium. By measuring the space and wall temperature of containment and the amount of condensate on the inner wall, the jet flow rate and the diameter of the break were studied. The influence of four factors such as break height and external spray flow rate on the thermal stratification phenomenon and heat transfer in the containment wall. The numerical calculation is carried out by FLUENT software. The Euler multiphase flow model is used to study the temperature distribution, gas composition and gas flow in containment under different conditions. The accuracy of the calculation model is verified and some references are provided for future experiments and the development of reactor proprietary procedures. By analyzing the experimental data, it is found that thermal stratification is common in the containment after the break accident, the temperature in the upper part of the containment is mixed uniformly, there is an obvious isothermal zone, and the lower part is the low temperature zone with a certain temperature gradient. The influence of jet flow rate, break diameter and break height on thermal delamination mainly shows that the thickness of isothermal zone is changed, while the spray flow rate changes the space temperature of containment as a whole. The heat flux of containment is influenced by the thickness and temperature of isothermal zone. The phenomenon of thermal stratification of containment was also found in the simulation results. Combined with the flow field in the shell, it was found that the gas velocity had a great influence on the thermal stratification, but the temperature of the containment space was higher and the temperature gradient of the lower part was not obvious.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TK124;TM623.2
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