【作者】 张雷； 董晓朦； 徐俊英； 张会勇； 贠相羽； 孙鹏；

【Author】 ZHANG Lei;DONG Xiao-meng;XU Jun-ying;ZHANG Hui-yong;YUN Xiang-yu;SUN Peng;Key laboratory of Thermo-Fluid Science and Engineering,Ministry of Education,School of Energy and Power Engineering,Xi’an Jiaotong University;China Nuclear Power Technology Research Institute Co.,Ltd.Guangdong Provincial Key Laboratory of Nuclear Power Safety;Institute for Advanced Study in Nuclear Energy and Safety,College of Physics and Optoelectronic Engineering,Shenzhen University;

【机构】 西安交通大学能源与动力工程学院热流科学与工程教育部重点实验室； 中广核研究院有限公司广东省核电安全重点实验室； 深圳大学物理与光电工程学院中国核能与安全高等研究院；

【摘要】 堆芯熔融物堆内滞留-压力容器外部冷却(IVR-ERVC)是核电厂重要的严重事故预防和缓解措施。在核反应堆严重事故发生后,IVR-ERVC策略实施期间,反应堆压力容器(RPV)下封头在堆内熔融物的多种类型换热作用下,会发生烧蚀、蠕变等现象。在压力容器外部冷却水的带热作用下,有必要对熔融物滞留条件下压力容器下封头的烧蚀过程开展研究,对IVR-ERVC策略的可行性及敏感性进行分析。本文针对IVR过程中,堆内熔池与压力容器之间的热量传递,以及由此引发的压力容器烧蚀过程开展数值模拟研究,综合考虑辐射传热、堆内自然对流、压力容器壁面热传导及对外冷却水对流传热等多种换热类型,开展多类型传热模式耦合的动态压力容器烧蚀过程模拟。研究中熔池划分为金属层、氧化层,区分沿下封头角方向上热流密度的差异性。计算中考虑金属层对压力容器内壁面辐射传热方式,与实际过程更加吻合。堆内熔池采用熔化凝固模型,在加热过程中体现由固相受热变为液相的动态过程。压力容器下封头也采用熔化凝固模型,根据熔点判断此时压力容器的烧蚀状态,动态显示剩余壁面厚度。堆外冷却水采用强迫单相流动方式,对压力容器外壁面进行冷却,文中也对比分析了不同冷却水流量对于动态烧蚀过程的影响。计算采用Ansys Fluent软件实现,结合VOF (Volume of Fraction)模型,捕捉压力容器下封头的动态烧蚀边界,分析最小剩余壁面厚度和发生位置。结果显示,使用VOF模型,叠加熔化凝固模型计算壁面烧蚀具有可行性,多种传热类型影响下,IVR-ERVC策略具有较高的可靠性。更多还原

【Abstract】 In-Vessel Retention-External Reactors Vessels Cooling(IVR ERVC) is an important method for preventing and mitigating serious accidents in nuclear power plants.During the implementation of the IVR-ERVC strategy after a serious nuclear reactor accident,the lower head of the reactor pressure vessel may experience erosion,creep,and other phenomena under various types of heat exchange inside the reactor.Under the heating effect of the external cooling water of the pressure vessel,it is necessary to research on the ablation process of the RPV lower head under the condition of molten retention and analyze the feasibility and sensitivity of the IVR-ERVC strategy.Numerical simulation is conducted on the heat transfer between the reactor melt pool and RPV during the IVR-ERVC process,as well as the resulting RPV ablation process.Various heat transfer types are taken into account,such as radiation heat transfer,natural convection inside the reactor,pressure vessel wall heat transfer,and external convection heat transfer of cooling water.Including all these heating types,a dynamic RPV ablation process simulation is carried out.In the study,the molten pool was divided into a metal layer and an oxide layer to distinguish the differences in heat flux density along the corner direction of the lower head.The radiation heat transfer mode of the metal layer is considered on the inner wall of the RPV,which is more consistent with the actual process.The molten pool in the reactor adopts a melting-solidification model,which reflects the dynamic process from solid phase heating to liquid phase during the heating process.The lower head of the pressure vessel also adopts a melting-solidification model,which judges the ablation state of the pressure vessel based on the melting point.Furthermore,it dynamically displays the remaining wall thickness.The forced single-phase flow method is used to cool the outer wall of the RPV for external cooling water.The article also compares the influence of different cooling water flow rates on the dynamic ablation process.The calculation is carried out using ANSYS FLUENT software,combined with VOF model,to capture the dynamic ablation boundary under RPV,and analyze the minimum remaining wall thickness and location of occurrence.The results show that using the VOF model and the melting-solidification model to calculate wall erosion is feasible,and the IVR-ERVC strategy has high reliability under the influence of various heat transfer types.更多还原