燃料棒破损热力学模块开发及在严重事故分析程序中的应用  

Development of Fuel Rod Rupture Thermal-mechanical Module and Application in Severe Accident Analysis Code

作　　者：高鹏程 张斌[1,2] 单建强 GAO Pengcheng;ZHANG Bin;SHAN Jianqiang(School of Nuclear Science and Technology,Xi’an Jiaotong University,Xi’an 710049,China;State Key Laboratory of Multiphase Flow in Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学核科学与技术学院,陕西西安710049 [2]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《原子能科学技术》2022年第7期1300-1307,共8页Atomic Energy Science and Technology

基　　金：中核集团领创科研项目。

摘　　要：包壳肿胀和破损是严重事故早期阶段的重要现象。包壳形变不仅会造成局部流动堵塞,同时,水蒸气会从破裂处进入包壳气隙,增加包壳被蒸汽氧化的表面积。广泛使用的一体化严重事故分析程序不能分析早期事故过程中燃料棒的热力学行为,判断包壳破裂也只是基于简单的参数模型。本文开发了分析燃料棒热力学行为的FRTMB模块,并集成在严重事故分析程序ISAA中。使用开发的耦合系统ISAA-FRTMB分析了CAP1400反应堆直接注射(DVI)管线小破口事故过程中燃料棒的热力学行为,并预计了包壳破裂时间及相应的失效温度。计算结果整体验证了ISAA-FRTMB分析瞬态事故过程中燃料棒热力学行为以及判断包壳破裂的适用性和可靠性。Cladding ballooning and rupture are the important phenomena at the early stage of a severe accident(SA).For example,the SA caused by the loss of coolant accident(LOCA),the decrease in primary loop pressure and the increase in core temperature will lead to the cladding ballooning and rupture.The cladding deformation affects the flow distribution and causes local flow blockage.Meanwhile,water vapor will enter the fuel gap from the rupture,thereby increasing the surface area of cladding that is oxidized by the steam.At present,the widely used integrated SA analysis codes cannot analyze fuel rods thermal-mechanical behavior at the early SA stage,and the judgment of cladding rupture is only based on simple parameter model.This paper integrates the developed FRTMB(core Fuel Rod Thermal-Mechanical Behavior analysis)module into the integrated SA analysis code ISAA,so that the coupled system ISAA-FRTMB can analyze fuel rods thermal-mechanical behavior and judge cladding rupture.Previous part introduced the need of developing the FRTMB module,verification of the module,how the module interactively worked in the SA analysis code,and evaluated the steady-state fuel rods thermal-mechanical behavior at different enrichment areas of the CAP1400 reactor.This part focuses on analyzing fuel rods behavior during a hypothetical DVI(Direct Vessel Injection)line small break-out accident(break diameter d=4 inch)of the CAP1400,and predicts the cladding rupture time and the corresponding failure temperature.Due to failure of components of the emergency core cooling system and assumed unavailability of several preventive and mitigative accident management measures(AMM),the accident developed into a SA scenario with core melt and reactor pressure vessel failure.The mechanical analysis results show the top of the fuel rod is the first to rupture,rather than the peak node.The primary factor affecting the fuel pellet strain is the deformation caused by thermal expansion,while the densification and swelling change little.These results demonstr

关 键 词：严重事故 燃料棒热力学行为 包壳破损 CAP1400 

分 类 号：TL364.5[核科学技术—核技术及应用]