压水堆燃料棒三维热-力学性能的精细模拟

压水堆燃料棒工作在复杂的辐照、热和力学环境中,对其性能进行定量评估涉及多种复杂的物理现象。目前常用的燃料性能分析程序一般对结构采用简化的轴对称假设,对辐照肿胀、辐照蠕变和高温蠕变等物理现象以及辐照-热-力等物理场之间的耦合考虑并不充分。基于ABAQUS有限元求解框架,开发了压水堆燃料棒三维热-力学性能的模拟程序,利用程序对压水堆燃料棒进行了稳态分析,以及升功率和反应性引入事故两种瞬态分析。结果表明:辐照引起燃料致密化和肿胀对燃料温度变化有重要影响;芯块应变增加主要是由裂变产物肿胀引起的;芯块几何结构导致包壳应力集中发生在芯块间的交界面处;燃料棒功率的急剧变化会加快芯块表面破裂的进程;反应性引入事故会导致芯块从内部开始破裂,并会引发芯块-包壳的接触。

Fine Simulation of Three Dimensional Thermo-mechanical Performance of Pressurized Water Reactor Fuel Rod

The fuel rods of pressurized water reactors operate under complex radioactive,thermal and mechanical conditions.Multiphysics have to be taken into account in order to evaluate their performance.Many existing fuel rod codes make great simplifications on analyzing the behavior of fuel rods.Based on the finite element method,a program evaluating the thermo-mechanical performance of pressurized water reactor fuel rod was developed.Steady-state analysis,transient analysis and reactivity insertion accident (RIA) analysis of fuel rods were carried out using the program.The results show that densification and swelling of the fuel caused by irradiation have an important influence on the fuel temperature.The swelling of fission products causes a noticeable increase of strain.The chamfers of pellets result in the occurrence of stress concentration at interface between the pellets.There is a significant influence in surface cracking of pellet if fuel rod power rapidly changes.The RIA causes the pellet to begin to rupture from the inside and leads to the pellet-cladding interaction.