项目名称： 高燃耗燃料包壳多轴热-机械疲劳特性及环境退化机理研究

项目编号： No.51471116

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 陈刚

作者单位： 天津大学

项目金额： 84万元

中文摘要： 面向先进核电关键部件长寿命可靠运行的需求，针对反应堆反应性引入事故时高燃耗燃料包壳的热-机械疲劳失效机理及寿命预测模型开展研究。主要包括：（1）阐明多轴载荷对包壳材料变形机制及疲劳抗力的影响，澄清温度、加载率、应力比、多轴应力对棘轮应变及其累积速率的影响规律，揭示棘轮变形与疲劳载荷的交互作用机制；（2）开展锆合金热-机械疲劳失效研究，澄清复杂应力、温度对析出氢化物形态、分布及指向的作用机制，揭示热-机械载荷、氢含量、氧化对锆合金延脆转化行为的影响规律并建立映射关联；（3）基于损伤耦合的粘塑性循环本构模型和应变能密度理论，建立虑及多轴应力、棘轮应变、热-机械载荷、氢致退化、氧化效应的寿命预测模型。本项目体现了力学、材料和化学等多学科领域的交叉，可望从热-力学-化学角度阐明反应性引入事故时芯块与包壳相互机械作用的基本规律并建立预测方法，为高燃耗燃料包壳的寿命设计方法和制造水平提升提供科学支持。

中文关键词： 多轴应力；棘轮效应；热-机械疲劳；寿命预测；氢致退化

英文摘要： To ensure the longlife and reliable service of some key components used in nuclear power, the project attemps to address the thermo-mechanical failure mechanism and fatigue life prediction model of high burn-up fuel cladding in advanced nuclear power plant due to the pellet cladding mechanical interaction (PCMI) during a reactivity-initiated accident (RIA) occurs. The following issues will be focused in the present project: (1) Illuminate the effect of multiaxial stress on deformation mechanism and fatigue resistance, clarify the influence of temperature, loading rate, stress ratio and multiaxial stress on ratcheting strain and its rate, realize the ratcheting and fatigue interaction mechanism. (2) Specific the thermo-mechanical fatigue failure of Zr alloy, investigate the roles of particular complicated loading conditions and temperature on hydride content, orientation,and distribution in detail, clarify the rules of competition behavior among thermo-mechanical loading, hydride concentration and oxidation on ductile to brittle transition of Zr alloy. (3) Develop a life prediction model through the combination of damage-coupled cyclic visco-plastic constitutive model and strain energy density theory. The effect of multiaxial stress, ratcheting strain, thermo-mechanical loading, dydride-induced degradation and oxidation on the fatigue life can be reflected in this model. In this interdisciplinary program, the mechancial, material and chemical analyses were included. Through the accomplishment of the project,the basic rule of PCMI during a RIA through the view point of thermo-mechanical- chemical analysis can be found and the life prediction model which can be used for engineering application can be developed. Also, this project could provide some important insights on the improvement of the long-life design and manufacturing of high burn-up fuel cladding in advanced nuclear power.

英文关键词： Multiaxial stress;Ratcheting;Thermo-mechanical fatigue;Life prediction;Hydride-induced degradation