考虑各向异性蠕变的锆包壳鼓胀行为数值模拟方法研究  

Numerical Method Study for Zircaloy Clad Ballooning Behavior Simulation Considering Anisotropic Creep

作　　者：李伟[1] 李小雨 段倩妮 王皓坤 武俊梅[1] 刘仕超 LI Wei;LI Xiaoyu;DUAN Qianni;WANG Haokun;WU Junmei;LIU Shichao(State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University,Xi’an 710049,China;Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]西安交通大学复杂服役环境重大装备结构强度与寿命全国重点实验室,陕西西安710049 [2]中国核动力研究设计院核反应堆系统设计技术重点实验室,四川成都610213

出　　处：《原子能科学技术》2024年第4期878-886,共9页Atomic Energy Science and Technology

基　　金：四川省自然科学基金青年科学基金(2022NSFSC1199)。

摘　　要：锆(Zr)合金包壳在高温和管内外压差作用下存在鼓胀及爆破失效行为,其中热蠕变是关键影响因素之一。针对α相Zr蠕变存在的各向异性特点,基于Hill准则推导了应力更新算法和一致切线刚度算法,并基于有限元方法加以实现,结合与温度和辐照相关的热-力学物性、α-β相转变模型和爆破失效限值经验模型,获得了Zr包壳的鼓胀行为分析工具。采用厚壁圆管蠕变问题的理论解析解进行了确认,通过与PUZRY系列鼓胀爆裂实验对比进行了验证,结果表明:相较于常规的各向同性蠕变算法,各向异性蠕变算法能够更好地预测α相区间的Zr包壳高温鼓胀;对于α+β混合相区间,目前常用的加权混合方法计算蠕变速率还存在较大误差;对于加压速率较大的工况,如果仅仅考虑蠕变的影响,则会存在较大误差。As the discharge burnup of nuclear fuel is increasing in light-water reactor(LWR)nuclear power plant for better economic performance,safety-related issues of high-burnup fuel is drawing much attention in the nuclear energy community.It has been widely reported that during a loss-of-coolant accident(LOCA),highly irradiated fuel pellet is prone to fragmentation,relocation and dispersion.This phenomenon brings about the question of whether current safety criteria is still applicable or how the safety margin would be affected by the high-burnup fuel,since current safety criteria was established several decades ago based on low-burnup irradiation experiment database.During a LOCA,Zr clad tube exhibits the mechanical damage behavior of ballooning under the condition of high temperature and pressure difference across the tube thickness,which would facilitate fuel relocation and generate intense heating to the clad by the high-temperature fuel fragments in the ballooned region.This paper aims to develop a robust and efficient algorithm in the framework of finite element method(FEM)to study the Zr clad tube ballooning in a high-fidelity manner.High-temperature creep has been recognized as one of the key influencing factors for the ballooning.For the purpose of simplifying calculation,the creep of Zr clad tube was often treated as isotropic in the literature,i.e.[KG-3],based on the von Mises criterion,which could lead in nonnegligible error in the prediction.In view of this,an algorithm for stress update and consistent tangential stiffness computation was derived based on Hill’s criterion,considering the fact that the creep of Zr clad in theα-phase region is anisotropic.Together with temperature-and irradiation-dependent thermo-mechanical properties,theα-βphase transition model as well as empirical burst limit models,an analysis tool for the ballooning simulation of Zr clad was implemented within the finite element software ABAQUS.The analysis tool was verified by the analytical solution of the thick-walled cylinder t

关 键 词：各向异性蠕变 包壳鼓胀 有限元模拟 

分 类 号：TL34[核科学技术—核技术及应用]