二代改进型核电站管道系统应力分析与评定

管道是核电站中的重要部件。为了使管道满足规范要求,需要对管道进行应力分析与评定。本文分析了二代改进型核电站1级和2级管道应力分析与评定过程,论述了不同载荷下管道应力的计算方法,并分析了RCC-M规范版本的变化对管道应力分析结果的影响。最后,以岭澳核电站二期工程安全注入系统为例,对管道进行了应力分析与评定,满足了RCC-M规范的设计要求,并输出了支撑载荷、接管载荷、管道位移等接口参数。本文可以为二代改进型核电站管道系统应力分析与评定提供帮助。     

安全壳管道贯穿件分析评定程序的开发

核电站中存在着一类特殊的管道穿安全壳部件,即安全壳贯穿件。其分析方法与规范要求不同于管道分析。因而,针对CAP1000电站中带封头的安全壳贯穿件,需要一套方法和流程对其进行计算、分析和评定。本文以CAP1000带封头的机械贯穿件为研究对象,经分析、研究及对比,基于通用有限元软件ANSYS,以及轴对称模型非轴对称加载和既定的载荷组合策略完成计算,基于通用文档处理软件Excel完成评定,并且应用VB软件将整个计算和分析流程界面化,开发了一套针对带封头的机械贯穿件进行应力分析和疲劳分析的应用程序。本文中的分析评定方法和流程以及基于该方法而编写的程序准确、可靠,可极大地提高工作效率。     

反应堆压力容器承压热冲击分析研究

依据RCC-M规范和美国NRC 10CFR50.61,对存在假想裂纹的反应堆压力容器堆芯带区进行承压热冲击分析研究.计算核电厂寿期末的基准温度,并采用承压热冲击筛选准则进行评定;计算了承压热冲击瞬态作用下裂纹尖端的应力强度因子,并按RCC-M规范进行评定.     

"华龙一号"双层安全壳贯穿件设计载荷计算方法研究

本文给出了HPR1000机械贯穿件在不同工况下设计载荷的确定方法,并根据载荷确定贯穿件封头的尺寸及给出贯穿件施加在安全壳的土建载荷.尤其对于高能管道中的主蒸汽和主给水管道贯穿件,由于管道管径大,且需考虑管道破裂载荷,这些巨大的破裂载荷也严重制约了安全壳和贯穿件本身的设计,为了去除分析中的保守性,本文根据管道详细破裂点位...     

循环水浸泡影响下的新型地坑过滤器抗震分析

安全壳地坑过滤器是核电厂专用的重要安全设施,用于在失水事故（LOCA）下收集安全壳内的泄漏水和喷淋水,以便再循环使用,从而保证安注泵和喷淋系统不被杂质损坏。为了对新型地坑过滤器结构的抗震性能进行分析,以其中的典型模块为例,采用ANSYS软件进行数值建模,并针对其在不同工况下进行了应力分析;地坑过滤器结构的附加水质量通过经验公式和试验的方法得到,在抗震分析中考虑了地坑过滤器结构周围流体对结构抗震性能的影响;并依据RCC-M规范对过滤器的滤筒和汇流槽进行了应力强度评定。该模块的计算结果表明,在不同工况下该新型安全壳地坑过滤器具有良好的抗震性能,满足规范的对强度的要求。     

针对热分层现象的稳压器波动管结构评价方法研究及分析程序应用开发

稳压器波动管热分层现象对核电厂安全运行具有潜在威胁。根据热分层发生机理,采用Fr数来判断热分层现象是否发生,研究热交换系数的计算方法,并将热分层引起的三维热应力解耦成一维总体应力和二维局部应力。根据RCC-M规范的要求,采用一维和二维组合的应力计算方法,将热分层产生的应力和其他载荷产生的应力叠加,进行结构完整性评定。配套本文提出的分析评价方法,对SYSTUS程序和ROCOCO程序进行应用开发。采用本文的分析评价方法和配套的分析程序,对秦山二期扩建工程稳压器波动管热分层进行分析评价,结果表明:稳压器波动管在热分层效应下结构完整性仍然满足RCC-M规范要求。     

核级转子流量计测量管段应力分析与评定

为论证流量计在各种工况下是否保持结构的完整性,利用有限元分析软件ANSYS对流量计测量管段进行分析和改进.利用计算结果,严格按照RCC-M规范对转子流量计测量管段作了应力评定.应力分析评定结果表明,转子流量计测量管段满足RCC-M对安全3级设备结构完整性的要求.     

基于APDL的反应堆压力容器接管三维应力和疲劳分析方法

应用ANSYS参数化设计语言(APDL)编制程序,对反应堆压力容器接管的应力和疲劳分析过程进行优化,快速得到接管的应力分布状况、最大应力及疲劳使用系数,并按照RCC-M规范进行评定.     

核级管道的应力分析

管道是核反应堆中重要的部件。本文介绍了核电站管道系统应力分析评定过程,即利用管道系统应力分析程序SYSPIPE,对管道承受的自重、内压、热膨胀、地震等载荷进行计算,根据RCC-M规范进行应力分析和评定。核级管道的应力分析不仅可以保证管道、支架、设备的安全,且可以优化设计,在核电站建造和运行中起到很重要的作用。     

核级管道计算程序的应用

开发一种核级管道计算程序,可采用多种规范对核级管道进行应力分析与评定。介绍程序计算原理,并以某核电工程管道系统为例,采用RCC-M和ASME规范进行计算,分别和SYSPIPE、PIPESTESS的计算结果进行对比。计算结果表明,开发的程序计算结果正确,精度满足要求。     

He冷却试验包层模块的热-力耦合分析

试验包层模块(TBM)是国际热核聚变实验堆(ITER)的关键核心组件,其设计涉及多学科综合优化分析.本文介绍了He冷却固态增殖试验包层的设计概念,并应用热功耦合模拟方法对所提出的包层概念模型的热力响应特性进行分析.结果表明,包层内部各区域的最大温度值和最大应力值均未超过材料容许的限值,所提出的包层设计概念在正常运行工况下是安全可靠的.     

FEMAXI-III,a computer code for fuel rod performance analysis

This paper presents a method of fuel rod thermal-mechanical performance analysis used in the FEMAXI-III code. The code incorporates the models describing thermal-mechanical processes such as pellet-cladding thermal expansion, pellet irradiation swelling, densification, relocation and fission gas release as they affect pellet-cladding gap thermal conductance. The code performs the thermal behavior analysis of a full-length fuel rod within the framework of one-dimensional multi-zone modeling. The mechanical effects including ridge deformation is rigorously analyzed by applying the axisymmetric finite element method. The finite element geometrical model is confined to a half-pellet-height region with the assumption that pellet-pellet interaction is symmetrical. The 8-node quadratic isoparametric ring elements are adopted for obtaining accurate finite element solutions. The Newton-Raphson iteration with an implicit algorithm is applied to perform the analysis of non-linear material behaviors accurately and stably. The pellet-cladding interaction mechanism is exactly treated using the nodal continuity conditions. The code is applicable to the thermal-mechanical analysis of water reactor fuel rods experiencing variable power histories.     

A three-dimensional method for integrated transient analysis of reactor-piping systems

A three-dimensional method for integrated hydrodynamic, structural, and thermal analyses of reactor-piping systems is presented. The hydrodynamics are analyzed in a reference frame fixed to the piping and are treated with a two-dimensional Eulerian finite-difference technique. The structural responses are calculated with a three-dimensional co-rotational finite-element methodology. Interaction between fluid and structure is accounted for by iteratively enforcing the interface boundary conditions.A thermal transient capability has been developed. A system energy equation is used to compute the coolant temperatures due to convection. A radial heat-conduction equation is employed to establish the temperature profile throughout the pipe-wall thickness. The constitutive equation used for the thermal-mechanical stress calculation is suited for a large number of materials under various loading conditions, such as those having thermal, plastic, and viscous effects. The flow surface, which defined the purely elastic regime, can be arbitrarily small; an associated flow rule is utilized for regimes of material plasticity.Three sample problems are presented to illustrate this method. The first one calculates the piping response under the seismic excitation. The second one validates the heat-conduction model. The third problem deals with a coupled hydrodynamic-structural-thermal analysis of a piping system. Results are discussed in detail.     

Finite element analysis of linear and nonlinear heat transfer

The finite element method is rapidly becoming a popular procedure for the evaluation of thermal stresses in complex structures. In linear analysis the method has been used extensively and has been coupled with stress analysis computer programs in order to automate thermal stress analysis. However, for the method to be effective, efficient numerical techniques need to be used. The purpose of this paper is to survey the recent developments in linear heat transfer analysis and, specifically, to present the techniques that permit the practical analysis of large and complex three-dimensional heat conduction problems. Typical practical problems are described and solution times are presented. In the analysis of systems with nonlinear thermal properties the method has had limited application. In this paper the general formulation of the incremental equations used in nonlinear heat transfer analysis are presented. An efficient numerical solution of the equations is given. Several types of nonlinearities are discussed and the solutions of some typical problems are presented.     

弥散型燃料板辐照肿胀行为的有限元分析

采用颗粒复合材料的细观力学研究思路,针对弥散型燃料板,选择一种代表性单元作为研究对象,用与裂变密度和燃耗相对应的、不断增大的裂变压力模拟燃料颗粒裂变对铝基体所产生的力学贡献,对研究对象进行了热力耦合分析.考察了裂变压力、温度应变和燃料颗粒沿厚度非均布对颗粒肿胀的影响,并对弥散型燃料板基体的米塞斯应力分布情况进行了分析.研究结果表明,颗粒百分比含量越高,颗粒肿胀的速度相对越快;随着裂变压力增大,颗粒肿胀的速率急剧增大,且颗粒不再是圆形;在正常工作和选取的参数条件下,温度应变对总变形的影响不大;当裂变压力不大时,非均匀分布对颗粒肿胀几乎没有影响,随着裂变压力的增大,非均匀分布的颗粒肿胀明显高于均布情况,而且越来越明显;基体的应力非球对称分布.     

多孔介质方法在池式快堆系统分析软件SAC-CFR三维钠池计算模型中的应用

为准确分析池式快堆热钠池内的热工水力学特性,在已开发出的用于池式快堆系统分析的钠池三维计算模型的基础上,应用多孔介质方法建立钠池内中间热交换器、主泵、事故热交换器及屏蔽柱模型,完成了含有多孔介质模型和复杂几何边界的钠池三维计算模型开发。将该模型嵌入池式快堆系统分析软件SAC-CFR后,分析了中国实验快堆在稳态运行和紧急停堆工况下钠池内的流场分布,初步证明了所采用的多孔介质模型的合理性,为下一步非能动余热排出系统模型的开发做准备。     

A general theory for elastic solids with temperature dependent mechanical properties

In this paper the linear theory of thermoelasticity is modified to include the case where the thermal and mechanical properties of the material depend on temperature. The study is motivated by a review of experimental data which clearly demonstrate that the properties of steel and aluminum vary significantly which moderate changes in temperature. The governing coupled equations are derived using the principles of mechanics and thermodynamics. The structure of the coupling between the temperature and strain rate is analyzed, and the requirements for uncoupling are discussed. The paper is concluded with the governing equations of the Airy stress function for thermal plane stress problems and the Helmholtz potential vector for three-dimensional problems.     

Thermal fatigue strength of type 304 stainless steel in simulated BWR environment

Thin-walled cylindrical carbon steel specimens were thermally fatigued in a pressurized autoclave. Since high and low temperature pure water were alternately supplied into the autoclave, the specimens were subjected to homogeneous thermal stress through the wall thickness. The thermal fatigue life was defined as the number of cycles to crack penetration to the inside of the cylindrical specimen. The thermal fatigue strength was compared with the mechanical fatigue strength performed in air and in high temperature water. Even if taking account of the Higuchi-Iida formula, which considers the effects of strain rate, dissolved oxygen concentration and water temperature on fatigue life, the thermal fatigue lives of carbon steel were found to be slightly shorter than the mechanical fatigue lives.     

Transient thermal stresses and displacements in a transversely isotropic, heat-generating circular cylinder

The transient thermal stress field in a traction-free, transversely isotropic, heat-generating circular cylinder is studied by means of a set of stress functions developed by Singh. The purpose of this paper is to present the results of theoretical analysis which consider the effects of the thermo-elastic anisotropies of the material on the thermal stress field in the transversely isotropic, circular cylinder due to an abrupt axial change in the internal heat-generation rate. A detailed qualitative picture of the thermal stress state for two values of the Biot number and various values of the ratio of the thermal conductivity coefficients in the axial and radial directions is given and it is demonstrated that the magnitude of the maximum thermal stress is significantly sensitive to the anisotropies of the thermal conductivity coefficient and the Young's modulus.     

基于流热固耦合的核电蒸汽发生器传热管热应力数值模拟

以大亚湾核电站蒸汽发生器为原型,基于相似模化原理建立了蒸汽发生器简化物理模型。采用两流体模型及热弹性力学基本关系式分别描述气液两相流沸腾相变过程和热应力变化规律。利用CFX对一、二回路侧流体流动传热及与传热管的耦合换热过程进行了数值模拟,并在ANSYS WORKBENCH中实现了流体温度场载荷向结构的传递,进而对传热管进行稳态热分析和热应力分析。计算结果表明：二回路出口质量含汽率为24.5%,冷却剂出口温度为296.2 ℃,均与大亚湾蒸汽发生器实际运行参数相符;传热管热应力与其壁面温差分布一致,且沿壁厚方向先减小后增大,并存在中性层,传热管最大热应力为54.5 MPa。研究结果为蒸汽发生器的优化设计及安全运行提供了一定的理论支撑。