某核电厂钢筋混凝土楼板热分析及裂缝原因初探

混凝土结构养护期间必须进行温度控制,以保证结构构件的裂缝宽度不超过规范规定的限值。针对某核电厂反应堆厂房20.450m楼板构件,采用数值方法对混凝土楼板结构浇注养护进行了热分析。分析结果表明,混凝土楼板裂缝是温度应力和结构约束等因素综合作用的结果,且结构约束对楼板温度应力的影响更大。同时,进一步分析了楼板温度收缩机理,提出了加固措施,可为楼板裂缝加固设计提供参考。     

用声发射技术监测模拟压力管道的破裂

在力学试验研究中,采用声发射技术对已具有疲劳裂纹的核反应堆一回路模拟压力管进行加载爆破断裂的监测。利用声发射所具备的特征,研究试件在加载过程中裂纹从开裂直到断裂的动态过程。用声发射所表征的参数来解释在加载过程中各阶段的力学特征,弥补了常规力学测试方法的不足,从而观察了带有疲劳裂纹的试件其“开裂前兆-开裂-扩展-块速断裂”的全部过程,并给出各阶段的压力值。试验过程中采用微机进行实时数据处理。给出监测结果并确定出断裂位置。所得数据可用于反应堆承压构件的力学分析。     

钢板-混凝土结构内部自密实混凝土工作性能与早期力学性能研究

具有良好工作性能的自密实混凝土是钢板-混凝土结构能够实现的前提。自密实混凝土的早期力学性能是钢板-混凝土结构设计的重要参数。本文通过实验的方法对自密实混凝土的工作性能和早期力学性能进行了研究。配制出满足钢板-混凝土结构要求的自密实混凝土,并给出钢板-混凝土结构设计所需的自密实混凝土早期力学参数。研究成果可以指导钢板-混凝土结构内部自密实混凝土的施工以及钢板-混凝土结构的设计和施工。     

CARR堆反应堆厂房结构分析与密封设计

CARR厂房为典型短周期结构,是由不同结构形式和不同材料结构单元构成的复杂结构体系.部分结构整体内力分析采用Algor程序,厂房结构局部应力分析采用ANSYS程序,预应力混凝土结构计算采用PREC程序.分析计算表明,结构的最大位移发生在侧墙的中部,打压状态下的位移量约为2.28mm.应力较大的部位发生在顶板与侧墙、侧墙与楼板交接部位及两面侧墙的交角处,最大应力为2.7MPa.大梁计算挠度为13.5mm,反拱值为7.5mm,预应力度为0.745.为了控制钢筋混凝土构件的裂缝,屋面部分采用预应力混凝土结构.选用环氧树脂加玻璃布涂装衬里为密封厂房的内衬方案.     

核安全壳截锥体区域受力性能试验研究

核安全壳的壳体与筏板基础交界处（截锥体区域）形状不规则且受力复杂，研究该区域的受力机理对掌握整个安全壳的结构性能十分重要。以核安全壳截锥体区域为研究对象，在利用ABAQUS软件计算分析得到合理的截锥体缩尺模型的基础上，制作了缩尺比例1∶3的2个试件，分别进行无内压和有内压2种荷载工况下的静力试验。试验结果表明：试件1（无内压）破坏方式为弯剪破坏，发生27.7 mm水平位移；试件2（有内压）破坏方式为剪切破坏，发生32.6 mm水平位移。两试件主要裂缝区均为内侧底板与截锥体区域交界处，钢筋屈服位置主要出现在上部底板长度方向钢筋处，截锥体外侧竖向钢筋未充分发挥作用。相关结果可指导结构配筋优化工作。     

钢板混凝土模块墙温度场和应力场研究

在给定温度曲线和材料热工参数的基础上,采用三维实体单元建立钢板混凝土墙体有限元模型,进行瞬态热分析和热应力分析。计算结果表明,不锈钢面板与混凝土间、剪力钉与混凝土间的温度梯度随着时间先变大再变小;墙体截面的热应力增量随着时间逐渐变小。这为钢板混凝土模块墙的高温力学性能及承载力研究提供参考。     

华龙一号堆内构件流致振动试验研究

本项研究采用试验研究和理论分析相结合的方法对堆内构件流致振动进行了研究。根据流致振动试验的相似准则,完成了1:5试验模型设计,按照美国核管会RG1.20的要求进行试验研究及有限元分析计算。试验研究解决了传感器布置的多项技术难题,获得了大量、完整、可靠的试验数据。结合流致振动试验数据对堆内构件进行流致振动响应计算。最后利用试验和计算分析相结合的方法完成了堆内构件关键部件流致振动疲劳强度的评估。研究方法对后续的流致振动试验研究具有重要的参考价值。     

堆内构件螺纹联接件应力分析与评定

堆内构件中的螺纹联接件数量众多且受力复杂,为确保堆内构件结构的完整性,螺纹联接件的应力和疲劳分析必须满足ASME规范的相关要求.鉴于堆内构件对核电厂安全运行的重要性以及在核电厂运行工况下受到多种静、动态外力的作用,本工作根据规范要求,对堆内构件螺纹联接件的预紧力、受力状态、变形计算、载荷分类和组合、应力分析与评定等进行了综合研究,并根据研究成果开发了堆内构件联接件应力评定专用程序,使堆内构件联接件的应力评定工作能更准确、有效地进行,为工程设计和应用提供了可靠和便捷的工具.     

先进核电厂安全壳结构模型试验

安全壳是承受设计基准事故工况的安全屏障。掌握其先进技术,对于保证我国的核电地位,适应核电技术发展方向有着重要意义。冶金工业部建筑研究总院受上海核工程研究设计院的委托,承担了先进核电厂安全完结构模型试验项目。安全壳结构模型试验与工程实体安全壳结构试验相比,可对关键技术问题进行更加深入的试验研究。本模型试验通过位移、应变、裂缝、预应力值的试验结果,检验结构的非线性分析理论,实测极限承载能力和破坏状态,并为实体设计提供试验依据。最终的破坏试验将在今年7月结束。本模型属于第三代预应力混凝土安全壳,模型与…     

AP1000核电厂CA模块转角部位承载力分析

基于ABAQUS有限元分析软件,对AP1000核电厂中的CA模块转角部位在不同内力工况下进行了详细的有限元分析,分析研究了CA模块转角部位在不同内力工况下的破坏部位及破坏状态,得到了不同内力工况下CA模块转角部位的承载力—位移曲线及极限承载力。分析研究了轴向力对结构模块转角部位的承载力的影响,以及模块中剪力钉的受力特性,对钢板与混凝土的共同受力进行了研究,对结构模块的分析提出了建议。     

Concept study for a combined reinforced concrete containment

A variety of different types of steel and concrete containments have been designed and constructed in the past. Most of the concrete containments had been pre-stressed, offering the advantage of small displacements and a certain leak-tightness of the concrete itself. However, considerable stresses in concrete as well as in the tendons have to be maintained during the whole lifetime of the plant in order to guarantee the required pre-stressing. The long-time behaviour and the ductility in the case of beyond-design-load cases must be verified. Contrary to a pre-stressed containment a reinforced containment will only be significantly loaded during test conditions or when needed in case of an accident. It offers additional margins which can be used especially for dynamic loads such as impacts or for beyond-design events.The aim of this paper is to show the feasibility of a so-called combined containment which means a containment capable of resisting both severe internal accidents and external hazards, mainly the aircraft crash impact as considered in the design of nuclear power plants in Germany.The concept is based on a lined reinforced containment without pre-stressing. The mechanical resistance function is provided by the reinforced concrete and the leak-tightness function is provided by a so-called composite liner made of non-metallic materials. Some results of tests performed at Siemens laboratories and at the University of Karlsruhe which show the capability of a composite liner to bridge over cracks at the concrete surface will be presented in the paper.The study shows that the combined reinforced concrete containment with a composite liner offers a robust concept with high flexibility with respect to load requirements, beyond-design events and geometrical shaping (arrangement of openings, an integration of adjacent structures). The concept may be further optimized by partial pre-stressing at areas of high concentration of stresses such as at transition zones or at disturbances around large openings.     

Comparative assessment of impact resistance of SC and RC panels using finite element analysis

In this paper, the impact resistance of steel-plate concrete (SC) and reinforced concrete (RC) panels is evaluated using the commercial software LS-DYNA. The structural components and their contacts are fully modeled in the analysis, and the material nonlinearity and strain rate effect for concrete and steel are considered. The analysis results of SC and half steel-plate concrete (HSC) panels under impact loading are compared with the test results conducted in previous research in order to determine the main factors influencing the analysis. The impact analyses as per four different concrete thicknesses with five different steel ratios are performed in order to compare the impact resistance of the SC and RC panels. Failure mode, damage size, and displacement of the SC and RC panels are investigated. The results show that the SC panel has better impact resistance than the RC panel. Finally, the impact analyses for optimal panel design are performed, and the optimal concrete thickness and steel ratio are recommended.     

The effect of a single tensile overload on stress corrosion cracking growth of stainless steel in a light water reactor environment

It has been found that a single tensile overload applied during constant load amplitude might cause crack growth rate retardation in various crack propagating experiments which include fatigue test and stress corrosion cracking (SCC) test. To understand the affecting mechanism of a single tensile overload on SCC growth rate of stainless steel or nickel base alloy in light water reactor environment, based on elastic-plastic finite element method (EPFEM), the residual plastic strain in both tips of stationary and growing crack of contoured double cantilever beam (CDCB) specimen was simulated and analyzed in this study. The results of this investigation demonstrate that a residual plastic strain in the region immediately ahead of the crack tips will be produced when a single tensile overload is applied, and the residual plastic strain will decrease the plastic strain rate level in the growing crack tip, which will causes crack growth rate retardation in the tip of SCC.     

不同方法评定核压力容器用A508CL3钢动态断裂韧性的比较

采用示被冲击试验及预制疲劳裂纹Ｃｈａｒｐｙ试样，通过几种不同的单试样试验方法对核压力容器用Ａ５０８ＣＬ３钢的动态断裂韧性进行了评定，比较了各种方法的优缺点。研究载荷能量法过高地评定了材料的动态裂韧性值；而柔度变化度法的评定值则过低，断口延伸带宽度测试法的评定结果具有较大误差，且试验过程复杂，成本较高；能量修正法是一种方便而精确的评定核压力容器钢动态断韧性的单试样方法。     

Recent results on the evaluation of the overpressure response of concrete and steel containments

Analytical studies have been performed for the evaluation of the ultimate load capacity of concrete containment structures. In addition, analyses of steel containment models were carried out to validate computer codes for the analysis of steel containment structures. This paper reports on some of the results of these analyses, dealing first with the global ultimate load behavior of typical prestressed and reinforced concrete containment structures. The results of these analyses are described, with particular attention given to identifying local effects and failure mechanisms of concrete containment structures. On the basis of the global analysis results, local effects analyses were carried out which show clear evidence of large strain concentrations in the liner. The utility of the ABAQUS-EPGEN code is also demonstrated for three steel containment small-scale models tested by Sandia National Laboratory. The basic geometry of the models consisted of a thin cylindrical shell with a hemispherical dome. One of the models included ring stiffeners in the cylinder, and the other model included penetrations without ring stiffeners. The results of these calculations are presented without test data comparisons.     

Nanoindentation on ion irradiated steels

Radiation induced mechanical property changes can cause major difficulties in designing systems operating in a radiation environment. Investigating these mechanical property changes in an irradiation environment is a costly and time consuming activity. Ion beam accelerator experiments have the advantage of allowing relatively fast and inexpensive materials irradiations without activating the sample but do in general not allow large beam penetration depth into the sample. In this study, the ferritic/martensitic steel HT-9 was processed and heat treated to produce one specimen with a large grained ferritic microstructure and further heat treated to form a second specimen with a fine tempered martensitic lath structure and exposed to an ion beam and tested after irradiation using nanoindentation to investigate the irradiation induced changes in mechanical properties. It is shown that the HT-9 in the ferritic heat treatment is more susceptible to irradiation hardening than HT-9 after the tempered martensitic heat treatment. Also at an irradiation temperature above 550 °C no detectable hardness increase due to irradiation was detected. The results are also compared to data from the literature gained from the fast flux test facility.     

Development of high-performance concrete having high resistance to chloride penetration

The resistance to chloride penetration is one of the simplest measures to determine the durability of concrete, e.g. resistance to freezing and thawing, corrosion of steel in concrete and other chemical attacks. Thus, high-performance concrete may be defined as the concrete having high resistance to chloride penetration as well as high strength. The purpose of this paper is to investigate the resistance to chloride penetration of different types of concrete and to develop high-performance concrete that has very high resistance to chloride penetration, and thus, can guarantee high durability. A large number of concrete specimens have been tested by the rapid chloride permeability test method as designated in AASHTO T 277 and ASTM C 1202. The major test variables include water-to-binder ratios, type of cement, type and amount of mineral admixtures (silica fume, fly ash and blast-furnace slag), maximum size of aggregates and air-entrainment. Test results show that concrete containing optimal amount of silica fume shows very high resistance to chloride penetration, and high-performance concrete developed in this study can be efficiently employed to enhance the durability of concrete structures in severe environments such as nuclear power plants, water-retaining structures and other offshore structures.     

基于W型试样确定A508-Ⅲ钢参考温度T0的方法研究

在我国早期开发的W型试样的基础上,参考ASTM E1921标准,开发了基于W型试样的断裂韧性测试技术,建立了包括断裂韧性计算、数据有效性判定和参考温度T₀计算等在内的数据分析方法。在-100～-40 ℃下开展了国产A508-Ⅲ钢的W型试样和标准1C(T)试样的测试分析和试验数据的有效性评价。结果表明,基于W型试样可得到满足ASTM E1921标准的有效断裂韧性数据,W型试样数据点均在标准1C(T)试样master curve(主曲线)的置信区间内,基于W型试样确定的参考温度T₀与标准1C(T)试样的非常接近,W型试样可成为RPV辐照监督备选试样。     

Recent developments in the finite element analysis of prestressed concrete reactor vessels

This paper describes recent developments in the nonlinear deformation and ultimate load analysis of prestressed concrete reactor vessels using finite elements. First, a number of finite element models are called into attention for the idealization of composite structures such as reinforced and prestressed concrete components. Then different inelastic constitutive models are proposed for the behaviour of concrete in the pre- and post-failure regime. Subsequently various numerical techniques are examined for the solution of nonlinear problems, especially with regard to their distortion of the constitutive model. In conclusion these modelling techniques are applied to the analysis of four typical examples, the nonlinear deformation analysis of a concrete specimen subjected to biaxial compression, the crack analysis of a thick-walled concrete cylinder, the overload analysis of the THTR 1 : 5 scale model, and the ultimate load analysis of a concrete top closure model.     

Results of large-scale test of discontinuity region in a prestressed concrete containment

The test described in this paper is part of an Electric Power Research Institute (EPRI) program (Research Program RP2172-2) to provide a test-verified analytical method of estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents.Phase 2 of the EPRI program, on which this paper is based, includes tests of five large-scale specimens with steel liner plates. The specimens represent structural elements of prestressed concrete containment buildings. Four full-scale square wall element specimens and one specimen representing the wall/basemat junction region were tested. This paper describes results of the wall/basemat junction region test.Results of this experimental work indicate that highly localized strains in the steel liner plate caused by internal overpressurization or other accident conditions can result in liner tearing and subsequent containment leakage. It appears that this liner tearing occurs in a controller manner. Extrapolating from these test results, leakage and depressurization is more likely to occur than global failure.