1000 MW核电站SEC系统鼓型滤网抗震计算

采用反应谱抗震计算方法,用SRSS方法组合鼓型滤网结构的各阶固有模态,并将多种地震波放大系数组成的包络线作为输入地震载荷,对1000 MW核电站重要厂用水(SEC)系统鼓型滤网结构进行了多种地震波输入的抗震计算。计算得到鼓型滤网应力最大响应发生在主轴与A型主辐条连接处,为69.75 MPa;位移最大响应发生在主横梁端部,为12.50 mm。按第三强度理论校核,强度满足抗震要求,但侧密封设计间隙(12 mm)小于位移最大响应,不满足抗震要求,需加大侧密封间隙以提高鼓型滤网抗震水平。     

某核电厂LOCA下预应力混凝土安全壳响应规律初探

核电厂LOCA发生后,预应力混凝土安全壳结构内温度场分布具有明显的非线性特征,但现行的混凝土安全壳设计规范未对LOCA下温度和应力的组合作用提出具体的计算方法。基于用ANSYS程序建立的包含预应力钢束的混凝土安全壳结构的有限元模型,本文计算了LOCA下不同时刻安全壳壳壁内的温度场分布,并与理论值进行了比较,验证了计算模型的正确性。初步分析了高温、高压作用下安全壳结构变形的规律,总结了混凝土温度效应和预应力系统的作用,可为安全壳结构设计提供参考。     

基于ANSYS的核电厂安全壳结构非线性有限元分析

对核电厂预应力混凝土安全壳结构进行了内压作用下的非线性有限元分析.详细介绍了ANSYS中的混凝土单元SOLID65及混凝土材料的本构关系,并对非线性求解过程中影响收敛的因素进行了分析；同时,以福清核电厂5、6号机组内层安全壳为工程实例进行有限元计算.结果表明,15 m至30 m标高范围内的径向位移大于其他高度的径向位移,标高25 m左右径向位移最大；内压加至0.42MPa,模型结构仍处于受压状态,满足使用要求.分析表明,福清核电厂5、6号机组安全壳结构在设计内压作用下是安全的,可为安全壳整体性试验提供参考.     

设计基准内压下混凝土安全壳的有效预应力作用研究

核电厂安全壳建造过程中大量采用预应力技术,预应力在设计基准内压下的分布状况、损失规律直接影响到安全壳结构的耐久性。介绍了某核电厂安全壳结构和预应力系统的布置情况和预应力损失的分析过程,以闸门洞口附近水平预应力钢柬为例进行了预应力损失计算,同时计算了5年打压试验时安全壳结构的有效预应力。基于以上分析,利用ANSYS程序建立预应力混凝土安全壳有限元模型进行结构计算,对设计基准内压下的有效预应力作用进行了总结。结果表明,预应力系统承担了打压试验下大部分设计内压,安全壳整体结构是安全的,这些结论与安全壳的预应力系统设计理念一致,可供工程设计人员参考。     

先进核电厂半球顶安全壳抗震分析

安全壳是核电厂反应堆主厂房的围护结构,是防止设计事故发生时放射性物质扩散的最后一道屏障,是确保核电厂安全的关键设施.因此,必须在设计中考虑到安全壳在可能的、会引发重大核事故的意外荷载作用下的工作性能.地震是核电厂整个使用过程中有可能出现的自然灾害之一,并可能引发重大事故,所以,必须对安全壳结构进行严格的抗震性能分析,设计要保证预应力混凝土安全壳能够承受SSE作用而不被损坏.本文通过有限元模型的计算与分析,得到先进核电厂半球顶安全壳结构在SSE作用下的应力、变形、位移等地震反应,由此进行安全壳结构构件抗震分析计算.计算表明,半球顶安全壳结构在SSE作用下,安全壳结构安全可靠,结构的设计能够满足我国核电厂安全导则对抗震Ⅰ类结构的规定.     

基于构件尺度的预应力混凝土徐变模型研究

为评估核电厂安全壳结构的长期预应力损失,以预应力混凝土梁为研究对象,采用试验研究与理论分析相结合的方法,建立预应力混凝土徐变预测模型。在已有的预应力混凝土梁徐变试验基础上,采用相同的混凝土材料进行相同环境下的收缩试验,以测定预应力混凝土梁的实际收缩变形。考虑到混凝土收缩、徐变、预应力筋松弛的耦合作用,引入龄期调整有效模量法,建立由试验数据推导混凝土徐变系数的计算方法,最终建立预应力混凝土徐变模型并预测其长期徐变变形,为核电厂安全壳结构长期预应力损失评估提供了理论支撑。     

核电厂混凝土安全壳中预应力的分布和损失

本文研究了核电厂安全壳预应力系统建立过程中混凝土的应力值、安全壳应力分布模式和由于预应力施加产生的变形情况，并把这些数据与在安全壳结构强度试验（SIT）中得到的值进行比较分析，通过理论计算，讨论安全壳中预应力损失以及其安全性问题。     

考虑土结相互作用下核电厂海域沉管隧道三维抗震分析

为研究核电厂海域安全级取水沉管隧道的动力响应规律，综合考虑结构-土体的相互作用、复杂土体参数的非线性、沉管内部动水的对流效应和脉冲效应，建立了复杂土质地基条件下沉管-土体三维精细化有限元模型，并运用UPFs二次开发在ANSYS中创建了等价线性单元及黏弹性人工边界，在此基础上开展了极限地震作用下的沉管隧道动力时程分析。计算结果表明：层间位移角符合规范；顶板和底板以受弯为主，其中顶板3的弯矩最大，底板2的剪力最大；三个竖墙以受压为主。其中，中隔墙轴力最大；沉管隧道各墙连接部位内力较大，受地震影响最大。应提高顶底板的抗弯能力及竖墙的抗压能力，适当加固各墙连接部位，同时反应位移法、线弹性动力时程分析法、等价线性分析法三种方法计算出的内力规律基本一致，且等价线性法结果较为合理，反应位移法内力值较为保守。     

结构材料核的原子位移截面计算

中子辐照引起的材料损伤是裂变反应堆设计的重要考虑因素。对于晶体结构材料,其辐照损伤主要来自晶格原子的位移。结构材料核与中子发生带电粒子反应的截面、原子位移(DPA)截面、KERMA因子是计算辐照损伤的基础。为比较不同程序计算的DPA截面的差异和基于不同评价核数据库的DPA截面的差异,采用核模型计算程序UNF及核数据处理程序NJOY计算了27 Al、48 Ti、90Zr、Cr、Fe、Ni、Cu等结构材料核的DPA截面,将二者计算结果进行了比较分析;比较分析了基于不同评价核数据库的采用NJOY计算的DPA截面;比较分析了NJOY与蒙特卡罗程序计算的DPA截面。结果表明,UNF与NJOY的结果存在一定的差别,不同评价库的结果也是有差别的,蒙特卡罗程序采用不同模型计算时结果也存在一定的差别。     

CARR堆反应堆厂房土壤-结构相互作用与楼层反应谱分析

土壤-结构动力相互作用(SSI)分析及楼层反应谱(FRS)计算是中国先进研究堆(CARR)工程抗震设计的重要环节.本文采用直接法,通过建立二维土壤-结构共同工作计算模型,并分3个方向进行地震动输入,考虑土壤-结构相互作用对反应堆厂房地震反应进行分析,计算出厂房基础部位和各楼层在不同工况下的地震反应及楼层反应谱.     

Analysis of blowdown experiment of scale steam generator model

A subcooled blowdown experiment in a scale steam generator (SG) model is analyzed by the use of a fluid-structure computer code (MULTIFLEX). The experimental model simulates the secondary side of a SG with a preheater. The MULTIFLEX code that solves simultaneously a coupled set of one-dimensional hydraulic conservation equations and structural dynamic equations is used to analyze the experiment, taking into account the fluid structure interaction between the secondary coolant and the SG structure, the baffle and tube support plates and the divider plate. The computed values of pressure and wall displacement histories agree well with the experimental data. The success of the analysis supports the use of the one-dimensional MULTIFLEX code to analyses of thermal hydraulic transients in the SG secondary side and the validity of the method for modeling the complicated system of the fluid-structure interactions.     

Analysis of blowdown experiment of 110 scale steam generator model

A subcooled blowdown experiment in a $\text{1}\text{10}$ scale steam generator (SG) model is analyzed by the use of a fluid-structure computer code (MULTIFLEX). The experimental model simulates the secondary side of a SG with a preheater. The MULTIFLEX code that solves simultaneously a coupled set of one-dimensional hydraulic conservation equations and structural dynamic equations is used to analyze the experiment, taking into account the fluid structure interaction between the secondary coolant and the SG structure, the baffle and tube support plates and the divider plate. The computed values of pressure and wall displacement histories agree well with the experimental data. The success of the analysis supports the use of the one-dimensional MULTIFLEX code to analyses of thermal hydraulic transients in the SG secondary side and the validity of the method for modeling the complicated system of the fluid-structure interactions.     

小型堆安全壳在地震激励下的动力响应分析

小型核反应堆(小型堆)因具有模块化、高灵敏性及安全性等优良特性备受关注,其安全壳结构在地震作用时的动力特性对小型堆的安全性评定有着重大影响作用。将小型堆安全壳用ABAQUS软件建立三维有限元模型并模拟非线性抗震分析,模拟在地震作用下小型堆安全壳模型的频率、振型和加速度及位移等动力特性,对比前16阶振型和频率,表明安全壳的1和2阶、3和4阶等阶次的振动频率分别接近且主要振动方向为水平方向。同时以峰值分别为02g、03g与04g的地震动作为荷载输入,得到3种加速度峰值作用时预应力钢束和混凝土安全壳结构的最大主应力云图,对比发现3种地震峰值作用下混凝土安全壳的最大主应力均小于抗拉强度标准值265 MPa,且最大主应力主要集中分布在安全壳结构的闸门孔周边及基础相连的底部附近。最后对比安全壳结构的加速度与位移响应,评定结果表明在极限地震动作用下小型堆安全壳结构具有良好的安全性。     

核安全一级主管道疲劳校核

本文对某核电厂主管道疲劳及热棘轮进行了独立校核。校核采用基于RCC-M标准的ROCOCO软件,比较了RCC-M标准与ASME标准在核安全一级管道疲劳评价方面的差异。对比的主要方面包括疲劳设计的计算范围界定、一次加二次应力强度的计算方法、弹塑性修正系数的计算、动态载荷叠加方法等。通过对ROCOCO中与ASME标准不一致的算法进行修正,得到主管道冷段壁厚65 mm和55mm的疲劳使用系数和热棘轮设计裕量。结果表明:某核电厂主管道最小壁厚不能小于55 mm,55mm壁厚的热棘轮设计值达到许用值的95%。     

聚变堆氦冷固态包层结构和6Li富集度对产氚率的影响

在聚变堆固态包层基本参数基础上，建立简化20°模型，包层分第1壁装甲、第1壁冷却板、氚增殖区和支撑结构。分别选择Li₄SiO₄和Li₂O做增殖材料，应用MCNP程序，研究第1壁结构布置和6Li富集度对产氚率的影响。结果表明：₆Li富集度适宜选择在30％~80％之间；第1壁选择Be装甲可提高产氚率；冷却管板的厚度应取3cm以下，以避免对产氚造成不利的影响。     

Missile impact on a reinforced concrete structure

In this analysis an attempt was made to study the behaviour of a reinforced concrete structure under missile impact loading. The local deformations in all directions including the wall thickness, the plasticity and the stress waves at and surrounding the impact point were taken into consideration. The data of the impacting steel missile and the shape of the target concrete wall were given. As the impacting time is short in comparison to the fundamental eigenfrequency of the structure, it is possible to study the local deformation by isolating the impacted zone and its surroundings from the total structure. The boundaries of this region were considered as fully clamped. The results justified this assumption as the stresses at and near the boundaries were negligible in comparison to their counterpart at the impacting point. The PISCES 2 DL code was considered suitable for this type of calculation. Special routines defining the material and yield models for reinforced concrete were integrated in the program system.     

确定论数值反应堆程序NECP-X的开发及应用

数值反应堆是基于大规模并行计算平台,利用先进的物理模型和数值模拟算法,采用精细化建模,从而精确模拟反应堆在正常运行与事故工况中发生的各类物理现象的模拟技术。西安交通大学NECP团队基于自研的多群和连续能量数据库,提出了全局 局部耦合输运计算方法、大规模并行的2D/1D耦合输运方法等,开发了基于确定论方法的数值反应堆物理程序NECP X,并在此基础上实现了物理 热工 燃料性能分析的多物理耦合模拟计算。基于该程序及其耦合系统,在商用大型压水堆、研究堆和实验堆中进行了验证应用。数值结果表明,NECP X程序及其耦合系统可准确预测反应堆在运行过程中的关键安全参数随时间的演变情况,如有效增殖因数、功率、温度、应力、间隙宽度等,可为商用大型压水堆、研究堆和研究堆的设计及安全分析提供可靠的工具。     

Analysis and application of prestressed concrete reactor vessels for LMFBR containment

An analytical model of a prestressed concrete reactor vessel (PCRV) for LMFBR and the associated finite element computer code, involving an explicit time integration procedure, is described. The model is axisymmetric and includes simulations of the tensile cracking of concrete, the reinforcement, and a prestressing capability. The tensile cracking of concrete and the steel reinforcement are both modeled as continuously distributed within the finite element. The stresses in the reinforcement and concrete are computed separately and combined to give an overall stress state of the composite material. The reinformcement is assumed to be elastic, perfectly-plastic; the concrete is taken to be elastic, with tensile and compressive stress limits. Cracking of concrete is based on the criterion of maximum principal stress; a crack is assumed to form normal to the direction of the maximum principal stress. Attention is also given to the fact that cracks do not form instantaneously, but develop gradually. Thus, after crack initiation the normal stress is reduced to zero gradually as a function of time. Residual shear resistance of cracks due to aggregate interlock is also taken into account. An existing crack is permitted to close. Prestressing of the PCRV is modeled by special structural members which represent an averaged prestressing layer equivalent to an axisymmetric shell. The internal prestressing members are superimposed over the reinforced concrete body of the PCRV; they are permitted to stretch and slide in a predetermined path, simulating the actual tendons.The validity of the code is examined by comparison with experimental data. Both static and dynamic data are compared with code predictions, and the agreement is satisfactory. A preliminary design has been developed for both pool and loop-type PCRVs. The code was applied to the analysis of these designs. This analysis reveals that the critical locations in such a design would be the head cover and the junction between the cover and the vessel wall and indicates the pattern of crack development. The results show that the development of a design adequate for current HCDA loads is quite feasible for pool-type or loop-type PCRVs.     

主泵高压冷却器盘管的流致振动分析

为验证反应堆冷却剂泵(简称主泵)用高压冷却器结构设计在正常运行工况下可避免流致振动的发生,本研究依次从漩涡脱落、流体弹性不稳定和湍流激励3个方面分析了高压冷却器的壳侧流体对中间盘管振动产生的影响。采用预应力模态分析得到了螺旋管的固有频率为1.877 Hz,便于后续评定的对比;针对最大流通面积和最小流通面积2种极限情况分别计算了漩涡脱落频率,得到固有频率与漩涡脱落频率的比值均小于2;应用卡曼涡流频率计算得出螺旋管的流弹不稳定临界流速大于壳侧间隙流速,说明壳侧流体的流速未达到螺旋管的流弹不稳定临界流速;选用合适的螺旋管束半经验模型计算得到湍流激振的中心主频率是螺旋管固有频率的3.76倍。漩涡脱落、流体弹性不稳定和湍流激励的计算分析结果充分证明高压冷却器的结构设计是安全合理的,可满足核电厂的使用要求。     

主泵高压冷却器盘管的流致振动分析

To verify that the high-pressure cooler structure of the reactor coolant pump (reffered to as the main pump) can avoid the flow-induced vibration under normal operating conditions, this work analyzes the influence of the shell-side fluid on the vibration of the intermediate coil from three aspects, including the vortex shedding, the fluid-elastic instability and the turbulent excitation. The natural frequency of the helical tube equal to 1.877 Hz is determined by using the pre-stressed modal analysis for the comparison of subsequent evaluations. The vortex frequency is calculated for the maximum and the minimum flow areas, respectively, and the ratio of the natural frequency to the vortex frequency is less than 2. The flow velocity instability of the helical tube calculated by the Karman vortex frequency is higher than that of the shell side gap, indicating that the flow velocity of the inner shell side does not reach the critical velocity of the flow elastic instability of the helical tube. Besides, the center frequency of the turbulent excitation calculated by appropriate semi-empirical model of the helical tube bundle is 3.76 times the natural frequency of the helical tube. The results of these three calculations prove that the structural design of the HP-cooler is safe and reasonable, and can satisfy the requirements of nuclear power plants.