压水堆堆内构件老化评估方法及其应用

本文介绍了压水堆堆内构件老化分析评定方法。该方法通过建立老化机理筛选准则、初步分类、堆内构件的故障模式、影响及危害分析(FMECA)以及识别主要潜在老化部件等步骤,最终完成堆内构件老化程度的评估。老化评估结果为堆内构件的老化管理奠定基础。该老化评估方法已首次成功应用于秦山CNP320机组和CNP650机组堆内构件的老化评估。     

CAP1000反应堆堆内构件在直接安注下流动传热特性研究

在CAP1000反应堆中，使用了压力容器直接安全注射方式。由于安全注射管嘴和堆内构件的布置方式可能导致堆内构件承受较强的低温水影响，本文研究了吊篮外壁上布置的关键部件的表面温度分布及对流换热能力。使用缩比模型实验测量了堆内构件关键部位在不同安全注射条件下的壁面温度分布和换热系数，使用数值分析获得了堆内构件表面整体温度分布和换热系数。研究得到了辐照监督管顶部等危险区域上几个关键点的壁面温度和换热系数与安全注射条件间的无量纲关联式。      

压水堆核电厂堆内构件制造的质量监督

分析了堆内构件制造工艺中的重点和难点,就如何进行堆内构件制造的质量控制与监督进行了探讨.特别对堆内构件中重要部件的制造过程和堆内构件装配过程中质最控制的重点、难点进行了详细的阐述,给出了堆内构件制造驻厂监造中的主要关注点,同时也给出制造过程质量监督中其他还需要注意的要点,如文件控制、人员控制.     

高温气冷堆石墨构件的碰撞力学行为研究

高温气冷堆的反射层和隔热层主要由数量庞大的石墨砖和碳砖组成，在地震或冲击载荷作用下，部件之间可能发生滑移和碰撞，影响其结构完整性。简化的数值分析模型是研究这种大规模散体结构的重要手段，而其中模拟碰撞的非线性连接单元参数对分析的收敛性和结果的准确性至关重要。本文对高温气冷堆中石墨构件的3种典型碰撞形式进行了实验研究，测量得到了各碰撞模式下碰撞时间和恢复系数与碰撞速度的关系。针对碰撞实验中边界条件与堆内实际构件的差别，采用商业有限元分析软件ABAQUS对不同碰撞形式进行了数值分析，进一步获得了更为准确的碰撞特性，并通过改进的Hertz碰撞模型对实验和数值结果进行分析，得出了非线性碰撞连接单元的等效刚度系数和等效阻尼系数。最后利用数值分析方法进行了与堆内构件设计相关的质量和间隙尺寸对碰撞单元等效刚度系数和等效阻尼系数的详细研究，为高温气冷堆石墨和碳堆内构件的设计提供参考。     

秦山核电厂堆内构件围板螺栓老化评估

介绍了秦山核电厂为评估堆内构件围板螺栓的实际老化状态,在吸收总结国际上堆内构件老化机理研究成果的基础上建立了堆内构件围板螺栓的老化机理判断准则,用其评估识别围板螺栓主要受磨损、应力松弛、辐照肿胀、辐照促进应力腐蚀开裂等老化机理的影响,并针对老化机理可能导致的缺陷类型,开发了水下超声检查技术补充常规的目视检查方法,从而制定评估老化状态的检查方案。评估结果表明,秦山核电厂堆内构件围板螺栓老化状态良好,尚未发生变形、裂纹等老化失效现象。实践证明该评估方法行之有效,可用于压水堆核电厂部件老化评估工作。     

冷中子源堆内部件失效分析

反应堆的冷中子源装置以液氢作为慢化剂,冷中子源堆内部件的安装位置靠近反应堆堆芯。基于对冷中子源及反应堆安全性影响的考虑,本文对冷中子源堆内部件在各种运行工况(包括失效事件)的状态及事故后果进行了分析。结果表明,堆内部件的失效影响仅局限于冷中子源内部,不会对反应堆安全造成危害。     

压水堆核电站堆本体主要部件的用户安全要求

堆本体主要部件(包括反应堆压力容器、堆内构件、控制棒驱动机构)的功能是压水堆核电站安全服役的关键。本文论述了这三个堆本体主要部件的功能要求、设计要求和其它特殊要求，可做为压水堆核电站设计工作的参考。     

二代加核电堆内构件实堆辐照监督结构研究

核电反应堆堆内构件在反应堆延寿分析中需考虑设备材料的辐照老化。目前国内尚无堆内构件材料的具体辐照数据,同时针对不同堆型及具体的机组,由于其运行使用也不尽相同,对于具体机组的辐照老化分析,还需考虑其具体的功率运行史,因此,为了较为准确地了解辐照老化对堆内构件使用的影响,本文提出了堆内构件实堆辐照监督结构方案。     

中国实验快堆堆内构件应力分析与评定

本文是中国实验快堆堆内构件主要部件的应力分析与评定汇总报告.主要构件包括堆内支承结构、堆芯支承结构、堆内热屏蔽等7类设备.堆内各部件采用有限元方法按其特点进行整体分析或部件分析.文章首先建立结构的计算模型,然后,对有限元计算模型进行在自重、流体流动压差、冷却剂流动引起的结构振动和温差载荷条件下的静态分析计算和结构的模态分析以及地震载荷下的动态分析.最后,按规范要求对堆内各结构在承受的各种载荷条件下进行载荷组合与评定.     

核反应堆故障早期检测和在线状态监测方法

即将颁布的核行业标准《核电厂反应堆堆内构件的振动监测》(简称标准)对早期监测反应堆压力容器堆内构件蜕化的方法、故障检测仪表和监测程序提出了要求,适用于以中子波动信号和反应堆压力容器振动信号为基础的堆内构件和一回路部件的动态特性的监测。本文强调了标准所包含的核电站新型仪表控制系统的监测方法。新系统不同于传统的监测系统,它的主要目的是早期故障检测．以便向电厂操纵员和检查维修人员提供有用的状态信息。     

A simpler approach for predicting LWR vessel failure during severe accident conditions

Using closed-form solution techniques, models were developed for assessing the thermal and structural response of light water reactor (LWR) vessels and penetrations during severe accident conditions. Results from models are displayed as failure maps, generally developed in terms of non-dimensional groups, so that a broader range of reactor design parameters and severe accident conditions can be considered. In this paper, failure maps are used to compare LWR vessel response to three accident conditions. Results discussed within this paper illustrate the importance of vessel and tube geometrical parameters and material properties for predicting which vessel failure mode occurs first.     

钠冷快堆换料系统可靠性研究

由于中子通量以及冷却剂运行温度高,钠冷快中子反应堆（简称钠冷快堆）的换料周期较一般轻水反应堆短。同时,换料过程中隔绝空气的要求以及换料设备本身的复杂性,钠冷快堆只能逐根进行换料,使得总的换料时间较轻水反应堆长。本文采用失效模式与影响分析、故障树分析等方法对典型钠冷快堆换料系统各部分的可靠性进行评价,获得了换料系统每次换料期间的失效概率。基于换料系统各部分失效的影响、失效概率以及恢复时间,分析了换料系统不同失效模式对反应堆运行效率的影响。     

田湾核电厂数字化反应堆保护系统故障模式与后果分析

从田湾核电厂数字化反应堆保护系统的结构出发，对数字化保护系统可能出现的故障种类、影响区域和故障后果等进行了详细分析,通过故障模式与后果分析（FMEA）方法，对田湾核电厂数字化反应堆保护系统是否存在设计薄弱环节作出了判断。本工作为国内数字化反应堆保护系统设计提供了一些新思路。     

Operational Experiences of Fast Neutron Source Reactor “YAYOI” as Pulsed Fast Reactor

University of Tokyo research reactor “YAYOI” is intended to be operated as a dynamic fast neutron source reactor as well as a stationary one. It is equipped with reactivity adding devices with both slow and quick action, and a LINAC PNS (Pulsed Neutron Source) to be operated with the devices mentioned above. The unique idea of fly-through type pulse reactivity addition into the core lends itself to minimizing thermal shock problems pertaining to fast burst reactors thereby increasing safety of a single shot type burst reactor.

Operational experiences of YAYOI obtained during the dynamic testing of super critical state are described here with some explanation of design aspects of YAYOI as a fast pulsed reactor.

Throughout present experiments, the super prompt critical state reactivity of about up to 29 cents was realized for YAYOI core, and it was confirmed that the sizes of pulse power were well controllable with this reactivity pulser (R-P) mode pulse operation.     

Recursively coupled thermal and mechanical FEM-analysis of lower plenum creep failure experiments

Postulating an unlikely core melt down accident for a light water reactor (LWR), the possible failure mode of the reactor pressure vessel (RPV) and its failure time have to be investigated for a determination of the load conditions for subsequent containment analyses. Worldwide several experiments have been performed in this field accompanied with material properties evaluation, theoretical, and numerical work.     

FMEA法评估反应堆控制棒驱动机构可靠性

控制棒驱动机构是反应堆本体中唯一的能动设备,其运行的可靠性对反应堆的反应性控制具有重要的作用。本文在介绍失效模式及影响分析(FMEA)方法的基础上,以我国新设计的反应堆控制棒驱动机构为对象,使用该方法进行可靠性评价。评价结果明确了各设备部件的失效原因和失效模式,确定了各部件的严重性等级和风险等级,为今后控制棒驱动机构的可靠性管理提供支持。     

Overview of NRC sponsored LWR lower head failure research program

The US Nuclear Regulatory Commission (US NRC) has sponsored a research program to investigate the mode and timing of vessel lower head failure. Major objectives of the program were to identify plausible failure mechanisms and to develop a method for determining which failure mode would occur first for different light water reactor designs and accident conditions. Failure mechanisms, such as tube ejection, tube rupture, global vessel failure, and localized vessel creep rupture, were studied. Newly developed models and existing models were applied to predict which failure mechanism would occur first in various severe accident scenarios. So that a broader range of conditions could be considered simultaneously, the calculations relied heavily on models with closed-form or simplified numerical solution techniques. Finite element techniques were employed for analytical model verification and examination of more detailed phenomena. High-temperature creep and tensile data were obtained for predicting the vessel and penetration structural response. This paper summarizes major accomplishments and conclusions from research performed in the NRC sponsored lower head failure project.     

严重事故IVR下反应堆压力容器耦合传热数值模拟分析

堆芯熔化严重事故下保证反应堆压力容器（RPV）完整性非常重要,高温蠕变失效是堆芯熔化严重事故下反应堆压力容器的主要失效模式。在进行严重事故堆芯熔化物堆内包容（IVR）下RPV结构完整性分析中,RPV内外壁和沿高度方向的温度分布以及剩余壁厚是结构分析的重要输入。本文采用CFD分析方法对RPV堆内熔融物、RPV壁以及外部气液两相流动换热进行热-固-流耦合分析,获得耦合情况下的温度场、流场、各相份额分布以及RPV的剩余壁厚,为RPV在严重事故IVR下的结构完整性分析提供依据。     

Experimental qualification of subassembly design for Prototype Fast Breeder Reactor

The Prototype Fast Breeder Reactor (PFBR) which is under construction at Kalpakkam, India, is a 500 MWe sodium cooled pool type reactor. The core of the PFBR consists of 1758 free standing subassemblies supported on the grid plate. The entire core is divided into 15 different flow zones and the flow rate required through each zone is calculated based on the fission heat generation. The coolant sodium flows from the bottom of the subassembly to top and the design of the subassembly for each flow zone is quite complex. There are 181 fuel subassemblies in PFBR core with 217 fuel pins in each subassembly, vertically held in the form of bundle within a hexagonal wrapper tube. The pins are separated by spacer wires wound around the pins helically. Analytical prediction of subassembly pressure drop, vibration and determination of inception of cavitation for this complex geometry is very difficult. So experiments were conducted extensively to get a more accurate evaluation of the design and for its qualification for the use in PFBR, which is designed for 40 years of operation.Pressure drop and cavitation experiments were carried out in water on full scale (1:1) subassemblies of all flow zones. The overall pressure drop of the subassembly determines the ratings of the pump. Cavitation of the pressure drop devices lead to erosion damage of fuelpins and may also result in reactivity fluctuation due to sodium-void effect. So it is essential to confirm that the subassembly is not cavitating in the operating regime of the reactor. Subassembly can vibrate in cantilever mode due to the turbulence in the flow and can result in reactivity fluctuation, reactor control problem and can even lead to the failure of the fuel pins. So vibration measurements were carried out in water on the maximum rated subassembly. This paper discusses various experiments carried out on PFBR subassembly, the similarity criteria followed, instrumentation, results and conclusion.     

Progress on PWR lower head failure predictive models

A good understanding of the mechanical behaviour of the reactor pressure vessel (RPV) lower head is necessary both for severe accident assessment and for the definition of appropriate accident mitigation strategies. Indeed, a well-characterized failure of the lower head leads to a better evaluation of the quantity and kinetics with which core material can escape into the containment. These are the initial conditions for several ex-vessel events such as direct heating of the containment or molten core-concrete interaction.In this context, the objectives of the joint on-going work of the WP10-2 group of SARNET are: (1) improvement of predictability of the time, mode and location of RPV failure; (2) development of adequate models with the ultimate aim of being included into integral codes; (3) interpretation/analysis of experiments with models/codes combined with sensitivity studies; and (4) better understanding of the breach opening process in order to better characterize the corium release into the containment.Different approaches are considered: a simplified but well predicting model recently implemented in the severe accident Astec and Icare-Cathare codes, and viscoplasticity models implemented in the Cast3m, Ansys and Code_Aster finite element codes. Several failure criteria are considered: stress criterion, strain criterion and damage evaluation (coupled way or post-evaluation).In this paper, the OLHF-1 experiment has been used to assess the models, to perform sensitivity studies and to evaluate failure criteria that could be applied in the case of reactors. All the partners performed 2D axisymmetric analyses, allowing the evaluation of time, mode and location of vessel failure. Nevertheless, CEA conducted further 3D calculations in order to study crack propagation and the corresponding results will be presented separately at the end of the paper. The numerical formulation of the different models used is given and a comparison of experimental and numerical results is presented. The paper also shows the progress made with the objective of defining failure criteria that can be used for reactor vessel applications.