基于PC/104计算机的X荧光分析软件的研制

研制了以PC/104嵌入式微机为数据处理设备、在DOS环境下运行的X荧光分析软件.该软件除能完成文件管理、峰面积计算、定时测量等原有功能外,还能完成谱线光滑、自动能量刻度、谱线识别、自动寻峰、元素的自动定性分析等功能.通过串口通讯,能够将DOS环境下的X射线荧光分析系统程序下载到X荧光分析仪中.应用该分析软件,能够更方便地对核谱数据进行处理与分析.     

A new method for on-line surveillance of nuclear power reactors based on decision theory

In this paper a new method for the automatic monitoring of reactor operational states based upon decision theory is introduced. The observation space is represented by spectral density functions estimated in discontinuous time intervals. After an empirical mathematical modelling of the process and its hierarchical structuring, a combined identification, estimation and detection algorithm is described. The classification of each subsystem is given via a sequential hypothesis test. Furthermore, the possibility of an adaptive learning or training is demonstrated. After a logical, system specific association of the resulting pattern, a diagnostic prognosis about the system state is made which contains integral information about a time interval extending in the past. The implementation of this method is illustrated by an example and the preliminary results are presented.     

Seismic response analysis of RCC structure with yielding dampers using linearization techniques

Passive energy dissipating devices like elasto-plastic dampers (EPDs) can be used for retrofitting of structures subjected to seismic loads. A model of reinforced concrete structure is tested on shake table with and without EPDs attached in its frames. Using a finite element model of the structure, linear and nonlinear time history analysis is carried out using Newmark's time integration technique. However, the most viable approach used by designers is response spectrum approach. Hence equivalent linearization techniques are used to address the nonlinearity of dampers and iterative response spectrum method is used for evaluating the response of the structure using equivalent damping and stiffness. The analytical maximum storey response of the structure is compared with experimental values and time history analysis values. It has been concluded that, iterative response spectrum technique using equivalent linearization techniques is simple and results in reasonably acceptable response of the structures retrofitted with energy dissipaters.     

Disturbance Identification Method of Pressurized Water Reactor Plant Operated with Automatic Frequency Control by Applying Projection Operator Technique

The identification method applying the projection operator for less small disturbances which do not instantly lead the alarm initiation has been extended to diagnose PWR plants operated with automatic frequency control. The authors previously proposed the non-linear transformation of the observed signals to satisfy with the linear relationship between the disturbances and the observed signals by utilizing several additional observed signals which are closely related with the non-linear characteristics of PWR plant. In addition, a method is proposed to compensate the fluctuation of observed signals due to automatic frequency control by utilizing both the input signal of the main steam valve control system and the input signal of the control rod control system. The effectiveness of the extended method has been examined by several computer experiments using a simple PWR plant simulation code.     

Application of Stable Adaptive Schemes to Nuclear Reactor Systems, (II)

The parameter identification and adaptive control schemes applied in a previous study to a nonlinear point reactor are extended to the case of a loosely-coupled-core reactor with internal feedbacks, constituting a nonlinear overall system. Both schemes are shown to be stable, with the system newly represented on the pattern of the Model Reference Adaptive System (MRAS) with use made of the Lyapunov's method.

For either parameter identification or adaptive control of a loosely-coupled-core reactor, there exists no canonical form of multiple input-multiple output system which can be directly applied for deriving the MRAS with the matrix version of the Kalman-Yakubovich lemma as it was in the case of the point reactor. This difficulty is circumvented by the practical assumption that the neutron density can be directly measured on each core as reactivity change is applied as input into the coupled core as a whole. For parameter identification, the model parameters are adaptively adjusted to those of each core, while for the adaptive control, plant parameters of each core can be adaptively compensated, again through control inputs, to asymptotically reduce the output error between the model and the plant.

The point reactor is shown to correspond to a special case.     

用飞行时间法鉴别粒子的在线三体谱仪的改进

针对迴旋加速器加速相位的不稳定,研制了频率自动微调系统,并用靶上二体事件单能粒子的时间线谱作监控修复信号,减小了迴旋加速器等系统的不稳定而带来的时间幌动,将迴旋加速器上谱仪鉴别粒子的时间分辨降低到<3ns。     

Application of Stable Adaptive Schemes to Nuclear Reactor Systems, (I)

Parameter identification and adaptive control schemes are presented for a point reactor with internal feedbacks which lead to the nonlinearity of the overall system. Both are shown stable with new representation of the system, which corresponds to the nonminimal system representation, in the vein of the Model Reference Adaptive System (MRAS) via the Lyapunov's method. For the sake of the parameter identification, model parameters can be adjusted adaptively as soon as measurements start, while plant parameters can also adaptively be compensated through control input to reduce the output error between the model and the plant for the case of the adaptive control.

In the case of the adaptive control, control schemes are presented for two cases, the case of the unknown decay constant of the delayed neutron and the case of the known constant. The adaptive control scheme for the latter case is shown extremely simpler than that for the former. Furthermore, when plant parameters vary slowly with time, computer simulations show that the proposed adaptive control scheme works satisfactorily enough to stabilize an unstable reactor and that it does even in the noise with small variance.     

Earthquake response of inelastic structures

The most commonly used method in the seismic analysis of structures is the response spectrum method. For seismic re-evaluation of existing facilities elastic response spectrum method cannot be used directly as large deformation above yield may be observed under Safe Shutdown Earthquake (SSE). The plastic deformation, i.e. hysteretic characteristics of various elements of the structure cause dissipation of energy. Hence the values of damping given by the code, which does not account hysteretic energy dissipation cannot be directly used. In this paper, appropriate damping values are evaluated for 5-storey, 10-storey and 15-storey shear beam structures, which deform beyond their yield limit. Linear elastic analysis is performed for the same structures using these damping values and the storey forces are compared with those obtained using inelastic time history analysis. A damping model, which relates ductility of the structure and damping, is developed. Using this damping model, a practical structure is analysed and results are compared with inelastic time history analysis and the comparison is found to be good.     

反应堆结构的泵致振动噪声研究

先进的振动噪声预报与减振降噪分析技术对于降低结构的振动噪声水平具有重要意义。为了进行准确的噪声预报,需要采用合适的方法并建立噪声预报模型进行计算分析。针对反应堆及一回路系统,首先研究了振动噪声预报分析方法的变量参数及其影响规律,研究比较了声学分析方法包括直接边界元法、声学有限元自适应层方法、自适应阶次有限元声学法、声学有限元自适应层方法联合自适应阶次有限元声学法;其次,联合有限元法和声学边界元法,研究了耐压壳模型对振动噪声的影响,得到了加强筋、双层壳对系统振动特性及辐射噪声的影响规律。基于研究结果,建立了声振计算模型,开展了减振效果评价、声辐射分析及减振措施研究,得到了典型传递路径的振级落差、通过耐压壳辐射的声压级和外声场以及不同减振措施的减振降噪效果。      

Stochastic prediction of maximum seismic response of light secondary systems

A stochastic model is presented for predicting the elastic response of light multi-degree-of-freedom secondary systems to strong motion earthquakes. Secondary systems may include light mechanical or electrical equipment, piping, or other light systems attached at one or several points to walls or floors of the supporting or primary structures. The critical functions of these secondary systems in nuclear power plants make the accurate prediction of their maximum responses important. The response of such secondary structures may be obtained by a direct time-history analysis, or more approximately, by the response spectrum method. The time-history solution is, of course, expensive; moreover, there is no single representative earthquake and thus a number of possible earthquake ground motions have to be considered. On the other hand, the response spectrum method applied to secondary systems can lead to unreliable results.Within the framework of the normal mode method, a decoupled stationary random vibration model is developed based on the assumption of Gaussian response process and Poisson barrier crossings. The accuracy of the proposed model is verified by comparing the calculated responses, at the 10 and 50% probability of exceedance level, with the second highest and average of the time-history responses from eight normalized accelerograms. The influence of decoupling, i.e. ignoring the dynamic interaction between the primary and the secondary systems, on the response is examined.The influence of nonstationarity is also evaluated. It is observed that nonstationarity is unimportant for earthquakes of relatively long duration, and that for a given damping most of the error can be accounted for by a simple scaling. It is also shown that one aspect of the proposed method constitutes the basis for some of the approximations in the response spectrum method; however, the proposed method yields results that are consistently more reliable than the response spectrum method. Moreover, results obtained with the proposed method represent maximum response statistics from an ensemble of earthquakes rather than a single earthquake.     

Structural safety and reliability of primary system pressure boundaries for water cooled power reactors: Panel Discussion at the Second International Conference on Structural Mechanics in Reactor Technology, Berlin, Germany, 10–14 September, 1973

A stochastic model is presented for predicting the elastic response of light multi-degree-of-freedom secondary systems to strong motion earthquakes. Secondary systems may include light mechanical or electrical equipment, piping, or other light systems attached at one or several points to walls or floors of the supporting or primary structures. The critical functions of these secondary systems in nuclear power plants make the accurate prediction of their maximum responses important. The response of such secondary structures may be obtained by a direct time-history analysis, or more approximately, by the response spectrum method. The time-history solution is, of course, expensive; moreover, there is no single representative earthquake and thus a number of possible earthquake ground motions have to be considered. On the other hand, the response spectrum method applied to secondary systems can lead to unreliable results.Within the framework of the normal mode method, a decoupled stationary random vibration model is developed based on the assumption of Gaussian response process and Poisson barrier crossings. The accuracy of the proposed model is verified by comparing the calculated responses, at the 10 and 50% probability of exceedance level, with the second highest and average of the time-history responses from eight normalized accelerograms. The influence of decoupling, i.e. ignoring the dynamic interaction between the primary and the secondary systems, on the response is examined.The influence of nonstationarity is also evaluated. It is observed that nonstationarity is unimportant for earthquakes of relatively long duration, and that for a given damping most of the error can be accounted for by a simple scaling. It is also shown that one aspect of the proposed method constitutes the basis for some of the approximations in the response spectrum method; however, the proposed method yields results that are consistently more reliable than the response spectrum method. Moreover, results obtained with the proposed method represent maximum response statistics from an ensemble of earthquakes rather than a single earthquake.     

Simplified approach for the seismic analysis of equipment attached to elastoplastic structures

A simple approximate procedure is presented to estimate the maximum response of equipment, piping, or any other light secondary system mounted on nonlinear structures subjected to earthquake ground motions. The procedure is based on the consideration of structure and equipment as an integrated combined system, and on a response spectrum method for the analysis of nonlinear multistory structures. It is formulated in terms of the initial dynamic properties of the independent structure and equipment components, and the nonlinear response spectrum of a specified earthquake ground motion. It may be applied to any linear multiple-degree-of-freedom secondary system connected at one or two arbitrary points of a multistory structure. It fully takes into account the interaction between primary and secondary systems and the nonclassical damping character of structure-equipment systems. It is restricted, however, to structures with elastoplastic load-deformation behavior and to those cases in which the mass of the secondary system is small in comparison with the mass of the structure. Its accuracy is evaluated by means of a comparative study with the numerical integration solutions of a number of idealized systems. In this comparative study, the proposed procedure estimates the numerical integration solutions with an average error of about 2%.     

Determination of earthquake loads on structures — Research and development required

This paper discusses the research and development work required in three aspects of seismic analysis, i.e. modal combination criteria in the response spectrum analysis, the techniques in modeling and simulating structures, systems and components, and the determination of dynamic lateral earth pressure during an earthquake.In the seismic analysis of structures, the lumped mass method is commonly used. For this method, the thin wall beam theory approach and the rigidity approach used in determining the effective shear areas and the distributions of translational shears are discussed. In the analysis of structures, either the time history or response spectrum method is used. When the response spectrum modal analysis method is used, the exact phase angle relation among maximum modal responses is not defined; therefore, a logical combination criterion must be established. The criterion for closely spaced modal responses to obtain system response is also mentioned. Finally, the significantly different lateral earth pressures on basement walls of embedded structures obtained using the Mononobe-Okabe method and the finite element method are also discussed. Hopefully, through further research and development work in these areas, safe and economic design can be achieved.     

基于自适应遗忘因子RLS算法的稳压器模型在线辨识

为提高稳压器时变系统模型辨识的准确性及其参数在线辨识的快速性和鲁棒性，并研究遗忘因子大小对遗忘因子递推最小二乘法算法特性的影响，提出了一种基于模糊算法的自适应遗忘因子递推最小二乘法算法。该算法以系统动态特性值与辨识模型值之间的残差时间序列平均值及其变化率作为模糊算法的输入，遗忘因子修正量为输出，从而实现遗忘因子的自适应调整。通过对某核电厂稳压器降压系统进行仿真，结果表明，该算法可实时调整遗忘因子大小，有效地解决了稳压器模型参数时变性的问题，得到了较精确的时变模型；有效地解决了参数辨识结果稳定性和收敛速度相互矛盾的问题。因此，该算法具有可行性和优越性。      

Multiplier Phototubes for Single Electron Counting

Typical operating characteristics of ITT Industrial Laboratories' special purpose multiplier phototubes are described, with particular emphasis on the ability of these tubes to count single photoelectrons with minimum interference from dark noise. This ability, of particular significance in the detection of low energy quanta, including single photons, follows from the Poisson-like output pulse height distribution observed in the tubes in which a well-defined most probable pulse amplitude appears, compared to a more complex but lower amplitude dark noise pulse height spectrum. Other features of these tubes, such as adjustable cathode size and shape, electrical deflection for automatic gain calibration, alignment and image tracking, and reduction of dark noise with cooling, are also described.     

Structural failure probabilities of the HDR-containment

A method to calculate failure probabilities of critical cross sections of containment structures is developed. Uncertainties of structural as well as of material parameters are taken into account. The HDR-containment under shaker loading conditions is utilized as sample structure. This provides the possibility to verify the mechanical i.e. structural model. The failure probabilities are calculated by utilizing the response surface method (RSM) along with advanced simulation procedures. Based on these developments a computational procedure for the evaluation of structural failure probabilities due to earthquake loading is suggested. Failure is defined in terms of exceedance probabilities (first passage problem). For this purpose, a new numerical approach is introduced, which is based on suitable transformations and simulation techniques such as adaptive sampling.     

Criteria for seismic analysis of nuclear plant structures and substructures

This paper encompasses criteria used for seismic analysis of nuclear power plant structures such as supporting structures founded on ground, as well as substructures. Nuclear power plant equipment and systems can be treated as substructures. Modeling of structures and substructures is described. Since instructure response spectra play an important role in the design and analysis of nuclear power plant equipment, systems and components, methods for development of instructure response spectra as well as variations of input parameters considered in determining these spectra are described.When the principal contribution to the equipment response is due to flexibility of the supporting substructures, an analytical approach to the problem for obtaining reduced stiffness and associated mass matrices of supporting substructures with finite element representation for use in the dynamic analysis of equipment and supporting structures is presented. When supporting structures and equipment, that have inherently different damping properties, are included as intergral parts of the dynamic models, the approximate evaluation of the modal damping based on the weighted damping according to the modal energy stored in each component is outlined. Use of time history and response spectrum analyses is presented. The effects of relative displacements due to different motion of the support points of substructures in each significant mode of the supporting structures as well as procedures of combining modal responses are detailed.     

Vibration Monitor for Rotating Machines Using Average Frequency Technique

A vibration monitoring technique has been developed which can be applied to continuous monitoring and to patrol checking of many kinds of rotating machines in nuclear power plants. In this method, the vibrating condition in such equipment are represented in terms of two parameters, i.e. a vibration amplitude (RMS value) and an average frequency. The average frequency is defined as the root value of the second moment of the vibration frequency weighted by the power spectrum. The average frequency can be calculated by simple analogue circuits and does not need the spectrum analysis. Using these two parameter, not only the occurrence of abnormal vibration but also the type of vibration can be detected.     

CPR1000核电厂蒸汽发生器排污系统频繁隔离原因分析与优化措施

中国改进型三环路压水堆（CPR1000）核电厂蒸汽发生器排污系统（APG）在正常运行期间频繁自动隔离，结合此隔离事件运行背景对事件原因进行了分类研究，并对APG进行了相应优化。具体措施为对冷却水温度控制器增加了微分环节并优化了控制参数；对排污水流量控制回路增加了前馈环节以消除扰动；对排污水流量计和压力开关信号下游增加了相应延时环节；对启机阶段运行程序进行了适应性修改。某核电厂实际运行经验证明，优化后的APG运行情况良好，自动隔离事件大幅减少，运行维护成本有效较低。      

Evaluation of torsional effects in the seismic analysis of symmetric and unsymmetric nuclear power plant structures

This paper summarizes evaluation of torsional effects of symmetric and unsymmetric structures in the seismic analysis of nuclear power plants. The idealization of structures to predict the response due to earthquakes is described. The determination of stiffness or flexibility matrices of structures, using an approximate method and finite element technique, is outlined. The evaluation of foundation-structure interaction for structures founded on soft soils, hard rocks, and piles is presented. The analytical methods of analysis such as time-history and spectrum approach are discussed.