腔体带通滤波器设计

在上海光源(SSRF)零模束流反馈系统中,腔体带通滤波器用来提取束流信号中的零模振荡信号,通过处理和反馈束流信号来控制高频系统对束流的作用.本文就是以Superfish为仿真软件,给出腔体带通滤波器的设计方法及其设计尺寸.并对腔体带通滤波器的参数进行了优化.最后给该滤波器的测试结果.     

上海同步辐射光源工作点稳定性研究

上海同步辐射光源（SSRF）是一台第3代高性能同步辐射装置,已稳定运行超过10年。储存环的线性光学模型稳定是光源稳定运行的基础。工作点反馈系统可实时地校正工作点,并间接地以降维的方式反馈难以在线测量到的线性光学函数。工作点反馈系统在SSRF的稳定运行验证了此方法的可行性,该反馈系统不仅使得工作点稳定度显著提升,也使得束流发射度、注入效率以及束流寿命等重要参数的稳定度得到大幅提升。衍射极限储存环光源是现阶段被广泛研究和建设的新一代同步辐射光源,工作点反馈系统也将发挥更重要的作用。本文分析电子储存环线性光学函数和工作点的稳定性,回顾SSRF工作点反馈系统的实际运行情况,介绍工作点反馈系统在SSRF衍射极限环lattice（SSRF-U）的模拟。工作点反馈在SSRF的实际运行情况和在SSRF-U的模拟结果显示,该系统可将工作点稳定在±0.001范围内,可满足储存环光源稳定运行和线性差耦合共振圆束斑模式对工作点稳定度的需求。     

SSRF电子枪控制系统的设计与实现

电子枪是上海光源SSRF(Shanghai Synchrotron Radiation Facility)中的直线加速器的关键部件,上海光源的束流品质很大程度上取决于电子枪的束流指标,因此电子枪需要一个稳定的控制系统来保证其可靠运行.本文介绍了上海光源电子枪控制系统的设计与实现过程.该系统底层采用可编程控制器PLC(Programmable Logic Controller)作为设备控制器,上层监控软件使用加速器控制系统通用软件EPICS (Experimental Physical and Industrial Control System),整个控制系统基于以太网连接.PLC和以太网技术的应用,使该系统具有可靠性好、易于维护等特点.     

上海光源储存环真空数据检索系统

本文介绍一种基于Web的上海光源(SSRF)储存环真空数据库检索系统的设计与实现。该系统建立基于实验物理和工业控制系统(EPICS)真空数据的采集系统,用Channel Archiver存储真空规的压强读数、动态真空度、束流流强及束流寿命等数据到历史数据库中,可从不同联网计算机检索数据,建立一个合理有效的SSRF储存环真空数据共享平台,为设备和科研人员提供一个可用可靠的数据来源。     

上海光源增强器工作点测量数据采集系统

介绍上海光源(SSRF)增强器工作点(Tune值)测量系统的数据采集与处理方法.该系统选用新一代数字BPM处理器Libera处理激励后的束流位置信号,在Soft IOC中进行快速傅里叶(FFT)变换,以得到束流横向振荡频率,进而实现工作点的实时测量.测试表明,该系统能够满足高精度、快速测量的要求.     

SSRF储存环高频屏蔽波纹管的研制

建造中的上海光源即上海同步辐射装置(SSRF)储存环将采用内装高频屏蔽机构的波纹管——高频屏蔽波纹管。SSRF采用了由接触指和弹簧指构成的双指型屏蔽机构。屏蔽机构的关键设计参数是由SSRF壁电流和壁电场所决定的指间接触力和高次模决定的相邻接触指间的缝隙宽度和长度。对高频屏蔽波纹管进行了热测试和阻抗测试。测试结果表明,接触力、缝隙和阻抗都适合SSRF的实际运行条件。     

SSRF直线加速器束流发射度测量

发射度是衡量束流品质的重要参数,随着加速器技术的不断发展,人们对束流品质要求越来越高,特别是对小发射度的测量要求更高的分辨率.本文基于"多次改变聚焦强度法"的发射度测量原理,讨论了上海同步辐射光源装置(SSRF)直线加速器部分测量技术和测量装置,包括薄透镜的合理采用、多点最小二乘法拟合、截面测量靶的选择和测量软件设计等,以提高发射度测量的准确性和可靠性.测量结果的高稳定性与重复性对接下来即将进行的自由电子激光发射度测量有重要的参考意义.     

上海光源XAFS光束线高次谐波抑制镜系统研制

讨论了上海光源(SSRF)XAFS光束线高次谐波抑制镜箱的研制.高次谐波抑制镜箱为XAFS实验提供高纯度光谱,主要机械结构包括镜子夹持机构、平移切换机构、三点调整机构.在机构设计中进行了分析与计算.根据测试获得的摇摆曲线对高次谐波抑制镜箱性能进行评估.     

FPGA横向反馈数字板在SSRF储存环的应用

上海光源（SSRF）正在构建基于数字信号处理模块的横向反馈系统。FPGA（Field Programmable Gate Array）结构可以调节数字板FIR滤波器的参数,具有较好的灵活性。图形用户界面（GUI,Graphical User Interface）程序用来实现滤波器设计,并生成供数字板下载的逗号分隔符.csv（Comma Separated Value）文件。我们通过调节横向工作点处增益和相位,使滤波效果达到最优化。本文介绍了SSRF横向反馈对单束团束流情况下的实验结果,已能够证明数字板调节的灵活性。系统在多束团情况下的研究将要进行。     

一个基于EPICS框架的EPU前端反馈系统

插入件是现代光源重要组成设备之一,其质量直接影响上海光源整体性能。由于建造和安装工艺的限制,插入件的磁场会对束流轨道稳定性产生影响。为降低对束流的扰动,在插入件电子束流入口和出口位置增加校正线圈实现自动补偿功能。因此我们设计了基于EPICS的插入件前端反馈系统,经测试,该前馈系统用户界面简洁,反馈控制功能完整可靠,实时性高,提高了束流的稳定性,为试验站稳定供光提供了保证。     

A Linear Stability Analysis of Supercritical Water Reactors, (I)

This paper summarizes the analysis results of the thermal-hydraulic stability of a high-temperature reactor cooled and moderated by supercritical-pressure light water (SCLWR-H). A linear stability analysis code in the frequency domain was developed to study the thermal-hydraulic stability of SCLWR-H at constant supercritical pressure. The analysis method is based on linearization by perturbation of numerically-discretized one-dimensional single-channel single-phase conservation equations. The effect of water rods on stability is considered. The thermal-hydraulic stability of SCLWR-H for full-power and partial-power normal operations was investigated by frequency domain method. Our analysis reveals that though SCLWR-H has low coolant flow rate and large density change in the core, the thermal-hydraulic stability can be maintained both at normal operation and during power raising phase of constant pressure startup by applying an orifice pressure drop coefficient at the inlet of the fuel assemblies. A parametric study was also carried out to determine the parameters affecting the stability.     

An advanced reduced order model for BWR stability analysis

An advanced reduced order model was developed and qualified in the framework of a novel approach for nonlinear stability analysis of boiling water nuclear reactors (BWRs). This approach is called the RAM-ROM method where RAM is a synonym for system code and ROM stands for reduced order model. In the framework of the RAM-ROM method, integrated BWR (system) codes and reduced order models are used as complementary tools to examine the stability characteristics of fixed points and periodic solutions of the nonlinear differential equations describing the stability behaviour of a BWR loop. This methodology is a novel one in a specific sense: we analyse the highly nonlinear processes of BWR dynamics by applying validated system codes and by the sophisticated methods of nonlinear dynamics, e.g. bifurcation analysis. We claim and we will show that the combined application of independent methodologies to examine nonlinear stability behaviour can increase the reliability of BWR stability analysis.This work is a continuation of previous work at the Paul Scherrer Institute (PSI, Switzerland) of the second author and at the University of Illinois (USA) in this field. In the scope of a PhD work at the Technical University Dresden (Germany), the current ROM was extended to an advanced ROM by adding a recirculation loop model, a quantitative assessment of the necessity for consideration of the effect of sub-cooled boiling and a new calculation methodology for feedback reactivity. A crucial point of ROM qualification is a new calculation procedure for ROM input data based on steady-state RAM (ONA) results. The modified ROM is coupled with the BIFDD bifurcation code which performs a semi-analytical bifurcation analysis (see Appendix C). In this paper, the advanced ROM (TU Dresden ROM, TUD-ROM) is briefly described and the results of a nonlinear BWR stability analysis based on the RAM-ROM method are summarised for NPP Leibstadt, NPP Ringhals and NPP Brunsbüttel. The results show that the TUD-ROM including the new approach for ROM input data calculation is qualified for BWR stability analysis in the framework of the RAM-ROM method.     

Application of a reduced order model to BWR corewide stability analysis

The determination of system stability parameters from power readings is a problem usually solved by time series techniques such as autoregressive modeling. These techniques are capable of determining the system stability, but ignore the physics of the process and focus on the determination of a nth order linear model. A nonlinear reduced order system is used in conjunction with estimation techniques to present a different approach for stability determination. The simulation of the reduced order model shows the importance of the feedback reactivity imposed by the thermal-hydraulics; the dominant contribution to this feedback is provided by the void reactivity, being a function of power, burnup, power distribution, and in general of the operating conditions of the system. The feedback reactivity is estimated from power measurements and used in conjunction with a reduced order model to determine the system stability properties in terms of the decay ratio.     

On the stability of the point reactor kinetics equations

As the basic neutronic problem is unstable by nature, maintaining a reactor critical is a task that requires a lot of effort. This work presents and discusses some aspects related to the stability of the basic physics behind a nuclear reactor core based on the well-known point reactor kinetics equations. First, the linear non-feedback case is studied where differences between Lyapunov and BIBO stability are found. These differences are shown both numerically and analytically, and explained using a reactor physics based reasoning. Finally, a simple model is used to analyse the intrinsic stability of the point reactor equations when reactivity feedbacks are taken into account. A method for constructing conceptual stability design maps is proposed and a basic interpretation of the simple results obtained is given.     

Stability Analysis of Chemical Fine-Control Reactor in State Space

Stability is studied of a nuclear reactor system which is controlled by the concentration change of poison solution circulating through the pipe installed in the reactor. Particular attention is paid to: (1) nonlinearities due to the reactivity feedbacks, (2) rigorous treatment of nonlinear control elements without employing approximate methods such as the describing function and (3) nonlinear characteristics of the concentration change of poison solution.

The stability of this complex reactor system is analyzed in the state space by applying the technique based on Lyapunov's method. A special technique is employed to cope with the difficulty such that the stability of a system with time lag depends on the present state as well as on the past history of the state which is usually indeterminable. Analysis is carried out for both simplified and realistic models. For the former model, one stability region is compared with another by varying the lag time, characteristics of nonlinear elements and the power at equilibrium point. Similar results are also obtained for the latter model.     

两相自然循环稳定性无量纲频域分析研究

基于一维均相平衡模型，导出系统无量纲特征方程，采用频域分析方法，开发了一个通用性程序，研究两相自然循环中流动不稳定特性。程序能直接求解自然循环回路的无量纲稳定边界，计算结果与所得到的实验数据吻合良好，并讨论了各参数对系统稳定性的影响。     

Stability estimations and quench simulations for the ITER conductors

Quench simulations and stability estimations for the International Thermonuclear Experimental Reactor (ITER) are discussed. Especially numerical issues and associated benchmark actions are summarized. Satisfactory agreement between the various codes from the 4 ITER parties is now obtained after numerical convergence problems have been resolved. However, these require confirmation by experiments on relevant conductor geometries. In multistage cables, a non-uniform current distribution within the cable affects the stability of the conductor. A possible mechanism for the non-uniform distribution is flux loops between the strands or cable substages as the current is ramped up or down. A preliminary estimation of stability with non-uniform current distribution is also discussed.     

BWR stability analyses with SIMULATE-3K benchmark against measured plant data

The best-estimate coupled neutronic/thermal-hydraulics code, SIMULATE-3K (S3K), is used by many utilities, research institutes, and regulatory authorities in Europe for performing BWR stability analysis. Analysis of many measured BWR stability tests (often performed in European BWRs) provides the basis for the validation for stability parameter calculations (decay ratio and natural frequency) with S3K. This paper summarizes part of the extensive validation database for the code, and discusses the influence of fuel pin model parameters on the stability results.     

Stability Analysis of BWRs Using Bifurcation Theory

Abstract

This paper presents a new approach using the bifurcation theory for the stability analysis of BWRs. In this approach, the dependencies of the equilibrium states on the parameters that have a large influence on the stability are investigated topological over a wide range of phase space. The stability information can be derived from the analysis of the bifurcation phenomena on the equilibrium states. This investigation enabled us to obtain qualitative and global information on the stability of a nonlinear system. The new approach was applied to the analysis of the stability associated with in-phase power oscillation (core reactivity stability). The loss of linear stability took place at a lower reactor power as the coolant flow rate decreased, and this instability occurs at the Hopf bifurcation point. The sensitivity analysis of the stability boundary for the various parameters revealed that the channel hydrodynamics heavily play a significant role in the stability. The Hopf bifurcation analysis proved that the periodic state bifurcating at the Hopf bifurcation point was orbitally unstable and a limit cycle attractor did not exist in the vicinity of the bifurcation point. This fact led to the conclusion that a limit cycle in-phase power oscillation observed in BWR instability was not excited directly by the bifurcation of the orbitally unstable periodic state.