温度-功率曲线对机械补偿控制策略运行影响研究

以秦山第二核电厂反应堆为研究对象,研究了不同反应堆温度-功率曲线对机械控制补偿(MSHIM)运行策略的影响。结果表明,通过对反应堆温度-功率曲线的优化,可以缩减负荷跟踪过程中对控制棒的移动范围,进而支持幅度更大的MSHIM负荷跟踪。     

压水堆堆芯双节点模型及其应用

基于节点方法建立双节点反应堆模型,并利用微小摄动理论对模型进行线性化处理,得到双节点线性化反应堆多变量模型;为了更加准确地对棒控系统进行仿真,建立了双节点棒控系统模型。参考AP1000的机械补偿控制策略(MSHIM),在Matlab/Simulink平台上搭建平均温度控制系统和轴向偏移控制系统的仿真程序,并对功率阶跃负荷瞬态工况进行仿真。仿真结果表明,功率偏差始终在目标控制带以内,平均温度和功率水平的实际值与目标值之间存在稳态偏差,偏差处于死区范围之内。因此双节点线性化堆芯模型适用于功率控制系统和功率分布控制系统的仿真和设计。     

AP1000堆芯动态仿真程序开发

AP1000堆芯采用了先进的机械补偿控制模式(MSHIM)控制反应堆功率和轴向功率偏差。以Matlab/Simulink为平台,开发AP1000堆芯动态仿真程序。首先建立优化的节点堆芯动力学模型,该模型既有较高的计算精度又有较快的计算速度;然后建立MSHIM控制系统模型,并对负荷跟踪工况进行了动态仿真。通过与已有仿真结果的对比,验证了仿真程序的正确性。     

基于DCS改造最小验证平台的稳压器压力控制回路比对测试研究

大亚湾核电站核岛模拟控制系统采用美国Bailey9020模拟平台,计划在30 a大修期间进行数字化升级改造。本项目将SpeedHold-N（SH-N）系统、Bailey9020模拟平台、大亚湾核电站工艺仿真模型通过可编程控制器（PLC）接口搭建最小验证平台,选取稳压器压力控制回路为验证对象,以调试程序为参考,通过对比相同扰动在不同平台的响应差异,验证了大亚湾核电站当前控制参数在目标数字化控制系统（DCS）平台的适用性,发现了Bailey9020模拟平台比例积分（PI）控制器在手自动切换时有比例作用无法响应的固有缺陷,并分别从电路设计和操作程序两方面提出了相应优化措施,达到了模拟平台解析、DCS组态验证、定值转换验证的目的,同时为当前大亚湾核电站机组运行提出了重要反馈。      

MSHIM运行模式在M310机组的初步应用研究

以大亚湾核电站1号机组为研究对象,尝试将机械补偿控制策略(MSHIM)运行模式应用于M310核电厂。分析表明,M310核电厂具有基负荷的MSHIM运行能力,具备一定的不调硼负荷跟踪能力,但G1、G2、G3棒组和R棒组存在控制能力不足的问题。在现有控制棒数量及布置前提下,通过重新分组并定义控制棒组,有可能在M310机组上实现MSHIM运行与控制策略。     

AP600概率安全研究对系统设计改进的启示

已经完成了由西屋公司设计的中等规模的改进型非能动轻水堆电站的完整的概率安全研究（ＰＳＳ），包括一级、二级和二级。这一研究是ＡＰ６００设计进展中相互合作工作的一部分。     

佛罗里达州提交新建核电机组申请

佛罗里达电力及照明公司（FPL）已向美国核管会（NRC）提出建设和运行联合许可证（COL）申请，拟在土尔其角厂址上建设2台西屋公司（Westinghouse）的AP1000核电机组。这2台机组是该厂址的5号和6号机组，预计将分别于2017年和2019年投运。     

基于CPSO滚动优化的堆芯功率自适应预测控制

针对核反应堆变功率过程中系统的非线性和反应性增量约束问题,本文将具备模型参数自适应辨识能力的改进型广义预测控制器（JGPC）应用于堆芯功率控制,该控制器通过预测模型参数和递推关系计算未来时刻的预测输出值,同时采用经正弦混沌策略和非线性惯性权重改进的混沌粒子群算法（CPSO）进行滚动优化,在优化过程中通过设定优化边界和混沌策略来处理反应性约束;以堆芯功率的受控自回归积分滑动平均模型（CARIMA）作为预测模型,并采用遗忘因子递推最小二乘法（FFRLS）自适应辨识模型参数,以克服堆芯功率模型非线性。基于MATLAB平台对本文控制器进行仿真验证,结果表明,该控制器在满足约束条件的情况下,能使堆芯功率快速、稳定地跟随设定值,且具备一定的抗干扰能力。      

基于人工免疫的直流蒸汽发生器压力控制研究

以生物免疫中T细胞和B细胞间的协同免疫机理为基础,结合多抗原多抗体协调免疫机理,提出一种分布式-多输入多输出耦合的人工免疫控制策略,并将该策略应用于直流蒸汽发生器(OTSG)压力控制。为了验证该控制策略,在1台快堆仿真系统中进行了仿真实验。仿真测试结果表明,该控制策略较比例、积分、微分(PID)控制具有更小的超调量和调整时间,能够有效改善OTSG压力和相关参数的动态运行特性。     

System80＋^TM标准电站设计和运行评价

System80^ 标准电站设计是一种1400MWe改进型先进轻水堆（ALWR），该设计满足电力研究所（EPR）先进轻水堆ALWR用户要求文件（URD）和国际核电市场的需求，它不仅更安全，而且维修和运行更经济。ABB燃烧工程公司的核电反应堆采用了纵深防御过程：（1）增加基本设备设计余量，提高正常运行期间的性能，并降低不可预计的瞬态或事故的可能性；（2）为了减缓设计基准事故和防止严重事故，提高了安全系统的冗余度和多样性；（3）提高了严重事故减缓能力。本文描述了最重要的改进系统和设备，重点是严重事故预防措施和减缓能力。改进的设计特点以渐进的方式使用已验证的设备来实施。这种方法确保电站安全和经济地运行，正如在美国和韩国运行中的电站所证实的一样。本文概述的详细研究表明System80^ 电站的可利用率预计超过了ALWR87％的要求，预计年运行和维修费用将减少1400万美元。     

Advanced operational strategy for the IRIS reactor: Load follow through mechanical shim (MSHIM)

The renaissance of nuclear power brings more attention to advanced reactor designs and their improved performance and flexibility, including their enhanced load follow capability. Reactor control strategy used to perform transients including power changes has impact on the overall control system design. In particular, as the power change is performed within a load follow maneuver, several modifications occur in the core from a neutronic view point: the fuel and moderator temperature change, the xenon concentration and distribution are modified, the power distribution skewed axially, etc. These changes need to be adequately counterbalanced to keep both the core critical and the power distribution acceptable. The traditional approach in PWRs is to compensate for the reactivity change due to the power variation by adjusting the soluble boron concentration and moving a limited number of control rod banks. However, advanced reactors may adopt a different strategy for a variety of reasons. For example, water-cooled reactors that do not use soluble boron in coolant obviously cannot use its adjustment for this purpose. Moreover, Integral Primary System Reactors (IPSRs) using soluble boron, due to their integral design, have a large inventory of primary coolant. Therefore dilution/boration strategy, while in principle an option, becomes expensive for short time changes and leads to large volume of liquid effluent, in particular toward the end of cycle. Therefore, a capability to perform load follow without changing soluble boron concentration is very desirable for a range of reactor designs.International Reactor Innovative and Secure (IRIS) is an advanced medium-size IPSR that has been selected as the reference reactor for the purpose of this study. A capability to perform load follow maneuvers without changing soluble boron concentration has been examined and demonstrated through implementation of the Westinghouse Mechanical Shim (MSHIM) control strategy. A control bank design suited for MSHIM operation has been devised. Nine load follow scenarios covering a wide range of possible operating requirements, including Westinghouse design basis plus others proposed by EPRI for Advanced LWRs, have been successfully performed through the control rod banks movement only, without soluble boron adjustment, and maintaining power peaking factors within the acceptable range. Thus, IRIS provides improved operation by enabling load follow through MSHIM.     

Robust nonlinear model predictive control for nuclear power plants in load following operations with bounded xenon oscillations

One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In this paper, a robust nonlinear model predictive control for the load-following operation problem is proposed that ensures xenon oscillations are kept bounded within acceptable limits. The proposed controller uses constant axial offset (AO) strategy to maintain xenon oscillations to be bounded. The constant AO is a robust state constraint for load-following problem. The controller imposes restricted state constraints on the predicted trajectory during optimization which guarantees robust satisfaction of state constraints without restoring to a min-max optimization problem. Simulation results show that the proposed controller for the load-following operation is so effective so that the xenon oscillations kept bounded in the given region.     

Soft computing systems applied to PWR''s xenon

The present work intends to introduce a soft computing technique as an effective and robust tool available to deal with nuclear engineering problems. This goal is reached by the presentation of an application: a genetic programming system (GP) able to automatically design a controller for the axial xenon oscillations in a pressurized water reactors (PWRs). The axial xenon oscillations control methodology is based on three axial offsets: the xenon axial offset (AOx), the iodine axial offset (AOi) and the neutron flux axial offset (AOf), effectively used in former work. Simulations were made using a two-point xenon oscillation model which employs the non-linear xenon and iodine balance equations and the one group, one-dimensional neutron diffusion equation, with non-linear power reactivity feedback, also proposed in the literature. Obtained results showed the ability of the GP in finding a strategy which can effectively control the axial xenon oscillations.     

Core physics analysis of 100% MOX core in IRIS

International Reactor Innovative and Secure (IRIS) is an advanced small-to-medium-size (1000 MWt) Pressurized Water Reactor (PWR), targeting deployment around 2015. Its reference core design is based on the current Westinghouse UO₂ fuel with less than 5% ²³⁵U, and the analysis has been previously completed confirming good performance for that case. The full MOX fuel core is currently under evaluation as one of the alternatives for the second wave of IRIS reactors. A full 3-D neutronic analysis has been performed to examine main core performance and safety parameters, such as critical boron concentration, peaking factors, discharge burnup, reactivity coefficients, shut-down margin, etc. In addition, the basis to perform load follow maneuvers via the Westinghouse innovative strategy MSHIM has been established. The enhanced moderation of the IRIS fuel lattice facilitates MOX core design, and all the obtained results are within the operational and safety limits considered thus confirming viability of this option from the reactor physics standpoint.     

基于钒探测器补偿的轴向偏移控制设计

机械补偿控制是基于控制棒调节反应堆功率并进行轴向功率偏移控制的先进技术,频繁移动的控制棒对传统堆外校准后的轴向功率偏差测量精度有较大的负面影响,采用能给出准确堆内功率分布的钒基自给能探测器的信号可对其进行校正。为补偿钒探测器较长的响应时间,设计了超前/滞后控制器,提出了用补偿后的信号对堆外测量得到的轴向功率偏差信号进行修正的方法。仿真结果表明,该方法能有效应对控制棒移动对轴向偏移控制的影响,可提高控制精度。对该方法的安全相关影响、可实施性及性能分析表明,其具有较高的实用价值。     

多模式机械补偿运行特性研究

经济、灵活及高自动化的运行控制策略是先进核电厂的设计目标之一。为适应这一发展趋势,近年来国际上提出了机械补偿运行控制的设计理念。机械补偿是一种主要通过控制棒的移动补偿堆芯反应性变化和控制轴向功率分布的先进控制策略。本文分别在基本负荷、负荷跟踪及启动/再启动运行模式下对机械补偿运行特性进行了研究。研究表明：机械补偿能自动实现堆芯的有效控制,并使功率峰因子保持在较低水平,是一种灵活、有效、经济的运行控制策略。此外,针对机械补偿运行对核电厂设计的影响进行了初步分析。     

CNP650压水堆不调硼负荷跟踪可行性研究

海南昌江核电厂等CNP650压水堆采用Mode-A控制模式,该模式采用黑体控制棒,有很好的基负荷运行能力,但负荷跟踪能力相对较差。而对一些具有小电网的国家或地区,负荷跟踪运行能力具有一定的市场需求。不调硼负荷跟踪通过棒控系统自动完成,大大减轻了操纵员负担;负荷跟踪过程基本不需要频繁地调硼操作,允许简化化学和容积控制系统设计,减少了废液处理成本。为此,在CNP650压水堆上进行了不调硼负荷跟踪研究。负荷跟踪过程主要有两个控制任务:一是反应性补偿;二是功率分布控制。根据不调硼负荷跟踪的控制任务,重新进行了控制棒的设计、分组和布置,设置两套独立控制的控制棒组(功率补偿棒组和轴向偏移控制棒组),分别用于堆芯反应性控制和轴向功率分布控制,以实现不调硼负荷跟踪。使用SCIENCE程序包进行典型的12h~3h~6h~3h、100%—50%—100%功率水平的日负荷循环计算来进行不调硼负荷跟踪分析。计算步骤为:进行三维堆芯模型计算;根据三维堆芯模型建立一维堆芯模型;在一维模型基础上,进行模拟计算。完成了海南昌江核电厂平衡循环寿期末典型的日负荷循环不调硼运行分析,模拟计算结果表明在CNP650压水堆上不调硼负荷跟踪运行模式是可行的。     

A fast-running core prediction model based on neural networks for load-following operations in a soluble boron-free reactor

A fast prediction model for load-following operations in a soluble boron-free reactor has been proposed, which can predict the core status when three or more control rod groups are moved at a time. This prediction model consists of two multilayer feedforward neural network models to retrieve the axial offset and the reactivity, and compensation models to compensate for the reactivity and axial offset arising from the xenon transient. The neural network training data were generated by taking various overlaps among the control rod groups into consideration for training the neural network models, and the accuracy of the constructed neural network models was verified. Validation results of predicting load following operations for a soluble boron-free reactor show that this model has a good capability to predict the positions of the control rods for sustaining the criticality of a core during load-following operations to ensure that the tolerable axial offset band is not exceeded and it can provide enough corresponding time for the operators to take the necessary actions to prevent a deviation from the tolerable operating band.     

Application of Fuzzy Logic Controller to Load-Follow Operations in Pressurized Water Reactors

The fuzzy logic controller was developed to control load-follow operations in pressurized water reactors. The reactor core characteristics change according to different fuel cycles or core exposures, thus making a nonlinear time-varying control problem. This proposed method, however, does not require a mathematical model to design the controller, and so avoids redesigning or tuning controller gain for various cores. Clearly, this method is very suitable for reactor load-following operation control. The control system has two subsystems: one is to track the desired power, and the other is to keep axial offset close to the target value. Both controllers use fuzzy logic: one is the conventional type, and the other uses fuzzy logic to tune the parameters of the controller so the controller can correspond to various core characteristics. Simulation results show that the control system performs well for different cores, and so this system is useful for load-follow operation.     

控制棒组件置换策略优化研究

目前国内在运核电厂控制棒组件并未考虑置换策略,控制棒组件在堆内位置固定,由于控制棒组件功能不同导致承受辐照不均匀,控制棒吸收体材料在辐照下发生肿胀及蠕变,影响电厂安全运行。使用控制棒组件工程分析评价程序CRABE V3.3对CPR1000核电机组控制棒组件设计寿命进行评价,通过对比分析控制棒组件置换策略对寿命的影响发现,若采用置换策略,功率调节棒组件设计寿命可显著提高至目前寿命的2倍以上,温度调节棒组件设计寿命也有明显提高。因此,在充分考虑电厂大修的实际情况下,通过优化控制棒组件在机组内置换策略,增加控制棒组件使用年限,从而提高机组安全性及经济性。