An enhanced integer coded genetic algorithm to optimize PWRs

The aim of this work is to develop a new hybrid mutation integer for integer coded genetic algorithm, ICGA, to design the loading pattern, LP, in pressurized water reactors. Because of the huge number of possible combinations for the fuel assemblies, FAs, loading in a core and finding the optimum solution is a truly complex problem. In common genetic algorithms the mutation and crossover techniques are used to optimize an objective function. In this study flattening of power inside a reactor core is chosen as an objective function. To obtain optimal FA arrangement an Enhanced Integer Coded Genetic Algorithm, EICGA, is developed in order to obtain an optimal FA arrangement. This code is applicable to all types of PWR cores having different geometries and designs with many number of FA types. The results show a marked improvement in comparison to published data.     

两级保障条件下设备的使用可用度优化

基于马尔科夫过程理论建立了两级保障条件下设备的使用可用度（A₀）模型。由于模型的复杂性，难以直观选定使用可用度的设计参数，需借助优化方法进行寻优计算。采用遗传算法对该问题进行了研究，在确定的λ、μ、σ₁、σ₂可行域内获得了A₀的优化解及对应的参数值，计算结果能对设备使用可用度的论证设计提供一定的指导。     

基于遗传算法的某作业现场辐射防护最优化问题

运用遗传算法(GA)对核电厂大修现场中一个阀门维修中管道临时屏蔽方案进行优化设计,建立对2根管道屏蔽的辐射剂量的数学模型,将模型转化为一个带约束的组合优化问题,然后采用GA对此问题进行求解。实验结果表明,GA可以给出精确、完整的屏蔽方案。     

Design and optimization of a multistage turbine for helium cooled reactor

This paper describes the aerodynamic design and explores the performance limits of a 600 MWt multistage helium turbine for a high temperature nuclear reactor closed cycle gas turbine. The design aims for maximum performance while limiting the number of stages for reasons of rotor dynamics and weight.A first part discusses the arguments that allow a preliminary selection of the overall dimensions by means of performance prediction correlations and simplified stress considerations. The rotational speed being fixed at 3000 rpm, the only degrees of freedom for the design are: the impeller diameter, number of stages and stage loading.The optimum load distribution of the different stages, the main flow parameters and the blade overall dimensions are defined by means of a 2D through-flow analysis method. The resulting absolute and relative flow angles and span-wise velocity variation are the input for a first detailed design by an inverse method. The latter defines the different 2D blade sections corresponding to prescribed optimum velocity distributions.The final 3D blade definition is made by means of a computer based 3D-DESIGN system developed at the von Karman Institute. This method combines a 3D Navier-Stokes (NS) solver, Database, Artificial Neural Network and Genetic Algorithm into a two level optimization technique for compressor and turbine stages. The use of 3D Navier-Stokes solvers allows full accounting of the secondary flow losses and optimization of the compound leaning of the stator vanes.The performance of the individual stages is used to define the multistage operating curves. The last part of the paper describes an evaluation of the cooling requirements of the first turbine rotor.     

基于遗传算法的聚变驱动次临界堆嬗变包层长寿命锕系元素初装料中子学优化

在聚变驱动次临界堆的多功能核废料嬗变包层中,长寿命锕系废料的嬗变处理是中子学设计中非常关心的问题。利用FDS课题组开发的多功能中子学程序系统VisualBUS1.0,针对该系统燃耗计算过程具有多变量和多目标函数复杂关系的特点,应用遗传算法对嬗变包层的锕系废料嬗变区的初装料量进行了优化处理,使其在一定的物理和工程参数约束下,指导嬗变区的装料份额取值,分析嬗变区的装料份额对锕系废料的年燃耗深度等参数的影响。     

Loading pattern optimization of PWR reactors using Artificial Bee Colony

In this paper a core reloading technique using Artificial Bee Colony algorithm, ABC, is presented in the context of finding an optimal configuration of fuel assemblies. The proposed method can be used for in-core fuel management optimization problems in pressurized water reactors. To evaluate the proposed technique, the power flattening of a VVER-1000 core is considered as an objective function although other variables such as K_eff, power peaking factor, burn up and cycle length can also be taken into account. The proposed optimization method is applied to a core design optimization problem previously solved with Genetic and Particle Swarm Intelligence Algorithm. The results, convergence rate and reliability of the new method are quite promising and show that the ABC algorithm performs very well and is comparable to the canonical Genetic Algorithm and Particle Swarm Intelligence, hence demonstrating its potential for other optimization applications in nuclear engineering field as, for instance, the cascade problems.     

核动力装置冷凝器体积的优化设计

冷凝器是核动力装置中的重要设备,它的尺寸是影响核动力装置经济性和合理布置的重要因素。本文在总结冷凝器设计经验的基础上,建立了冷凝器的数学模型,并开发了相应的计算程序。在此基础上对影响冷凝器体积的设计参数进行了敏感性分析。以冷凝器总体积最小为目标函数,在所确定的约束条件下,采用复合形 遗传算法对冷凝器进行了优化设计。结果表明,参考冷凝器的设计并非最优方案,尚有较大的优化空间。也证明了该优化设计方法的可行性。本文的计算结果可为工程设计提供参考。     

Effect of noncondensable gas in a vertical tube condenser

An experimental study is performed to investigate the effects of noncondensable (NC) gas in the steam condensing system. A vertical condenser tube is submerged in a water pool where the heat from the condenser tube is removed by boiling heat transfer. The design of the test section is based on the passive condenser system in an advanced boiling water nuclear power reactor. Data are obtained for various process parameters, such as inlet steam flow rate, noncondensable gas concentration, and system pressure. Degradation of the condensing performance with increasing noncondensable gas is investigated. The condensation heat transfer coefficient and heat transfer rate decrease with noncondensable gas. The condensation heat transfer rate is enhanced by increasing the inlet steam flow rate and the pressure. The condensation heat transfer coefficient increases with the inlet steam flow rate, however, decreases with the system pressure. For the condenser submerged in a water pool with saturated condition, the strong primary pressure dependency is observed.     

核电站凝汽器设备运行性能监督及诊断分析

发电厂热力循环中的凝汽器及循环冷却水系统,是保证汽轮发电机组经济、安全、稳定运行的重要系统设备。在汽轮发电机组的实际运行中,由于凝汽器压力变化受到蒸汽热负荷、冷却水进水温度、流量,以及真空系统严密性等诸多因素的影响,运行人员无法通过凝汽器运行压力、温度等直接监测数据来分析判断设备运行性能的好坏。本文依据制造厂家提供的凝汽器特性曲线,通过对某一核电机组的实际运行数据进行分析,并考虑实际运行中海水温度变化引起的凝汽器的变工况运行,提出了凝汽器冷却水温升、传热端差和运行压力等设备运行性能指标参数的基准曲线的确定方法。利用基准曲线可方便获取凝汽器设备运行性能指标参数的应达值,为凝汽器性能变化趋势分析及设备故障原因和诊断提供依据。在核电机组实际运行中,快速识别设备实际运行状态是否偏离设计工况,及时查找凝汽器设备性能劣化原因和处理设备故障,对于保障机组设备安全可靠运行至关重要。     

蒸汽排放系统蒸汽冷凝器动态特性仿真研究

根据核动力商船高压定压蒸汽冷凝器的结构及工作特性,建立了适合蒸汽冷凝器实时仿真分析计算的两相流仿真模型。利用该仿真模型对蒸汽冷凝器进行了稳态计算和动态仿真分析,并将其稳态计算结果与蒸汽冷凝器试验结果进行对比验证。结果表明：该模型能准确模拟蒸汽冷凝器的动态特性,满足核动力装置蒸汽排放系统实时仿真分析要求。研究结果对二回路系统启动及停运的运行和控制系统设计具有指导意义。     

New genetic algorithms (GA) to optimize PWR reactors: Part I: Loading pattern and burnable poison placement optimization techniques for PWRs

The objective of this study was to develop a unique scientific methodology as well as a practical tool for designing the loading pattern (LP) and burnable poison (BP) pattern for a given Pressurized Water Reactor (PWR) core. Because of the large number of possible combinations for the fuel assembly (FA) loading in the core, the design of the core configuration is a complex optimization problem. It requires finding an optimal FA arrangement and corresponding BP placement design that will achieve maximum cycle length while satisfying the safety constraints. To solve this optimization problem, a core reload optimization package, GARCO (Genetic Algorithm Reactor Code Optimization) code is developed. This code is applicable for all types of PWR cores having different geometries and designs with an unlimited number of FA types in the inventory. GARCO has three modes: the user can optimize the core configuration (LP pattern) with or without BPs in the first mode; the second mode is the optimization of BP placement in the core and the last mode is the user can optimize LP and BP placements simultaneously in mode 3. In this study, the first mode finds the optimal LPs using the Haling Power Depletion Method (HPD) for placing BPs in the core. The second mode, which depletes the core accurately, places BPs in the selected optimum LP pattern. This methodology is applied only to the TMI-1 PWR. However, the improved Mode 1 GA option was applied to both the VVER-1000 and the TMI-1 to demonstrate and verify the advantages of the new enhancements in optimizing the LP pattern only. The “Moby-Dick” code is used as reactor physics code for VVER-1000 analysis in this research. The SIMULATE-3 code, which is an advanced two-group nodal code, is used to analyze the TMI-1. The libraries of the BP designs used in SIMULATE-3 in this study were produced by Yilmaz (2005) [Yilmaz, S., 2005. Multilevel optimization of burnable poison utilization for advanced PWR fuel management. Ph.D. Thesis in Nuclear Engineering. the Pennsylvania State University].     

船舶汽轮机优化设计

船舶汽轮机是船舶动力装置中关键设备之一,且随着汽轮机大功率的发展趋势,其重量体积进一步增加,这给设备的设计安装带来困难,并严重影响船舶的机动性。因此,有必要在汽轮机设计中,应用优化技术寻找设计参数的最优组合,以减小汽轮机的重量或体积。建立船舶汽轮机设计计算数学模型,对其重量受冷凝器压力、高低压缸功率比和低压缸末级径高比影响的敏感性进行分析。以船舶汽轮机重量最小为目标函数,在满足一定的结构及性能约束条件下,利用混合粒子群算法对其进行优化设计。研究结果显示,采用优化方案后,汽轮机重量减小了3.13%。最后对优化结果进行了分析,指明了汽轮机优化设计的方向。     

GA-based dynamical correction of dispersion coefficients in Lagrangian puff model

In atmospheric dispersion models of nuclear accident, the dispersion coefficients were usually obtained by tracer experiment, which are constant in different atmospheric stability classifications. In fact, the atmospheric wind field is complex and unstable. The dispersion coefficients change even in the same atmospheric stability,hence the great errors brought in. According to the regulation, the air concentration of nuclides around nuclear power plant should be monitored during an accident. The monitoring data can be used to correct dispersion coefficients dynamically. The error can be minimized by correcting the coefficients. This reverse problem is nonlinear and sensitive to initial value. The property of searching the optimal solution of Genetic Algorithm(GA) is suitable for complex high-dimensional situation. In this paper, coupling with Lagrange dispersion model, GA is used to estimate the coefficients. The simulation results show that GA scheme performs well when the error is big. When the correcting process is used in the experiment data, the GA-estimated results are numerical instable. The success rate of estimation is 5% lower than the one without correction. Taking into account the continuity of the dispersion coefficient, Savitzky-Golay filter is used to smooth the estimated parameters. The success rate of estimation increases to 75.86%. This method can improve the accuracy of atmospheric dispersion simulation.     

屏蔽材料组分含量的优化设计

防辐射材料的屏蔽性能跟材料的组成成分含量是有关的,成分含量不同,屏蔽效果也不同。利用遗传算法,对衰减公式进行优化计算,得出各组分含量的最佳配比。用MCNP程序对几种组分配比的材料进行X射线屏蔽模拟,结果表明利用遗传算法计算出来的配比材料屏蔽效果最好。     

A Metropolis algorithm combined with Nelder–Mead Simplex applied to nuclear reactor core design

A hybridization of the recently introduced Particle Collision Algorithm (PCA) and the Nelder–Mead Simplex algorithm is introduced and applied to a core design optimization problem which was previously attacked by other metaheuristics. The optimization problem consists in adjusting several reactor cell parameters, such as dimensions, enrichment and materials, in order to minimize the average peak-factor in a three-enrichment-zone reactor, considering restrictions on the average thermal flux, criticality and sub-moderation. The new metaheuristic performs better than the genetic algorithm, particle swarm optimization, and the Metropolis algorithms PCA and the Great Deluge Algorithm, thus demonstrating its potential for other applications.     

Scaling of passive condenser system for separate effect testing

The passive containment cooling system (PCCS) of the simplified boiling water reactor (SBWR) is a passive condenser system designed to remove energy from the containment for long term cooling period after a postulated reactor accident. Depending on pressure condition and noncondensable (NC) gas fraction in drywell (DW) and suppression pool (SP), three different modes are possible in the PCCS operation namely the forced flow, cyclic venting and complete condensation modes. The prototype SBWR has total of six condenser units with each unit consisting of hundreds of condenser tubes. Simulation of such prototype system is very expensive and complex. Hence a scaling analysis is used in designing an experimental model for the prototype PCCS condenser system. The motive for scaling is to achieve a homologous relationship between an experiment and the prototype which it represents. A scaling method for separate effect test facility is first presented. The design of the scaled test facility for PCCS condenser is then given. Data from the test facility are presented and scaling approach to relate the scaled test facility data to prototype is discussed.     

冷凝器小型化技术研究

介绍了核动力装置中冷凝器小型化技术。通过冷凝器模拟体的实验研究，给出了螺纹槽管冷凝器的实验研究结果，分析了螺纹槽管冷凝器的工作特性和强化传热效果。所得实验结果对螺纹槽管冷凝器的实际应用有指导性意义。     

核电站凝汽器仿真模型研究

凝汽器是核电站汽轮发电机组的主要设备之一,采用仿真手段研究核电站凝汽器的运行特性对于优化设计和运行、提高运行的安全性和经济性具有实际意义。本文以核电站中普遍采用的表面式单流程对分制凝汽器为研究对象,运用分布式热动力学的建模思想,考虑不凝结气体（空气）对换热特性的影响,建立了凝汽器的动态数学模型。通过仿真计算,得到不同控制参数阶跃情况下凝汽器的动态响应,仿真结果与实验结果符合良好,表明所建立的仿真模型正确、合理。     

Multiobjective fuel management optimization for self-fuel-providing LMFBR using genetic algorithms

One of the conceptual options under consideration for the future of nuclear power is the long-term development without fuel reprocessing. This concept is based on a reactor that requires no plutonium reprocessing for itself, and provides high efficiency of natural uranium utilization, so called Self-Fuel-Providing LMFBR (SFPR). Several design considerations were previously given to this reactor type which, however, suffer from some problems connected with insufficient power flattening, large reactivity swings during burnup cycles, and peak fuel burnup being significantly higher than recent technology experience, which is about 18% for U-10 wt%Zr metallic fuel to be considered. Yet, the mentioned core parameters demonstrate high sensitivity to the fuel management strategy selected for the reactor. Therefore, the aim of this study is to develop a practical tool for the improvement of the core characteristics by fuel management optimization, which is based on advanced optimization techniques such as Genetic Algorithms (GA). The calculation results obtained by a simplified reactor model can serve as estimates of achievable values for mentioned core parameters, which are necessary to make decisions at the preliminary optimization stage.     

钠冷快堆丧失蒸汽发生器模块后的最佳工况研究

钠冷快堆通过采用模块式蒸汽发生器的设计方案以提高核电厂的负荷因子。核电厂运行中若发生丧失蒸汽发生器模块事件,核电厂工况将发生变化,应进行适当的调节,调节的目标工况可通过设计与研究给出。本工作对某典型池式钠冷快堆丧失1个蒸汽发生器模块后的最佳工况进行研究,主要研究内容包括对其主热传输系统进行建模,开展主热参数匹配计算,根据相关运行限值来筛选方案并分析关键参数,最终给出较为合适的运行工况。本工作为钠冷快堆在丧失蒸汽发生器模块后的工况设计提供了重要依据。