汽水分离再热器多目标优化研究

汽水分离再热器在核电系统中属于大型设备,其重量、体积较大。同时,汽水分离再热器对核电系统整体热经济性具有较大影响,因此汽水分离再热器也是核电系统中的重要设备。众所周知,为了降低核电的初投资成本,提高核电系统在电力市场中的竞争力,有必要对核电系统中的大型设备进行优化设计研究。寻找可使汽水分离再热器重量、体积得以降低的设计方案。本文根据汽水分离再热器的物理过程,建立了可靠的数学模型,并利用C#语言编写了相应的评价程序。结合优化程序模块,实现了对汽水分离再热器运行及结构参数的多目标优化实例研究,其优化目标是在保证功能性的前提下,降低汽水分离再热器的重量、减小其体积。优化结果给出了汽水分离再热器多目标最优决策方案,方案显示,在满足所给定的结构及性能约束的条件下,经优化,汽水分离再热器的净重量减轻约3.4%,体积减小约4.9%,优化效果显著。通过对汽水分离再热器进行参数分析,一方面定性验证了设备模型的正确性和可用性,另一方面对于最优决策方案的合理性在一定程度上也给出了依据。结果可为核动力装置小型化优化研究提供理论参考和优化方向。     

压水堆核电机组抽汽改造

压水堆核电汽轮机主要工作在湿蒸汽区,比相同功率火电机组蒸汽流量高,单台机组具有更大的供热能力,适合供暖.借鉴火电机组抽汽供热改造的工程经验,以AP1000压水堆为例,给出汽水分离再热器(MSR)前抽汽改造方案.分析了抽汽供热对机组运行控制、热经济性、安全分析的影响,分析表明改造没有对现有安全分析结论形成挑战,但给运行控...     

方家山核电汽水分离再热器壳侧疏水设计优化与改进

方家山核电为两台百万千瓦级压水堆核电机组,采用二代改进型压水堆技术。两台汽水分离再热器的壳侧疏水泵长期在高温条件下连续运行,故障率较高。原设计仅考虑每列MSR的壳侧疏水设置1台疏水泵,故当疏水泵故障停运时,MSR壳侧疏水必须切换排至凝汽器,会造成机组热效率下降,如同时备用疏水阀门故障会危及机组安全。通过对汽水分离再热器壳侧疏水设计优化的必要性与改进的可行性进行分析,采取在每列MSR的壳侧疏水管增设一台疏水泵回路构成备用列的方式,实现当一台疏水泵故障停运后另一台疏水泵启动,将疏水排至ABP系统上游管道。避免了因一台疏水泵故障停运导致MSR的壳侧疏水只能依靠单一管线切换至凝汽器。改进结果达到了预期,增加了MSR疏水泵运行方式的灵活性,提高了GSS系统壳体疏水的可靠性。     

核电站MSR疏水闪蒸引起的非预期跳机风险分析研究

核电机组在甩负荷工况下,汽水分离再热器开关量高液位触点会因闪蒸而产生虚假信号,存在误触发跳机保护风险。通过深入分析闪蒸原理及跳机逻辑,挖掘潜在的机组非预期跳机风险,并结合设备布置结构、系统运行原理、关联调节阀控制以及跳机保护需求等,提出两种优化改进方案,并对比分析其优缺点,实现既能避免原有的误动风险,又防止引入新的拒动风险。通过高功率平台下的瞬态试验对优化方案进行验证,结果表明,通过本次优化可有效消除潜在的跳机风险,在保护设备本身安全稳定运行的同时,也提高了核电站汽轮发电机组整体运行安全,对其他核电机组瞬态过程中疏水闪蒸风险防范也有很好的借鉴意义。     

汽水分离再热器的传热系数及出口温度随功率变化规律的分析

本文从传热学的基本原理出发,推导出核电站汽水分离再热器的传热系数随功率变化的关系式,并用该关系式导出了汽水分离再热器的出口参数随功率的变化,从而为计算和设计汽水分离再热器的温度控制系统提供了理论基础。     

核电站除氧系统孔板后管道减薄机理分析与改进措施研究

田湾核电站1号机组除氧系统某节流孔板后方的直管段在一个换料周期内壁厚由6.6 mm减薄至2.5 mm,极易造成管道泄漏,为机组安全运行带来潜在的隐患。本文就除氧系统孔板后管道减薄磨损位置、汽蚀原理进行分析,对除氧系统孔板设计存在的缺陷、采用多级节流孔板代替单级节流孔板优势及管道减薄改进措施进行综合论述。通过改造,满足了除氧系统给水管线的运行要求,且有效降低了管道腐蚀速率。     

压水堆核电站汽轮机汽水离-中间再热器

在水堆核电站汽轮机的汽水分离-中间再热器的设计中,除了选择好最佳设计参数,采用高效的汽水分离元件和提高再热器的传热效率外,合理的结构形式亦是必须考虑的主要问题之一。     

原子能电站的汽水分离-中间再热器

本文介绍水冷堆原子能电站特有的一项重要设备——汽水分离-中间再热器(MSR)的各种技术问题、国外现状和动向、设备故障及其它有待进一步研究的课题。     

卧式蒸汽发生器排污穴室水力冲洗设备的研发和应用

为清理田湾核电站1、2号机组蒸汽发生器（SG）二次侧排污穴室内积聚的腐蚀产物、降低其对壳体母材和焊缝造成腐蚀的风险，研制了排污穴室水力冲洗设备并且在机组大修期间进行了应用。通过水力冲洗工作，清理了SG排污穴室内积聚十余年时间的沉积物、检查确认排污穴室内壁和焊缝无异常，提高了蒸汽发生器运行的安全性、可靠性。      

RtCM方法在某核电厂汽水分离再热器系统的应用实践

以可靠性和技术特性为中心的维修(Rt CM)方法是确定资产预防性维修需求、优化维修制度的一种系统工程方法。介绍以Rt CM方法的分析流程和特点,并以某核电厂汽水分离再热器系统为应用试点,详细阐述Rt CM实施过程、设备维修策略优化的效益。实践表明,Rt CM分析方法通过引入故障模板、技术特性分析、设备分级和定量化分析,提高了分析效率,对提高系统设备可靠性发挥了重要作用。     

EAST安全巡检与联锁保护系统设计与实现

全超导托卡马克系统不同于常规托卡马克系统,有独特的运行特性和更高的运行风险.安全巡检与联锁保护系统是托卡马克系统中必不可少的-个重要组成部分.EAST (Experimental Advanced Superconducting Tokamak)是我国自主研发的世界上第-个全超导托卡马克系统.本文详细分析了EAST的主要运行风险,针对运行风险制定的各子系统的安全监测和保护机制,及分布式 EAST 安全巡检与联锁保护系统的系统体系结构和系统的实现.EAST 已在中国科学院等离子体物理研究所建成并于2006年9月运行成功,获得等离子体,本系统已在EAST装置的2006-2007年度的几轮实验中成功应用.     

CdMnS的制备及其铁电铁磁性研究

用共蒸发的方法制备了六角多晶结构的CdMnS薄膜,研究了薄膜的铁电性和铁磁性.2%Mn浓度的样品的剩余极化强度Pr为1.72μC/cm2,矫顽场强Ec为14.3kV/cm.Au掺杂的CdMnS样品的居里点超过了300K.在10K低温磁滞回线中,得到的剩余磁化强度和磁矫顽力分别为1.39×10-6emu和75.4 G;用磁力显微镜清楚地观察到从几个纳米到一百纳米大小不等的磁性团簇,还发现掺杂元素的浓度对其磁性具有明显影响.     

L边密度计稳定性监控及U、Pu测量

本文采用金属Zr片作为质控样品监控L边密度计的长期稳定性,在此基础上采用L边密度计测量系列水相U标准溶液和水相Pu标准溶液,绘制水相U工作曲线和水相Pu工作曲线,建立了L边密度计测量U、Pu的分析方法,并采用该工作曲线测量了系列U和Pu标准溶液。结果显示,该方法既可测量水相U、Pu,也可测量有机相U、Pu,对于10 g/L以上的U溶液,测量结果的相对偏差小于5%;对于5 g/L以上的Pu溶液,测量结果的相对偏差小于1.7%。以上结果表明,本文所建立的L边密度计测量U、Pu的方法准确度良好,可用于实际U、Pu的测量。     

Thermophysical and mechanical properties of CrB and FeB

ABSTRACT

Fuel debris in the Fukushima Daiichi nuclear power plant is thought to contain borides that are generated from B₄C control material. In order to successfully devise methods to effectively remove the debris material, characterization of the properties of the fuel debris is essential. This paper presents some of the thermophysical and mechanical properties of two types of borides, FeB and CrB, and compares them with those of Fe₂B and ZrB₂. These are the representative borides that might have been generated in the Fukushima Daiichi (1F) nuclear power plant accident. We observed that the thermal conductivity values of both CrB and FeB are much lower than that of ZrB₂, and are similar to that of Fe₂B. Moreover, the Vickers hardness and fracture toughness of FeB and CrB are almost identical to each other, and similar to those of ZrB₂ and Fe₂B.     

Mechanics and mechanisms of creep deformation and damage

In recent years, several important advances in the understanding of the mechanics and mechanisms of creep deformation, damage and fracture in polycrystalline alloys have been achieved through the synergistic efforts of materials scientists and applied mechanicians. Current understanding, while far from complete, nonetheless provides a physically-based framework for developing computationally tractable continuum constitutive relations which capture major features of the intrinsic mechanisms of creep damage and deformation. Such models, when applied to the analysis of scientifically and technologically relevant boundary value problems, provide a basis for a local approach to high temperature fracture. The first section of the paper reviews certain aspects of the phenomenology, mechanisms, and mathematical models of creep fracture. It is concluded that an important internal damage parameter influencing macroscopic tertiary creep in conventional polycrystalline materials is the density of grain boundary facet cracks. The development of a “damage” constitutive model can conceptually be broken into two parts. One aspect is to quantify the effect of an (instantaneous) state of damage on the mechanical behavior. In the second part of the paper, this topic is explored for the case of a (generally non-dilute) distribution of aligned facet cracks in a power law creeping matrix. The remaining aspect of the model is to provide evolution equations for the damage variable(s). In the third section of the paper, we develop a simplified model for the evolution of facet crack density under conditions of creep-constrained cavitation. A central feature of the model is the variability in cavity nucleation potency over the grain boundary population.     

Calculations of the trapping and migration of vacancies and nickel self-interstitials in the presence of rare gases and dislocations

Recent models of swelling, void growth, and solute segregation under irradiation all require knowledge of the trapping and migration of vacancies and self-interstitials in the presence of lattice defects. The present calculations include trapping of both vacancies and nickel self-interstitials to substitutional and interstitial rare gas atoms. The results show a systematic dependence on rare gas atom size. It is found for example, that a vacancy is bound to a small fixed rare gas interstitial (He) by ～0.5 eV and to a large fixed interstitial (Xe) by ≥3 eV. In addition, a fixed substitutional rare gas or rare gas interstitial is found to be a strong trap for a self-interstitial. It is found that a single vacancy can significantly affect the migration energy of another vacancy. For example, a 0.4 eV decrease in migration energy is found at a distance of three half-lattice constants. However, this interaction is of limited range; at distances greater than five half-lattice constants vacancy migration is unaffected. The migration of vacancies near the core of a partial dislocation was also investigated. This partial is found to provide a 1 eV (compared to 1.4 eV in the bulk) path for the pipe diffusion of vacancies. In addition, the activation energy for vacancy migration along the slip plane is reduced by as much as 0.2 eV.     

丝状真菌F54的分离鉴定及其对铯的吸附特性

从新疆放射性污染土壤样本中,采用微生物分离方法,结合压力试验及吸附实验,获得一株对放射性核素污染具有修复能力的土著丝状真菌F54。通过形态学、分子生物学鉴定及Biolog碳源利用实验,F54为镰刀霉菌属真菌,与Fusarium oxysporum strain ATCC MYA-3931同源性最高。最适宜生长条件是:马铃薯葡萄糖培养基,30℃,pH=7.0。菌株F54吸附Cs+的最佳条件是:pH=7.0,30℃,伴随生长进行吸附约3~4d,吸附率最高能达到约84%,常见金属阳离子K~+、Na~+、Ca~(2+)、Mg~(2+)、Al~(3+)、Fe~(3+)对其吸附均有一定的抑制作用。菌株F54能够耐受10kGy的钴源照射,对重金属离子Ni~(2+)、Cr~(3+)、Zn~(2+)、Co~(2+)、Pb~(2+)、Hg~(2+)均有较高耐受性,对放射性137 Cs的吸附率为62%。菌株F54在有较高的重金属离子混合污染的放射性环境中具有一定的修复应用潜能。