“华龙一号”ZH-65型蒸汽发生器研发

"华龙一号"是我国自主研发的具有完全自主知识产权的第三代压水堆核电技术。介绍了"华龙一号"核电机组反应堆冷却剂系统关键设备ZH-65型蒸汽发生器(SG)的自主研发情况,主要包括SG的设计、设计软件研发、设计验证试验和关键材料研制。ZH-65型SG在技术上达到第三代PWR核电站SG的水平,具有完全自主知识产权,是"华龙一号"头上的一颗璀璨明珠。该型SG的研发成果已用于出口巴基斯坦的K2K3工程项目和福建福清核电站第5、6号机组工程项目。K2机组的3台ZH-65型SG已于2017年7月12日验收出厂,必将创造良好的经济效益和显著的社会效益。     

蒸汽发生器传热管动态特性研究

蒸汽发生器(SG)传热管束受二次侧横向流动流体的激励而产生的振动,是引起SG传热管失效的主要原因之一,传热管的固有频率和振型是进行流致振动响应分析评价的关键因素。采用理论分析与试验相结合的方式对ZH-65型SG的传热管开展动态特性研究,获得了传热管的固有频率和振型。试验值和计算值的相对偏差在8%以内。     

基于高抗震性能的华龙一号蒸汽发生器上部支承设计研究

为提高华龙一号核电机组ZH-65型蒸汽发生器抗震性能,提出了一种新型的蒸汽发生器支承方案,即对蒸汽发生器上部支承釆用连接拉杆与液压阻尼器结合的结构形式,并针对总体设计方案和连接拉杆的热膨胀相容性进行了设计研究。相比原有二代加核电机组蒸汽发生器上部支承,本文所设计研究的上部支承在设备重量、焊缝数量、安装调试难度等方面,均有大幅优化;可有效减少支承载荷,最大减少幅度约为24%;可降低蒸汽发生器接管焊缝载荷,最大降低幅度约为28%。      

蒸汽发生器二次侧打压试验水温控制与水质调节

M310型机组蒸汽发生器二次侧水压试验,是对蒸汽发生器二次侧管板的严密性及相关系统耐压性的验证。由于蒸汽发生器的重要性,其水压试验用水对温度及水质有着严格的要求。通过对福清核电1号机组二回路水压试验水温控制和水质调节的探讨,有助于对M310型机组蒸汽发生器水压试验准备工作起到良好的指导意义。     

CAP1400蒸汽发生器汽水分离装置研究

汽水分离装置是蒸汽发生器中的主要部件,其性能不仅会影响蒸汽发生器水力循环特性及水位适用性,决定上部尺寸大小,而且会影响汽轮机的正常运行。对CAP1400核电厂蒸汽发生器汽水分离装置进行了不同蒸汽负荷、饱和水量及高水位和正常水位等试验工况下的热态性能试验,获得了SP3型初级分离器与P3X型干燥器组合随蒸汽负荷、饱和水量、水位变化的分离特性。通过初级分离器和干燥器的阻力测量,分别获得了分离器和干燥器的阻力特性,对CAP1400蒸汽发生器的设计研发起到支撑作用。     

多模块直流蒸汽发生器给水系统特性分析

为给中国示范快堆给水控制系统的控制方案设计及直流蒸汽发生器结构参数设计提供必要参考依据，本文搭建了多模块直流式蒸汽发生器给水系统的仿真模型，对示范快堆给水系统的静态特性和动态特性进行了仿真研究。分析了蒸发器出口钠温和蒸汽发生器一次侧流量偏差等关键参数对各模块工作状态的影响，并得出了系统可靠工作条件下这些关键参数变化的限值。研究结果表明，为防止蒸发器出口蒸汽过热度不足，保证蒸发器可靠工作，需限制蒸发器出口钠温过低，以及蒸汽发生器一次侧流量相对于平均值过高。     

螺旋管蒸汽发生器三维热工水力程序HeTAF开发

针对核动力系统螺旋管蒸汽发生器,本文采用多孔介质方法对具有复杂换热组件区域多层螺旋套管结构进行简化,构建了壳侧工质流动换热特性数学物理模型,并基于均相流假设建立了管侧水-水蒸气两相流动沸腾换热特性分析模型,采用网格-节点映射方法实现了管壳两侧耦合传热计算,基于开源OpenFOAM平台开发了适用于螺旋管蒸汽发生器的三维全尺寸热工水力特性分析程序HeTAF。基于螺旋管两相流动沸腾换热实验开展了模型验证,并以高温气冷堆示范工程中螺旋管直流式蒸汽发生器为分析对象开展了单换热组件模拟,获得的氦气和蒸汽出口温度计算结果与设计值符合较好,表明HeTAF能有效预测换热组件内管壳两侧流动换热特性。本文的研究对螺旋管蒸汽发生器的设计和安全分析具有参考意义。     

蒸汽发生器二次侧两相流传热特性数值研究

以AP1000核电站蒸汽发生器为原型,建立蒸汽发生器二次侧"平均通道"模型,利用计算流体动力学软件ANSYS CFX,基于相界面模型对蒸汽发生器二次侧两相流流动和沸腾换热过程进行研究。结果表明:数值模拟计算方法能准确模拟蒸汽发生器二次侧汽液两相流沸腾和传热过程;满负荷运行时,流体由预热区经过泡核沸腾区过渡到稳定沸腾区,含汽率和传热系数沿流动方向逐渐增大,出口含汽率与该型号蒸汽发生器设计值符合较好,平均传热系数的模拟结果和JensLottes经验关联式的预测值基本一致。     

基于可视化实验台架的蒸汽发生器二次侧自然循环现象研究

对于传统压水堆核电站的蒸汽发生器,U型管热段热流密度大,冷段热流密度小,两侧不同的热流密度使得二次侧的热侧与冷侧的沸腾情况不一致,而真实的蒸汽发生器体型庞大,结构复杂,其内部真实的流动情况也不得而知。为弄清核电站蒸汽发生器二次侧的流动现象,搭建了单排非均匀加热管的可视化蒸汽发生器实验台架,并借助高速摄像机对其内部流动情况进行了拍摄,利用所拍摄的图像得到了相应位置气泡的横向流动速度。结果表明,在实验运行过程中,两侧不同的热流密度导致空泡份额差异很大,从而产生横向的自然循环流动现象,这一现象在二次侧流体流经U型弯管时,表现得更为剧烈。     

基于多孔介质模型的快堆蒸汽发生器热工水力特性数值研究

蒸汽发生器（SG）作为钠冷快堆一次侧钠与二次侧水的热交换器,其可靠程度直接影响反应堆能否安全运行,因此对SG的一次侧热工水力特性的研究具有重要意义。本研究采用多孔介质模型,对快堆蒸汽发生器一次侧流场进行分析。通过对支撑板模型的计算,获得多孔介质控制方程的阻力源项。一次侧向二次侧的释热量通过系统程序Relap5计算,确定多孔介质控制方程的能量源项。通过用户自定义程序将动量源项与能量源项编译至FLUENT求解器中。通过FLUENT求解器求解控制方程,获得SG一次侧流场、压力场、温度场等信息。并通过对比模拟结果与设计值,验证了计算的准确性。      

A new LMR steam generator free from SWR with a double tube bundle configuration

This paper describes the activities made at KAERI to develop an advanced liquid metal reactor (LMR) steam generator which is free from a sodium water reaction (SWR) to resolve the concern of the SWR possibility and improve the economic features of the LMR. The steam generator design houses two tube bundles that are functionally different and its tube bundle region is radially or vertically divided into two. The SG is equipped with hot and cold fluid tube bundles, a medium fluid and a pump. It prevents the occurrence of the sodium water reaction while sodium is still used as the coolant for the primary heat transport system. The feasibility of using the SG with a double tube bundle for an actual use in a LMR plant is evaluated by setting up the skeleton of the NSSS for various possible configurations of the SG tube bundles.Analysis was made for various types of the new steam generator with a double tube bundle. Since the heat transfer in the SG is made among three different fluids, it has unique heat transfer characteristics. The analysis showed the possibility of the occurrence of an undesirable reversed heat transfer not only in the integrated single-region bundle type but also in the integrated double-region bundle type. The performance analysis revealed practical performance characteristics for the various bundle configurations. Also the feasibility study for the various NSSS configurations with the new SG is described.     

Thermal-Hydraulic Study of Integrated Steam Generator in PWR

One of the safety aspects of innovative reactor concepts is the integration of steam generators (SGs) into the reactor vessel in the case of the pressurized water reactor (PWR). All of the reactor system components including the pressurizer are within the reactor vessel in the SG integrated PWR.

The simple heat transfer code was developed for the parametric study of the integrated SG. The code was compared to the once-through 19-tube SG experiment and the good agreement between the experimental results and the code predictions was obtained. The assessed code was used for the parametric study of the integrated once-through 16 m-straight-tube SG installed in the annular downcomer. The proposed integrated SG as a first attempt has approximately the same tube size and pitch as the present PWR and the SG primary and secondary sides in the present PWR is inverted in the integrated PWR. Based on the study, the reactor vessel size of the SG integrated PWR was calculated.     

HTR-10一体化换热装置和联合循环

10MW高温气冷实验堆 (HTR 10 )有两个突出的特点 :(1)采用气体轮机和汽轮机联合循环 ,可以提高其发电效率 ,并且能保持较低的堆芯入口温度 (30 0℃ )。 (2 )中间换热器和蒸汽发生器一体化设计 ,减少了一个壳体和一个热气导管 ,提高了安全性和经济性。描述了一体化的中间换热器和蒸汽发生器以及气体轮机和蒸汽轮机联合循环的设计特点。     

高温气冷堆螺旋管式直流蒸汽发生器热工水力学

高温气冷堆蒸汽发生器具有一次侧氦气工质、二次侧直流、螺旋管结构、工作温度高等特点,其热工水力特性与传统压水堆自然循环蒸汽发生器存在很大区别。针对高温气冷堆蒸汽发生器的特点,对其基础热工水力及特有热工水力学问题进行了阐述,主要包括螺旋管内单相及两相流阻及换热计算、横掠螺旋管束流阻及换热计算、温度均匀性及两相流不稳定性等。同时介绍了清华大学核能与新能源技术研究院针对高温气冷堆蒸汽发生器热工设计、温度均匀性及两相流不稳定性等热工水力学问题所开发的一维稳态程序、一维瞬态程序、二维分析程序和方法,并对分析结果和结论进行了讨论。相关研究方法、程序和结论对其他相似参数螺旋管和直管式直流蒸汽发生器具有参考和借鉴意义。     

Experiment and Verification Test of the Once-through Steam Generator of the 10 MW High-temperature Gas-cooled Reactor Flow Stability of the Once-through Steam Generator

In January 2003, the 10MW High-temperature Gas-cooled Reactor (HTR-10) reached its full power for continuous operation of seventy-two hours in the Institute of Nuclear Energy Technology, Tsinghua University. The reactor operated smoothlyqbthe design parameters were successfully attained.

The once-through steam generator (SG) is one of key equipments of the HTR-10 reactor. The SG includes 30 modular heating helical tube assemblies. There are two thermal hydraulic requirements to be satisfied for the once-through steam generator: (1) enough heat transfer surface; (2) qualified steam can be produced under rated electrical generation power, and water-steam two phase flow un-stability can be avoided. In order to obtain the thermal hydraulic characteristics of the SG reliably, before design, a numerical code was developed for the design, and a full-scale test loop with two heating tubes as model was established, and series experiments had been carried out.

The purpose of this paper is to introduce the design of SG and researches on the stability of small bending radius helical coil-pipe used in HTR-10, for exempla, the effects of outlet steam pressure, inlet water sub-cooling degree, thermal power and inlet throttling degree. Up to now, the SG has experienced full power operation smoothly, and approvingly reached its original design requirements.

In the paper, some operational experimental data of the HTR-10 S.G have been presented.     

Prediction of SG Tube Support Plate Flow Area Blockage Rate Using SG Wide Range Level Measurements and Hydrodynamic Analysis

Some nuclear power plants have recently experienced hydrodynamic instability in steam generators (SGs). Instability, if present in the SG of a pressurized water reactor, results in the periodic oscillation of the water level, steam flow, feedwater flow, and the flow through the circulation loop. In this instability analysis, the major parameters are the power level and flow area of the tube support plate (TSP). The threshold power above which instability may occur is generated by variations in TSP flow area. The current method of estimating the blockage rate is the visual inspection of the SG interior. This type of visual inspection, however, requires many resources. To improve this method, we focus on measurements of the SG level. The measurements of the level change because the SG downcomer flow rate varies due to the blockage of the TSP flow area. To quantify this effect, we calculate the circulation ratio in relation to changes in TSP flow area. In addition, we evaluate the pressure drops that affect the SG water level. Sensor drift analyses of the level measurements are performed to confirm that the level variance is derived from system characteristics rather than sensor drift. Finally, the blockage rates of the TSP flow area are generated by using measurements of the SG water level.     

蒸汽发生器U型管低含气率两相倒流现象研究

针对立式倒U型管自然循环蒸汽发生器传热管内的两相倒流现象,基于均相流模型,建立了U型管内低含气率两相流动传热理论模型,给出了U型管的进出口压降-质量流量曲线,分析了U型管内出现两相倒流现象的机理,研究了二次侧流体温度和入口含气率对倒流现象的影响规律,并与单相倒流进行了对比。利用RELAP5/MOD 3.3程序对相同条件下的倒流问题进行了计算。研究表明,提高蒸汽发生器二次侧工作压力可减少倒流,两相流入口含气率越高,倒流越易发生,两相流较单相流在U型管内更易倒流。     

Experiments on the Heat Transfer and Natural Circulation Characteristics of the Passive Residual Heat Removal System for an Advanced Integral Type Reactor

Experiments on the heat transfer characteristics and natural circulation performance of the passive residual heat removal system (PRHRS) for the SMART-P have been performed by using the high temperature/high pressure thermal-hydraulic test facility (VISTA). The VISTA facility consists of the primary loop, the secondary loop, the PRHRS loop, and the auxiliary systems to simulate the SMART-P, a pilot plant of the SMART. The primary loop is composed of the steam generator (SG) primary side, a simulated core, a main coolant pump, and the loop piping, and the PRHRS loop consists of the SG secondary side, a PRHRS heat exchanger, and the loop piping. The natural circulation performance of the PRHRS, the heat transfer characteristics of the PRHRS heat exchangers and the emergency cooldown tank (ECT), and the thermal-hydraulic behavior of the primary loop are intensively investigated. The experimental results show that the coolant flows steadily into the PRHRS loop and that the heat transfers through the PRHRS heat exchanger and the emergency cooldown tank are sufficient enough to enable a natural circulation of the coolant. The results also show that the core decay heat can be sufficiently removed from the primary loop with an operation of the PRHRS.     

全厂断电引发的严重事故下蒸汽发生器传热管蠕变失效风险研究

全厂断电引发的严重事故若处置不当,可能发展为长期、高压的严重事故进程,此时堆芯冷却系统中的自然循环在导出部分堆芯余热的同时,也增加了蒸汽发生器（SG）传热管、稳压器波动管以及热管段出现蠕变失效的风险。本文基于两环路设计的秦山二期核电厂设计特点,结合蠕变失效风险模型,对全厂断电引发的严重事故后未能执行“严重事故管理导则中向蒸汽发生器注水（SAG-1）”时SG传热管的蠕变失效风险进行了研究,从而为全厂断电引发的严重事故的负面影响提供量化结果,为技术支持中心（TSC）最终决策提供参考依据。分析结果表明,全厂断电引发的严重事故后16 361 s可能出现蠕变失效;自事故后16 610 s,SG传热管出现蠕变失效的可能性均远低于稳压器波动管与热管段,秦山二期核电厂全厂断电引发的严重事故下因SG传热管蠕变失效而导致安全壳旁通的风险很小。