临界热流密度实验研究进展

临界热流密度是重要的限制性热工参数，它的大小直接影响反应堆的安全性和经济性。本文介绍了我国核电站临界热流密度实验研究进展，比较了国外核电站临界热流密度研究发展状况，文章认为，我国临界热流密度实验研究的发展方向是进行全长棒束非均匀加热临界热流密度的实验研究。     

临界热流密度关系式与DNBR热工裕量

采用不同的临界热流密度关系式、不同的DNBR子通道分析程序、不同的DNBR限值、不同的DNBR验收准则和DNBR热工裕量计算方法。得到的DNBR和DNBR热工裕量是不相同的，通过使用最新的子通道分析程序。利用EC-2000和WRB-2M临界热流密度关系式对CNP1000核电厂277MW、2895MW和3150MW热功率堆芯进行了DNBR和DNBR裕量分析。DNBR值满足验收准则的要求，反应堆是安全的。     

自然循环临界热流密度实验研究

本文介绍高压自然循环临界热流密度(CHF)实验研究。结果表明,对于稳定流动,自然循环与强迫循环CHF值几乎没有差別;不稳定流动将导致CHF降低。文中还给出了自然循环CHF工况预算模型。     

水平圆管临界热流密度实验研究

对水平圆管内低质量流速临界热流密度(CHF)进行了实验研究和分析。实验研究发现,水平流动圆管沸腾临界发生在圆管加热壁面顶部。通过对沸腾临界发生时圆管出口的质量含汽率和流型进行分析发现,本文研究的参数范围内沸腾临界时的出口含汽率高,流型为环状流,沸腾临界类型为干涸型(Dryout)。将经验公式预测值与实验结果进行比较发现,Bowring公式和Lookup table的预测值远大于CHF的实验值。导致此现象出现的主要原因为:Bowring公式和Lookup table是基于竖直流动CHF实验数据开发的模型,水平流动时在重力的作用下环状流液膜呈非均匀分布,顶部液膜干涸提前触发沸腾临界造成CHF值降低。     

低压临界热流密度公式评述

本文介绍５０年代以来，欧美及日本学者提出的多种低压临界热流密度（ＣＨＦ）公式及其特点。在分析比较的基础上，指出了选用低压ＣＨＦ公式应注意的事项及在这方面我国目前急待解决的问题。     

稳压器电加热元件泄漏分析和检测方案设计

稳压器电加热元件包壳破损吸湿肿胀引起的开裂事故在国内外均有发生,这种事故均与电加热元件包壳存在泄漏有关。国内某核电项目热试期间发现部分电加热元件绝缘性能不符合设计要求,通过检测,发现与密封性相关的焊缝存在泄漏缺陷。为避免严重的由于泄漏引起的电加热元件肿胀开裂事故,对出现绝缘降质的电加热元件进行了详细的检查和分析。分析表明单纯进行表面检测是有风险的。为了保证电加热元件的密封性能,除了对包壳管材料进行氦检漏,端塞-包壳焊缝也需要进行氦检漏。结合电加热元件的结构和制造工艺特点,设计了专用的检测系统,并设计了一套完整检测方案。至此,稳压器电加热元件的密封完整性得到了全面的检测,排除了泄漏隐患。     

临界热流密度实验数据库的整理

采用切片法、相似度概念和热平衡以及进口温度检验法,对收集到的圆管垂直向上流动临界热流密度实验数据库进行了分析.分辨出坏数据库522点、实验坏点326点、重复点1640点、不满足热平衡点619点,进口温度错误10点,得到一个完善的CHF数据库.     

临界热流密度机理模型发展综述

为厘清临界热流密度（CHF）机理模型的发展脉络,促进CHF实验和理论研究,本文系统梳理了CHF机理模型已取得的研究成果和研究进展,分析研判了各模型的基本假设和建模过程,论证了各模型存在的问题并给出了可能的解决方向,可为当前CHF的实验和理论研究提供参考和借鉴。      

SUDO临界热流密度关系式在柱状燃料元件程序中的应用探讨

SUDO临界热流密度关系式适用于在低温低压状态下使用板状燃料元件的反应堆。如果SUDO临界热流密度关系式被应用到非低温低压状态和柱状燃料元件模型的(包括瞬态)计算机程序进行DNBR分析时，首先必须对该程序进行以满足几何条件要求的修改，以达到SUDO临界热流密度关系式要求的相关使用条件．同时必须进行与SUDO临界热流密度关系式实验数据相关的DNBR限值计算，使程序的计算值尽可能地与实验值保持一致．否则计算得到的最小DNBR值可能带来较大的误差．     

不对称加热矩形窄缝通道临界热流密度研究

以氟利昂12为冷却介质,对4种加热比条件下的矩形窄缝通道双面不对称加热工况下的临界热流密度(CHF)进行实验分析,获得各种工况下CHF与冷却剂质量流速、入口过冷度、出口含汽率的关系。实验结果表明:低含汽率下,CHF随加热比的增加而增加,随着含汽率的增加,不同加热比的实验通道内CHF差异减小;高含汽率下,CHF随加热比变化趋势与低含汽率的相反。     

Behavior of Brazed W/Cu Mockup Under High Heat Flux Loads

In order to transfer the heat from the armor to the coolant, tungsten has to be connected with a copper heat sink. The joint technology is the most critical issue for manufacturing plasma facing components. Consequently, the reliability of the joints should be verified by a great number of high-heat-flux （HHF） tests to simulate the real load conditions. W/Cu brazed joint technology with sliver free filler metal CuMnNi has been developed at Southwestern Institute of Physics （SWIP）. Screening and thermal fatigue tests of one small-scale fiat tile W/CuCrZr mockup were performed on a 60 kW electron-beam Material testing scenario （EMS-60） constructed recently at SWIP. The module successfully survived screening test with the absorbed power density （Pabs） of 2 MW/m2 to 10 MW/m2 and the following 1000 cycles at Pabs of 7.2 MW/m2 without hot spots and overheating zones during the whole test campaign. Metallurgy and SEM observations did not find any cracks at both sides and the interface, indicating a good bonding of W and CuCrZr alloy. In addition, finite element simulations by ANSYS 12.0 under experimental load conditions were performed and compared with experimental results.     

Thermal Performance Study of VPS-W Coatings on CuCrZr Under High Heat Flux

Three tungsten coatings with a thickness of 250 μm, 600μm and 220 μm, respectively, were deposited on a CuCrZr substrate by the vacuum plasma spraying technology. In order to study the thermal performance of the coatings, heat load limit, thermal fatigue lifetime and thermal response tests were performed by means of the electron beam irradiation with a heat flux from 0 MW/m^2 to 10 MW/m^2. Experimental results indicated that tungsten coatings on CuCrZr with a titanium or tungsten/copper interlayer could expel heat flux timely and had good thermal fatigue properties, titanium was a promising compliant layer which provided a reliable way to join tungsten onto the CuCrZr heat sink, even suffering from a heat flux of 10 MW/m^2 or withstanding 54 cycles of fatigue tests under 5 MW/m^2. However, the better quality of tungsten coating itself was necessary because its surface temperature was higher than that of the sample with a tungsten/copper interlayer.     

管内竖直向上流动水的临界热流密度研究

在高温高压回路上，对φ１０×１竖直管内临界热流密度现象进行了实验研究．实验参数范围为：压力ｐ＝６．３７～１４．７ＭＰａ；质量流速Ｇ＝５７１～５４６６ｋｇ／（ｍ２·ｓ）；人口欠热焓△ｈｉｎ＝９６～７４４ｋＪ／ｋｇ．通过实验，得出了在上述参数范围内的临界热流密度关系式，并用实验数据对Ｂｉａｓｉ关系式和Ｂｏｗｒｉｎｇ关系式进行了评价．     

流动不稳定性对CHF的影响

本文成功地训练了一个用于预测流动不稳定性条件下CHF的人工神经网络,利用所训练的人工神经网络,分析了流动不稳定性对无量纲因子F的影响规律.分析结果表明,系统压力对F的影响是非单值的;平均质量流速增大,总体上F也增大.还分析了流动不稳定性条件下系统主要参数对临界热流密度的影响.结果表明:当质量流速的振幅与平均质量流速的比增加时,CHF 减小;质量流速的振幅与平均质量流速的比不变时,随着周期增大,CHF减小.     

Evaluation of The Thermal Performance of Multi—Element Doped Graphite under Steady—State High Heat Flux

Multi-element doped graphite,GBST1308 has been developed as a plasma facing material(PFM) for high heat flux components of the HT-7U device.The thermal performance of the material under steady-state(SS) high heat flux was evaluated under actively cooling conditions,the specimens were mechanically joined to copper heat sink with supercarbon sheet as a compliant layer between the interfaces.The experiments have been performed in a facility of ACT (actively cooling test stand) with a 100kW electron gun in order to test the suitability and the loading limit of such materials.The surface temperature and bulk temperature distribtuion of the specimens were investigated.The experimental results are very encouraging that when heat flux is not more than 6 MW/m^2,the surface temperature of GBST1308 is less than 1000℃,which is the lowest,compared with IG-430U and even with CX-2002U(CFC),The primary results indicate that the mechanically-joined material system by such a proper design as thin tile.Super compliant layer,GBST as PFM and copper-alloy heat sink,can be used as divertor plater for HT-7U in the first phase.     

Analysis of Divertor Heat Flux with Infrared Thermography During Gas Fuelling in the HL-2A Tokamak

In HL-2A tokamaks, the behavior of heat flux deposited on the divertor targets has been studied during deuterium gas fuelling. The heat flux is reduced significantly after supersonic molecular beam injection （SMBI） fuelling during Ohmic and electron cyclotron resonance heating （ECRH） divertor discharges. The SMBI fuelling causes an increase in the plasma density and this change results in the experienced change of the edge properties. Most of this reduction in divertor target heat flux occurs together with a high plasma radiation region located at near the X-point. The largest reduction in heat flux profiles is observed at the outboard divertor separatrix strike point, while the heat flux far from the strike point remains almost unchanged. In particular, with SMBI multi-pulses gas fuelling, a partially detached divertor regime is observed with a highly radiating region at the X-point. With the onset of the partially detached divertor regime, a sudden drop in both heat flux and power flow on the divertor target is observed. The reduction in power load on the divertor targets is roughly equal to the increase in plasma radiation loss.     

关于核电站燃料棒束临界热流密度研究中一些问题的讨论

本文分析了定位格架对临界热流密度(CHF)影响的机理,讨论了如何判断定位格架热工性能的好坏;对我院已做过的几种带不同定位格架的核电站燃料棒束的 CHF 实验结果作了对比分析,并与国外最新的 CHF 经验公式作了对比。     

竖直及倾斜环隙流道内自然对流沸腾临界热负荷

以水为工质 ,在常压下对垂直和倾斜环隙流道内的自然对流沸腾临界热负荷进行了实验研究和理论分析 ,得到了计及进出口局部阻力的计算公式 ,讨论了流道几何尺寸、几何形状、倾角、压力和进出口局部阻力等因素对临界热负荷的影响 ,最后提出了一个新的 ,可用于计算竖直环隙、圆管及长方形流道内自然对流沸腾临界热负荷的半经验公式 ,其计算精度和适用范围较现有的计算公式有显著提高 ,原则上不受H/De 值大小的限制。     

Manufacturing and High Heat Flux Testing of Brazed Flat-Type W/CuCrZr Plasma Facing Components

Water-cooled flat-type W/Cu Cr Zr plasma facing components with an interlayer of oxygen-free copper(OFC) have been developed by using vacuum brazing route.The OFC layer for the accommodation of thermal stresses was cast onto the surface of W at a temperature range of 1150oC-1200 oC in a vacuum furnace.The W/OFC cast tiles were vacuum brazed to a Cu Cr Zr heat sink at 940 oC using the silver-free filler material Cu Mn Si Cr.The microstructure,bonding strength,and high heat flux properties of the brazed W/Cu Cr Zr joint samples were investigated.The W/Cu joint exhibits an average tensile strength of 134 MPa,which is about the same strength as pure annealed copper.High heat flux tests were performed in the electron beam facility EMS-60.Experimental results indicated that the brazed W/Cu Cr Zr mock-up experienced screening tests of up to 15 MW/m~2 and cyclic tests of 9 MW/m~2 for 1000 cycles without visible damage.