反应堆安全壳电气贯穿件绝缘支撑盘耐潮性能试验研究

近年来我国在运核电厂相继发生两起反应堆安全壳中压电气贯穿件绝缘支撑盘绝缘击穿短路故障,造成反应堆非计划停堆停机,发生故障的中压电气贯穿件均为国外同一厂家同一批次设计生产的产品.上述故障造成核电厂巨大经济损失的同时,也对反应堆的安全稳定运行提出了挑战.本文针对发生故障的绝缘支撑盘和中国核动力研究设计院同类型产品开展试验研...     

高温气冷堆氦气环境中电气设备绝缘设计研究

应用巴申定律研究了氦气的电气击穿特性,并与空气的绝缘特性进行比较。以高温气冷堆氦气透平发电系统电机腔室的设计参数为例,结合氦气的巴申曲线,对氦气条件下气体压力和极间距离的关系进行深入探讨,并提出氦气环境中电气设备绝缘设计需关注的问题。研究结果表明,氦气最小击穿电压为150~200V,绝缘特性较差,电气设备绝缘结构设计应考虑氦气环境压力的影响,现有针对压水堆电站电气设备绝缘结构的验收准则和试验方法并不完全适用于氦气环境。     

射频磁控溅射法制备氧化铝涂层绝缘性能及吸氢特性

氧化铝具有优良的绝缘和阻氚性能,是ITER候选功能材料之一。本工作采用射频磁控溅射法在中国低活化马氏体（CLAM）钢基底上制备了氧化铝涂层。分别采用掠入射X射线衍射、Raman激光光谱和原子力显微镜对氧化铝涂层的结构和表面形貌进行了表征;测量了氧化铝涂层体电阻率;研究了氧化铝涂层样品的吸氢特性。结果表明：氧氩比为0.1和0.5下制备的氧化铝涂层为非晶结构,氧氩比为0.4下制备的涂层中出现了结晶程度较差的氧化铝δ相结构;氧氩比为0.1和0.4下制备的涂层粗糙度和粒径均小于氧氩比为0.5下制备的涂层;不同氧氩比下制备的氧化铝涂层体电阻率均超过2.7×10¹⁴Ω•cm,氧氩比为0.4下制备的涂层电阻率最高,达到2.1×10¹⁵Ω•cm;氧氩比为0.5下制备的涂层样品具有最低的吸氢量。氧氩比对涂层的电绝缘特性和吸氢特性有显著影响。     

喷淋液滴在中低压饱和蒸汽环境下传热特性研究

本文以喷淋液滴在中低压饱和蒸汽环境下传热特性为工程背景,分析液滴初始动力学参数、环境蒸汽参数对液滴与蒸汽间传热特性的影响。计算结果表明,不同液滴初始速度下单位质量换热量随时间变化趋势基本一致,初始速度越大,换热系数越高,单位质量换热量也越大,液滴表面温度和平均温度达到饱和蒸汽环境温度的时间越短;液滴直径对单位质量换热量随时间变化趋势影响较为显著,液滴直径越大,单位质量换热量随时间降低的趋势逐渐变缓,液滴表面温度和平均温度达到饱和蒸汽环境温度的时间越长;饱和蒸汽压力越大,液滴表面温度和平均温度上升越快,但不同蒸汽压力下液滴表面温度或平均温度达到饱和温度的时间基本一致;不同液滴初始温度时,液滴表面温度、平均温度、单位质量换热量随时间变化基本一致。计算结果有助于优化工程实际中喷淋系统的设计。     

氧氩比对低活化马氏体钢表面氧化铪涂层性能的影响

本文采用射频磁控溅射法在不同氧氩比下制备氧化铪涂层.研究了涂层的沉积速率、表面形貌、微观结构和电绝缘特性随氧氩比的变化.结果表明用此方法在低活化马氏体钢上制备的氧化铪涂层表面致密、无明显孔洞;低活化马氏体钢为衬底时涂层较易结晶为以单斜相为主的晶体结构;且涂层的绝缘特性受氧氩比影响较大,氧氩比为0.7和1.2下制备的涂层击穿场强小于1 MV/cm,电绝缘特性较差,在较低氧氩比下制备的涂层有较理想的绝缘性能.     

辐照交联对膨胀阻燃剂/乙烯-辛烯共聚物复合材料力学性能及阻燃绝缘性能的影响

采用机械共混法向乙烯-辛烯共聚物中添加不同含量的膨胀阻燃剂(聚磷酸铵、季戊四醇、三聚氰胺),然后采用电子束辐照,制备出交联型膨胀阻燃复合材料。通过极限氧指数、热失重、燃烧性能等参数表征电子束辐照交联对其阻燃性能的影响。结果表明,辐照交联后,复合材料的氧指数提高1~2;对力学性能而言,断裂伸长率随着吸收剂量的增加呈现下降趋势,拉伸强度则呈现上升趋势;对热释放的影响,复合材料的燃烧过程缩短,释热、释烟更为集中,在200 kGy吸收剂量下辐射交联后,总热释放量由94.8 MJ/m~2下降至79.1 MJ/m~2,总烟释放量由1 122.9 m~2/m~2下降至928.4 m~2/m~2,燃烧过程缩短约25%,CO释放率由0.062 2kg/kg下降至0.043 9 kg/kg,CO_2生成率由1.44 kg/kg上升至1.51 kg/kg;对绝缘性能而言,随着吸收剂量的增加,材料的体积电阻率变化幅度很小,提示辐照对材料的绝缘性能影响很小。     

固态气溶胶吸湿生长对过滤器检测效率的影响

本文使用加湿串联差分迁移分析仪（HTDMA）系统,研究了荧光素钠气溶胶在不同相对湿度（RH）环境中粒径的变化规律及对现场过滤效率的影响,且与NaCl气溶胶进行了对比。研究结果表明,荧光素钠气溶胶无潮解点,其粒径随相对湿度的增大而增大;NaCl有明显的潮解点,在小于75%相对湿度时,其粒径基本不变。随相对湿度的增加,直径为100 nm的荧光素钠测得的效率逐渐降低,而直径为100 nm的NaCl测得的效率在75%相对湿度以下时基本保持不变,但在大于75%相对湿度环境中大幅下降。因此,从气溶胶吸湿性能的角度来说,作为现场检测用的固态气溶胶,若保证环境相对湿度小于75%,NaCl和荧光素钠均可用于过滤器现场检测,且前者性能优于后者,但当相对湿度大于75%时,NaCl气溶胶已不能用于现场检测用途。     

核电厂电仪设备延寿再鉴定试验研究

在核电厂电气仪表设备（简称电仪设备）环境鉴定研究成果的基础上,开展核电厂电仪设备延寿再鉴定分析和试验研究。以秦山第一核电厂DDG-1型电气贯穿件（EPA）为研究对象,根据运行实际制定了再鉴定试验研究的遵循原则,在此原则下结合分析法确定了试验方案和试验项目序列以及EPA修复依据和方案,并在此基础上开展再鉴定试验研究。适当修复后的DDG-1型EPA按试验大纲依次通过了设备性能随时间变化的试验、抗震试验、设计基准事故（DBA）条件下热力学试验和DBA后极限电性能试验,试验后状态完好,表明该DDG-1型EPA经适当修复后能够完成继续延寿20 a的预期目标,可为核电厂其他电仪设备再鉴定试验研究提供指导和借鉴。      

基于SEM图像的BESⅢ束流管支撑法兰材料辐照拉伸性能研究

根据BESⅢ中束流管支撑法兰材料的工程运用,对G10环氧/层压玻璃布板的辐照拉伸性能进行研究.受辐照环境限制,将试验件尺寸在长度方向缩小为标准件尺寸的27.2%,发现缩小尺寸试验件的拉伸强度约为标准尺寸试验件的49.4%;经104Gy的γ辐照和4.068×1018 m-2的中子辐照后,缩小尺寸试验件的拉伸强度下降2.35%.由此推断,同等辐照条件下,G10板标准尺寸试验件拉伸强度将下降至约317.10MPa,能够满足BESⅢ对束流管支撑法兰材料提出的113MPa的要求.利用扫描电镜对G10板辐照前后的拉伸断口进行微观观察.     

出土饱水梓木的辐射法保护

利用乙醇浓度梯度脱水、保护单体(PEG200DMA)逐级置换、60Co γ射线辐射固化(吸收剂量率为30.72 kGy,剂量率90.35 Gy/min)的方法对信阳长台关出土的棺木残片进行了试验性保护.保护后的试验样品外观颜色接近原文物,无开裂翘曲、无表面泛光和发黑现象、纹理清晰;顺纹压缩强度(33.06 MPa)接近现代新材;保护前后相比的最大收缩率分别为:长度方向1.05%,径向4.10%,弦向4.32%;在常温常湿(温度:20-28℃,相对湿度:35%～65%)条件下贮存180 d前后相比的收缩率分别为:长度方向0.076%,径向1.17%,弦向1.86%;在干燥环境(温度:(25±2)℃,相对湿度:(5±2)%)中贮存90 d前后相比收缩率分别为:长度方向0.066%,径向0.115%,弦向0.279%;在高湿环境(温度:(25±2)℃,相对湿度:(5±2)%)中放置90天后的湿胀率与干燥环境相比分别为:长度方向1.79%,径向2.42%,弦向2.61%.微观结构研究表明:固化后的聚合物充满了残存饱水梓木内的毛细孔隙,提高了木材的力学强度和尺寸稳定性.     

Effects of fast neutron radiation on polypropylene

Capacitor-grade polypropylene films were irradiated in a 2-MW thermal nuclear reactor and exposed to fast neutron radiation at a flux rate of 2.6×10¹² neutron/cm² s and gamma radiation at a level of 10⁷ rad/h. The postirradiation effects on changes in the electrical and chemical properties of the films were studied for irradiation times up to 10 h. The electrical properties were DC and AC breakdown voltages, life under pulsed voltage stress, dielectric permittivity, dielectric losses, and volume resistivity. Chemical analysis was performed using the infrared spectroscopy technique. Small changes were detected in the dielectric strength, dielectric properties, and volume resistivity of the film. These changes are believed to be caused by oxidation of the polypropylene film, as was evidenced by the infrared spectra showing an increase in the carbonyl absorption peak at 1720 cm^-1     

Effect of ionizing radiation on the electrical characteristics ofpolyvinylidene fluoride (PVF2)

The influence of high-energy electron irradiation on the electrical properties of biaxially oriented polyvinylidene fluoride (PVF ₂) film was investigated. The film was irradiated in air with a 1-MeV electron beam at a dose rate of 10⁶ rad/min to different dose levels of up to 10⁸ rad. Electrical properties measured included dielectric permittivity and dielectric loss, AC and DC breakdown voltages, and DC volume resistivity, X-ray diffraction and IR spectroscopy measurements were also made. The most pronounced of the radiation-induced changes were a decrease in like AC breakdown voltage and an increase in dielectric loss, both corresponding to increasing total absorbed dose. DC breakdown voltage and volume resistivity also showed noticeable changes. These changes are believed to be associated initially with a radiation-induced crystal phase transformation. This was confirmed by the X-ray diffraction curve and the IR spectra, which showed an increase in the β-phase and a decrease in the α-phase peaks at higher dose levels     

Numerical study of the influence of dielectric tube on propagation of atmospheric pressure plasma jet based on coplanar dielectric barrier discharge

A 2D fluid model was employed to simulate the influence of dielectric on the propagation of atmospheric pressure helium plasma jet based on coplanar dielectric barrier discharge (DBD). The spatio-temporal distributions of electron density, ionization rate, electrical field, spatial charge and the spatial structure were obtained for different dielectric tubes that limit the helium flow. The results show that the change of the relative permittivity of the dielectric tube where the plasma jet travels inside has no influence on the formation of DBD itself, but has great impact on the jet propagation. The velocity of the plasma jet changes drastically when the jet passes from a tube of higher permittivity to one of lower permittivity, resulting in an increase in jet length,ionization rate and electric field, as well as a change in the distribution of space charges and discharge states. The radius of the dielectric tube has a great influence on the ring-shaped or solid bullet structure. These results can well explain the behavior of the plasma jet from the dielectric tube into the ambient air and the hollow bullet in experiments.     

Analysis of an Ar plasma jet in a dielectric barrier discharge conjugated with a microsecond pulse

In this work, an Ar plasma jet generated by an AC-microsecond-pulse-driven dielectric barrier discharge reactor, which had two ring-shaped electrodes isolated from the ambient atmosphere by transformer oil, was investigated. By special design of the oil insulation, a chemically active Ar plasma jet along with a safe and stable plasma process as well as low emission of CO and NO_x were successfully achieved. The results indicated that applied voltage and frequency were basic factors influencing the jet temperature, discharge power, and jet length, which increased significantly with the two operating parameters. Meanwhile, gas velocity affected the jet temperature in a reverse direction. In comparison with a He plasma jet, the Ar plasma jet had relatively low jet temperature under the same level of the input parameters, being preferable for bio-applications. The Ar plasma jet has been tested to interact with human skin within 5 min without the perception of burnt skin and electrical shock.     

Insulation characteristics of triple mixtures of c-C4F8/N2/CO2 under lightning impulse voltage

This paper has researched the insulation characteristics of 10%c-C₄F₈/N₂/CO₂ mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of 10%c-C₄F₈/N₂/CO₂ gas mixtures rise linearly as the electrode gap distance and gas pressure increase and under the same conditions, the positive lightning impulse breakdown voltage of the gas mixtures is always higher than the negative lightning impulse breakdown voltage. As the gas mixtures have a little higher liquefied temperature than SF₆ and the comprehensive GWP is about 5% of SF₆ , and the positive and negative lightning impulse breakdown voltages can both reach 60% of SF₆ , 10%c-C₄F₈/N₂/CO₂ gas mixtures can be applied as insulation gas in electrical equipment such as C-GIS, GIT, GIL and so on.     

High Temperature Baking Test and Study on Axial Insulation Breaks

Axial insulation breaks are needed in ITER superconducting magnet system, which are used for separation of high voltage area from grounded cooling pipes system. To determine the maximum safe temperature that the insulating break can withstand without damage, such as preventing damage by overheating during welding of the insulating breaks to the helium cooling pipes for the superconducting magnets and high temperature baking to remove moisture, the glass transition temperature was tested by using the dynamic mechanical analysis with the standard sample made from epoxy resin. Furthermore, the high temperature baking test of axial insulation break was performed, further helium tight test and high voltage tests indicate the baked insulation break is in good condition.     

Equation of Energy Injection to a Dielectric Barrier Discharge Reactor

The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge(DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, barrier thickness, peak voltage, gap distance, electrode area,and operation temperature were experimentally investigated. The energy injection is a function of relative permittivity, barrier thickness, peak voltage, gap distance, and electrode area. The influence of operation temperature on energy injection is slight in the range of 27–300℃ but becomes obvious in the range of 300–500℃. A model was established using which the energy injection can be easily predicted.     

内置稳压隔热水层的设计与数值研究

针对ACP100+模块化小型堆的内置稳压器，设计了一种隔热水层结构，采用数值分析方法，对隔热水层的流动与传热特性进行了数值研究，并分析了功率运行稳态工况和降功率瞬态工况下，隔热水层的温度分布与速度分布。结果表明，隔热水层内流体的流动和导热能力较弱，可以有效地实现高温流体和低温流体的隔离。      

Transient electrical behaviour of the ITER TF coils during fast discharge and two fault cases

Improvements of high voltage design criteria and quality assurance for ITER coils are indispensable taking into account the problems occurred during high voltage tests of the ITER TF model coil. One important aspect to consider is the transient electrical behaviour because fast changes of voltages may cause local overloading and destruction of the insulation system. This paper will present the calculation of the terminal voltages within the ITER TF coil system and the voltage stress of the insulation within an individual ITER TF coil for the fast discharge and two fault cases. Proposals for the high voltage tests are discussed based on the calculated voltage stress of the two fault cases and the experiences gained during the ITER TF Model Coil test to ensure appropriate dielectric quality of the ITER TF coils.     

Research on the characteristics of atmospheric air dielectric barrier discharge under different square wave pulse polarities

Energy efficiency limits the application of atmospheric pressure dielectric barrier discharge(DBD),such as air purification,water treatment and material surface modification.This article focuses on the electrical and optical effects of the DBD under three square wave pulses polarities-positive,negative and bipolar.The result shows that under the same voltage with the quartz glass medium,the discharge efficiency of bipolar polarity pulse is the highest due to the influence of deposited charge.With the increase of air gap distance from 0.5 to 1.5 mm,average power consumed by the discharge air gap and discharge efficiency decrease obviously under alumina,and increase,and then decrease under quartz glass and polymethyl methacrylate(PMMA).Through spectrum diagnosis,in the quartz glass medium,the vibration temperature is the highest under negative polarity pulse excitation.Under bipolar pulse,the vibration temperature does not change significantly with the change of air gap distance.For the three dielectric materials of quartz glass,alumina and PMMA,the molecular vibration temperature is the highest under the quartz glass medium with the same voltage.When the gap spacing,pulse polarity or dielectric material are changed,the rotational temperature does not change significantly.