环形多丝反符合屏蔽正比计数管的研制

~(14)C年代测定方法,可以精确测定五万年内含碳标本的年代,在地球化学、第四纪地质学、海洋学和考古学等学科方面已得到广泛应用,测定方法一般有气体计数和液体计数两种。本工作所研制的环形多丝反符合屏蔽正比计数管,其品质因子与液体闪烁计数器相当,但两方法所需要的纯碳量不同,后者约为5—10g,而前者一般只为1—2g,从这个意义上说,在实际应用中,本工作弥补了目前液体闪烁计数法的不足。     

基于单球多计数器、GM计数管同时测量n、γ剂量当量的装置研制

介绍了一款同时测量混合辐射场中n、γ剂量当量的装置研制,该装置通过单球多计数器和GM计数管相结合的方法构成,单球多计数器的探测器由三根两两垂直的3He正比计数管构成,通过解谱的方法得到中子剂量当量。在Am-Be和Cf-252中子参考辐射场中进行了测试,剂量当量相对误差30%;在能量范围为63keV-1.25MeV的入射光子下进行了能量响应试验,相对误差30%。     

多探头辐射测量仪环境γ探头的研制

现在国内各核电站日常使用的便携式辐射测量仪表普遍是进口的,存在售价和维修成本高且返修周期长的问题,因此开发了一款MPR200多探头辐射测量仪。仪器主机采用双GM管阴极切换设计,可自动识别多种外接探头,软件采用滑动平均数据处理方法实现剂量率快速测量。本文重点介绍外接环境γ探头的研制,它采用两级放大,通过CD4528型双单稳态集成电路处理信号并输出,大容量的锂电池可保证整机连续工作50个小时以上。     

测定GM计数管死时间的新方法

本文提出GM计数管的死时间是一个统计平均值,死时间的修正公式适用于nτ<1的全范围。给出测定死时间的简单、准确的新方法,并提出对γ灵敏度的修正。     

NSD-A型地下水流向仪的研制和应用

在水利工程、农田水利和各种水文地质勘探中,地下水的流向测定十分重要。1963年Arsenal研究所的J.Mairhofer最早提出了利用放射性同位素方法在单独钻孔内确定地下水流向(俗称“单孔定向”)的方法,并进行了一些室内外试验。随即许多国家开展了这方面的研究。有的还研制成同位素地下水流向仪,获得了实际应用。 自1973年以来,我院利用研制的NSD-A型地下水流向仪,作了测定地下水流速流向的室内试验,并在几个大中型重点险库现场试用,配合其他同位素示踪法观测资料,为水库大坝渗流安全分析与除险保坝加固工程提供了科学依据。     

大面积流气式多丝正比计数管的空间电场强度分布及参数选择

为了解大面积流气式多丝正比计数管工作空间的电场分布,本文提出了近似计算的物理模型,并在设定的条件下进行了数值计算,得到了电场分布的近似结果及其某些参数,诸如丝距和电极间距等的关系,以便于多丝正比计数管的正确设计和使用。     

基于正比计数管的核反应堆初次装料监测系统研制

为了确保反应堆初次装料及换料过程的安全临界,防止堆芯装料过程发生临界事故,研制核反应堆初次装料系统。对系统探测器组件、监测机柜、测量通道机箱及吊装方案进行设计,并对系统进行实验验证。对涂硼正比计数管为核心的探测器组件进行耐压、密封结构设计,电缆设计采用一体化、高屏蔽性、抗干扰的方案,以保证信号传输稳定性。信号处理装置采用机柜、插件式机箱形式,实现信号调理、脉冲计数、报警显示、周期值计算及历史记录等功能,测量通道机箱信号处理与显示插件隔离设计进一步保证系统的可靠性。经测试验证,该系统耐水压密封性、辐射特性及稳定性可满足初次装料过程中子注量率监测要求,已应用于防城港核电站3、4号机组。     

基于RS-485总线的双G-M计数管γ剂量率探测器研制

根据放射性场所工作人员辐射防护需求,设计了γ剂量率探测器。介绍了探测器硬件电路及软件设计,利用双G-M计数管覆盖高低量程范围,采用RS-485通信接口,可连接最多128个节点,具有远程传输能力,适用于多点分布式实时监测。探测器结构紧凑,功耗低,抗干扰能力强,工作稳定可靠。     

反应堆控制棒组件超声检测探头的研制

为了检测核电站反应堆控制棒组件,保障核电站在役检查顺利实施、降低检测成本。对反应堆控制棒组件（RCCA）检测用超声探头进行自主研制,本文详细介绍了15MHz-Φ4mm-FP8 mm RCCA超声探头制作流程,通过对压电晶片、声透镜、背衬3方面详细介绍探头制作工艺。通过对超声探头进行性能测试,测试脉冲周期数为1.5周,频带宽度为105%,在高温环境下仍能保持优良性能。对超声探头进行模拟检验测试,缺陷测试结果清晰可见,满足检验需求,可完全实现国产化替代进口产品。       

一种中子剂量当量仪的探头设计

针对单探测器中子剂量当量仪的能量响应性能普遍不好的情况,设计了一种由三个慢化球壳和三个3He正比计数管构成的多探测器中子剂量当量仪的探头,对它的能量响应进行了计算,并与ICRP的推荐值进行了比较和分析,提出了对它的能量响应性能进行进一步改善的方法。     

同位素~(113m)In在地下水示踪研究中的应用

利用热释光探测器(TLD)或电离室(IC)作为射线探测器,以~(131)I等作示踪元素测定单井中地下水流速流向的原理及实验已有专门论述,它能测定φ50—200mm的单井中地下水的流向和渗透流速。通常,测定地下水流速用的示踪剂应选择吸附性小的阴离子形态的金属核素,但如用来测定地下水的流向,有吸附作用的阳离子形态的金属离子仍可被选用。如何寻找一种既可较长时间使用、半衰期较短且又不污染水源的放射性同位素示踪剂,从而使单     

Local measurement of bubbly flow in helically coiled tubes using double-sensor conductivity probe

ABSTRACT

The two-phase flow in helically coiled tubes (HCTs) is rather important in many industries, such as the heat exchange facility in nuclear power plant. In this work, a double-sensor conductivity probe was used to study the air/water bubbly flow in HCTs. The cross-sectional distribution profile of the interfacial parameters (void fraction, interfacial area concentration, bubble size, etc.) of air–water bubbly flow were systematically studied. Through carefully processing the raw data collected by the double-sensor conductivity probe, the distribution of the void fraction, interfacial area concentration, the bubbles number frequency over the cross-section are demonstrated, as well as the bubble velocities and sizes vertically in the dense region. Some statistical parameters of cross-sectional-averaged quantities, coefficients of variation, and bubble aggregation core coordinates are defined to quantitatively describe the distribution characteristics of interfacial parameters. The measured data are helpful for improving the understanding of two-phase flow characteristics in HCTs.     

核电小孔径深孔管板的加工

秦山二期扩建工程热交换器的管板材料为00Cr19Ni10锻件,管板厚度为125mm,要求加工178-φ10.350+0.05孔,管孔排列形式为等边三角形排列,孔心距15mm,管孔粗糙度Ra3.2。核电厚管板高精度小孔的加工,首先采用导向套定位,利用枪钻和BTA钻分别试验,最终采用BTA钻内排屑方法钻孔成功。克服BTA钻的不利因素,找寻解决的方法。BTA钻直径φ10.34mm。加工后孔径尺寸为φ10.375～φ10.355mm,管孔椭圆度全部小于0.01mm,管桥尺寸都稳定在4.6mm,符合图纸要求。提出加工中注意的问题,为此类管孔的加工提供借鉴。     

Development of the five-sensor conductivity probe method for the measurement of the interfacial area concentration

The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The purpose of this study is to develop the local IAC measuring method by using the five-sensor conductivity probe. In this paper, the mathematical approach of the five-sensor conductivity probe method for measuring the local time averaged IAC is described, and numerical simulations are carried out for cap bubbles and two types of ellipsoidal bubbles, as well as spherical bubbles, in order to evaluate the new method. The sizes and locations of the bubbles are determined by using random number generators. To investigate the probe size effect on the accuracy of IAC measurement, three cases for length scales of the probe are applied to the simulations. The simulations show that the five-sensor conductivity probe method proposed in this paper produces better results than the four-sensor method.     

微型X射线管灯丝电源的研制

根据微型X射线管的特点,设计了基于推挽电路和闭环反馈电路的灯丝驱动电源。采用了UCC3808脉宽调制(Pulse Width Modulation,PWM)控制芯片产生两路相位相反的PWM信号,并经由UCC37324金属氧化物半导体(Metal-Oxide-Semiconductor,MOS)管大电流驱动器提高驱动效率,实现推挽结构的后端驱动电路。闭环反馈电路的设计采用精密电阻将管电流的信号转换为等比例的电压信号引入到反馈环节,通过系统自身的闭环控制实现管电流的恒定,并保持高效率和低功耗。实验首先通过外接1.5?的功率电阻测量系统功率,测得输入功率为11 W,效率超过80%,符合灯丝电源的功耗指标要求;然后连接实际的X光管灯丝,经测试可正常工作,管流稳定度为0.227%。     

Machine learning combined with Langmuir probe measurements for diagnosis of dusty plasma of a positive column

This paper reports the use of machine learning to enhance the diagnosis of a dusty plasma. Dust in a plasma has a large impact on the properties of the plasma. According to a probe diagnostic experiment on a dust-free plasma combined with machine learning, an experiment on a dusty plasma is designed and carried out. Using a specific experimental device, dusty plasma with a stable and controllable dust particle density is generated. A Langmuir probe is used to measure the electron density and electron temperature under different pressures, discharge currents, and dust particle densities. The diagnostic result is processed through a machine learning algorithm,and the error of the predicted results under different pressures and discharge currents is analyzed,from which the law of the machine learning results changing with the pressure and discharge current is obtained. Finally, the results are compared with theoretical simulations to further analyze the properties of the electron density and temperature of the dusty plasma.     

Bended probe diagnostics of the plasma characteristics within an ECR ion source with a rectangular waveguide

To reveal the argon plasma characteristics within the entire region of an electron cyclotron resonance(ECR) ion source, the plasma parameters were diagnosed using a bended Langmuir probe with the filament axis perpendicular to the diagnosing plane. Experiments indicate that,with a gas volume flow rate and incident microwave power of 4 sccm and 8.8 W, respectively,the gas was ionized to form plasma with a luminous ring. When the incident microwave power was above 27 W, the luminous ring was converted to a bright column, the dark area near its axis was narrowed, and the microwave power absorbing efficiency was increased. This indicates that there was a mode transition phenomenon in this ECR ion source when the microwave power increased. The diagnosis shows that, at an incident microwave power of 17.4 W, the diagnosed electron temperature and ion density were below 8 eV and 3?×?10~(17) m~(-3), respectively, while at incident microwave power levels of 30 W and 40 W, the maximum electron temperature and ion density were above 11 eV and 6.8?×?10~(17) m~(-3), respectively. Confined by magnetic mirrors, the higher density plasma region had a bow shape, which coincided with the magnetic field lines but deviated from the ECR layer.     

Visibility of the growth direction of an alpha-particle track in a diffusion cloud chamber

The growth direction of an alpha-particle track in a diffusion cloud chamber can be observed with the naked eye. Unlike the track of a beta-particle, an alpha-particle track appears first at the beginning of its path and proceeds to the end of the path. However, the alpha-particle covers the path in less than 10 ns, which is inconsistent with the visibility of the track-growth direction. This inconsistency was attributed to the following reasons: the number of ion pairs per unit length in the path is very large compared with that of a beta particle, the ion density near the end of the path is larger than that near the beginning, and alcohol droplets have to grow to a diameter of about 3 μm for being able to be seen. The alcohol molecules have to diffuse from a distant place to the region where the ions are created by the alpha-particle and the diffusion time near the end of the path is longer than that near the beginning of the path. This phenomenon was examined by diffusion theory.     

Thermal hydraulic performance analysis of a double tube bundle steam generator for a liquid metal reactor

In this study, thermal-hydraulic performance of a double tube bundle steam generator (DTBSG) using helically coiled tubes was analyzed numerically. For this purpose a one-dimensional thermal-hydraulic analysis computer program was developed.