Time-To-Count测量方法在辐射检测中的应用

以脉冲计数形式作总量测量的核辐射探测器,死时间是影响探测效率的主要因素.为减少测量误差,必须对测量系统分辨率进行确定或者对死时间进行校正,这是一件很复杂的工作,而且不能从根本上解决死时间问题.文章首先讨论了Time-To-Coumt测量方法的理论基础,给出计算辐射强度的估计公式R=k/t(k为常数),在此基础上提出了一套Time-To-Count测量方法的试验方案.最后用传统方法与Time-To-Count测量方法进行了测量比较,得出了试验结果.     

GM计数管死时间及其对辐射测量的影响

本文阐述了GM计数管的两种死时间概念,分析了它们对辐射测量的影响,并给出了输出计数率与照射量率和两种死时间的关系式。     

一种使用单片机的宽量程GM管探头

针对GM计数管量程窄,非线性误差大的不足,本文提出了一种新的非线性误差补偿方法,并将计数管置于一种新的工作方式下工作,扩展计数管量程范围,提高测量精度。其基本技术途径是借助于MCS-48微型单片计算机来实现的。 一、扩展CM计数管量程的原理及方法 计数管在作照射量率测量时,其实际和理想照射量率响应如图1所示。在计数率较高时,由于死时间的影响,计数管计数出现漏记现象,产生非线性,需要补偿。在计数率较     

双源净计数法测定航空γ能谱仪的死时间

对γ能谱仪死时间产生的原因、死时间的表示方法、传统双源法的有关理论、测量方法以及一种新型的航空伽玛能谱仪做了简单介绍。在单晶探头连接条件下,通过对无屏蔽的双源净计数法、无屏蔽直接忽略本底、铅屏蔽条件下忽略本底、屏蔽条件下的净计数取得的计算结果进行对比,证明了双源净计数法的有效性,并利用该方法对新型航空γ能谱仪进行了死时间测量,给出了有关结论和建议。     

核燃料芯块装管动态测长的研究

介绍了当今一些核电站燃料组件制造厂,如前苏联、西欧一些国家和我国,在燃料组件单棒生产的装管过程中,测量装入包壳管即锆管中核燃料芯块长度值的方法。利用力学、光学、电学等学科的原理,分析和论述了各种动态自动测长的方法和原理,及各自的特点。较详细地介绍了所研制的实验装置的结构,论述了该装置的测量原理,并分析了装置的测量精度和系统的偏差。最后介绍了模拟芯块的长度测量考核。结果表明该动态测长装置的方法和原理是可行的,在单根包壳管的装管中采用这种测量方法,是较为理想和先进的。其测长原理运用到其它工业部门上也有一定的参考意义。     

一种用于双GM计数管的量程控制测量方法

实现双盖格-米勒（Geiger-Müller,GM）计数管量程扩展测量的关键是双GM计数管量程切换控制技术,该技术可使探测器自动选择合适量程的GM计数管进行测量。但是由于两种不同测量量程的GM计数管存在性能差异,传统的将测量量程分成两个区域的方法会导致双GM计数管在量程交叠区域内线性拟合度较低。为了提高双GM计数管在测量量程交叠区域内的线性度,提出了一种量程控制测量方法。该方法将测量范围划分为低量程、中量程以及高量程三个区间,并且还可在三个测量量程之间进行快速自动切换,其中在中量程测量中,分别将两个GM计数管获得的数据进行加权处理。采用241Am源和60Co源进行双GM计数管探测器电路测试,初步测试结果表明：设计的双GM计数管探测器可实现在三个测量量程区间内快速自动切换。同时,双GM计数管在剂量率交叠区域1 000～10 000μGy·h-1中的线性拟合度得到改进,使得在251～25 130μGy·h-1的测试范围内,双GM计数管的测量线性度提高至0.999 1,有效地提高了双GM计数管的整体测量线性度。     

CSNS漂移管直线加速器隧道高精度准直方法及精度分析

中国散裂中子源(China Spallation Neutron Source, CSNS)漂移管加速器(Drift Tube Linac, DTL)是CSNS直线加速器段的末端,其准直精度直接关系到直线加速器的最终性能。由于其长度长、腔体和腔内漂移管数量多,准直精度要求高,因此准直难度极大。针对该问题,通过外符合全面测量对漂移管预准直后的精度进行检核,可知漂移管中心孔和端面的测量值在DTL腔的预准直精度达到±0.035mm;采用大跨度、全覆盖的全面测量方法及平差在CSNS中的应用,实现直线隧道±0.03 mm和环隧道±0.04 mm的相对测量精度。提出了基于加速器准直的平滑计算及调整方法,实现DTL腔间的平滑调整,获得腔体±0.08 mm的隧道相对准直精度,漂移管±0.03 mm的腔内相对准直精度。     

气球法测环境氡浓度

氡浓度测量是放射性环境监测中的一项常规工作,测量方法有多种,多数方法因操作繁琐、测量时间长、受电源控制或装置的体积较大等原因,在实际工作中使用受到限制,而气球法测环境氡浓度操作简便、快速,较适合于现场工作.本文介绍采用气球法结合FD-3005低本底α探测仪测环境氡浓度的基本原理和测量程序,并通过与双滤膜法从测量的灵敏度、精度等方面进行比较,验证该方法在实际工作中的可行性.     

云母窗型G-M管辐射响应特性研究

云母窗型G-M管能够探测α粒子、β粒子和γ射线。论文建立了云母窗型G-M管测试平台,通过漏计数修正减少了G-M管的死时间影响。分别对α和β放射源进行探测,得到云母窗型GM管对α和β粒子的响应特性,为云母窗型G-M管用于多种射线的探测作了特性研究。     

NaI（Tl）－HPGeγ－γ符合谱仪系统死时间校正方法

本文讨论了ＮａＩ（ＴＩ）－ＨＰＧｃγ－γ符合谱仪系统死时间的校正方法。用双源法分别对符合道和分析道的死时间进行了测量，给出了γ－γ符合谱仪系统死时间校正因子的计算公式。并将该公式应用于核数据的测量工作中，对测量的γ活性进行了死时间的校正。     

一种新的GM计数管Time-To-Count 测量方法

主要介绍了目前最新的GM计数管Time-To-Count测量方法的基本原理及其工作模型，对测量方法的基本特点进行了探讨，通过方案设计加工加以实现并给出了试验结果。     

A statistical methodology for quantification of uncertainty in best estimate code physical models

A novel uncertainty assessment methodology, based on a statistical non-parametric approach, is presented in this paper. It achieves quantification of code physical model uncertainty by making use of model performance information obtained from studies of appropriate separate-effect tests. Uncertainties are quantified in the form of estimated probability density functions (pdf’s), calculated with a newly developed non-parametric estimator. The new estimator objectively predicts the probability distribution of the model’s ‘error’ (its uncertainty) from databases reflecting the model’s accuracy on the basis of available experiments. The methodology is completed by applying a novel multi-dimensional clustering technique based on the comparison of model error samples with the Kruskall–Wallis test. This takes into account the fact that a model’s uncertainty depends on system conditions, since a best estimate code can give predictions for which the accuracy is affected by the regions of the physical space in which the experiments occur. The final result is an objective, rigorous and accurate manner of assigning uncertainty to coded models, i.e. the input information needed by code uncertainty propagation methodologies used for assessing the accuracy of best estimate codes in nuclear systems analysis. The new methodology has been applied to the quantification of the uncertainty in the RETRAN-3D void model and then used in the analysis of an independent separate-effect experiment. This has clearly demonstrated the basic feasibility of the approach, as well as its advantages in yielding narrower uncertainty bands in quantifying the code’s accuracy for void fraction predictions.     

小面积α/β/γ表面污染探头的研制

文章介绍一款基于GM端窗计数管的便携式小面积α/β/γ表面污染探头。该探头设计简单,携带方便,测试灵敏,适用于一些小面积场所的表面污染检查。文中着重对探头的硬件设计进行描述,并给出了根据国标及行业标准对探头性能进行测试的结果。     

GM计数管能量响应补偿的MC法模拟

针对GM计数管低能段过响应特性,探讨了一种用MC法对其进行能量响应补偿的方法。该方法在结合能量响应补偿理论与MCNP蒙特卡罗模拟方法的基础上,寻求利用理论方法先行计算出较为合适的补偿条件,继而应用MCNP有目的的进行模拟,减少模拟海选过程,提高实验效率。     

A case study on detection and sizing of defects in steam generator tubes using eddy current testing

Eddy current testing (ECT) method is widely used to detect various types of defects occurring in nuclear steam generator tubes. Therefore, the reliability of its detection and sizing accuracy for defects should be validated. For this purpose, two tubes with defect signals were pulled from an operating steam generator and destructively examined. The defect type was a circumferential crack for one tube and an intergranular attack (IGA) for the other tube. The plus point coil probe showed a better capability to detect and size both a circumferential crack and a volumetric IGA than pancake and bobbin coil probe. The destructive results are correlated with the ECT results obtained during the in-service inspection.     

量子粒子群融合算法在放射源探测标定中的应用

为有效进行辐射剂量探测,设计了有源在线监控模块。针对监控模块辐射测量值标定这一难题,提出了基于量子粒子群的融合算法实现对测量值与剂量值之间的高精度逼近。使用聚类和数据融合算法实现了拟合数据的自主最佳分段,避免了分段选择的主观性。仿真结果表明,融合算法能有效减少计数率较小时拟合函数的误差,提高各数据段测量值与剂量率之间的拟合精度,与整体拟合函数相比,进一步提高了拟合的精度。     

单相流体横向作用下传热管束间耦合振动数值模拟研究

换热管束作为蒸汽发生器的重要组成部分,其可靠程度直接影响到核电厂反应堆的安全运行。借鉴相关领域的研究提出并发展了一种具有较高精度的计算流体动力学（CFD）/计算结构动力学（CSD）耦合计算方法,对相邻管束间耦合振动现象开展了数值模拟研究。在时域和频域内分析了管阵的涡结构及相邻管束间振动响应规律。研究结果表明:漩涡在管束的上游产生、脱落并向下游逐渐发展,管束间大量的脱落涡的相互作用极大地丰富了流场中的涡脱频率;管束振动受管束固有频率和涡脱频率的共同影响;周围相邻管束的振动会对管束流体力波动及频率主导性产生显著影响,在一定程度上削弱升力波动;当相邻振动管束在同一排时,对管束的振动位移影响较为显著。      

单相流体横向作用下传热管束间耦合振动数值模拟研究

The heat exchange tube bundle is an important part of the steam generator, and its reliability directly affects the safe operation of the nuclear power plant reactor. Based on the research in related fields, a computational fluid dynamics(CFD)/computational structural dynamics(CSD) coupling calculation method with higher accuracy is proposed and developed, and the numerical simulation research is carried out on the coupling vibration phenomenon between adjacent tube bundles. The vortex structure of the tube array and the vibration response law between adjacent tube bundles are analyzed in the time domain and frequency domain. The research results show that the vortex is generated and shed in the upstream of the tube bundle, and then gradually develops downstream. The interaction of a large number of shedding vortices between the tube bundles greatly enriches the vortex frequency in the flow field, and the vibration of the tube bundle is affected by the natural frequency and the vortex frequency of the tube bundle. The vibration of the surrounding adjacent tube bundles will have a significant impact on the fluid force fluctuation and frequency dominance of the tube bundle, and weaken the lift fluctuation to a certain extent, and when the adjacent vibrating tube bundles are in the same row, the impact on the vibration displacement of the tube bundle is more significant.     

基于Geant4的盖革计数管能量补偿研究

重点研究了盖革计数管对于较宽能量范围的各能量γ射线的响应情况,从理论上简要说明了盖革计数管的能量响应特点,并针对国产的J4403型计数管使用蒙特卡罗软件Geant4分析了实际情况下能量补偿的各个影响因素,得到不同结构参数下计数管的能量响应情况,为计数管的能量补偿提供了依据.     

Study of the MTC estimation by noise analysis in 2-D heterogeneous systems

The effect of a heterogeneous distribution of the temperature noise on the MTC estimation by noise analysis is investigated. This investigation relies on 2-group diffusion theory, and all the calculations are performed in a 2-D realistic heterogeneous core. It is shown, similarly to the 1-D case, that the main reason of the MTC underestimation by noise analysis compared to its design-predicted value lies with the fact that the temperature noise might not be homogeneous in the core, and therefore using the local temperature noise in the MTC noise estimation gives erroneous results. A new MTC estimator, which was previously proposed for 1-D 1-group homogeneous cases and which is able to take this heterogeneity into account, was extended to 2-D 2-group heterogeneous cases. It was proven that this new estimator is always able to give a correct MTC estimation with an accuracy of 3%. This small discrepancy comes from the fact that the reactor does not behave in a point-kinetic way, contrary to the assumptions used in the noise estimators. This discrepancy is however quite small.