煤田选择γ-γ测井仪

本文介绍煤田低能γ射线散射测井的一种方法。定名为选择γ-γ测井。该装置使用~(241)Am放射源,对等效原子序数Z_e_q灵敏,并可估价煤中灰含量。     

γ能谱仪

本发明是关于γ能谱测量,可用于道数少的γ能谱仪中,供测定各种介质(例如,岩石)中放射性元素的含量。对测定放射性元素含量所使用的γ能谱仪已很熟悉。为了减少宇宙辐射和大气放射性的影响在γ谱仪中所造成的误差,除使用一个主要γ辐射探测器外,     

γ-γ法的理论基础及其应用——对“关于γ-γ密度计问题”和“利用γ

一、引言自1959年以来,在“原子能科学技术”上已先后发表了曾繁超、李业彬和刘雨人等提出的三篇关于γ-γ法问题的文章。从这些文章里可以看出,近年来γ-γ法在我国生产实践上的应用已有相当成绩,而且对γ-γ法的具体应用也有了新的发展。但是也不能否认,γ-γ法在实际应用上还存在一些重要问题,许多作者对这些问题的看法也还存在一些分歧,这就需要今后对该法继续进行深入的研究。这里,笔者仅在力所能及的范围内提出下列几个问题,和大家讨论。     

关于γ-γ密度计问题

一、前言γ-γ密度计,也称作γ射线散射式密度计,如图1所示。它是根据在轻物质中,放射性点源在周围介质中某点的散射强度与介质密度有关的原理制成的直接测量介质密度的仪器。     

智能化γ探头研究

利用Time-to-Count测量方法,同时将单片机和高压电源植入到γ探头中,设计出新型的智能化γ探头.智能化γ探头是一种小型化、一体化的γ射线监测仪器.介绍了智能化γ探头的设计方案,性能指标,探测器的结构设计.此研究已得到工程应用.     

γ谱分析中的γ-γ级联辐射的符合相加校正方法简介与评价

介绍了γ谱分析中的γ－γ级联辐射的符合相加校正的两种方法的原理及相应的计算表达式,并对它们作了评价。通计比较可知,不考虑级联γ辐射角关联的符合相加效应的校正方法通常不应采纳。     

快慢γ-γ符合时间谱仪

本文介绍FH-1911型快慢γ-γ符合时间谱仪,对~(60)Co源在20％能量窗条件下获得FWHM为295ps的实验结果。     

高能量γ射线源

文章介绍了用Am-Be中子源得到5-10MeV能区单能γ射线,以及在反应堆上得到高能单色低本底γ射线的方法。它们可以用来刻度γ探测器如Ge(Li),HPGe,NaI(Tl)和BGO等的能量线性,能量分辨和相对效率。     

蒙特卡洛洁计算γ谱仪的源γ总效率

叙述了蒙特卡洛法计算γ谱仪源γ总效率和体源自吸收因子的基本原理及主要公式。采用了立体角加权技术。用ＱｕｉｃｋＢａｓｉｃ语言编制了ＨＰＧｅ深测器对“ＭａｒｉｎｅｌｌｉＢｅａｋｅｒ”型体源的计算程序。计算中仔细考虑了源盒、真空壳、死层及Ｐ型芯等的影响。程序可给出源γ总效率，立体角因子，自吸收因子，γ射线穿过源、晶体等的几何距离和γ射线穿过源的等效距离等结果。计算结果与文献和实验作了比较。     

高能γ射线标准源

文章介绍γ射线能量大于1.5MeV标准源的类型及其特性,特别是核反应高能γ射线源。本工作主要研究高能γ射线能量和发射概率的确定及多普勒展宽效应的起因及其对效率校准带来的影响。     

Hazard curve evaluation method development for a forest fire as an external hazard on nuclear power plants

A method to obtain a hazard curve of a forest fire was developed. The method has four steps: a logic tree formulation, a response surface evaluation, a Monte Carlo simulation, and an annual exceedance frequency calculation. The logic tree consists domains of “forest fire breakout and spread conditions”, “weather conditions”, “vegetation conditions”, and “forest fire simulation conditions.” Condition parameters of the logic boxes are static if stable during a forest fire or not sensitive to a forest fire intensity, and non-static parameters are variables whose frequency/probability is given based on existing databases or evaluations. Response surfaces of a reaction intensity and a fireline intensity were prepared by interpolating outputs from a number of forest fire propagation simulations by fire area simulator (FARSITE). The Monte Carlo simulation was performed where one sample represented a set of variable parameters of the logic boxes and a corresponding intensity was evaluated from the response surface. The hazard curve, i.e. an annual exceedance frequency of the intensity, was therefore calculated from the histogram of the Monte Carlo simulation outputs. The new method was applied to evaluate hazard curves of a reaction intensity and a fireline intensity for a typical location around a sodium-cooled fast reactor in Japan.     

Recent activities in the field of nuclear waste management

Buffer construction using bentonite pellets as filling material is a promising technology for enhancing the ease of repository operation. In this study, a test of such technology was conducted in a full-scale simulated disposal drift, using a filling system which utilizes a screw conveyor system. The simulated drift, which contained two dummy overpacks, was configured as a half-cross-section model with a height of 2.22m and a length of 6.0 m. The average dry density of the buffer obtained in the test was 1.29 Mg/m³, with an angle of repose of 35 to 40 degrees. These test results indicate that buffer construction using a screw conveyor system for pellet emplacement in a waste disposal drift is a promising technology for repositories for high level radioactive wastes.     

A Fat strange Repeller

This article reports an observation on a fat strange repeller, which appears after a characteristic crisis observed in a kicked rotor subjected to a piecewise continuous force field. The discontinuity border in the definition range of the two-dimensional mapping, which describes the system, oscillates as the discrete time develops. At a threshold of a control parameter a fat chaotic attractor suddenly transfers to a fat transient set. The strange repeller, which appears after the crisis, is also a fat fractal, This is the reason why super-transience happens     

Irradiation test of component for radiation-resistant small sized motor

A small-sized motor with a resistance to radiation was developed. This motor has been able to operate at a gamma-ray dose of a value 700 times as high as the specification of a commercial motor. The present work describes results of post-irradiation examinations (PIEs) to evaluate effects of neutron irradiation on the lifetime of some major components of the motor such as a bearing, a magnet and a fixation agent for a field coil wire. It became clear from the results of PIEs that the radiation-resistance dose of the motor using a Sm–Co magnet will be expected to be one order of magnitude higher than that of the motor using a Nb–Fe–B magnet.     

PIV Measurement of Pressure Distributions about Single Bubbles

Measurements of velocity and pressure distributions around a bubble are of fundamental importance to model the forces acting on the bubbles and to verify detailed numerical methods for the prediction of flow in nuclear reactors. The measurements of velocity distributions around a bubble have been conducted to understand the interaction between liquid flow and bubbles. However there are few studies on pressure distributions around a bubble for the lack of measurement method. In this study, we developed a method for evaluating a pressure distribution by making use of velocity data obtained by a particle image velocimetry (PIV) or a particle tracking velocimetry (PTV), and applied it to laminar pipe flows, laminar flows around single particles and single bubbles in a pipe to examine its accuracy and applicability to the flow around single bubbles. As a result, we could confirm that the method can evaluate the pressure distribution in various laminar flows, provided that the velocity data possess a good quality and a flow of concern is two-dimensional. The proposed method therefore has a potential to provide the important information for modeling of the bubble motion and verification of CFD methods such as interface tracking and lattice Boltzmann methods.     

Radiation Field for Fission Neutron Enhanced Boron Neutron Capture Therapy Employing Fast Neutron Source Reactor “YAYOI”

Boron Neutron Capture Therapy (BNCT) of a localized tumor needs a sufficient thermal neutron flux at the tumor. A surgical operation including ennucleation of the main part of tumor is required for the case of thermal neutron beam from a thermal reactor because of the rapid decrease of the neutron flux in the tissue. Intermediate neutrons with little fast neutron component are only produced by a specifically designed reactor which awaits to be build.

In the present paper, a positive use of fast neutron beams in addition to BNCT is proposed for treatment of some kind of localized tumors employing a fission fast neutrons from a fast neutron source reactor “YAYOI” of University of Tokyo which is licenced as such. Dose distributions in a water phantom located at a proposed position for two collimator cases were measured and its availability was confirmed as a possible port for therapy.     

不锈钢管道焊缝金属240℃循环变形行为的试验研究

基于增量步和成组法低周疲劳试验,研究了1Cr18Ni9Ti不锈钢管道焊缝金属在240℃下的循环变形行为。结果表明,材料为循环软化材料,具有轻微Non-masing行为特征。相同总应变范围的循环应力、应变（CSS）行为存在很大分散性,意味着任何外载,即使恒幅载荷也将导入一个随机应变载荷史,现有确定性方法可能导致偏于危险的设计分析,有必要引入概率方法表征材料的循环变形行为。基于验证的应力幅统计分布－正态分布,建议了概率Ramberg-Osgood CSS曲线的描述方法。文中试验结果分析验证了方法的有效性。     

Ternary Compounds PuNiC2 and PuCoC2

In order to determine a crack propagation rate of less than 10^-8 mm/s in a 24-hour integrated measurement, major parameters of a coupled system of a constant tension specimen and crack depth measurement, based on potential drop method, have been optimized. Influences of sensor geometry, location for detecting potential drop and data processing of the ratio of signal to noise (S/N) were optimized by applying Taguchi's Method. Then a suitable sensor geometry and data processing method were proposed to get a robust measurement system with higher sensitivity and lower susceptibility for geometrical and procedural fluctuations.

By applying the optimal crack propagation rate measurement system, it was confirmed that a crack propagation rate of lxlO^-8 mm/s can be measured under a low concentration condition of hydrogen peroxide with less than a 20% error by a 24-hour integrated measurement.     

A remote handling rate-position controller for telemanipulating in a large workspace

This paper presents a new haptic rate-position controller, which allows manipulating a slave robot in a large workspace using a small haptic device. This control algorithm is very effective when the master device is much smaller than the slave device. Haptic information is displayed to the user so as to be informed when a change in the operation mode occurs. This controller allows performing tasks in a large remote workspace by using a haptic device with a reduced workspace such as Phantom. Experimental results have been carried out using a slave robot from Kraft Telerobotics and a commercial haptic interface as a master device. A curvature path following task has been simulated using the proposed controller which was compared with the force-position control algorithm. Results obtained show that higher accuracy is obtained when the proposed method is used, spending a similar amount of time to perform the task.     

Strip line beam position monitor for HLS LINAC

1 Introduction Beam position monitors at HLS LINAC and transfer line will deliver the information about the transverse positions and phases of beam passing by. Typical requirement for position resolution is within 1mm within 1/3 of half aperture rb (rb of HLS LINAC is 25mm). The HLS LINAC BPMs will also serve as beam phase detectors, which require a tough broad-band frequency response and impedance match for the BPMs. Additionally, space available for the BPMs at the HLS LINAC…