IAEA2008年国际比对水体样品中总α/β放射性分析

为了评估本实验室对环境样品中天然放射性核素的分析和测量技术,本实验室参加了IAEA 2008年世界开放实验室国际比对磷石膏和水体样品天然放射性核素的分析测定活动.本工作主要针对水体样品中总α/β放射性活度的测量进行讨论.按照比对要求,应用比较测量法,以UO2(NO3)2和KCl分别作为总α和总β分析的亚基准物和基准物,...     

日本标准岩石JG—1样品的非破坏性测量

一、引言日本标准岩石JG—1样品是我所李德平教授1982年12月访日期间,由日本金泽大学低水平实验室提供的。样品中的放射性物质含量有确切的数值。在重新封装之前,我们进行了非破坏性测量。在测量和分析过程中,对样品的物理性质和化学性质及样品中核素的含量均不知道。本工作给出了测量和分析结果。     

环境样品γ放射性测量国际比对

为了提高测量水平，促进环境样品放射性测量的质量保证工作，从１９８５年起本实验室开始参加环境样品放射性测量国际比对，本文报道了所参加的国际比对项目、γ放射性核素分析方法及部分比对结果。１　ＷＨＯ－ＩＲＣ和ＩＡＥＡ－ＡＱＣＳ比对项目从１９８５年到１９９３...     

核素实验室样品测量及分析数据归档系统研制

介绍了禁核试北京放射性核素实验室样品测量及分析数据归档系统的研制过程.该系统由样品测量及分析数据库、测量数据的自动存储、能谱数据的分析和基于Web的数据检索统计工具等四部分组成,实现了核素实验室样品测量数据及其分析结果的自动存储和统计查询,提高了北京放射性核素实验室对样品测量数据及其分析结果的管理能力.     

放射性核素核查氙总量分析及不确定度评估

氙总量分析是放射性核素核查的重要技术内容。本文针对国际监测系统（IMS）放射性核素台站惰性气体氙取样监测设备归档样品的特点,研究了热导池检测器（TCD）测量氙气体样品的进样条件,建立了实验室测量分析惰性气体样品中氙总量的标准流程及其不确定度评估方法。以国际惰性气体实验（INGE）传递样品的分析为例,评估了样品中氙总量分析结果的相对合成标准不确定度,结果为1.96%。     

爱尔兰与IAEA联合监测爱尔兰海域

爱尔兰辐射防护研究所与 IAEA和北爱尔兰环境遗产部合作 ,在西北爱尔兰海设置了一个试验浮筒 ,上面配备有能连续测量海水中放射性污染的辐射监测器。该探测器特别适用于测量英国Sellafield后处理厂释放的 137Cs,浮筒中还载有测量理化参数如流速、盐分和温度的仪表。测量结果每天通过卫星传送到 IAEA的摩纳哥海洋环境实验室 ,然后再转送到都柏林的爱尔兰辐射防护研究所。同时收集海水样品进行实验室分析 ,对测量结果给与补充。试验浮筒以及仪表组件是由一家挪威公司联合 IAEA海洋环境实验室共同研制和建造的。爱尔兰海洋项目是由爱尔兰…     

2008年度CTBT惰性气体氙传递样品测量

介绍了禁核试北京放射性核素实验室参加CTBTO组织的放射性核素台站惰性气体氙样品传递实验的情况,详细描述了样品分析的流程、测量设备和分析方法,对实验室和台站结果之间存在差异的原因进行了分析,并讨论了提高惰性气体氙样品测量准确度的方法。     

广东大亚湾核电站若干环境监测项目测量结果的比对

本文报道了由中国辐射防护研究院组织的、国内5个实验室参加的大亚湾核电站若干环境放射性监测项目的测量比对结果。文中介绍了比对样品的准备情况，给出了各实验室对于沉积物、生物灰样品中总β、水中^3H、土壤中^90Sr、海藻灰和海底沉积物中^110mAg及^241Am、^109Cd、^57Co等人工放射性核素γ谱分析的测量结果，并对结果进行了分析。     

铀同位素标准物质在核燃料系统实验室间比对中的应用

在核燃料系统分析检测实验室间比对活动中，首次开展铀同位素检测项目的设计、策划和实施，选取国家一级标准物质“八氧化三铀中铀同位素标准物质”作为分割样品对，分别采用Z比分数、标准物质测量结果的误差允许限（E）作为能力统计量，对实验室间铀同位素丰度的比对结果进行统计和分析，对测量结果有问题或不满意的情况进行分析和建议。通过首次开展铀同位素项目的比对，拓展了核工业系统实验室能力验证范畴，进一步提高实验室的检测水平，对核燃料循环生产中铀同位素的测量提供了技术基础保障和质量保证。     

鱼粉样品中放射性核素的测量方法及质量控制研究

介绍了鱼粉样品的采集、预处理、制备和测量的整套方法,通过对比对实验室测量结果的分析,总结了各个实验室在样品制备、测量方法和设备条件方面需要进一步改进的方向,加强了监测方法的统一和监测质量的控制.     

反应性测量中本底与中子源修正计算方法研究

在核电厂反应堆的反应性测量中,γ本底电流、中子源引入的电流、电路噪声等干扰项在实测电流中占有显著份额,给反应性的测量计算带来很大影响,在动态刻棒等反应性测量工作中必须对其进行修正。本文分析了本底与中子源电流对反应性测量的影响,并自主开发了一种本底电流、中子源电流修正方法--双重拟合法。该方法基于点堆模型,通过对包含本底与中子源的逆动态方程的分析,计算得到准确的反应性以及本底电流、中子源电流。通过试验堆动态刻棒实验的数据对本方法进行了验证,得到了理想的结果。     

铀矿环境质量评价中进风井对大气扩散影响的随机行走模拟

在核工业铀矿环境质量评价中，进风井通风量较大，对局地流场产生一定的影响，从而影响污染物的散。本文应用粒子随机行走模拟方法模拟核工业铀矿出风井污染物的排放，在模拟区中考虑下风向有进风井存在的情况，估算了进风井对污染物弥散的影响。     

A new method for the evaluation of neutron elastic transformation matrices

A new method for the evaluation of the center-of-mass to laboratory co-ordinates system transformation matrix is developed, by which each element of the matrix is represented as a finite sum of terms depending on the mass number of the scattering nucleus. At present, the elastic transformation matrices given in the ENDF/B files are evaluated by the Amster method, by which each element of the transformation matrix is represented as an infinite sum of terms. A comparison is made between the values of the elements of the elastic transformation matrix of ⁶Li obtained by the new method and those given in the ENDF/B-V file, and some discrepancies are revealed.     

Elemental analysis of limestone samples from Ewekoro limestone deposit in southwest Nigeria

Limestone samples of different colours from Ewekoro limestone deposit in Ogun State, Nigeria were subjected to elemental analysis by proton-induced X-ray emission (PIXE) and proton-induced gamma-ray emission (PIGME) techniques. The irradiation was by 2.5 MeV proton beams from the ion beam analysis (IBA) facility of the 3 MV Van de Graaff accelerator at the Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights. Elemental composition and concentrations of 22 major, minor and trace elements were determined. The NIST geological standard, NBS278, was analysed for quality assurance. The concentrations of the major elements (Ca, Fe, K and Al) are similar in the samples while the other major elements differed. Calcium accounts for about 38%, giving 86.8% CaCO₃ content in the limestones. The major elements (Al, Ca, Fe, Si, S and K), present in the limestones, were also found to be enriched in airborne particulate matter studied by earlier workers, thus confirming cement dust as the major contributor to the particulate matter within and around cement factories.     

新一代多模型迭代算法在70 kVp成人副鼻窦CT扫描中的应用

探讨成人在70 kVp副鼻窦CT检查中降低有效辐射剂量的同时,获取最佳图像质量的新一代多模型迭代算法(Adaptive Statistical Iterative Reconstruction-V,Asir-V)的权重。本研究对20例成人患者进行副鼻窦Revolution CT检查,采用70 kVp、230 mA条件下进行螺旋CT扫描,扫描完成后对每例患者的原始数据采用不同权重(0,20%,40%,60%,80%,100%)的后置新一代多模型迭代算法(Adaptive Statistical Iterative Reconstruction-V,Asir-V)重建的方法,共获得120幅图像,并对每例6组图像进行客观评价及主观评分。客观评价包括噪声(standard deviations, SD)和对比噪声比(contrast noise ratio,CNR),主观评价由2名评价医生对图像质量评分并对两者的主观一致性进行评价。每例患者扫描完成后,记录其剂量长度乘积(dose-length product,DLP)和CT容积剂量指数(CT dose index volume,CTDI_vol),并计算其平均有效辐射剂量(effective dose,ED)。客观评价结果表明不同权重的Asir-V图像噪声随着Asir-V权重的提升而降低,CNR值随着Asir-V权重的提升而升高,且有效辐射剂量ED较常规头颈部CT检查的平均辐射剂量明显减少;主观评价结果表明不同权重的Asir-V图像评分不同,在Asir-V 60% 时评分最高,且2名医生主观评价一致性好。结合主客观评价结果,认为在70 kVp、230 mA成人副鼻窦Revolution CT检查中,Asir-V 60％的图像既可满足临床诊断的需要,也可明显降低有效辐射剂量。     

工业脉冲X射线发生装置放射防护检测与评价方法研究

目的探讨利用热释光剂量计对工业脉冲X射线发生装置进行放射防护检测与评价的可行性。方法分别用热释光剂量计和AT1123型X/γ辐射剂量率仪测量脉冲X射线发生装置的辐射剂量,通过对测量结果的分析和比较验证热释光剂量计测量脉冲X射线的有效性,通过对周围环境中年累积剂量的估算来评价试验人员和公众的受照剂量是否满足辐射防护要求。结果1号脉冲X射线发生装置曝光4次,2号脉冲X射线发生装置曝光10次,热释光法测得不同距离处的累积剂量符合距离平方反比衰减规律,实际检测结果与理论推算值较为吻合。两个X射线发生装置现有的工作负荷下,工作人员和公众的年累积剂量均在辐射防护控制目标值内。结论热释光法得出检测结果与理论推算值较为吻合,能够满足工业脉冲X射线发生装置放射防护检测需求。     

Recording length criteria as applied in ultrasonic testing

An appreciable method used to assess the quality and integrity of safety-related components in light water reactors is the ultrasonic examination, in which case great importance is attributed to the criteria pertaining to recording length and permissible defect size.The development of the recording length criteria as applied when employing this method of examination is portrayed, the latter being based on the criteria which have proven themselves throughout long years of practice in the examination of conventional components. When taking these criteria into account the application of conventional ultrasonic techniques often leads to problems in the case of thick-walled components the reason being that indications are overrated.Taking the design of reactor components as the basic point of consideration, modified criteria are derived particularly when the size of discontinuities calculated by fracture mechanics analyses is taken into account. The introduction of new ultrasonic examination techniques such as, for example, focussed probes revealed that a considerably more realistic assessment is possible and consequently results in a reduction of unnecessary repairs.A comparison of the size of indications determined using conventional and analytical techniques renders possible the anchoring of an intermediate stage in the evaluation of indications which is encompassed in the consideration of the bundle divergence. Thus a new concept is realized for the evaluation of ultrasonic indications detected in reactor components, which in the meantime has found its way into the associated regulatory guides.     

Development of an effective dose calculation method for the downstairs room of a linac facility

ABSTRACT

An effective dose calculation method is important in the design of efficient shields in radiation facilities. Some analytical methods have been shown to provide a simple and quick design analysis; however, no suitable method exists that can be applied to a room located directly under an X-ray irradiation room. We propose a new analytical method that uses the multiple reflection ratio predetermined by a Monte Carlo simulation and the differential dose albedo given by the Chilton–Huddleston semi-empirical equation. Our method is verified by comparison with the Monte Carlo simulation, performed for the case of an electron linac facility with an accelerated energy of 10 MeV, where the shielding floor has a thickness of 1.6–2.0 m and the downstairs room has a height of 0.5–1.5 m. The difference between the effective X-ray doses in the downstairs room calculated via the proposed analytical method and the Monte Carlo simulation is less than 25% when the horizontal distance from the X-ray beam to the evaluation point exceeds 3 m and the evaluation point is set at half of the height of the room. The new analytical method can be efficiently and accurately applied to the calculation of the effective dose.     

锰浴法测量中子源发射率中各修正因子的蒙特卡罗计算

在采用锰浴法对放射性同位素中子源的发射率进行测量时,MnSO₄溶液中⁵⁵Mn仅俘获部分源中子,故需考虑对未被⁵⁵Mn俘获部分的修正。用蒙特卡罗粒子输运程序MCNP对中子源强标准装置的锰浴系统进行模拟计算,对实验测量结果进行修正,并通过由国际计量局（BIPM）组织的中子源强度国际比对,验证了计算所建立模型的可靠性。利用MCNP程序的微扰计算功能,通过考虑MnSO₄溶液的密度、源及其承托物材料的密度、源的位置、锰浴半径以及反应截面的改变对计算结果的影响,对模拟计算结果的不确定度进行了详细评定,提供了一种蒙特卡罗模拟计算结果不确定度的评定方法。     

乏氧显像剂~(99)Tc~m-EtAO的制备和活性研究

为寻找结构简单、性能优良的乏氧显像剂 ,合成并用99Tcm 标记了 3 甲基 3 N (2 羟乙基 ) 2 丁酮肟 (EtAO) ,进行了体内外活性的研究 ,并与已知乏氧显像剂99Tcm Bn(AO) 2 比较。细胞实验结果表明 ,与99Tcm Bn(AO) 2 一样 ,99Tcm EtAO也具有亲乏氧性。荷瘤小鼠体内分布结果表明 ,99Tcm EtAO能选择性地滞留于肿瘤组织。作为一种潜在的乏氧显像剂 ,99Tcm EtAO有进一步研究的价值