简易桶装废物非破坏检测装置设计及检验

介绍了组装的桶装废物非破坏检测装置及其探测效率获得方法,并将探测效率的实验值与计算值进行了比较,其变化趋势一致。使用^{137Cs标液制作实验源模拟桶装废物进行验证实验,在放射源随机分布、介质密度低于1.761 g/cm3情况下,计算结果偏差在±20%内;在放射源极端分布、介质密度为1.538 g/cm3情况下,计算结果偏差达-76%~152%,说明该方法用于核设施退役产生的桶装废物的分级是可行的。}     

标准氡室氡浓度不确定度评定方法探讨

标准氡室为氡测量仪器的校准提供氡浓度的参考标准,氡室氡浓度可由氡源的氡产生率、补氡时间、氡的自然衰变规律以及吸附/泄漏率等因素进行理论计算,也可用标准氡浓度测量仪测定,同时需要对氡室氡浓度的不确定度进行科学合理的评定.本文分析了这两种氡浓度定值方法的不确定度来源,并分别介绍和探讨了氡浓度值不确定度的评定方法.结果表明:由标准测量仪器测定氡浓度并进行不确定度评定,其方法优于基于氡源参数进行计算所得氡浓度值的不确定度评定方法.     

~(60)Co放射源运输容器屏蔽性能检测

工业及医疗用放射源主要包括60 Co、137 Cs、131I、32P、153Sm、99 Mo、90Sr、89Sr等核素,射线形式有α、β、γ、中子等。本文针对运输活动中γ辐射,使用现有的60 Co放射源运输容器,开展辐射屏蔽性能检测技术研究。通过模拟计算和实验测量,得到运输容器最大装载活动情况下外部辐射水平,并对计算和实验结果进行了比较。针对放射源在屏蔽容器中安放位置发生偏移和放射源在容器中安放方式不同对容器外部的辐射水平影响进行了相关研究。研究结果可对今后完善放射性物质运输容器的辐射屏蔽性能检测提供一定的借鉴。     

Study of equivalent efficiency calibration method for radioactive gas source measured on HPGe detectors

ABSTRACT

In view of the complexity of current detection efficiency calibration of radioactive gas sources, a method using solid planar sources to be equivalent to gas sources was studied. For the 50 mL gas source box, an optimal equivalent scheme was selected by Monte Carlo Simulations. Then, the full-energy-peak efficiency curve of gas sources at the measurement position of 25 cm, with source-to-detector distance of 25 cm, was fitted by measuring solid planar sources with known activity. To verify the accuracy of the efficiency curve, ⁴¹Ar, ¹³³Xe and ⁸⁷Kr gases were produced and determined by length-compensated method. Then, their full-energy-peak efficiencies at 25 cm position away from the detector were directly calibrated. The percentage efficiency deviations between interpolation from the efficiency curve and direct calibration are all less than 2.5%, which proves the accuracy of the equivalent method. This calibration method is a general one and can be also used for some other radioactive sample measurements, such as non-destructive analysis of gaseous fission product samples with a suitable source-to-detector distance.     

预估带法搜寻丢失放射源模拟研究

为了能快速高效的搜寻丢失的放射源,本文提出了一种预估带法丢失放射源搜寻方案,该方案具有操作简单,定位准确性高,实用性强,用时短,搜寻人员所受剂量低的优点。实验模拟了226Ra丢失情况下,采用BH3013B环境辐射剂量率仪进行搜寻,验证了该方案在无遮挡、单面遮挡和掩埋三种情况下搜寻丢失放射源的效率与定位准确性。实验结果表明,此搜寻方案能有效、快速、准确的确定丢失放射源的位置,为搜寻人员提供了依据,从而尽可能的减少损失。     

大流量气溶胶滤膜标准γ体源制备技术

为制备大流量气溶胶滤膜标准γ体源,采用参数优化的专用滴源装置,将放射性标准溶液⁶⁰Co定量滴注在气溶胶取样滤膜上,晾干后对角折叠,并采用专用压样装置压制成与测量样品几何形状一致、密实的圆盘形固态物,密封保存。采用差重法对制备的滤膜标准γ源进行活度定值,制备的气溶胶滤膜标准γ体源活度值为4.4×10⁴ Bq,相对扩展不确定度U（k=2）为3.6%。采用分割压制法对气溶胶滤膜标准γ体源进行均匀性测量,相对标准偏差低于5%。制备的滤膜标准γ源可为测量大流量气溶胶样品的γ谱仪效率刻度服务。     

放射性同位素制品技术标准建设的现状与思考

随着国家对民用核技术应用领域的大力支持,我国放射性同位素制品行业迎来了前所未有的机遇与发展.然而,行业快速扩张也带来了市场规模与行业技术标准体系发展不匹配的问题.目前有关国内放射性同位素制品行业技术标准体系建设的研究甚少,本文从行业市场规模及标准体系现状出发,分别探讨放射性药物和放射源行业在标准体系建设方面的现状及存在...     

放射源安全管理中一些问题的讨论

放射源的安全已成为我国当辐射防护的一个主要问题。已经发生的辐射致死事故均是放射源引起的,96.6%的急性放射病患者是因放射源事故造成的。约有2000枚完全失控的放射源散布在环境中,其中有些可能产生十分严重的危害。为了解决放射源安全管理的现状,制定一个“减小放射源危害计划”是必要的。     

城市放射性废物库设计探讨

针对江苏省放射性废物的特点,提出城市放射性废物库库型、吊装工具、防洪抗震、安全防御及污染防治等方面的设计方案,既保证江苏省放射性废物和废旧放射源能得到安全收贮,又确保库区环境不受污染,促进江苏省核技术利用企业的发展。     

Standoff 3D Gamma-Ray Imaging

We present a new standoff imaging technique able to provide 3-dimensional (3D) images of gamma-ray sources distributed in the environment. Unlike standard 3D tomographic methods, this technique does not require the radioactive sources to be bounded within a predefined physical space. In the present implementation, the gamma-ray imaging system is based on two large planar HPGe double sided segmented detectors, which are used in a Compton camera configuration. A LIDAR system is used in conjunction with the gamma-ray imaging system to confine the gamma-ray image space to the interior of physical objects situated within the detection range of the gamma-ray imager. This approach results in superior image contrast and efficient image reconstruction. Results demonstrating the operating principle are reported.     

Modeling the diffusion yield of radioactive fission products from uranium dioxide fuel

The numerical aspects of a systematic solution of the problem of diffusion and yield of radioactive fission products from a homogeneous sphere, simulating a uranium dioxide fuel kernel, with realistic boundary conditions are discussed. The numerical scheme is based on a one-group method of calculating the production and radioactive mutual transmutations of fission products in combination with the standard expansion of the radial dependence of the concentration in terms of the eigenfunctions of the Laplace operator. It is demonstrated on illustrative examples that the approach is highly economical.     

A Variable Coincidence Unit Hasl Type TL-9

The variable coincidence gate is a multifunction logic unit designed for use with the HASL quarter chassis line of nuclear instrumentation. It provides a flexible unit which is applicable to several of the techniques used for counting radioactive events. The circuit can be used for prompt, delayed and decay coincidence, anticoincidence, and pulse height window measurements. It also operates as a signal generator of paired pulses and of delayed pulses. The unit is 3 1/2? high by 9 1/2? wide and 6? deep.     

用微型反应堆制备放射性核素

为扩大微型反应堆的应用领域，文章讨论了在该堆上制备放射性核素的可行性，采用热中子的（ｎ，γ）反应，已制备出２０种放射性核素，其中一些核素已被用于放射性示踪和用作放射源。     

Leakage test methodology development in iodine-125 seeds production

Brachytherapy using iodine-125 seeds has been used in prostate cancer treatment. In the quality control routine during seed production, leakage tests are taken to detect any leakage of radioactive material from inside the titanium shield, avoiding patient contamination. Leakage tests are carried out according to the International Standard Organization – Radiation protection – sealed radioactive sources – ISO 9978. This standard recommends different methods of essay applied to radioactive seeds. The aims of this work were the study of the different leakage test methods applied to radioactive seeds recommended by the ISO 9978 and the choice of the appropriate method to be used in the seeds production. The authors evaluated five different immersion methods to detect leakage, following the standard guidance, and in some case exceeding its requirement. One hundred iodine-125 seeds were intentionally cuted, causing the release of its content. Each immersion method was applied to twenty seeds. After the immersion period, the resulting liquid activity was measured. The activity values measured in the immersion liquid indicated best results with distilled water as immersion liquid and with the application of ultrasound to the bath. The temperature of the bath ranged from 20 °C to 70 °C and the immersion time ranged from 30 min to 24 h. In this experiment, the use of scintillator liquid as immersion liquid was not effective to detect the leakage. The results allow the authors to choose the best methods to be applied in the production routine, to detect leakage in the seeds. The choice of the method will also depend on the production rhythm for schedule. In a moderate production rate, the test at 20 °C and 24 h immersion may be used. In a fast production rhythm, the shortest test 50 °C or 70 °C should be used.     

空间用238pu放射源辐射影响分析

我国在某航天任务中,将首次应用238Pu放射源.本文从该放射源所用的原料、放射源的结构、产生的射线种类以及包壳活化等方面分析了238Pu放射源在航天应用过程中的辐射特性.通过分析实验表明,距单个放射源1m处的中子辐射剂量率约为60 u Sv·h-1,在采取适当措施后,238Pu放射源将不会对人员和环境产生明显的辐射影响.     

GY-20和GY-40型大容量钴-60运输容器关键技术研究

GY-20和GY-40型大容量钴-60运输容器是为运输工业用钴-60成品源和钴-60棒束而设计的专用设备。由于内容物放射性活度水平高、衰变热大，仅有加拿大、英国、俄罗斯等少数国家具有设计能力。本文综合考虑容器结构、热工、力学、屏蔽等方面的要求，对容器设计和制造过程中的关键技术以及解决方案进行了分析研究。试验验证结果表明，容器的结构设计、包铅边界设计准则的确定和制造过程的质量控制措施合理、有效，能保证容器在各种工况下的屏蔽完整性，容器具有安全运输大容量钴-60源项的能力，其设计满足相关标准和规范要求，可为其他B型货包的设计提供参考。     

国际原子能机构全球实验室放射性表面污染测量比对

为提高各国辐射工作人员的监测能力,国际原子能机构(IAEA)组织了实验室放射性表面污染测量比对。本文根据IAEA的要求,采用自制的3层辅助支架进行测量,得到的测量结果在IAEA比对报告中评价均为“接受”。根据此次比对结果,提出了放射性表面污染测量中应注意的几个问题。     

回收冶炼废旧金属的辐射监测

介绍了废旧金属中放射性物质的来源,分析了废旧金属及其制品产生射线的类型、监测仪器选用原则、监测方案制定、监测方法及质量保证措施。     

废放射源整备用封装管的设计与检测

研制废放射源整备封装管,使整备后废放射源满足处置或者长期贮存要求,是废放射源管理的重要组成部分。本文针对不同活度、不同核素的废放射源,设计制造了不同的封装管,并对其中的螺纹封装管进行了跌落性、抗冲击性、耐热性等一系列检测。检测结果表明,本研究设计的封装管,满足封装废放射源的要求。     

固体核径迹技术在热粒子定位和源均匀性检验中的应用

介绍了固体径迹和火花计数器技术在热粒子定位中的应用，测定了6种滤膜的最大流量，流阻及流量变化，并在某工号进行了模拟粒子取样，火花放放电图像可以大面积，清晰地展现出热粒子在滤膜上的位置。利用固体径迹技术对放射源均匀性进行了检验，结果表明，采用推荐流程制备的钚（α）标准源，其均匀性比前苏联制备的同类标准源优越（前者U在10％－18％，而后者在33％－47％）。