IAEA国际比对样品的γ谱分析

本实验室使用超低本底HPGe γ谱仪参加了2006年IAEA组织的γ核素放射性活度测量比对.按比对要求测量了土壤和水样中54Mn, 60Co, 65Zn, 134Cs, 137Cs, 241Am, 109Cd, 210Pb以及草样中的40K, 137Cs.使用无源效率刻度软件LabSOCS对HPGe γ谱仪进行效率刻度,γ谱分析采用Genie 2000分析软件.与IAEA的参考值相比,本实验室报出的测量值的总体接受率为89%,不被接受率为0,高于327个参加比对实验室分析结果为64%的总体可接受率,明显低于29%的总体不被接受率.     

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,...     

NBS环境放射性标准物质SRM4350B的γ能谱分析

一、引言环境放射性测量,由于放射性含量低,核素成份复杂,环境介质成份,密度变化很大,很难得到准确的数据。为了减少分析的系统误差,环境放射性分析中往往采用环境放射性标准物质和参考物质。1973IAEA(国际原子能机构),1975NBS(美国国家标准局)开始发布环境放射性标准物质和参考物质。我国也开展了与环境放射性参考物质有关的工作。1982年中国计量科学院组织NBS河泥标准放射性参考物质的比对。1984年七所组织核工部环境样品γ能谱测量和比对。国防科工委放射性计量一级站获     

IAEA 2008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,采用MPC 9604超低本底α/β计数器分别测定了IAEA提供的Sample03、Sample04和Sample05三个水体样品中总α/β放射性活度.反馈结果表明,三个样品总α和总β的测量结果全部在IAEA给出的参考值范围之内,接受率为100%.此外,本工作还对测量中可能引起误差的几个主要因素诸如α/β计数器灵敏度的确定、基准物质的选择、测控曲线的绘制等方面进行了分析与讨论.测量结果表明,当选用UO2(NO3)2取代U3O8基准物作为总α分析的亚基准物时,由于本实验室所使用的UO2(NO2)1中238U与234U尚未达到久期平衡,故其总α放射性远小于国标GB 5750-85的推荐值,但通过α谱仪对238U和234U准确定量后,不影响总α的分析结果.     

关于气溶胶总放射性IAEA亚太地区国际比对的一些讨论

2015年亚太区域IAEA的ALMERA实验室举行了气溶胶总放射性和土壤伽马核素比对,参加比对的有来自11个国家的14个ALMERA实验室。其中气溶胶中总α仅有9个实验室报出数据,其通过率67%;气溶胶中总β有10个实验室报出数据,其通过率50%。气溶胶中总放射性较低的通过率应引起从事该项测量工作人员的重视。同时介绍了本实验室参加这次比对详细过程。通过气溶胶滤膜直接测量方法,总α和总β的相对偏差分别是2.50%、-3.95%,结果可接受,顺利通过该项比对活动,并从中总结了经验。     

国际比对模拟气溶胶滤膜γ能谱测量及分析讨论

自制参考源，结合LabSOCS模拟软件的符合相加修正功能，用γ能谱法测量了2019年国际原子能机构(IAEA)全球实验室间比对3个模拟气溶胶滤膜样品中¹³⁴Cs、¹³⁷Cs含量，测量结果与IAEA参考值相对偏差<4%。¹³⁴Cs 5个发射几率较大的能峰符合相加修正系数范围为0.729～0.829;近几何测量时不考虑符合相加修正可能导致结果的偏差>20%;探测效率受滤膜到探测器表面距离影响显著。本文的研究结果对核电厂气载流出物气溶胶样品测量有借鉴意义。     

参加IAEA低水平氚比对小结

1985年6至9月我们参加了国际原子能机构(IAEA)放射性水文学部组织的低水平氚测量第四次国际比对。4个送测样品的浓度范围为<5—150Tu。比对中使用的浓集装置为有效体积是150ml的镍-镍电极周期性加样玻璃电解池。液闪计数器为LS-9000,仪器对无猝灭样品E≥57％,n_b≈20计数/min,品质因子Q=180。     

HFM100TS两步式手脚表面污染监测仪的研发设计

介绍了自主研发的HFM100TS两步式手脚表面污染监测仪的组成、软件设计、电路原理设计。本设备选用了4个ZnS(Ag)塑闪复合探测器作为主要探测单元,测量模式为两步式测量,测量过程语音提示、污染语音报警,操作简单,可以对放射性控制通道中出入的操作人员进行手部和脚部的表面污染测量,通过分析测量数据及时发现事故隐患。     

放射性检测领域的能力验证

放射性检测领域长期以来没有能力验证提供者,从事放射性检测工作的人员对实验室间比对和能力验证的认识不够深入。能力验证的关键过程包括能力验证物品的制备及其均匀性和稳定性检验、包装及分发、参加者结果的评定等内容。其中参加者结果的评定可参考IAEA的评定方法,更为全面可靠。     

β放射性测量比对及其标准

为提高β放射性测量的可靠性和可比性,把~(90)Sr-~(90)Y源的标准化工作推进一步。1983年上海市计量技术研究所组织了“低水平参考源~(90)Sr-~(90)Y全国比对”,最大偏差48%;1984年北京放射性计量一级站又组织了一次“全国~(90)Sr-~(90)Y参考源比对测量”,最大偏差大于80%。可见β放射性测量虽然简单,但要给出准确的结果并不容易。本文通过参加这两次全国比对的总结,提出造成β平板源测量比对偏差较大的原因及提出解决办法、力求提高β放射性测量的精度。     

关于表面放射性物质污染标准的讨论

本文综合了英法等一些国家和 IAEA 推荐的表面放射性物质污染标准,并与我国标准进行了比较。在理论计算和现场调查基础上,讨论了我国现行表面污染标准中存在的问题,并提出了具体建议。     

Safety considerations during transport of radioactive material

Abstract

The International Atomic Energy Agency (IAEA) regulations establish requirements that must be satisfied to ensure safety and to protect people, property and the environment from the effects of ionisation radiation during the transport of radioactive material (RAM). The package types A and B most frequently used for the transport of RAM in Romania are subjected to various qualification tests in accordance with the National Regulations and IAEA recommendations; these tests are carried out by the Reliability and Testing Laboratory of the Institute for Nuclear Research, Pitesti. These tests include the evaluation of non-fixed contamination, as is described in the present paper. Regulatory requirements related to contamination for packages used for transport and storage of RAM and the method used to monitor the evaluation of the surface contamination of packages are also presented. These test requirements are performed under a strict quality assurance programme based on specific procedures given prior approval by the Romanian Nuclear Regulatory Body (National Commission for Nuclear Activities Control).     

对核应急放射性沉降监测中一些问题的探讨

针对核应急放射性沉降监测的特点,本文分析了地面剂量率监测和环境介质中的放射性活度浓度测量中存在的一些问题,探讨了基于谱仪测量地面放射性污染面活度以确定剂量率的方法。     

光纤传输型便携式大面积表面污染监测仪的实验研究

以β放射性表面污染测量为对象,基于薄片式大面积塑料闪烁体探测器,建立了光纤传输型大面积塑料闪烁体表面污染监测仪实验装置,探测灵敏面积达1 200 cm2。初步实验表明,在10根光纤作为光收集的条件下,对90Sr-90Yβ面源的探测效率可达到7%。该探测器具有面积大、结构简单、环境适用性强等优点,未来可用于大面积β核素放射性表面污染的测量。     

The design and calibration of a phantom for depth profiling measurements of entrained radioactivity in silica-based media

The development of a phantom which replicates the effect of concrete on radioactivity entrained within it is described. The phantom was designed as a basis on which methods can be developed to measure the depth of radioactive contamination in the concrete of defunct nuclear facilities. In particular, this apparatus has been used to validate a differential attenuation method for the profiling of radioactive contamination at depth. Entrained radioactive contamination is a significant issue in defunct nuclear facilities where in situ, non-destructive assay of radioactive waste arisings is a routine requirement.The phantom comprises a polymethylmethacrylate structure filled with high-purity silica-sand which, for the purposes of the application, is an effective analogue of fully-hydrated concrete paste. A void was created within the silica sand which incorporates a sliding mechanism for the insertion of a radioactive source to a required depth. The sealed source represents the entrained radioactivity in the phantom but is also specifiable, removable and poses no long-term contamination risk beyond the expected life of the apparatus. The remainder of the void either side of the source is filled with silica-sand to complete the homogeneity of the phantom. The void was situated near the front of the phantom constructed at a 5.14° angle with respect to the front scanning surface; thus the apparent depth within the silica-sand can be varied by changing the position of the source along the phantom's void.The steps taken to develop the concrete phantom are described. The design has been validated with a set of radiation transport simulations affording comparison with an exemplar of the concrete found used in nuclear facilities. Some initial results from measurements taken with the phantom and a caesium-137 γ-radiation source in combination with a sodium iodide radiation detector are provided. These measurements are used to validate the differential attenuation method and compared with data from previous measurement attempts with concrete slices.     

大面积地表放射性污染评价与治理技术现状

介绍了大面积地表放射性污染的产生和危害,重点对世界上主要核试验场的大面积地表放射性污染状况、污染调查和治理技术等进行了综述,提出了我国大气层核试验场地表污染治理的思路和建议。     

Practical judgment of exemption by applying isotope specific exemption levels for surface contamination

Abstract

In terms of applying the concept of exemption to safety standards for surface contamination, we have derived isotope specific exemption levels for surface contamination (Bq cm^–2) by developing an original dose assessment model for surface contamination to develop reasonable radiation protection systems that reflect the radiological properties of nuclides and avoid excessive regulatory procedures. These exemption levels can be applied to the radiation, waste and transport safety fields by assuming a universal scenario and by applying radiation protection systems consistent with the current International Atomic Energy Agency (IAEA) Basic Safety Standards, safety series no. 115 and safety guide RS-G-1·7. In the case of materials containing a mixture of nuclides, the exemption can generally be judged on the basis of whether the condition ΣD/C<1 is satisfied (where D represents an actual measurement result and C represents the exemption level), and the estimation of the surface contamination density of key nuclides such as ⁶⁰Co, which are easily measured and dominant nuclide components, can be practically applied to the judgment of exemption. In this study, the contribution of nuclides to the summation defined in terms of relative importance was assessed using the exemption levels for surface contamination derived in previous Central Research Institute of Electric Power Industry (CRIEPI) studies and the technical data of nuclide composition ratios contributing to contamination assumed to occur in Japanese nuclear power plants. Important nuclides, whose relative importance was >0·1, were extracted following the 10% summation rule described by the European Commission in its document Radiation Protection 134. It was found that ⁶⁰Co was the only important nuclide in most of the cases and other nuclides can be ignored according to the reasonable exemption levels for surface contamination derived in CRIEPI's previous study, where the α emitter was the most important nuclide in the case of estimating fuel damage by applying the exemption levels for surface contamination derived from the dose conversion factors given in IAEA TECDOC-1449. It is expected that the resulting reasonable exemption levels for surface contamination will be applied practically to future regulation and that consistent radiation protection systems will then be realised throughout the radiation, waste and transport safety fields.     

Some aspects on harmonization between IAEA 'Regulations for the safe transport of radioactive material' and UN 'Recommendations on the transport of dangerous goods'

Abstract

Since 2001, the IAEA 'Regulations for the safe transport of radioactive material' are directly implemented into the UN 'Recommendations on the transport of dangerous goods', Model Regulations (the so called 'Orange Book') as class 7: radioactive material. At the same time, consistent with the time schedule of the United Nations Sub-Committee of Experts on the Transport of Dangerous Goods and the relevant international modal organisations, a regular review process of the IAEA Transport Regulations intended to issue a revised or amended edition, as necessary, every two years, was established. The last published version, the fourteenth revised edition of the 'Orange Book', includes the IAEA Transport Regulations, 2005 edition. However, the IAEA had decided not to publish a 2007 edition of the Transport Regulations, and as a consequence, did not recommend to the UN to implement the changes which had been adopted in the IAEA review cycle 2004–2005. In the last two years, further efforts have been made for better harmonisation between both documents. The harmonisation and assimilation with the UN Model Regulations concerning the transport of all nine classes of dangerous goods brings the class 7 'radioactive material' in line with the other classes for a worldwide implementation into the national and international modal regulations. The paper will discuss the benefits as well as some problems of this harmonisation process. The option to publish the 2009 edition of the IAEA Transport Regulations with the changes from the review revision cycle 2004–2005 and the harmonisation changes with the UN is considered to be important to keep the leading role of the IAEA in the further development of all aspects concerning the safe transport of radioactive material based on their competence in radiation protection.     

Remote radiation imaging system using a compact gamma-ray imager mounted on a multicopter drone

A remote radiation imaging system comprising a lightweight Compton camera and a multicopter drone was developed to remotely and quickly measure radioactive contamination inside the buildings of the Fukushima Daiichi Nuclear Power Station (FDNPS). The drone system is used for measuring detailed radiation distributions in narrow areas, which have been difficult to gauge with conventional aircraft monitoring using helicopters. A measurement of radiation distributions in outdoor environments in the coastal areas of Fukushima, Japan, was performed. The drone system with the Compton camera succeeded in remote observations of dense hotspots from the sky over a contaminated area near the FDNPS. The time required for image reconstruction is approximately 550 s in the case of a 9-m flight altitude for the hotspots with a surface dose rate of several tens of µSv/h. This drone system will be used inside the buildings of the FDNPS for remote measurement of radioactive contamination.