几种过滤型鉴别式热释光个人剂量计性能探讨

鉴别式热释光个人剂量计在个人剂量监测中具有能量鉴别功能。对3种过滤型鉴别式热释光个人剂量计的能量响应、能量鉴别曲线、剂量响应等性能进行实验,结果显示选取实验的3种鉴别式热释光个人剂量计在上述性能方面有区别也有联系,均可在光子能量的鉴别上发挥一定的作用。     

热释光剂量计在环境监测中的应用：参加国际环境剂量计比对总结

本文介绍热释光在环境监测中应用的概况,国际环境剂量计比对的形成和比对方法,我们参加的第6、7、8三次比对的总结,以及关于比对中存在问题的讨论。     

国内35个单位外照射个人剂量计比对

本文介绍了由１７个省的３５个单位参加的国内外照射个人剂量第三次比对结果。参加比对的单位中核工业系统所属单位１７个，卫生和环保系统单位１８个。参加比对的均采用热释光剂量计，共４０２支剂量计。辐射源是由国防科工委二级站提供的按ＩＳＯ标准的宽，窄系列Ｘ射线，荧光Ｘ射线及＾１＾３＾７Ｃｓ源，辐射能量在１７．５－６６２ｋｅＶ范围内，选取８个能量点进行照射。统计的２７４组数据表明，实测值与参考值比值的平均值为     

1983年个人剂量计照射量比对结果

本文给出核工业部组织的、有厂、矿、院、所和高等院校等19个单位参加的第二次个人剂量计照射量比对结果。参加本次比对的有热释光剂量计(TLD)、辐射光致荧光玻璃剂量计(RPL-D)和胶片剂量计(Film-D)三种类型,共72组、222个剂量计。比对所选取的辐射是有效能量为47keV 的重过滤 X 射线和~(226)Ra 的γ射线。选取的参考照射量值,对于 TLD 是62—66mR;对于 RPL-D 和 Film-D 是110—160mR。由三种剂量计测得的306个数据表明,实测值(X_1)与参考照射量(X)比值的平均值为1.06±0.23,中位值为1.03,落在0.74—1.38范围内的约占总数的85%。     

热释光剂量计与电子剂量计比对中时间差异问题的浅析

对田湾核电站一、二号机组运行期间热释光剂量计和电子剂量计定期比对中存在差异的主要原因——剂量计更换的时间差异进行了研究。本文设计了一套技术方案,按照数据采集—数据入库—数据整理—数据输出的流程,从几种剂量数据管理软件中采集到了所需要的数据,补充了现有软件中缺少的记录热释光剂量计更换状态的数据表,编写了剂量计比对软件,通过查询获取到了两种剂量计实际监测周期内的剂量数据并进行偏差比对,最终较好地解决了比对中存在的时间差异问题。     

热释光个人中子剂量计的刻度及性能试验

本文叙述了用作个人剂量监则的镉帽型热释光子中子剂量计的中子能响特性和刻度方法。用标准Ａｍ－Ｂｅ中子辐射场测量了剂量计的响应因子，检验了反平方律。给出了相对刻度的总不确定度为７．６％。对油田中子测井和使用中子水份测量仪等测量仪器的单位，可用该剂量计作个人中子防护剂监测。     

比值法在热释光个人剂量计中的应用

目前广泛使用的个人剂量计不具有能量鉴别能力,在混合辐射环境、复杂辐射环境和未知能量的辐射环境中使用可能有较大的误差,为解决此问题,将比值法应用在了热释光个人剂量计。使用MCNP程序模拟计算能量响应、在标准辐射场进行实验验证并参加了全国比对。实验结果和比对结果表明,应用了比值法的剂量计能大幅度提高监测结果的质量。论文相关的剂量计设计合理、能够有效区分光子能量,在混合辐射场、复杂辐射场和未知能量辐射环境中的个人剂量监测工作中有很好的应用前景。     

直读式个人中子剂量计转换屏的设计

结合直读式个人中子剂量计的发展动态,在参考比较的基础上,提出了快中子剂量计和热中子剂量计转换屏设计方案。前者为一层聚乙烯膜,后者为~6LiF膜并罩以开孔的(靠体模一侧中心处)的Cd套。根据中子与转换屏相互作用的特点,利用蒙特卡罗方法(随机抽样)编制了不同转换屏中子剂量能量响应和角响应的计算程序。计算结果表明,对于快中子剂量计,影响因素主要是聚乙     

个人剂量计校准装置及其性能试验

本文介绍一种个人剂量计校准装置。剂量计放在圆盘上,圆盘可以绕源回转,以保证它们都受到相同的照射量。实验测定了圆盘不回转时各方位的差异,证明回转是必要的。另外还测量了相对散射系数和散射辐射的能量,提出了减小散射的措施。     

亚太地区放射性个人剂量监测国际比对与思索

报告了参加亚太地区放射性个人剂量监测国际比对的结果,并提出了一些看法。     

热释光剂量片γ射线响应的线性上限和重复性研究

本文利用 60 Co试验研究了国产LiF(Mg,Ti)-M热释光剂量片（TLD）对γ射线的线性响应上限及其重复性。结果表明,国产LiF(Mg,Ti)-M的线性响应上限在150～200 Gy之间,超过线性上限后灵敏度下降,退火后再次使用灵敏度增加。试验结果还表明,即使接受到的吸收剂量在非线性区域,1组剂量片的响应一致性仍可在后续多次使用中保持。据此,本文提出采用成批使用的方法测量非线性区域的吸收剂量,这可提高大吸收剂量测量的准确性。     

超低功耗单片机MSP430在FJ3000个人剂量仪中的应用

介绍了基于超低功耗单片机MSP430在FJ3000个人剂量仪中的设计,详细阐明了其设计原理和软硬件实现方法。充分利用了MSP430系列单片机的低电压、超低功耗特性,实现了剂量仪使用单节1.5V五号电池供电的长时间稳定工作。     

IAEA"放射性废物处置评价中所选择的安全指标的应用"协调研究项目第二次研究协调会简介

1　会议背景及目的IAEA于 2 0 0 0年 4月启动了“放射性废物处置评价中所选择的安全指标的应用”研究协调项目。项目由 IAEA辐射和废物安全处废物安全科发起并负责管理 ,参加成员包括阿根廷、巴西、中国、古巴、捷克、芬兰、日本、瑞典和英国共 9个国家 [1]。该项目的主要目的是达成在废物处置评价中用附加安全指标来对剂量、风险等主要指标予以补充的国际共识 ,从而使评价结果更直观和更易于被非专业技术人员所理解和接受 ,具体目的包括 :(1 )建立天然核素和化学毒物在不同介质中浓度的数据库 ;(2 )计算不同环境条件下通过某些界面的核…     

Performance of a Monte-Carlo solution for the H.B. Robinson-2 Pressure Vessel Dosimetry Benchmark

At the Paul Scherrer Institut, a methodology for PWR fast neutron fluence estimations, based on the Monte-Carlo particle transport code MCNPX with general-purpose neutron data libraries and using neutron source data from deterministic 3-D core-follow calculations, has been developed. The methodology has been validated on the basis of experimental data related to the fluence at the inner surface of a Swiss PWR Reactor Pressure Vessel. In this technical note, a first objective is to enlarge the validation basis of the methodology as well as to extend it for applications to RPV outer-surfaces. To that aim, a preliminary analysis with the MCNPX-2.4.0 code, along with the JEFF-3.1 continuous-energy neutron data library, of the “H.B. Robinson-2 Pressure Vessel Benchmark”, providing in-vessel and out-vessel experimental dosimetry data, is presented. In addition, considering that the available original solutions of the benchmark employed deterministic transport methods with associated libraries, a second objective of this technical note is to assess the progress achieved for this type of problems when applying modern Monte-Carlo based methods. The results show that for the ²³⁷Np and ²³⁸U fission dosimeters, which were of primary interest in the given study, a non-negligible improvement is seen in the MCNPX solution, indicating thus a rather good performance of the employed Monte-Carlo method and providing thereby, additional confidence for the overall PSI fluence methodology. For other high-energy dosimeters, the presented new results do not show yet any significant accuracy improvement versus previously reported results. This can however not be confirmed before additional studies, e.g., with focus on improvements of the involved modelling approximations and the statistical precision of the MCNPX calculations, be carried out. Similarly, investigations of neutron cross-section and dosimetry libraries effects remain to be addressed. These further studies are however not included here since at this stage, the principal aim was mainly to model and analyse this benchmark at most consistent manner with the previous solutions using a continuous-energy Monte-Carlo based method.     

Performance of the IAEA transport regulations in controlling doses and risks from a large-scale radioactive waste transport system

Abstract

The role of United Kingdom Nirex Ltd is to provide the UK with safe, environmentally sound and publicly acceptable options for the long-term management of radioactive materials generated by the UK's commercial, medical, research and defence activities. An important part of this role is to set standards and specifications for waste packaging. Waste producers in the UK are currently developing processes for packaging many different types of intermediate-level waste (ILW), and also those forms of low-level waste that will require similar management to ILW. When packaging processes are at the proposal stage, the waste producers consult Nirex about the suitability of the resulting packages for all future aspects of waste management. The response that Nirex provides is based on detailed assessments of the proposed packages, their compliance with Nirex standards and specifications, and their predicted performance through the successive phases of waste management. One of those phases is transport through the public domain. This paper draws on experience gained from more than 200 separate transport safety assessments which have cumulatively covered a wide range of waste types, waste packages and transport packages.     

The Effect of the Size of Radiotherapy Photon Beams on the Absorbed Dose to an Al2O3 Dosimeter

The effect of the size of radiotherapy photon beams on the absorbed dose to an Al2O3 dosimeter was investigated using the Monte Carlo method. The EGSnrc/DOSRZnrc program code was used to simulate the absorbed dose to the Al2O3 dosimeter, as well as the absorbed dose to water at the corresponding position in the absence of the dosimeter. The incident beams were 60Co γ and 6 MV with a different beam radius ranging from 0.1 cm to 2 cm. Results revealed that the absorbed dose ratio factor depends on the size of the incident photon beam. When the radius of the incident beam is smaller than that of the dosimeter, the absorbed dose ratio factor decreases as the incident beam size increases. The absorbed dose ratio factor reaches its minimum when the radius of the incident beam is almost the same as that of the dosimeter. When the radius of the incident beam is larger than that of the dosimeter, the absorbed dose ratio factor increases as the incident beam size increases. The maximum difference among these absorbed dose ratio factors can be up to 14% in 60Co γ beams and 23% in 6 MV beams. However, when the size of the incident beam is much larger than that of the dosimeter, the effect of the incident beam size on the absorbed dose ratio factor becomes quite small. The maximum discrepancy between the absorbed dose ratio factors and the average value is not more than 1%.     

Correlation Study of Energetic Ion Induced Optical Absorption and Thermoluminescence in Crystalline LiF and CaF2

The parallel effect of step-wise annealing on induced absorption and thermoluminescence in crystalline LiF and CaF2 irradiated with gamma rays and He+ ions is investigated. The thermoluminescence centers are found to correlate to the entire absorption spectrum rather than to isolated bands. The results also indicate a preferential production of centers of higher thermal stability by the energetic ions, and the possible existence of reservoirs of trapped species resistant to common annealing practices.     

Relations Between the Effective Dose and the Indications of an Individual Dosimeter in Anisotropic Photon Fields

The effective dose, the personal dose equivalent, and the indications of an individual dosimeter are calculated, using the ROBOT computer program (Monte Carlo method), for the conditions of irradiation of an anthropomorphic heterogeneous ICRP phantom with wide beams of 40 keV–11 MeV photons for all solid angles. In anisotropic photon fields, the dosimeter indications satisfactorily estimate the personal dose equivalent. The dependence of the ratio of the effective dose to the indications of an individual dosimeter on the irradiation conditions is analyzed. It is noted that the individual dosimeter indications are not conservative when the phantom is irradiated from the back half-space. It is shown that for wide photon beams the ratio of the effective dose to the dosimeter indications determined neglecting the scattering of radiation inside the working room is an upper limit of the indicated ratio calculated taking scattering into account.     

Thermoluminescence properties of nanocrystalline K2Ca2(SO4)3:Eu irradiated with gamma rays and proton beam

Thermoluminescence properties of nanocrystalline K₂Ca₂(SO₄)₃:Eu prepared by ball milling technique have been studied and the nanophosphor’s suitability as an effective gamma radiation and proton beam dosimeter material has been examined. It is found that the nanophosphor is suitable for dosimetry over a very wide range of doses ∼1 Gy to 1 kGy for gamma radiation. And for proton beam the same nanophosphor shows a more or less linear response for the dose range 0.1-100 Gy. A comparative study of this nanophosphor with its corresponding microcrystalline form (prepared by solid-state diffusion method) as well as the nanocrystalline form prepared by (the more conventional) co-precipitation technique has shown that the nanophosphor prepared by the ball milling technique is in almost all respects better than the other two forms reported earlier.