事故中的辐射标准与监督

在苏联,照射及辐射状况的参数的标准化是根据辐射防护标准(SRP-76/87)来实现的。按照对人的照射,为受照的个人建立了三个类别:A类(职工),B类(公众中的一个有限的部分)、C类(一个地区、区、共和国与全国的公众)。对A类、B类规定了二级标准、基本剂量限值与容许水平。对于B类没有制定标准,而对照射的限制是通过管理或控制环境物体或技术过程(technological Processer)的放射性、医疗照射剂量及技术发展增加的辐射本底而进行的。     

辐射化学在辐射生物学发展和研究中的作用

辐射化学是连接辐射物理与辐射生物学的时空桥梁,其理论、模型和实验方法对促进辐射生物学的研究和发展起到不可缺少的重要作用。辐射诱导的化学变化不仅是辐射生物学效应的早期事件,在辐射诱导的DNA损伤与修复、生物辐射敏感修饰剂、辐射诱导的活性氧分子代谢和功能等研究领域都扮演重要角色。随着辐射生物学效应研究朝着系统辐射生物学方向发展,辐射生物学效应发生机理的精确研究和定量描述更需要辐射化学的方法和手段支持。     

低空环境辐射水平快速测试

环境辐射水平是环境监测的主要部分，近期采用新型快速辐射监测系统通过航空的手段对低空环境辐射水平进行了快速测试。简述了这一测试情况，给出了测试结果并进行了讨论。     

光子和电子辐射外照射剂量当量的测定

光子和电子辐射外照射剂量当量的测定１引言多年以来，剂量当量就是辐射防护中的基本量。然而，在什么条件下来测定剂量当量却一直意见不一。１９７７年国际放射防护委员会（ＩＣＲＰ，１９７７）建议，对随机性效应的剂量限值应基于有效剂量当量ＨＥ来制定。国际辐射单位...     

核电厂放射性烟羽在环境空气中产生γ辐射的监测方法

核电厂放射性烟羽在环境空气中产生γ辐射的监测方法丁民德（电力工业部苏州热工研究所，２１５００４）盛沛茹支仲骥（浙江省环境放射性监测站，杭州，３１００１２）１引言为了把核电厂对厂址边界以外周围地区的γ辐射量保持在“合理地可实现的最低”水平，国外一些管理...     

低剂量辐射风险

低剂量辐射风险①Ｄ．Ｂｅｎｉｎｓｏｎ１引言近年来，对风险及风险源的研究日渐广泛与深入。风险的内涵无非是损失的概念与其几率的组合。注意，几率的概念是必不可少的，尽管不可避免的危害是人们所不希望的，但缺乏几率就不能称其为风险。即使没有仔细研究“损失”的细...     

无水乙二胺的γ辐射稳定性研究

以气相色谱（GC）、气相色谱-质谱（GC-MS）、质谱（MS）和傅立叶变换红外光谱（FTIR）等手段研究了室温下空气和氮气条件下无水乙二胺的γ射线辐射效应。分析发现,无水乙二胺在γ射线作用下不仅生成了H2、CH4、NH3、CH2CH2等气体产物和一些液态挥发性产物,而且在液态剩余试样中还生成了多种聚合的胺类产物。相同条件下,气体产物H2和CH4的量均随剂量的增大而增加。两种气氛中辐射降解和聚合产物的量均很显著,其中在氮气气氛中尤为明显,显示无水乙二胺的γ辐射稳定性较差。无水乙二胺的辐射聚合效应尚未见相关文献报道。     

聚碳酸酯材料的辐射老化

应用拉伸强度测试(Tensile strength testing,TST)、扫描电镜(Scanning electronic micrograph,SEM)断口形貌分析、差示扫描量热分析(Differential scanning calorimetry,DSC)、富立叶变换红外光谱(Fourier transform infrared absorbption spectroscopy,FTIAS)、凝胶渗透色谱(Gel permeation chromatography,GPC)、X射线光电子能谱(X-Ray photoelectron spectroscopy,X-RPS)等多种手段研究了聚碳酸酯材料在γ射线辐照下的老化行为.结果表明,聚碳酸酯材料的力学性能、玻璃化温度、分子量和数均聚合度均随吸收剂量的增加而下降;其断口表面的光滑程度随吸收剂量的增加而增大;只观察到结构上微小的变化;动力学分析表明其辐射降解属于无规降解类型.间接证明了聚碳酸酯在0-12MGy剂量范围内辐射降解机理占优势.     

A CaS:Ce,Sm-based dosimeter for online dosimetry measurement

A film dosimeter based on optically stimulated luminescence (OSL) material of CaS:Ce,Sm was developed for online irradiation dosimetry measurement.The stimulation is provided by a laser with a wavelength of 980 nm,and the OSL luminescenceis collected by a photodiode.Using 60Co γ-rays,we investigated the dosimetry characteristic of the dosimeter at different dose rates and total doses.The real-time detection results showed that the OSL signals versus total ionizing dose exhibited a good linearity in a dose range of 0.1-185 Gy.     

A track structure model of optically stimulated luminescence from Al2O3:C irradiated with 10-60 MeV protons

We investigated the optically stimulated luminescence (OSL) signal from Al₂O₃:C irradiated with 10-60 MeV protons to estimate the potential use of this material as a proton dosimeter. After irradiation, OSL decay curves were read out and we used both the initial part and the total area of these curves as response signal. A precondition for optimal proton dosimetry is an LET-independent response and the experimental data showed such an independence at 0.3 Gy for the initial OSL signal.To understand the experimental results, we applied target and track structure theory. Here, the OSL signal is considered to be a result of target activation and the OSL proton signal is calculated from the OSL gamma signal and a radial dose distribution around the proton track. Although several simplifications were made to ease calculations, the classic track structure theory can qualitatively account for all the main features of the experimental data. We estimate a target radius to be between 30 and 150 nm and associate this radius with a charge migration distance in the crystal.The model calculations suggest that the dose and LET-dependency of the OSL signal is a result of an unique mixture of one- and two-hit targets. This implies that the initial OSL signal from Al₂O₃:C in general is not LET-independent at 0.3 Gy or lower doses. However, a mixture of the initial and total OSL signal could provide an LET-independent response in a given LET and dose interval.     

光致荧光剂量计的研究

介绍了光致荧光剂量计的原理和组成,并进行了辐射剂量测量,探讨了应用中存在的一些实际问题。     

AlON:C透明陶瓷的光释光性能

以高纯a-Al_2O_3粉与AlN粉为原料,采用无压烧结,通过气氛渗透,在烧制过程中掺入等量碳的方法制备AlON:C透明陶瓷,研究AlON:C透明陶瓷的光释光性能。结果发现:AlON:C透明陶瓷光释光衰变曲线都随着时间呈指数变化衰减,前期衰减快,后期衰减速率变慢;470 nm蓝光不能清空光释光信号,光释光有信号堆积现象。β射线辐照下,AlON:C陶瓷的光释光剂量响应曲线呈线性、亚线性,并有趋向饱和的特点;AlON:C透明陶瓷对b射线的光释光响应曲线在50 m Gy~50 Gy与50~100 Gy吸收剂量范围内呈非常良好的线性关系;在50~500 m Gy吸收剂量范围内,β与γ射线光释光响应线性良好,γ射线辐照下的光释光强度约为β射线辐照下的光释光强度的76%。     

光致荧光及其在电离辐射剂量测量中的应用

近年来,用于电离辐射个人剂量监测的光致荧光技术日趋成熟,目前已经开发出了商用光致荧光剂量计。本文主要文献资料简要介绍了光致荧光的基本原理,目前用于光致发光剂量计的常用材料以及剂量计测量设备,同时简要介绍光致荧光剂量计相对于热释光剂量计的优点,光致荧光的应用前景。．     

Investigation of OSL signals from very deep traps in unfired and fired quartz samples

This paper presents an attempt to isolate experimentally optically stimulated luminescence (OSL) signals which may originate from very deep traps (VDT) in quartz samples. As VDT we consider those traps which are responsible for TL glow peaks with a peak maximum temperature above a TL readout temperature of 500 °C. The basic experimental procedure used to isolate OSL signals from VDT is heating the quartz samples to 500 °C immediately before measuring the OSL signal. The study was carried out on eight quartz samples of very different origins; it is found that all eight samples exhibit OSL signals from VDT, and for a wide region of OSL stimulation temperatures. The OSL signal from VDT depends strongly on the type of quartz sample studied and on whether the sample was fired at high temperatures or not. The behavior of the OSL signal from VDT as a function of the stimulation temperature is found to be very different in fired and unfired samples. The thermal activation energy E for the OSL signals from VDT is obtained in both fired and unfired samples. The OSL signal from VDT in quartz samples fired at 800 °C for 1 h is very high, and the OSL curves consist of three well-defined components and a fourth slow component which is rather poorly resolved. The dose response of these components is obtained using a computerized deconvolution procedure for the dose region 0.5-300 Gy. The results are of importance for dating of ancient fired ceramics, since OSL signals from VDT could potentially extend appreciably the equivalent dose region toward both lower and higher values.     

CaS:Ce，Sm材料光致荧光辐射剂量相关性能测量

本工作对光致荧光材料CaS:Ce,Sm的辐射剂量特性进行研究。利用⁶⁰Coγ源对CaS:Ce,Sm/PMMA剂量片进行辐照，应用自行搭建的测试系统对剂量片发出的荧光信号进行测试。测试结果表明，CaS:Ce,Sm材料是短余辉材料，环境温度对材料性能影响显著，在0.1~100Gy内，荧光信号峰值强度与辐照剂量线性关系良好。     

Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al2O3:C

This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al₂O₃:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with ⁶Li (⁶LiF), lithium carbonate 95% enriched with ⁶Li (⁶Li₂CO₃), boric acid enriched with 99% of ¹⁰B and gadolinium oxide (Gd₂O₃). The proportion of Al₂O₃:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare ²⁵²Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters (⁶LiF:Mg,Ti and ⁷LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al₂O₃:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the ⁶⁰Co equivalent gamma dose and the reference neutron absorbed dose) and neutron–gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al₂O₃:C.     

Green stimulated luminescence of ZrO2 + PTFE to UV radiation dosimetry

The use of optically stimulated luminescence (OSL) as a method for the determination of environmental radiation absorbed dose using solid state materials has become the main interest of the most great research centers. The aim of this work is to study some dosimetric characteristics of ZrO₂ to be used as a UVR dosemeter by using the OSL method. The most attractive characteristic of ZrO₂ is its very high intrinsic sensitivity to UV radiation. Optical characteristics of ZrO₂ were also studied. OSL typical decay was obtained. OSL response of ZrO₂ samples as a function of irradiation time was linear in the range of 30–1000 s. Experimental results showed that ZrO₂ exhibit attractive characteristics which make it suitable for UV dosimetry applications.     

Optically stimulated luminescence: Searching for new dosimetric materials

Optically stimulated luminescence (OSL) is increasingly being used as a dosimetric technique in various fields such as medical, environmental and space dosimetry, and sediment and archaeological dating. Nevertheless few compounds are suitable as OSL materials. In this work, a survey was made of various insulators, searching for candidates for new OSL dosimeters. Natural and synthetic crystals and glasses from numerous sources are included. Luminescence was stimulated with blue LEDs (470 nm) and with IR laser (830 nm) provided by an automatic reader. Irradiation was performed with a ⁹⁰Sr/⁹⁰Y beta source, and the emitted light was measured with a photomultiplier tube, protected with suitable optical filters. Thermoluminescence (TL) of the samples was also measured, with the same equipment, to evaluate the thermal and optical stability of the defects related to OSL and TL. Among the various investigated materials, Al₂O₃:Cr, Mg, Fe, MgAl₂O₄ spinels, Mg₂SiO₄:Tb, and natural fluorite show potential as OSL dosimeters. Some materials, as barium aluminoborate glasses, although showing intense OSL signals, present a high fading at room temperature. In that situation the OSL signal is related to low temperature TL peaks that also fade at room temperature. None of the investigated materials was specially prepared to be used as an OSL dosimeter, which means that work can be done, mainly in the impurity nature and content, in order to improve OSL signals and to overcome some of the shortcomings that were noticed.