Immobilization of Radionuclides in Irradiated Reactor-Graphite Blocks

The immobilization of radionuclides in samples of GR-280 reactor graphite by the fixative atomik is described. A graphite block extracted from RBMK masonry after 17 years of operation is used for the investigations.The investigations showed that the strength of the fixative samples increases only with irradiation doses above 15000 Mrad. The radiation–chemical yield of gaseous products of radiolysis from samples of the fixative under irradiation in vacuum is 12·10^–10 cm³/(g·rad). , , and -emitting nuclides are leached from the samples of irradiated graphite; this process proceeds continually. When the irradiated graphite samples are permeated with the fixative atomik, no release of radionuclides is observed at 20°C for 2 yr.     

Methods in Environmental Sampling for Radionuclides

This paper reviews methods of environmental sampling for radionuclides around operational and preoperational nuclear power plants. We examine in detail the implications of the established radiation standards and their effect on sampling procedures. Transport mechanisms of radionuclides in liquid effluent, and the deposition of airborne radionuclides onto soil and vegetation are discussed. We evaluate water- and soil-sampling procedures. The Lawrence Livermore Laboratory program of terrestrial gamma-ray surveys at preoperational nuclear power plants is described.     

生活用品中放射性核素的探测

讨论了实验室检测中经常遇到的怎样给出生活用品中不含放射性的结论的难题,介绍了检测工作的科学性、严谨性,放射性核素衰变的种类及特性,放射性的通用物理探测方法,推荐了一套使用通用物理探测仪器逐步排除样品的放射性污染,以及如何给出生活用品中没有放射性的结论。     

In Situ Methods for Quantifying Specific Radionuclides

Field spectrometry methods utilizing high resolution detectors can be used to quantify the concentration of radionuclides in soil, and the resulting external exposure rate. Advantages of the method compared to soil sampling followed by laboratory analysis are greater speed of analysis, integration of inhomogeneities of radionuclide areal distribution, and the immediate availability of data to guide further field studies. A disadvantage is that the calculation of results depends upon some knowledge or assumption about the distribution of radionuclides with depth in soil. The procedures necessary to calibrate and use a field spectrometer are discussed, and a practical guide is developed. Examples of uses of field spectrometry are the quantitation of complex mixtures of radionuclides in soil, the calculation of the resulting external gamma exposure rate apportioned by radionuclide, geochemical studies, preoperational and continuing studies at nuclear reactor sites, and the identification of short-lived, noble gas radionuclides in reactor plumes.     

Type A Packages for Medical Radionuclides and Samples

Abstract

There is a particular need by hospitals and research organisations (e.g. universities) for simple and inexpensive packaging for the transport of Type A quantities (<A₂) of radioactive materials in solid or liquid form. In many cases, these organisations receive radioactive materials from commercial vendors in single-use packagings that are not suitable (and not certified) for use for further shipment. This leaves the hospital or research organisation with the problem of how to ship these materials to laboratories that they support, within packaging compliant with regulatory requirements. A further burden is that the design, testing and procurement of the required transport packaging has to be effected under an ISO 9000 QA programme. Although commercial vendors of radioactive materials find it convenient to use single-use (disposable) packagings, hospitals and research organisations usually find it preferable to use re-usable packagings: this avoids having to dispose of used packaging and enables robust, re-usable packaging to be used economically. Some of the problems encountered in developing simple and inexpensive re-usable Type A packaging are addressed and details are given of a range of packagings developed by Croft specifically to meet these requirements.     

放射性核素长距离迁移模拟研究进展

放射性核素在大气中的长距离迁移扩散问题,在核事故应急响应、突发事件应急响应、裂变材料生产、核厂址风险评价、源项反演等领域都倍受关注。本文概述了近二十年来长距离迁移模式的发展及特点,总结了模式有效性研究的方法,并对目前放射性核素长距离迁移模式的应用及今后的发展方向进行了综述。     

放射性核素标记溶瘤腺病毒治疗肿瘤的可行性

目前,溶瘤腺病毒治疗肿瘤的研究发展非常迅速,虽然有些溶瘤腺病毒进入临床试验阶段,并取得一定疗效,但其有效性和安全性仍是临床医生所担心的问题。本工作就此对溶瘤腺病毒的研究现状及如何更有效提高溶瘤腺病毒的杀伤作用进行分析,提出了用放射性核素标记溶瘤腺病毒,以期达到溶瘤治疗和核素治疗相结合,双重杀伤肿瘤细胞的目的。     

Analytical Models for Migration of Radionuclides in Geologic Sorbing Media

In safety evaluation of nuclear waste repository systems, the analysis on migration of radionuclides in geologic media is important. In previous analytical models called Band- Release, Step-Release and Impulse-Release for decay chains, nuclide-specific release rate and time-dependence of release rate can not be taken into consideration. In this paper, two new release models are proposed. In Preferential-Release model, both of nuclide-specific release rate and time-dependence of leach are taken into account. Exponential-Release model is a special case of Preferential-Release model, in which no preferentiality in leach is assumed. The obtained analytical solutions for these new models are applicable even to four or more member decay chains and are as simple as those for the previous models.

As an example of the application of the new models, the discharge rates of the four nuclides in the decay chain of ²³⁸Pu→²³⁴U→ ²³⁰Th→²³⁶Ra→ into a surface water body are calculated as a function of time after the start of leach and path length from the repository. By using the result, heavy hazard due to ²³⁸Pu at short distance and ²²⁶Ra at long distance are also discussed briefly.     

放射性核素在花岗岩上的吸附行为

综述了放射性核素在花岗岩上吸附作用的研究现状和进展。相关研究表明:(1)花岗岩的物化性质(包括形貌、化学组成及表面酸碱特性)对放射性核素的吸附有一定的影响;(2)放射性核素在花岗岩表面的吸附速率普遍较快,吸附可在较短时间内完成;(3)各种环境因素如pH值、离子强度、温度、地下水中的主要离子、天然有机质、低氧条件等对放射性核素在花岗岩表面吸附的影响因吸附质离子不同而变化各异;(4)建立在基本吸附数据基础上的表面配位模型可以用于间接探讨相应的吸附机理,拓展了研究核素迁移的思路;(5)采用先进光谱表征技术如XPS可对放射性核素在花岗岩上的吸附机理进行分子或原子水平上的论证。     

富烧绿石人造岩石固化模拟锕系废物

采用国际上较少研究的烧绿石为主要矿相,针对分离的锕系核素进行人造岩石固化研究。设计并制备了对模拟锕系元素包容量为46.8％的富烧绿石人造岩石固化体。对其物理性能、抗浸出性能、耐辐照性能和微观结构进行的研究结果表明富烧绿石人造岩石固化体具有很好的性能。     

放射性核素毒性分组的比较

根据最新资料,在按放射性核素在肺部吸收速度和物态分类对１４３５个核素所做的毒性分组的基础上,根据我国《电离辐射防护和辐射源安全基本标准》编制组的要求,经合并处理,得到了８５１个放射性核素毒性分组清单。本文将此清单与拟被取代的ＧＢ４７９２和ＧＨＢ８７０３两标准的相应内容做了比较,总体上仍是相近的,部分差异来源于剂量限值和剂量转换系数的变化。     

Dynamic Studies of Central Circulation Using Radionuclides

With the development of the scintillation camera, it is now possible to record sequential radionuclide images from the precordium after injection of a high specific activity bolus of a radioactive intravascular indicator. From these images, the passage of the bolus can be visualized as it transits each of the cardiac chambers, the great vessels, and the lungs revealing both anatomic and functional characteristics of these elements of the central circulation. This qualitative technique can be used to diagnose a large number of congenital and acquired diseases of the heart and great vessels in a manner similar to contrast angiography. When a small computer is interfaced to a scintillation camera, time-activity curves can readily be generated from subregions of interest within the field of view of the detector. Quantitative analysis of these curves gives important and clinically useful functional information relative to the heart and circulation including cardiac output, stroke volume, left ventricular ejection fraction, left ventricular end-diastolic volume, and pulmonary blood volume. In addition, the size of intracardiac shunts can be quantified and certain wall-motion abnormalities can be detected and evaluated.     

Development of Vehicle Security Portal for Special Nuclear Material and Other Radionuclides

After indoor debugging the vehicle portal special nuclear material monitor was mounted at the outdoor scene in 2005. The tests of detection sensitivity of the monitor for high enrichment uranium（HEU） and low-burnup plutonium with different type of vehicles have been performed. The tests of statistical false alarm rate and stability of the monitor have been performed too.     

基于GB 18871—2002的放射性核素肺吸收类别的选用

当核与辐射突发事件发生时,对相关人员进行内照射剂量快速估算,便于做出及时的处理和干预。本文主要针对使用肺吸收类别时可能会遇到的一些问题及GB 18871—2002附表中缺失核素的剂量转换系数的取值,结合福岛核电站事故污染情况进行简单的介绍,提出相关使用建议:(1)针对附表B3工作人员的肺吸收类别的选用可参考附表B5,后者给出了89种元素的不同化学形态的肺吸收类别。对于附表B3中氢、碳、硫的数据缺失可以选用ICRP第68号出版物中的具体数值。(2)针对附表B7公众人员的肺吸收类别的选用,可参考附表B8列出的ICRP出版物,后者还列出了肺吸收类别情况已知的31种元素及其参考缺省值。(3)对于公众吸入的其余60种元素,ICRP第71号出版物建议在具体资料未知的情况下使用M类别的系数进行计算,这样既不过分高估也不过分低估待积有效剂量。     

Possibilities for Producing Radionuclides in Nuclear Power Plants with RBMK Reactors

It is shown that radiation doping of silicon and the production of medical and industrial radioisotopes in the reactors at the Leningrad nuclear power plant are possible and safe. The production of cobalt with specific activity ~100 Ci/g in an RBMK-1000 reactor is studied. Some promising developments for improving the quality of the radioisotopes produced are described. It is shown that the production volumes can be increased by linking up other nuclear power plants with RBMK reactors into the production chain.     

α放射核素靶向治疗研究进展

α放射核素在内照射时具有极强的细胞毒性,对肿瘤细胞具有较强的杀灭作用,而其短射程对正常组织影响较小,因此α放射核素类药物是放射性药物研究的重要领域和研究热点之一。α放射核素类药物的生产和研究关键在于核素的选择、高纯度核素的稳定可靠供应、核素载体及合适的体内动力学。目前国内外研究比较活跃的α放射核素主要包括223 Ra、225 Ac、213 Bi、211 At、212 Bi、149 Tb和227 Th等。本文主要介绍了以上核素的来源制备及用于肿瘤靶向治疗的最新进展,对存在的问题、现状及临床应用前景进行了简要的探讨。     

核爆放射性核素的分凝研究

为了研究核爆粒子中放射性核素分凝的影响因素和规律,基于Freiling的半经验分凝模型和放射性衰变链的Bateman公式构建核爆粒子放射性活度分布的计算模型.计算了给定载体物质和粒子尺度分布条件下的粒子放射性活度分布,结果表明挥发性核索呈面分布特征,难熔性核素星体分布特征.分析了粒子尺度、凝固温度和凝固时间对放射性活度分布的影响程度,结果表明粒子尺度分布和凝固温度的影响较大,粒子的放射性活度分布与爆炸当量、比高以及爆炸地点的地理条件密切相关.     

CEPR核电机组停堆过程中主要放射性核素控制指标估算

介绍了CEPR核电机组停堆过程主要放射性核素控制指标的估算方法,给出了各控制指标的建议值。