辐射防护规程中的豁免值问题

规程豁免值是辐射防护工作中十分重要的限值,和可忽略量一起已日益引起有关方面的注意和研究。本文简单介绍了有关豁免值的一些概念、制定原则和方法,及某些国际机构提出的建议值。还讨论了制定中的某些特殊问题。建议我国进一步加强这方面的讨论和研究。     

制定我国新辐射防护规定中值得研究的几个问题

本文描述了制定新辐射防护规定时值得研究的几个问题。１．明确规定人为活动引起的天然辐射照射的控制要求，包括地下矿山和矿物提取工业的职业照射，喷气飞机机组人员的职业照射，以及居室中氡的照射。２．明确和加强当前辐射防护工作需要解决问题的内容，包括流出物的控制，下水道中放射性物质的控制和监测。讨论了应用ＢＳＳ豁免标准时的某些问题。３．吸取国际辐射防护的新经验，其中特别是ＩＣＲＰ的推荐书和ＩＡＥＡ的标准和导     

软X射线能谱法测定电子温度Te的计算机数据处理…

本文阐述在某一核聚度装置上用ＳＣＯＲＰＩＯ－２０００计算机探测系统测量软Ｘ射线能谱，进而由能谱算出等离子体电子温度Ｔｅ．对１－４ｋｅＶ软Ｘ射能区的数据进行系统处理，所编制的程序大多用ＦＯＲＴＲＡＮ语言写成，只有一个子程序ＳＵＢＳＢ用编语言写成。程序运行方便，修改参数活，计算所得结果与预期值完全吻合，计算所得图表与预期图表完全一致。     

离子交换法测定双氧铀与巩县风化煤黄腐酸络合物的稳定常数

在离子强度为０．１ｍｏｌ／ｋｇ，ｐＨ值分别为４．０及７．２条件下，用离子交换平衡法测定了国内研究及使用较多的河南巩县风化煤黄腐酸与双氧铀的络合物的稳定常数。在稳定常数的求算中，对Ａｒｄａｋａｎｉ和Ｓｔｅｖｅｎｓｏｎ提出的方法作了修改。     

在处置反应堆及其它核设施产生的低放固体废物过程中豁免原则的应用

本文叙述了在处置反应堆及其它核设施产生的低水平放射性固体废物过程中实现豁免管理的方法。分别介绍了采用土埋和焚烧的方法或采用回收利用和复用的方法处置低水平放射性固体废物的豁免值问题，供审管部门在辐射源和实践的豁免管理的申请、审批和实施过程中参考。     

双消色散270°偏转磁铁的物理设计

介绍了１４ＭｅＶ医用电子驻波直线加速器上所需用的２７０°双消色散偏转系统的物理设计过程与设计结果。系统的光路设计用ＴＲＡＮＳＰＯＲＴ程序计算，并且应用传输理论推导了双消色散满足的条件，两者结果一致；磁场计算利用ＰＯＩＳＳＯＮ程序完成，验证了磁铁中心磁感强度、好场区范围的场分布满足设计要求。此外，还研究了磁铁尺寸误差及安装误差对束流的影响，为工程设计和系统安装提供了依据。     

豁免原则应用中某些有关问题的讨论

豁免原则及其应用，无论在国际还是国内，不少方面还存在一些不同的看法和做法；还在不断完善和发展之中。本文就有关问题的国内外动态作一介绍，并对实际应用中存在的若干重要问题进行了讨论。     

对ICRP,BSS和现行国标中有关职业照射的控制和管理规定的比较和分析

本文介绍了ＩＣＲＰ６０、新的ＢＳＳ和现行国标中有职业照射射控制和管理方面的规定，并在综合，比较，分析的基础上，对国标的修改提出一些意见和建议。     

SOS—CMOS电路的电离辐照响应特性

本文通过对ＳＯＳ－ＣＭＯＳ门电路４０８２进行不同偏置条件下的电离辐照实验，研究了电离辐照环境中引起ＳＯＳ－ＣＭＯＳ门电路失效的几种重要漏电机制，。探讨了ＳＯＳ－ＣＭＯＳ电离辐射损伤的最劣辐照偏置条件。     

^131I生产废液中^131I的净化方法研究

研究了碘选择性吸附剂－铜基铂（ＰＣＣ）的制备方法及其对碘的吸附条件，同时也研究＾１３１Ｉ生产废液过柱前的化学处理方法，在稀硫酸介质并有足量Ｎａ２ＳＯ３存在条件下，Ｉ＾－能够吸附在ＰＣＣ上，吸附容量达１．１２ｍｇ／ｃｍ＾３（ＰＣＣ粒度为７４～１４９μｍ）当流速为４０ｍｌ／ｃｍ＾２．ｍｉｎ时，其吸附效率大于９９％，为了满足ＰＣＣ对碘的吸附条件，需用浓氨水将废液ｐＨ值调至１～２。用２５％Ｎａ２ＳＯ３去除     

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.     

Transport of low-level NORM – a case for consistency and practicality

Abstract

In 1996 the International Atomic Energy Agency (IAEA) adopted a system for exemption of lowlevel radioactive material from transport regulations based on the principle that exemption values should be commensurate with the risk posed by the material as represented by the maximum potential radiation dose to individuals. For many naturally occurring radionuclides the derived dose-based, radionuclide-specific exemption concentrations were substantially lower than the previous radionuclide-independent definition of radioactive material (70 Bq g^–1) [1900 pCi g^–1] due to the stringent dose criterion applied. It was recognised that this would bring large quantities of previously unregulated naturally occurring radioactive material (NORM) handled in industry into the scope of the transport regulations. To minimise the economic impact of the dose-based values, a special provision was included to provide for a 10-fold increase in exemption values for radionuclides in natural material provided the material is not intended to be, and has not previously been, processed for recovery of its radionuclides (the wording regarding previous use was added in 2003). This '10 times' or '10×' provision for certain natural material reflects a second concept underlying IAEA guidance, namely, that a dose criterion may be relaxed within cautious bounds to achieve a balance between practical issues and radiological concerns. On the other hand, restriction of the provision on the basis of past or intended use of the material is inconsistent with the basic principle underlying the Transport Regulations in that there is no risk basis for assigning different exemption values to identical materials on the basis of their past or anticipated use. In fact, the same material can move in and out of the scope of regulatory control as its anticipated use changes. As a practical matter, safety guidelines for potentially hazardous material should be based on measurable properties of the material and not the whims of human intentions. To improve the practicality as well as the consistency of the Transport Regulations as applied to NORM, the 10× provision should be revised to apply to all natural materials, regardless of their intended use.     

关于物料解控和场址开放

本文阐述了受放射性核素污染的物料解控和场址开放的目的,比较了解控与豁免的异同点,介绍了作为物料解控水平和场址清除标准基础的剂量限制值和约束值,讨论了以可测量值表述的物料解控水平(包括物料表面污染水平和活度浓度)和场址清除标准(包括土壤中核素残存量可接受水平和地表氡析出率限制值),强调了照射情景、模式及参数对推荐的导出水平的影响及注意以特定条件来修正导出水平的必要性。     

Scope of radiological protection control measures

In this report, the Commission recommends approaches to national authorities for their definition of the scope of radiological protection control measures through regulations, by using its principles of justification and optimisation. The report provides advice for deciding the radiation exposure situations that should be covered by the relevant regulations because their regulatory control can be justified, and, conversely, those that may be considered for exclusion from the regulations because their regulatory control is deemed to be unamenable and unjustified. It also provides advice on the situations resulting from regulated circumstances but which may be considered by regulators for exemption from complying with specific requirements because the application of these requirements is unwarranted and exemption is the optimum option. Thus, the report describes exclusion criteria for defining the scope of radiological protection regulations, exemption criteria for planned exposure situations, and the application of these concepts in emergency exposure situations and in existing exposure situations. The report also addresses specific exposure situations such as exposure to low-energy or low-intensity adventitious radiation, cosmic radiation, naturally occurring radioactive materials, radon, commodities, and low-level radioactive waste. The quantitative criteria in the report are intended only as generic suggestions to regulators for defining the regulatory scope, in the understanding that the definitive boundaries for establishing the situations that can be or need to be regulated will depend on national approaches.     

辐射防护新概念对放射性废物管理的启发意义

本文通过对源项、途径、剂量、效应的讨论，进一步明确放射性废物管理的地位和作用；通过对实践、干预、豁免和潜在照射的讨论，增强在放射性废物管理中正确使用辐射防护原则的认识；通过对市管体系、现场防护体系、事故应急体系的讨论，促进国际放射防护委员会的建议在放射性废物管理中的实施。     

Evaluation of the specific radioactivity of 40 elements created by nuclear transmutation of fission products

A burnup calculation was performed to analyze Après ORIENT process which aims at creating highly-valuable elements by nuclear transmutation of fission products (FPs) separated from LWR spent nuclear fuels. In this paper, numerical evaluation of the specific radioactivity of 40 created elements, from reloaded each FP element, with atomic number from 31 to 70 at the end of the time of 5-year-cooling after the irradiation for 1125 days in each LWR and FBR was carried out. These 40 created elements were classified in 6 categories according to levels of the specific radioactivity and the length of additional cooling period, which was needed for the specific radioactivity to decrease below the exemption level defined by International Atomic Energy Agency. As a result, created ₃₁Ga, ₃₂Ge, ₃₃As, ₃₅Br, ₆₈Er, and ₇₀Yb did not contain any radioisotopes at the end of the 5-year-cooling. It should be noted that created ₃₇Rb, ₅₇La, and ₆₀Nd had much lower specific radioactivities than natural composition of them. Moreover, specific radioactivities of created ₄₀Zr, ₄₂Mo, ₄₄Ru, ₄₆Pd, ₄₉In, and ₅₄Xe were sufficiently lower than their exemption levels at the end of the 5-year-cooling. On the other hand, created ₃₉Y, ₄₅Rh, ₅₀Sn, ₅₂Te, ₅₈Ce, ₅₉Pr, ₆₅Tb, and ₆₆Dy needed additional cooling period less than 10 years until their specific radioactivities decreased below their exemption levels. Then, each additional cooling period required for created ₄₈Cd, ₅₁Sb, ₆₄Gd, and ₆₉Tm was estimated at 10–100 years. Additionally, specific radioactivities of other 13 created elements would not decrease below their exemption levels even if they had been stored for 100 years. There could be significance to create important elements as resources classified in first 4 of the 6 categories defined in this paper, by nuclear transmutation of fission products. In consideration of the efficiency of creation, the radioactivity, and the importance as resources of each product, ₄₄Ru, ₄₆Pd, ₅₂Te, ₆₀Nd, and ₆₆Dy were specially selected as the most important created elements to be more researched in the future Après ORIENT program.     

轻微放射性污染金属再循环再利用中的剂量评价

根据GB18871—2002所规定的豁免剂量准则和国际原子能机构所推荐的相关方法,对钢铁、铝、镍和铜4种轻微放射性污染金属的再循环再利用中的剂量评价方法作了介绍。所得计算结果合理可信,已作为修订相关国家标准的基础。保护环境和实现再循环经济是我国科学发展的基本国策,标准颁布后可发挥很好的社会效益和经济效益。     

Analysis of the criteria used by the International Commission on Radiological Protection to justify the setting of numerical protection level values

This report compiles the various numerical protection level values published by the International Commission on Radiological Protection (ICRP) since its 1990 Recommendations (Publication 60). Several terms are used to denominate the protection levels: individual dose limit, 'maximum' individual dose, dose constraint, exemption level, exclusion level, action level, or intervention level. The reasons provided by the Commission for selecting the associated numerical values is quoted as far as available. In some cases the rationale is not totally explicit in the original ICRP report concerned; in such cases the Task Group that prepared the present report have proposed their own interpretation. Originally, this report was prepared by a Task Group at CEPN, a French research and development center, in behalf of IRSN, a French public expert body engaged in radiological protection and nuclear safety. It is published here with kind permission by CEPN and IRSN.     

Protection of the public in situations of prolonged radiation exposure. The application of the Commission's system of radiological protection to controllable radiation exposure due to natural sources and long-lived radioactive residues

This report provides guidance on the application of the ICRP system of radiological protection to prolonged exposure situations affecting members of the public. It addresses the general application of the Commission's system to the control of prolonged exposures resulting from practices and to the undertaking of interventions in prolonged exposure situations. Additionally, it provides recommendations on generic reference levels for such interventions. The report also considers some specific situations and discusses a number of issues that have been of concern, namely: natural radiation sources that may give rise to high doses; the restoration and rehabilitation of sites where human activities involving radioactive substances have been carried out; the return to 'normality' following an accident that has released radioactive substances to the environment; and the global marketing of commodities for public consumption that contain radioactive substances. Annexes provide some examples of prolonged exposure situations and discuss the radiological protection quantities, radiation-induced health effects and aspects of the Commission's system of radiological protection relevant to prolonged exposure. Quantitative recommendations for prolonged exposures are provided in the report. They must be interpreted with extreme caution; Chapters 4 and 5 stress the upper bound nature of the following values: Generic reference levels for intervention, in terms of existing total annual doses, are given as < approximately 100 mSv, above which intervention is almost always justifiable (situations for which the annual dose threshold for deterministic effects in relevant organs is exceeded will almost always require intervention), and < approximately 10 mSv, below which intervention is not likely to be justifiable (and above which it may be necessary). Intervention exemption levels for commodities, especially building materials, are expressed as an additional annual dose of approximately 1 mSv. The dose limit for exposures of the public from practices is expressed as aggregated (prolonged and transitory) additional annual doses from all relevant practices of 1 mSv. Dose constraints for sources within practices are expressed as an additional annual dose lower than 1 mSv (e.g. of approximately 0.3 mSv), which could be approximately 0.1 mSv for the prolonged exposure component. An exemption level for practices is expressed as an additional annual dose of approximately 0.01 mSv.