Decommissioning of the TVR Research Heavy-Water Reactor at the Institute of Theoretical and Experimental Physics

The key work on decommissioning of the TVR research heavy-water reactor at the Institute of Theoretical and Experimental Physics is described. The processes involved in the preparation for hauling away the spent nuclear fuel, mothballing the high-activity heavy water, salvaging the contaminated water in the holding pond, and removal of radioactive contaminants from the holding pond are described. Special attention is devoted to selecting a variant of decommissioning of the TVR and solving the problems associated with the implementation of decommissioning. The processes of dismantling the connecting pipes of the horizontal experimental channels inside the reactor vessel and preparing the fittings and equipment for performing this work are described.It is reported that work has been performed on the dismantling of the heavy- and light-water and gas loops of the reactor and on the dismantling of the experimental setups operating on the neutron beams of the horizontal and vertical channels of the reactor.     

大型石墨反应堆退役策略研究

大型石墨反应堆由于废石墨放射性活度大,处理处置工艺不成熟,拟采用延迟拆除策略,而长期安全封存就得有效控制放射性物质外溢、抵御地下水浸入、堆芯支承可靠、便于检测和监督等.     

Decommissioning and Disassembly of a Research Reactor at the Noril'sk Integrated Mining–Metallurgical Plant

A 100-kW RG-1M research reactor has operated at the Noril'sk integrated mining–metallurgical plant for about 30 yr. The reactor was used in an integrated activational analysis laboratory. This laboratory also included radiochemical and radiometric laboratories for analyzing irradiated samples. In 1998, a decision was made to decommission the laboratory and the reactor.The structures in the integrated laboratory were decommissioned according to plan. First, the spent nuclear fuel was removed for reprocessing. Next, the in-reactor equipment was disassembled and, being most highly radioactive, moved for storage to the plant Moscow Scientific-Industrial Association Radon. The low-activity equipment from the radiochemical laboratories was stored in the existing buildings located below the zero marker and rebuilt following the design into a stationary storage site for radioactive wastes.A network of observational wells was constructed to monitor the storage site and radiation monitoring of environmental objects was provided.It is shown in this paper that the stationary wastes-storage structure does not present any problems for the environment, since for 300 yr the construction of the storage facility will prevent radionuclides from escaping the site in amounts exceeding admissable values. After this period, the radioactivity of the wastes will decrease and will fall below the minimum significant value.     

北京城市放射性废物库退役中场地清污实践

介绍了北京城市放射性废物库退役工程中场地清污实践。通过采用网格布点、取样测量、分层清污等精细化作业,严格控制了清污工作量和废物的产生量,使库区场地中放射性残留量全部低于控制标准。     

Final Status of the Decommissioning of Research Reactors in Korea

A decommissioning project for the Korean Research Reactors KRR-1 and KRR-2 was started in 1997 and had been carried out with the goal of completion by the end of 2008. All the facilities were dismantled and the building surfaces decontaminated. The radioactive waste was packed into 200 liter drums and 4m³ containers and temporarily stored on site until their final disposal at the national repository facility. Some of the releasable waste was freely released and utilized for non-nuclear industries. The assessment of the residual radioactivity was carried out according to the Multi Agency Radiation Site Survey and Investigation Manual (MARSSIM), and accordingly, the safety of the site release was verified. The site and buildings will be cleared for reuse for non-nuclear purposes after a review of the assessment. In this paper, the final status of the decommissioning of research reactors in Korea including dismantlement processes, waste management, and a final assessment for unrestricted use of the site and buildings as the final goal of the decommissioning project will be described.     

Database for Decommissioning Power-Generating Units at the Leningrad Nuclear Power Plant

It is shown that the database plays a role and has a place in the decommissioning of a nuclear power plant. The technical requirements for the program structure and the functional possibilities of the database are formulated.     

核设施退役工程的综合一体化管理模式研究

随着进入退役期的核设施的增多,核设施退役工程管理的优化也越来越重要．本文提出了综合一体化管理模式的概念,并从核设施退役工程综合一体化管理模式构建的目标、范围、原则和核设施退役工程综合一体化管理模式的内容几个方面进行设计,最后从组织角度对该模式进行了设计和说明。     

国外核设施地下管道退役的经验教训

介绍了国外核设施地下管道退役中存在的问题、管道出路的决策过程、特性调查及调查方法、测量仪器的选择,以及管道的去污、就地处置或拆除等方面的经验与教训,以期对我国的退役实践有所帮助。     

核设施退役虚拟仿真系统框架研究

退役核设施具有放射性,其退役过程危险且复杂,基于虚拟现实等技术的退役虚拟仿真系统可为退役工程提供辅助工具。本文在分析国内外研究成果的基础上,结合一专项退役工程的需求提出了该虚拟仿真系统的功能模块组成。基于软件开发技术进一步给出了系统的框架结构,并对各模块实现的相应技术进行了分析和探讨。分析中结合了计算机软硬件技术的最新研究成果,对退役中的切割、爆破、流体及放射性等的仿真技术进行了探讨。分析表明,基于普通个人计算机也可实现退役过程的全面虚拟仿真。经专家论证本方案具有可行性。     

从几个例子看手套箱的退役

通过对手套箱退役的几个实例分析，论述了在手套箱退役中应关注的主要问题、技术手段、工程措施、安全考虑等，以期对我国的退役实践有所帮助。     

普贤堆退役放射性评价方法及主蒸汽管道室的中子能谱计算

介绍了日本普贤堆(Fugen)的概况和主要设计参数,以及该堆今后的技术发展趋势。根据该堆的退役现状,介绍日本的退役战略方针以及普贤堆采用的退役方法和今后的退役步骤,并采用MCNP程序对普贤核电厂主蒸汽管道内蒸汽^17N(β,n)反应产生的相对中子通量和中子能谱进行计算,据此分析了主蒸汽密度、主蒸汽管道半径对中子能谱计算结果的影响。结果表明．改变电厂运行瞬态不会影响主蒸汽管道室的中子注量分布,而增大主蒸汽管道尺寸则能够有效地降低管道保温材料所受的中子照射,这一结果对今后电厂核设施的辐照影响分析以及放射性评价具有一定的意义。     

氚靶制备玻璃系统的退役

介绍了某氚靶制备玻璃系统的退役流程及退役过程中氚的辐射防护,估算了退役过程中氚对公众和工作人员的照射剂量,两者的照射剂量均远低于国家标准。     

Transport of Large Items Arising from Decommissioning

Abstract

When decommissioning nuclear facilities, large items such as boilers or reactor pressure vessels may be reduced in size for transport to a disposal site or moved as a single, large item. The key technical and regulatory issues that need to be addressed in assessing whether to transport large items of decommissioning waste are (1) the type of package required, based on the activity and form of the radioactive material; (2) the extent of work required to enable the large decommissioning item to form a package, e.g. welding blanks over openings; (3) compliance with the regulatory requirements for the pelformance of the package under normal transport conditions and, for Type B packages, accident conditions; (4) potential use of special arrangement shipments, where it can be justified; (5) size capability of the receipt site; and (6) consideration of the most appropriate route, taking account of the size and weight of the package and the facilities at thedespatching and receipt sites. The paper discusses these various issues, and considers three case studies from the UK and USA.     

济南微堆退役场址的终态检测

采用γ谱测量和低本底β谱测量的方法对济南微堆退役场址中¹³⁷Cs、⁶⁰Co、⁶⁵Zn和⁹⁰Sr的放射性水平进行了终态检测。所有样品中均未检测出⁶⁵Zn;水池中⁶⁰Co的最高值在原堆芯正下方的池底,达49.3 Bq/kg,由中子活化而产生;其他检测单元中,¹³⁷Cs、⁶⁰Co和⁹⁰Sr的最高值分别为5.7、6.8和8.1 Bq/kg,分别出现在运输通道、堆厅和土壤中,这些核素可能为退役活动污染所致。检测结果表明：所有样品的放射性水平均低于基于年有效剂量为10 μSv所导出的清洁解控水平和可接受水平,其中大部分样品接近本底水平。检测方法对¹³⁷Cs、⁶⁰Co和⁶⁵Zn的探测下限分别为1.1、1.0和1.3 Bq/kg,检测结果的不确定度小于33.0%,标准物质GBW08304a的测量值与标准值的相对偏差小于3%。