放射性物质运输事故分析及后果评价方法

主要介绍国内外近年来在放射性物质运输事故后果评价方法方面的研究成果，描述了铁路运输和公路运输的事故景象、放射性物质运输事故的严重程度和类别，列出了运输事故情况下不同照射途径的剂量计算方法，并介绍了事故可能引起的健康效应和经济影响。     

乏燃料运输事故中放射性物质的释放机制及途径

符合国际原子能机构《放射性物质安全运输规定》要求的乏燃料运输容器,具有相当高的抗事故能力。但在运输过程中,仍有可能出现超过容器设计基准的冲撞(撞车、撞击山体或其它构筑物)、翻车、火灾等事故,导致乏燃料组件及其运输容器受损,向环境释放出放射性物质;或者导致运输容器屏蔽能力减弱乃至丧失,使意外接近容器的人员或公众受到较高水平的外照射。     

放射性物质运输风险概览

根据国外的事故统计资料,介绍了各种交通工具的概率以及放射性物质运输事故的情景和辐射后果。可以认为,放射性装运事故的概率较低,事故中放射性物质从货包中泄漏的概率更小。     

放射性物质运输与环境安全

本文用实际事例说明:只要包装的设计和试验符合《放射性物质安全运输规程》的要求,则放射性物质运输事故不会对工作人员、公众和环境产生显著的影响。     

新燃料元件运输容器热工安全分析及试验验证

新燃料元件运输容器是为运输493反应堆燃料元件设计的专用设备。为保证燃料元件在运输过程中的安全性,使运输容器及燃料元件的各项性能指标符合标准GB 11806-2004的要求,对运输容器进行了热工设计计算和验证试验。通过计算与相应热工试验结果的比较,验证了运输容器热工设计的准确性。采用该运输容器运输新燃料元件,在正常运输工况和事故运输工况下可保证燃料元件的安全,完全满足GB 11806-2004的规定。     

基于长短期记忆网络的涉核运输事故后果预测

涉核部件在运输过程中，会因不可抗力因素发生化学爆炸事故，造成放射性核素的泄漏。在此类源项信息不完整、地形复杂的放射性核素扩散情景下，实现核素浓度变化的快速预测对于核应急决策具有重要意义。本文以山丘下垫面下含钚炸药运输化学爆炸事故为研究场景，提出了一种基于堆叠式LSTM网络的核运输爆炸事故放射性核素浓度预测方法。本文通过计算流体学（CFD）软件OpenFOAM模拟生成放射性核素Pu-239的扩散数据，根据地理特征和人口密度，选择特定区域的核素浓度和气象时序数据作为堆叠式LSTM网络训练和预测的数据集。基于网格搜索寻找局部最优的模型结构，最终所提出的模型在150次迭代内可以稳定地达到平均绝对百分比误差（MAPE）低于5%的Pu-239核素浓度预测效果。该模型具有较好的预测效率，在突发核应急场景中具有较高的实用价值。     

乏燃料运输安全分析中的铁路运输事故统计方法

本文分析了一般铁路运输事故与乏燃料运输事故分级方法的不同之处,并根据乏燃料运输安全分析的特殊要求,将铁路运输事故分成4大类10种事故景象,提出了一种适用于乏燃料铁路运输安全分析的铁路运输事故统计方法。     

UX-30型UF_6运输货包核临界安全分析

利用MONK-9A和MCNP程序对UX-30型UF6运输货包进行了正常与事故工况下的核临界安全分析与评价。首先选取国际公布的临界基准实验数据,验证并确定了MONK-9A和MCNP程序计算分析类似物料形态时的偏倚和次临界限值。其次采取较为包络的临界安全假设条件,计算分析了UX-30型UF6运输货包正常与事故工况下的中子有效增殖因数,评价了运输过程的安全性。计算结果表明,UX-30型UF6运输货包在最严重事故工况下最大的keff小于确定的次临界限值,处于次临界的安全状态。根据临界安全指数的定义,UX-30货包的临界安全指数CSI可定为0。     

我国乏燃料运输现状探讨

随着我国经济的持续发展,核能作为安全、清洁能源在我国能源战略中地位日益突出。在保证安全的前提下,我国核电机组按照国家规划合理增加,乏燃料的产量也将逐步增加。根据我国核电站乏燃料贮存及外运规则,以及我国核电站主要位于东部沿海,而乏燃料后处理厂处在西北腹地这一国情,必将面临乏燃料的大量、长距离及安全运输的问题。乏燃料运输作为联接核电站与后处理厂或最终处置场的纽带,在维持核燃料循环体系的正常运行上发挥至关重要的作用。对国内外乏燃料运输涉及的运输方式、运输容器、运输安全监管及事故应急体系等问题进行了分析和讨论,对我国乏燃料运输中存在问题的解决提出了建议。     

核废物的运输

【欧洲核学会《核新闻网》2001年2月2日报道】 每年有超过1000宗高放核废物通过公路、铁路或船舶运输。这些运输使用坚固且安全的钢桶。在海上,它们通常用专门建造的船舶装运。至今从未发生过任何钢桶因此破裂或泄漏的事故。截至1999年8月的统计数字显示,已进行大约300宗海上运输,将数千吨高放核废物移动超过800万公里。 全世界每年约有2000万个各种型号的包含放射性材料的货包进行常规运输。这些材料包括核燃料、乏燃料和(高放射性)废物、医用同位素和工业用同位素。 所有这些材料的包装都被设计成能够保护搬运它们的人员和发生事故时的公…     

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.     

WAGR Decommissioning: The Transport of WAGR Heat Exchangers to Drigg Low Level Waste Repository

Abstract

The Windscale Advanced Gas-Cooled Reactor (WAGR) operated between 1963 and 1981 and was used as a prototype for experimental research and development related to the Advanced Gas-Cooled Reactor programme. WAGR is now the UK's demonstration project for power reactor decommissioning. A major operation in the decommissioning of the WAGR was the removal of the four heat exchangers (REs) from their concrete bioshields inside the secondary containment sphere and transporting them to Drigg low level waste repository. The issues involved with the transport of the four heat exchangers are described, covering details of the heat exchangers themselves as a transport package. Preparation of the route along public roads is described along with details of the transport vehicles and transport operations.     

Consideration of aging mechanism influence on transport safety of dual purpose casks for spent nuclear fuel or HLW

When storage of spent nuclear fuel or high level waste is carried out in dual purpose casks (DPC), the effects of aging on safety relevant DPC functions and properties have to be managed in a way that a safe transport after the storage period of several decades is capable and can be justified and certified permanently throughout that period. The effects of aging mechanisms (e.g. radiation, different corrosion mechanisms, stress relaxation, creep, structural changes and degradation) on the transport package design safety assessment features have to be evaluated. Consideration of these issues in the DPC transport safety case will be addressed. Special attention is given to all cask components that cannot be directly inspected or changed without opening the cask cavity, like the inner parts of the closure system and the cask internals, like baskets or spent fuel assemblies. The design criteria of that transport safety case have to consider the operational impacts during storage. Aging is not the subject of technical aspects only but also of ‘intellectual’ aspects, like changing standards, scientific/technical knowledge development and personal as well as institutional alterations. Those aspects are to be considered in the management system of license holders and in appropriate design approval update processes. The paper addresses issues that are subject of an actual International Atomic Energy Agency TECDOC draft ‘Preparation of a safety case for a dual purpose cask containing spent nuclear fuel’.     

Current Activities and Issues Affecting the International Regulations for the Safe Transport of Radioactive Material: An Update at the Turn of the Century

Abstract

There are many activities and issues affecting the international regulations for the safe transport of radioactive material. A review of these activities and issues is here presented. This includes: an overview of recent actions taken by the International Atomic Energy Agency's Board of Governors and General Conference; a review of the status of updated. advisory material to support the application of the new (1996 Edition) international Transport Regulations; a discussion of steps being taken to simplify and better rationalise the Transport Regulations; a review of the status of the Agency's Coordinated Research Projects, training, and database efforts, which are performed in support of the Transport Regulations, the newly emerging activity of a Transport Safety Appraisal Service (TransSAS) which Member States are being encouraged to utilise; and a brief discussion of some emerging issues.     

以栅元为模块进行特征线跟踪的中子输运方程解法

为解决复杂几何条件下中子输运方程的求解问题,分析了特征线法理论模型,探讨了以栅元为模块的高效特征线产生方法,以及与之相关的空间角度离散和边界条件处理问题.采用自行研制的特征线法数值计算软件--PEACH,对经济合作组织核能机构(OECD/NEA)UO2和MOX燃料混合装载的7群(C5G7MOX)基准问题的数值进行了检验.结果表明,无论是计算Keff还是棒功率分布该方法都具有很高的精度.     

浮动核电站跨界转运的安全和法律问题初步研究

浮动核电站具有模块化、多用途、可移动、运行灵活、适应性强等优势,受到了国际社会的广泛关注,具有广阔的应用前景和发展空间。然而,浮动核电站由于特殊的海外部署场景和可移动特性,不可避免地面临着跨越主权边界转运的安全和法律问题。结合浮动核电站不同的海外部署场景,重点对浮动核电站在不同部署场景下跨界转运可能面临的安全和法律问题进行梳理总结和讨论分析,并从法律、安保和应急层面提出可能的解决方案建议,对浮动核电站跨界转运相关的国际公约和规则制定具有一定参考意义。     

SARNET integrated European Severe Accident Research—Conclusions in the source term area

The overall aim of the SARNET (Severe Accident Research NETwork), in the EU 6th Framework programme was to integrate in a sustainable manner the research capabilities of fifty-one European organisations from eighteen member states of the European Union (EU) plus the Joint Research Centres, with one Canadian company, to resolve important remaining uncertainties and safety issues concerning existing and future nuclear plant, especially water-cooled reactors, under hypothetical severe accident conditions. It emphasised integrating activities, spreading of excellence (including knowledge transfer) and jointly executed research, with the knowledge gained being encapsulated in the European severe accident modelling code ASTEC. This paper summarises the achievements over the whole project in the Source Term Topic, which dealt with potential radioactive release to the environment, covering release of fission products and structural materials from the core, their transport in the primary circuit, and their behaviour in the containment.The main technical areas covered, as emphasised by the earlier EURSAFE project, were the effect of oxidative conditions on fission product release and transport (especially the behaviour of the highly radiotoxic ruthenium under air ingress conditions), iodine volatility in the primary circuit, control rod aerosol release (Ag-In-Cd) that affects iodine transport, containment by-pass in the case of steam generator tube rupture, aerosol retention in containment cracks, aerosol remobilisation in the circuit, and iodine/ruthenium behaviour in the containment especially concerning the volatile fraction in the atmosphere. The studies also covered performance of new experiments, analysis of existing data, and formulation and improvement of theoretical models. Significant progress was made in each area. Looking to the future, the 7th Framework successor project SARNET2 covers the remaining issues concerning iodine and ruthenium, including practical application of the results. The results outlined here will make a good basis for this continued endeavour.     

核科技领域相关的若干复杂网络研究进展与应用前景

简要总结和评述了核科技领域相关的若干复杂网络的研究进展。这些复杂网络包括：强流加速器中传统的和混合的束流传输网络及其束晕 混沌的控制方法、核反应中连续渗流演化模型网络、全球核电站网络、化学反应网络、核能武器网络与网络作战中心、核辐射监测与反核恐怖网络和美国核武器综合系统网络等。最后,指出了网络科学的若干挑战性课题与应用发展前景。     

Looking to the future – a UK industry perspective

Abstract

The theme of the 10th PATRAM Conference has been ‘looking to the future’. This contribution aims to give a UK perspective on future issues and challenges. In doing so, I will give a short summary of UK transport experience before going on to discuss the future and in particular the challenges and opportunities facing the UK radioactive transport industry.     

远东地区核风险厂址释放的气载放射性污染物长距离迁移的模拟

气载放射性物质在大气中的长距离迁移问题逐渐受到关注。我们开发建立了轨迹模式TraModel和粒子扩散模式ParModel,用以模拟计算气载物质的迁移轨迹和扩散影响,并利用欧洲示踪实验(ETEX)数据对模式进行验证,同时也与国外同类模式进行了比对。结果表明,本研究所开发的模式具有较高的精度。利用美国国家环境预测中心(NCEP)的气象数据进行模拟计算,将其用于模拟我国田湾、秦山核电站以及俄罗斯远东Vladivostok(海参崴)核风险厂址释放的放射性物质的跨国界迁移。模拟结果表明,相对于等熵轨迹,三维轨迹能更真实地反映污染物的实际迁移,对于长距离迁移问题的概率分析,等熵轨迹和三维轨迹的模拟结果基本相同。释放高度对大气迁移途径有显著影响,故由一个释放高度得到的模拟结果用于其它释放高度时应当慎重。此外,由于在中国东部沿海地区气象场的复杂性,特别是受东亚季风的影响,释放点不同地理位置的影响结果也是很不相同的。这些模式、方法今后可用于开展远东核风险厂址大气迁移的概率风险分析以及事故后果评价。