放射源运输容器安全设计有限元分析方法

放射性物质运输容器力学试验是证明货包安全设计满足法规标准要求的重要工作之一。根据法规标准要求,应采用能够导致货包产生最严重损坏的姿态进行力学试验,评价力学试验后容器的安全性能。通过有限元分析来确定容器最严重损坏的姿态是目前国际上通常采用的方法,能够极大地节约时间和成本。本工作针对某型号放射源运输容器,通过分析容器力学有限元计算结果,确定容器最严重损坏的姿态,分析比较有限元计算结果和试验结果,证明放射源运输容器安全设计满足法规标准要求。     

放射性物质运输货包安全试验

介绍了中国放射性物质运输遵守的法规和中国辐射防护研究院用于放射性物质运输货包试验的下落试验设施、耐热试验设施和数据获取能力。试验设施根据IAEA的《放射性物质安全运输条例》（TS-R-1）和中国的《放射性物质安全运输规程》（GB 11806-2004）的要求建设。下落试验设施能用于13 t级以下的A型和B型货包的自由下落试验、贯穿试验、力学试验（自由下落试验Ⅰ、自由下落试验Ⅱ和自由下落试验Ⅲ）。耐热试验设施能完成B型货包的耐热试验。利用这些设施已进行了FCo70-YQ型货包、30A-HB-01型货包、SY-I型货包和XAYT-I型货包的遵章取证试验     

一种医疗放射源运输容器冲击试验和数值仿真

设计了一种用于运输和储存医疗用密封放射源的运输容器,外形尺寸为 1 141 mm×1 206 mm,质量约3 600 kg,满载 444 TBq(12 000 Ci)⁶⁰Co放射源时属于B型货包,根据GB 11806和SSR-6的要求进行验证货包经受事故能力的自由下落试验I(冲击试验)。采用三维非线性显式动力分析软件ANSYS/LS-DYNA对货包顶角下落冲击试验进行了计算分析,结果表明在冲击部位约 200 mm×200 mm范围内受力较大,2条螺栓可能断裂,冲击部位最大变形量为 45.9 mm。进行了顶角下落试验,测量了外容器外壳的应力和容器的变形。将计算结果与试验结果进行了比较,其结果相互吻合,表明了有限元算法应用于大冲击的破坏性试验中,可很好地预测应力最大区和形变量。     

重水运输容器货包自由下落分析

本文采用ANSYS有限元程序,对重水运输容器货包进行了自由下落分析,计算模型包括3种下落方式:水平下落、垂直下落和倾斜下落.根据ASME规范NB分卷进行了应力强度评定.结果表明,重水运输容器满足强度与密封要求.     

放射性物质运输货包力学试验评价技术

放射性物质运输容器是放射性物质安全运输的唯一物理屏障,运输容器需能抵抗可能的碰撞事故,GB 11806和IAEA的SSR-6针对碰撞事故情景规定了相应的力学试验项目。本文结合GB 11806和SSR-6规定的试验要求,介绍了中国辐射防护研究院自由下落冲击力学试验装置和应力、加速度、形变、影像测量系统。针对3m3六氟化铀运输容器、XAYT-Ⅰ型医用伽马刀治疗头及密封放射源运输容器、ZHQY-QG-001型退役辐照源运输容器,采用试验和有限元仿真计算相结合的方法,分别研究了容器关键部件的形变、应力、加速度数据在容器安全性能评价中的应用。结果表明,综合应用有限元仿真计算与试验技术,采集和分析影像、应力、加速度、形变等数据,可分析货包结构失效模式和评价货包安全性能。     

高温气冷堆新燃料运输货包的撞击事故分析

介绍了高温气冷堆新燃料运输货包严重撞击事故的仿真计算分析方法。根据实际货包结构及运输条件,确定了分析的严重撞击事故景象。通过有限元法计算分析了货包在不同姿态、不同速度下的碰撞结果,给出了容器不同部分及所装载的燃料组件的损坏情况。在此基础上,计算了严重事故景象下有效增殖因子k_eff。     

CEFR-MOX新燃料组件运输货包临界安全计算

易裂变材料运输过程中重要的安全问题之一是临界安全。在对运输货包进行临界安全分析中必须要同时考虑多货包阵列形式、事故后货包损伤对临界安全影响、最佳水慢化条件等因素。本文采用MCNP 程序针对CEFR-MOX新燃料组件运输货包进行了临界安全计算。计算结果表明:MCNP程序(采用核截面库为ENDF/B-V库)对本问题的次临界限值为0.924 6;正常运输条件下无限个运输货包的最大k_eff值为0.574 4,运输事故条件下无限个运输货包的最大k_eff值为0.659 7。根据临界安全指数的定义,确定CEFR-MOX新燃料组件运输货包的临界安全指数为0。     

放射性污染金属废物包装容器的屏蔽设计

针对活度较高的放射性污染金属废物包装容器的屏蔽设计进行了研究。重点阐述了计算废物货包外γ剂量率的圆柱体源模型,推导了圆柱体源剂量场分布的计算公式。通过圆柱体源模型对Ⅷ型钢箱废物货包的计算值与监测数据对比分析,表明圆柱体源模型计算结果能较准确地反映废物货包外γ剂量率分布。基于圆柱体源模型的计算结果,对废物包装容器进行了合理的屏蔽设计,满足了放射性物质运输和处置标准的有关要求。圆柱体源模型对单体货包外剂量率的计算方法简单易实现,而且其计算值比监测值稍大,提供了一定的安全裕度,适合应用于放射性工程实践中。     

解读《放射性物质安全运输规程》GB 11806-2004中的货包试验

本文总结归纳了《放射性物质安全运输规程》GB 11806-2004中关于货包试验(包括货包试验的准备、货包试验的要求、货包试验结果的评定等)的内容,以期对理解和执行该《规程》有关货包试验部分有所帮助。     

某型乏燃料运输容器中子辐射屏蔽性能检测

中子辐射水平测量的可靠性是辐射屏蔽性能检测的难点。本文采用便携式中子测量仪和多球谱仪对某型乏燃料运输货包外部中子辐射水平进行了测量,并基于SCALE程序计算得到的乏燃料中子源项,采用MCNP程序模拟计算得到货包外部中子辐射水平。对测量结果和计算结果进行比较,分析相关影响因素,提出了优化测量方案的建议。     

Qualification Tests for a Type B(U) Package

Abstract

The primary objective for the safety of radioactive materials transport is to protect human health and the environment taking into consideration its potential risks and radiological consequences. Romania as a Member State of the International Atomic Energy Agency hasimplemented national regulations for the safe transport of radioactive materials in accordance with the Agency's recommendations as well as other international specialisedorganisations. The paper will describe the qualification tests performed for a Type B(U) package, intended to be used for the transport of the radioactive sources ²⁴¹Am and ¹³⁷Cs. For this kind of package the tests were performed for the first time inRomania and include: the water spray test, the 1.2 m free drop test, the stacking test, the penetration test, the 9 m free drop test, the thermal test and the submersion under a head of water of at least 15 m. The test facilities used for performing qualification tests for the Type B(U) package as well as experience and conclusions will be also presented.     

The First 40 FT Freight Container in Europe Qualified as an IP-2/IP-3 and Type a Package

Abstract

The first successful free fall drop test with a 40 ft ISO freight container in Europe (as far as we know also in the world) took place in Bremen (Germany) at the dry dock of the former Vulkan ship yard on 25 September 1998. This drop test was performed to qualify the ISO Boxcontainer as an IP-2/IP-3 and Type A package in accordance with IAEA Regulations Safety Series No 6 (1985 edition, as amended 1990) and the new IAEA Safety Standards Series No ST-1 (1996 Edition). The freight container has successfully passed the whole sequence of required tests to demonstrate compliance with Type A requirements (free drop test, stacking test, penetration test and, instead of the water spray test, the more stringent pressure and bubble test was performed) of the IAEA Regulations. This paper concentrates on the free fall drop test because this is the most difficult of the required Type A tests which needs to be passed. Further, the free fall drop test is required to qualify a freight container in accordance with the alternative requirements for industrial packages IP-2,3 (new ST-1, § 627), the requirements for industrial packages (new and old IAEA Regulations) and Type A requirements. Therefore, the freight container was qualified as IP-2,3 and Type A package performing a free fall drop test. The overall dimensions of the so called LONGFORCE® container are: length 12192 mm (40 ft); width 2438 mm (8 ft); height 2491 mm (8 ft 6 in). The 40 ft ISO freight container prototype was fully loaded with 28 t of steel plates together with shock absorbing material to simulate the load and load securing system. The total drop test weight was 35·6 t. In accordance with IAEA Regulations Safety Series No 6 and ST-1, the LONGFORCE® container was dropped onto an unyielding foundation in a position which suffered the maximum damage in respect of the package safety features. The package was dropped on its corner, door side down on the roof, with the centre of gravity over the impact area (slap-down drop). The container was lifted 12·6 m high (highest point) respectively 0·3 m (lowest point) under a drop angle of 70°. The combined mass of the concrete block and the steel plate (impact pad) was way above 100 times that of the container test specimen. The first impact resulted in an acceleration of about 100 g where the maximum was near the impact. The second impact, in general, yielded far higher acceleration values in the vertical direction of 160 up to 200 g. A third impact was recorded which turned out to be decisive, showing maximum acceleration readings in the range of about 200 up to 250 g. The container was inspected after the drop test and deformations of the container rear corner castings (area second impact) and a small weld crack in one of the corner castings welds was found. On the container floor one third of transverse support beams showed Sform distortion. The LONGFORCE container was leak tested prior to and after the drop test in compliance with the STM (STM stands for Safety Technology Management GmbH, owner of the container design and rights and sponsor of the drop test work) leak test procedure. The leak tests consisted of filling the container with pressurised air up to 5 kPa and recording a possible pressure drop over a determined test period. The container was considered leak tight prior to and after the drop test based on the permissible limits set in the leak test procedure. The free fall drop test is considered a full success qualifying the 40 ft LONGFORCE container as an IP-2/IP-3 Type A package in compliance with the IAEA SS No 6 and also with the new IAEA ST-1 regulations.     

Qualifying a 40 ft ISO Freight Container as a Type IP-2, IP-3 Package by Performing a Full Scale Drop Test

Abstract

The first successful worldwide free fall drop test with a 40 ft ISO freight container took place in Bremen (Germany) at the dry dock of the former Vulkan shipyard on 25 September 1998. This drop test had to be performed to qualify the ISO Boxcontainer as a Type IP-2, IP-3 package in accordance with the new IAEA Safety Standards Series No ST-1 (1996 Edition). Dynamic impact requirements will become mandatory for freight containers to be qualified as Type IP-2,3 packages in compliance with IAEA ST-1 paragraph §627 ‘Alternative Requirements for IP-2,3 Packages’ (comes into force in January 2001). STM has fulfilled the dynamic impact requirements in performing a full scale drop test. The 40 ft ISO freight container prototype (L × W × H = 12192mm × 2438 mm × 2491 mm) was fully loaded with 28 t of steel plates together with shock absorbing material to simulate the load and load securing system. The total drop test weight was 35.6 t. In accordance with the new IAEA Safety Standards Series No ST-1 requirements, the so-called LONGFORCE® container was dropped onto an unyielding foundation in a position which produced the maximum damage in respect of the package safety features. The package was dropped on its comer, door side down on the roof, with the centre of gravity over the impact area (slap-down drop). The container was lifted 12.6 m high (highest point) and 0.3 m (lowest point) under a drop angle of 70°. The combined mass of the concrete block and the steel plate was more than 100 times that of the container test specimen. The first impact resulted in an acceleration of about loog where the maximum was just before the impact. The second impact, however, turned out to be decisive showing maximum acceleration readings in the range of 250g. The container has been inspected after the drop test and deformations of the container rear comer castings (area of second impact) and a small weld crack in one of the comer casting welds was found. On the container floor one third of transverse profiles showed S-form distortion. The LONGFORCE container was leak tested prior to and after the drop test in compliance with the STM leak test procedure. The leak tests consisted of filling the container with pressurised air up to 5 kPa and recording a possible pressure drop over a determined test period. The container was considered leak tight prior to and after the drop test based on the permissible limits set in the leak lest procedure. The free fall drop test is considered a full success qualifying the 40 ft LONGFORCE container as Type IP-2, Ip-3 package in compliance with the new IAEA Safety Standards Series No ST-1 requirements.     

IRSN's experience feedback list for assessment of transport package design safety reports

Abstract

Since 1996, the Institute for Radiation Protection and Nuclear Safety (IRSN), the technical support organisation of the French Competent Authority for the safety of transport of radioactive materials, has recorded the list of the difficulties most frequently encountered during the assessment of the safety reports of package designs. This experience feedback list takes into account the most recent evolutions of the regulations and the latest technological knowledge. For instance the safety reports should include the analysis of the most unfavourable configurations such as the 1 m free drop onto the bar when the package is in oblique position, the 9 m drop test of a package with slapdown, the thermal dissipation under a tarpaulin or canopies, the brittle fracture analysis at –40°C. IRSN's experience feedback list for transport package designs, which is published annually, is used as a guide by applicants to improve their package design safety reports and by IRSN for their assessments. Recently, it has been integrated in the French transport applicant guide and in the European technical guide for drafting the package design safety reports.     

Characterising polyurethane foam as impact absorber in transport packages

Abstract

Transport and storage packages used for the safe transport of radioactive materials are required to satisfy IAEA regulations. One key design requirement for a radioactive material transport package is that under a 9 m regulatory drop test, containment functions are maintained. For certain payload types, such as fuel assemblies, impact loads on the payloads may need to be controlled in order to maintain spacing and confinement. To achieve all of this, detailed and accurate characterisation of the impact absorbing material is important in order to design an effective shock absorber. Polyurethane foam is an excellent energy absorbing material because it has a relatively high specific strength, a large compressive deformation, much of this at constant force, and a predictable compressive strength characteristic. Traditionally various types of wood have been used for this purpose, however foams are a more cost effective alternative, which are readily available, and can be formed and shaped easily. Some grades may have the added advantage of providing an almost isotropic crush response, combined with significant thermal protection. The general compressive strength properties of foams and their temperature dependencies are well documented by manufacturers; however, strain rate sensitivity and stiffness variation with orientation are not readily available. Hence impact compression tests for polyurethane foams for a range of densities from 56 to 320 kg m^–3 were specified by Rolls-Royce and performed by the Health and Safety Laboratory. These tests included dynamic conditions for a range of strain rates and temperatures and a selection of orientations of the foam. Following collation of the test results, property curves were derived for the range of temperatures at which the package was expected to operate in service between –10 and +75°C. The properties for a given specification of foam will vary within a defined tolerance range, mainly due to the variables inherent during manufacture. Hence nominal static curves were derived for each foam and a number of factors were taken into account to derive the full range of foam properties: density, compressive strength, temperature and manufacturer supplied tolerance. The net result of this work was a series of force displacement plots, depicting upper and lower bounds to account for the cumulative effects of many variables. Accounting for these upper and lower performance bounds is an essential approach in justification of any modern package design. This paper describes the characterisation and mathematical modelling of polyurethane foam for use as the main impact energy absorber in a new design of package for transporting fresh fuel. The non-linear finite element (FE) code LS-DYNA was used to carry out simulation of the tests. The HONEYCOMB material model available in LS-DYNA was used to accurately predict the test measurements of the foam material. The properties derived for the foam were then used as input to the full FE model used for the licensing of the new package design. Full scale drop testing of the package demonstrated good correlation of deformations between test and FE model analysis, providing good validation evidence of the foam characterisation in the transport package.     

快堆MOX元件运输容器的缓冲器研究

快堆MOX元件运输容器的缓冲器是决定其放射性包容边界安全的重要部件。某型号MOX元件运输容器的缓冲器材料首次选择泡沫铝,通过自由下落试验的标准姿态进行吸能原理分析,设计出了适用于缓冲器材料的型号、结构及关键参数。对选定的材料进行了拉伸、压缩、剪切3种准静态和动态力学性能试验,获得了用于数值模拟计算的材料本构关系参数,并对模型参数进行了测试,用弯曲试验进行了验证。有限元分析和试验结果对比显示：运输容器缓冲器材料的本构关系具有适用性,可用于快堆某型号MOX元件运输容器的自由下落分析计算。     

CONSTOR® V/TC drop tests: pre-test analysis using the finite-element method

Abstract

CONSTOR^® is a family of steel–CONSTORIT–steel sandwich cask designs that have been developed with special consideration for an economical and effective method of manufacture by using conventional mechanical engineering technologies and common materials. The CONSTOR^® concept fulfils both the internationally valid IAEA criteria for transport and the requirements for long-term intermediate storage in the USA and various European countries. A full-scale prototype test cask, CONSTOR^® V/TC, of the latest CONSTOR^® design has been developed, with a heat removal capacity of up to 32 kW. A comprehensive drop testing programme consisting of five 9 m drops onto a flat unyielding target and seven 1 m drops onto a punch is to be carried out by BAM at the test facilities in Horstwalde during Autumn 2004, with the first 9 m side drop to be carried out during PATRAM 2004. The drop tests will form part of the application for a transport licence in both Germany and the USA. Extensive pre-test calculations have been performed using finite-element methods. The objectives of the analyses are as follows: (1) As an intermediate step in demonstrating the performance of the package in fulfilling the requirements of 10 CFR 71 and the IAEA transport regulations. (2) To justify the selection of drop tests. (3) To predict the performance of the V/TC in the drop tests. (4) To estimate the strain and acceleration–time history at measuring points to aid the setting up of the instrumentation. (5) To develop an analysis model that can be used in future safety analyses for transport and storage licence applications to confidently demonstrate the performance of the package. This paper will: present an overview of the analyses; discuss the methodology of the analysis, including the design and make-up of the models taking into account the behaviour of the package, the requirements of the licensing regimes and the present and future purposes of the model; discuss the modelling techniques used; present key results from the analyses; and discuss the behaviour of the package.     

When is a crush test not a crush test? or What constitutes a valid crush test?

Abstract

Recent discussions at the international level are elaborated regarding the intent and method for clarifying acceptable package/drop mass orientations for the dynamic crush test that is required for some Type B and some Type A fissile radioactive material packages. Coverage includes part of the discussions that occurred at an International Atomic Energy Agency Consultants Services Meeting convened to discuss this issue in September 2008.     

Behaviour of a Package Dropped Onto Yielding and Unyielding Targets

Abstract

IAEA transport regulations require the 9 m drop test for type B packages. The target used in this drop test must be unyielding. However, the real target that a transport package might encounter at an accident during transport is a yielding target, such as concrete, asphalt, or soil. To compare the impact acceleration between a real target and an unyielding target, analyses of the drop test onto a real target and an unyielding target were performed by using a LS-DYNA-3D computer code. A road surface is usually concrete or asphalt, and such surfaces are very hard; but there are soil, sand, etc. under these materials, so the impact caused by a drop accident is relatively small. It becomes clear that the drop height onto a road, corresponding to the 9 m drop height required by IAEA regulations is about 50 m, and the impact velocity is about 110 km.s^?1