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。     

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。     

采用有限元方法的放射性物质货包自由下落试验研究

放射性物质货包力学试验是证明货包结构设计安全性的重要试验之一。货包力学试验通常是一种破坏性试验,为得到对货包损坏最大的下落取向,通过预先计算分析确定货包下落取向成为目前国际上使用较多的方法。本工作采用ANSYS/LS-DYNA有限元分析软件,对货包的力学试验进行仿真分析。通过对计算结果分析,得到货包最大损坏的下落取向及应变和加速度数值,并与试验结果进行了比较。     

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     

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。     

CNSC乏燃料组件运输容器临界安全分析

临界安全作为乏燃料组件运输容器的一项重要安全指标,需经过计算和分析以判断其是否满足法规标准。为分析中国核工业集团有限公司(China National Nuclear Corporation,CNSC)乏燃料组件运输容器临界安全设计是否满足《放射性物品安全运输规程》的要求,使用蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code)构建了保守临界计算模型,对正常和事故工况下CNSC乏燃料组件运输容器进行了临界计算分析。分析表明:正常运输条件下单个货包和货包阵列的k_(eff)最大值为0.804 25,小于次临界限值,临界安全指数为0;事故工况下单个货包和货包阵列的k_(eff)最大值为0.813 17,小于次临界限值,临界安全指数为0。可见,正常和事故工况下,CNSC乏燃料组件运输容器的keff最大值均小于0.94的次临界限值,临界安全指数为0,满足法规标准要求。     

FCTC10型工业辐照~(60)Co运输容器屏蔽测量与评价

FCTC10型容器设计用于装载工业辐照60Co源,在装载18万居里(Ci)60Co放射源时属B(U)型、Ⅲ级(黄)货包。FCTC10型容器由屏蔽容器、吊篮、防护罩与运输托架组成,主要利用屏蔽容器主体和铅塞的钢壳层及其中间填充的钨合金、铅屏蔽层实现货包的屏蔽功能。采用蒙特卡罗方法模拟计算和实验测量相结合的方法给出FCTC10运输容器在满载时的辐射水平,结果表明FCTC10容器满足GB 11806—2004对货包辐射水平的规定。根据运输实践经验假设了工作人员和公众的受照情景,计算出的单次运输工作人员和公众的受照剂量小于设计考虑的剂量约束值,也低于GB 18871—2002对工作人员和公众的剂量限值。在设计基准事故情况下,容器外部局部区域辐射水平增加量不超过1倍,对事故处理人员的剂量很小。     

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。     

AP1000新燃料组件运输货包的临界安全计算

新燃料组件运输过程中最主要的核安全问题是临界安全。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、事故后货包损伤情况、最佳水慢化条件等因素。本文采用MCNP程序针对美国西屋公司XL型运输容器装载AP1000新燃料组件货包的实例进行了临界安全计算。结果表明,在XL型运输容器设计许可书中允许装载货包数N=75的限制条件下,临界安全是有保障的。     

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.     

A study on the free drop impact of a cask using commercial FEA codes

The package used to transport radioactive materials, which is called a cask, must be designed to keep its contents safe under normal and hypothetical accident conditions. The design requirements of the cask are verified by test or finite element analysis (FEA). Comparing evaluation procedures for the safety of a new cask, the cost of FEA is generally much less than that test. Therefore, FEA is mainly used to verify safety of a cask under the considered conditions. However, one commercial FEA code may show different results from another FEA code for the same problem due to the modeler's several assumptions for simplifying actual states into the FE model and due to modeling technique. Materials of the components of a cask display elastic–plastic or elastic–perfectly plastic behavior under the considered conditions in which large deformation, impact and contact mechanism are included. The behavior is simulated with difficulty and may have different results depending on FEA codes. In this paper, finite element analysis is carried out for the 9-m free drop and the puncture condition under the hypothetical accident condition by using LS-DYNA3D and ABAQUS/Explicit. Energy and effective stress on each component are presented and compared between the two FEA codes, where the effective stress designates the maximum von Mises stress on inner and outer shells.     

基于光滑粒子与有限元耦合算法的放射性废液运输容器跌落分析

基于光滑粒子和有限元耦合算法,利用显式动力学分析软件LS-DYNA,对装载放射性废液的车载式废树脂接收装置在三种不同跌落方式下的跌落冲击过程进行了数值分析。以装置水平跌落为典型算例,对其在跌落过程中所受的动态激励、装置的压力变化和装置的应力状态进行了分析。结果表明,光滑粒子和有限元耦合算法对于解决装载放射性废液的运输容器在跌落冲击过程中流固耦合问题是有效的。同时,基于有限元分析结果,提出了一种按照RCC-M《压水堆核岛机械设备设计和建造规则》等规范对放射性物质运输容器跌落冲击过程进行应力强度评定的方法,并依据该方法对装置的结构强度进行了评定,结果显示装置在三种不同跌落方式下的应力强度均满足要求。     

3m^(3)天然六氟化铀运输货包满载及卸载后的辐射水平分析北大核心CSCD

对运输天然UF_(6)原料的3 m^(3)运输容器在满载和卸料后容器内部的辐射源项及分布情况进行分析,计算两种状态下容器表面及1 m处辐射水平,并与实际测量结果进行了对比。计算结果表明:容器外部辐射主要来源于^(234)m Pa、^(234)Pa和^(235)U的γ辐射;满载时,容器外部辐射水平随时间增加而增加,至3个月时基本达到稳定;卸料后,残料容器中由于衰变子体^(234)Th、^(234)m Pa和^(234)Pa的大量残留,且缺少UF_(6)的自屏蔽作用,容器外部辐射水平高于满载状态,在卸料后2个月,残料容器表面最大辐射水平从167.5μSv·h^(-1)降到30.3μSv·h^(-1)。对卸料后约2个月的两个3 m^(3)运输容器表面辐射水平进行测量,测得最大辐射水平分别为31.3μSv·h^(-1)和28.1μSv·h^(-1),测量结果与计算结果基本一致。鉴于天然UF 6运输活动频繁,运输量大,因而在残料容器返厂运输活动中的辐射防护不容忽视,可通过增加残料容器空置时间、远距离操作和减少操作时间来减少工作人员遭受的照射。     

Use of impact analysis in licensing industrial container for transporting new fuel

Abstract

The finite element (FE) method is a powerful tool for the simulation of mechanical and thermal behaviour of structures. In recent years, the explicit FE method has increasingly been used in the development of transport packages and as part of approval applications to demonstrate the performance of packages. Testing and analysis are the two methods specified in the IAEA Regulations for the Safe Transport of Radioactive Material for demonstrating the structural and thermal performance of a transport package against the requirements of the Transport Regulations. The roles of testing and analysis, and the relative prominence of the two, may vary between Competent Authorities in different countries. This can range from analysis being regarded as the primary mode of demonstration with testing as confirmatory, to testing being the primary mode of demonstration supplemented by analysis. This paper describes the use of the non-linear FE code LS-DYNA in the licensing of a new container for the transport of new nuclear fuel. The package was classified as an Industrial Package (Fissile) in accordance with the IAEA Regulations, and hence it was necessary, among other things, to demonstrate that criticality criteria were satisfied under postulated impact conditions. Physical drop tests were carried out and the results are compared with LS-DYNA computer calculations using the same FE models developed to support the design of the new container. The analyses and tests clearly demonstrate the novel use of polyurethane foam as the container main energy absorber. The FE predictions are compared for accelerations, bolt loadings and global deformations of the container. In general good correlation was obtained between predictions and tests and the differences, which did occur, particularly for accelerations, are discussed and reconciled. The paper concludes that explicit analysis codes are now so reliable for container impact calculations that minimal test work should be pursued basically for key confirmatory impact scenarios.     

Immersion Tests For Cask Transporting Vitrified High-Level Radioactive Waste

Abstract

To ensure the safe transport of high-level radioactive wastes, the demonstration tests stipulated by the International Atomic Energy Agency (IAEA) transport regulations were carried out in the Central Research Institute of Electric Power Industry (CRIEPI). This paper describes the water immersion test. The test cask for the test was designed as a Type B package and the design combines the specific structural features of both the COGEMA and the BNFL (planned) casks, which are used for shipping HLW from France and the United Kingdom respectively. The test results show that strains due to the water pressure were negligible at the test of a head of 15 m. At the immersion test at 200 m water depth the measured maximum strain was sufficiently within the elastic limit and no rupture was observed. In addition, the immersion test at a water pressure of more than 2 MPa, which is beyond specification, was carried out to assess the capability of the cask against water pressure. Maximum water pressure was set to 30 MPa. No rupture was observed during the test and the leak rates did not show any differences before and after the test.