Transport of radioactive sources in Africa: the Nigerian experience

Abstract

In his plenary presentation at PATRAM 2010, Professor Shamsideen Elegba of the Nigerian Nuclear Regulatory Authority, Abuja, Nigeria, reviewed the regulatory framework for transport of radioactive materials in Africa.     

Results of full scale CONSTOR® V/TC prototype 9 m horizontal drop test

Abstract

In the context of the research on the mechanical safety of packages for radioactive material, full scale drop tests with spent fuel and high activity waste transport and storage casks have been performed by the Federal Institute for Materials Research and Testing (BAM). The research reflects national and international interest in acquiring comparative knowledge of full and reduced scale model drop tests as well as in finite element calculations. This paper presents the experimental, analytical and first numerical results of the full scale drop test with the full scale CONSTOR^® V/TC prototype, manufactured by GNS, Gesellschaft für Nuklear-Service mbH, Germany. The prototype was tested by BAM in a 9 m horizontal drop test onto the unyielding target of the BAM drop test facility in Horstwalde, Germany.     

Spent fuel transport using cask loaded outside pool

Abstract

During the last year, Sogin (the Italian company in charge for decommissioning of Italian nuclear power plants) had to implement an accelerated decommissioning plan of a EUREX spent fuel pool due to finding a water leakage into the environment from the pool. EUREX is no longer operating a pilot reprocessing plant, which some years ago became the responsibility of Sogin. There were 52 spent fuel assemblies from the Trino Vercellese PWR nuclear power plant, 48 irradiated pins from a Garigliano BWR fuel assembly, and 10 plates from an irradiated MTR fuel assembly stored in the EUREX pool, so the first step of the accelerated decommissioning plan consisted in the evacuation of this spent fuel. Considering the necessity to start the evacuation as soon as possible, Sogin decided to use an already existing cask (AGN-1) used in the past for the transport of Trino and Garigliano fuel assemblies. This cask was requalified in order to obtain a transport licence for the fuel assemblies stored in the EUREX pool according to ADR 2005 regulation. The transport license for the AGN-1 cask loaded with EUREX fuel assemblies was released by APAT (the Italian Safety Authority) in the spring of 2007. Owing to the limited capacity of the EUREX pool crane (27 t for nuclear loads) and limited dimensions of pool operational area, it was not possible to transfer the AGN-1 cask (50 t) into the pool for fuel assemblies charging. The solution implemented to overcome this problem was the loading of the cask outside the pool. A special shielding shuttle was developed and used to allow safe spent fuel transfer between the pool and the cask. This procedure avoided also the problem of excessive contamination of cask surfaces that could have occurred due to very high level of contamination of EUREX pool water if the cask had been immersed in the pool. Additional shielding devices were developed and used to reduce dose rate during cask loading operations. Although the evacuation of spent fuel assemblies from the EUREX pool was a very challenging activity due to the short time available, unfavourable space conditions inside the pool building and handling tool limitations; all loading and transport operations were performed successfully and without particular problems. Ten transports were carried out to evacuate all of the spent fuel stored in the EUREX pool. Spent fuel was transferred to the Avogadro Deposit pool. The first loading sequence started on 2 May 2007 and the first transport was performed on 6 May 2007. The tenth and last transport was performed on 21 July 2007. A dose less than 50 μSv (neutron + gamma) was measured for the most exposed operator during a complete cask loading sequence.     

Scale model impact limiter in type assessment of radioactive material transport packages

Abstract

In Germany, the Federal Institute for Materials Research and Testing (BAM) is the competent authority for the mechanical and thermal design safety assessment of transport packages for radioactive material according to IAEA regulations. The combination of experimental and numerical safety proof forms the basis for a state of the art evaluation concept. Reduced scale models are often used in experimental investigation for design assessment of transport packages corresponding to IAEA regulations. This approach is limited by the fact that a reduced scale model cask can show different behaviours from a full scale cask. The paper focuses on the peculiarities of wood filled impact limiter of reduced scale models. General comments on drop testing with reduced scale models are given, and the relevant paragraphs of the IAEA regulations and Advisory Material are analysed. Possible factors likely to influence the energy absorbing capacity of wood filled impact limiting devices are identified on the basis of similarity mechanics. Among possible significant influence factors on the applicability of small scale models are strain rate and size effects, failure mechanisms, underground compliance, gravitational and friction effects. While it was possible to derive quantitative estimations for the influence of strain rate, size effects and target compliance, it was not possible to evaluate the influence of compression mechanisms and gravitation. In general, if reduced scale models are used in proof of safety, uncertainties increase in comparison with full scale models. Additional safety factors to exclusively cover the uncertainties of reduced scale model testing have to be demanded. The possible application of reduced scale models in regard to crucial aspects for proof of safety has to be analysed critically.     

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.     

BWR spent fuel transport and storage with TN9/4 and TN24BH casks

Abstract

In 2001 the Swiss nuclear utilities started to store spent fuel in dry metallic dual purpose casks at ZWILAG, the Swiss interim storage facility. BKW FMB Energy Ltd, as the owner of the Mühleberg nuclear power plant, is involved in this process and has selected to store the spent fuel in a new high capacity dual purpose cask, the TN24BH. For the transport Cogema Logistics has developed a new medium size cask, the TN9/4, to replace the NTL9 cask, which has performed numerous shipments of BWR spent fuel in past decades. Licensed by the IAEA 1996, the TN9/4 is a 40 t transport cask, for seven BWR high burnup spent fuel assemblies. The spent fuel assemblies can be transferred to the ZWILAG hot cell in the TN24BH cask. These casks were first used in 2003. Ten TN9/4 shipments were made, and one TN24BH was loaded. After a brief presentation of the operational aspects, the paper will focus on the TN24BH high capacity dual purpose cask and the TN9/4 transport cask and describe in detail their characteristics and possibilities.     

Similarity aspects for closure systems in reduced scale package drop testing

Abstract

An exact scaling of all structural components of a package for radioactive materials and their mechanical characteristics is not always possible in drop tests with reduced scale models. This has to be especially considered for bolted closure systems. On the one hand, the sizes of the bolts cannot be scaled with the same geometrical scale factor. On the other hand, the possibilities of an accurate scaling of seal characteristics are very limited. Owing to non-linearity of the force–compression relationship of a gasket, it is, for instance, impossible to simulate the maximum compression force and permissible elastic decompression of a metallic gasket simultaneously on the same scale model. Additional problems can also result from a dispersion of friction conditions in the bolted joints (at threads and under bolt heads). This dispersion, as well as an imprecise bolt tightening technique, leads to more or less considerable scatter of the bolt pretension. The minimum pretension creates more severe conditions in a drop test with regard to the seal function (higher probability of the lid opening and sliding). The maximum pretension is usually conservative for the total bolt stress (the sum of the initial tension and additional load due to the drop test). These circumstances should be considered in planning drop tests as well as regarding the interpretation and transfer of test results to the original package design. In this paper some recommendations are described concerning the modelling of closure systems based on Federal Institute for Materials Research and Testing (BAM) experience in the approval assessment of transport casks for radioactive materials.     

Transport of radioactive material in South Africa

Abstract

This paper aims to present an overview of the activities related to the transport of radioactive material in South Africa. In particular, the applicable legislation, the scope of authority and regulatory functions of the competent authority (CA) is discussed. The categories of radioactive materials transported and the packaging requirements for the safe transport of these radioactive materials are also described.     

Guidance for Package Approvals in the United Kingdom

Abstract

Approval is required under the transport regulations for a wide range of package designs and operations, and applications for competent authority approval and validation are received from many sources, both in the UK and overseas. To assist package designers and applicants for approval, and to promote consistency in applications and their assessment, the UK Department for Transport issues guidance on the interpretation of the transport regulations and the requirements of an application for approval and its supporting safety case.The general guidance document, known as the Guide to an Application for UK Competent Authority Approval of Radioactive Material in Transport, has been issued for many years and updated to encompass the provisions of each successive edition of the IAEA transport regulations. The guide has been referred to in a number of international fora, including PATRAM, and was cited as a 'good practice' in the report of the IAEA TRANSAS appraisal of the UK in 2002. Specialist guides include the Guide to the Suitability of Elastomeric Seal Materials, and the Guide to the Approval of Freight Containers as Types IP-2 and IP-3 Packages. This paper discusses the guidance material and summarises the administrative and technical information required in support of applications for approval of package designs, special form and low-dispersible radioactive materials, shipments, special arrangements, modifications and validations.