Surface Contamination of Spent Fuel Convoys: Resumption of Transport in France

Abstract

In France, 1998 was marked by transport of spent fuel from EDF plants being suspended and then resumed. From the time the first inspections were carried out by the Nuclear Installations Safety Directorate, in charge of monitoring radioactive and fissile material for civil use since June 1997, surface contamination was found in a high percentage of packages and/or wagons containing spent fuel. The different expert appraisals showed that this had consequences for the health of neither the public nor of workers. Aiming at the resumption of transport, EDF and Cogema presented to the Safety Authority a plan of action including the increase in monitoring (number of points and cross-checking by SGS Qualitest), more widespread observance of good practices resulting from analyses by EDF and conclusions of its nuclear inspectorate and an improvement in radiological cleanliness in the area where casks are loaded. During the inspections carried out at EDF plants, the Nuclear Installations Safety Directorate verified the application of this plan. Several observations were, nevertheless, made regarding maintenance of equipment, failure to apply procedures on a corporate level and the traceability of certain operations. The measures taken to inform the public sufficiently were applied. The Nuclear Installations Safety Directorate is continuing its monitoring actions to· ensure that all EDF plants adopt the best practices. However, the overall clean-up of EDF plants is a long-term operation. Finally, the Nuclear Installations Safety Directorate is continuing its monitoring of the different stages of spent fuel transport as well as other types of transport of radioactive materials associated with nuclear activities.     

Movements of radioactive material on nuclear licensed sites

Abstract

The regulations governing the transport of radioactive materials are prepared by the International Atomic Energy Agency (IAEA) and then introduced into modal regulations and national legislation. These regulations are based on a graded approach to contents limits for packages and conveyances and to performance standards applied to package designs depending upon the hazard of the radioactive contents.

They apply to the transport of radioactive material in the public domain in which the packages can be conveyed by road, rail, sea, inland waterways or air transport modes and may share transport routes with movements of people and cargoes in close proximity.

In contrast, the movement of radioactive materials on nuclear sites is a much more controlled operation. Normally, only road or rail transport is involved, there are much lower volumes of other traffic and any hazards during the movement are generally less severe than the test conditions in the IAEA transport regulations representing accident conditions of transport.

Furthermore, there is no internationally accepted set of design standards applicable to packages intended purely for onsite movements.

In the UK, suitable safety cases need to be prepared to demonstrate the acceptability of the onsite movement of radioactive material to the regulator, the Nuclear Installations Inspectorate (NII). The safety case includes engineering substantiation against appropriate design standards. However, the criteria in the design standards do not need to be as demanding as those in the IAEA transport regulations because of the controlled environment within which onsite movements take place.

The principles of the graded approach in the IAEA transport regulations can be applied to onsite movements of radioactive material. However, the high level of safety resulting from compliance with these regulations can be achieved for movements of radioactive material packages on a nuclear licensed site by amending limits and test criteria to take account of the stringent onsite controls and environment. Examples of this are increasing the package contents limits for a particular package type, reducing the package test requirements or a combination of the two.

There are also general requirements in the IAEA transport regulations for all packagings and packages, and aspects of these can be applicable for packages used for onsite movements of radioactive material. However, there are aspects of these where the detailed implementation can be relaxed for onsite movements, such as the acceleration values experienced at the typically low speeds of onsite movements and the limited ambient temperature and pressure ranges for a specific site.

The present paper discusses various differences between transport of radioactive material in the public domain and on nuclear licensed sites.     

Transport of radioactive materials: the need for radiation protection programmes

Abstract

The increase in the use of radioactive materials worldwide requires that these materials be moved from production sites to the end user, or in the case of radioactive waste, from the waste generator to the repository. Tens of millions of packages containing radioactive material are consigned for transport each year throughout the world. The amount of radioactive material in these packages varies from negligible quantities in shipments of consumer products to very large quantities in shipments of irradiated nuclear fuel. Transport is the main way in which the radioactive materials being moved get into the public domain. The public is generally unaware of the lurking danger when transporting these hazardous goods. Thus radiation protection programmes are important to assure the public of the certainty of their safety during conveyance of these materials. Radioactive material is transported by land (road and rail), inland waterways, sea/ocean and air. These modes of transport are regulated by international 'modal' regulations. The international community has formulated controls to reduce the number of accidents and mitigate their consequences should they happen. When accidents involving the transport of radioactive material occur, it could result in injury, loss of life and pollution of the environment. In order to ensure the safety of people, property and the environment, national and international transport regulations have been developed. The appropriate authorities in each state utilise them to control the transport of radioactive material. Stringent measures are required in these regulations to ensure adequate containment, shielding and the prevention of criticality in all spheres of transport, i.e.routine, minor incidents and accident conditions. Despite the extensive application of these stringent safety controls, transport accidents involving packages containing radioactive material have occurred and will continue to occur. When a transport accident occurs, it is unlikely to result in a significant release of radioactive material, loss of shielding or loss of criticality control.     

International Working Group for Sabotage Concerns of Transport and Storage Casks

Abstract

The International Working Group for Sabotage Concerns of Transport and Storage Casks (IWGSTSC), gathers multiple organisations from different countries (for US party Department of Energy, Nuclear Regulatory Commission, and Sandia National Laboratories; for German party Gesellschaft für Anlagen- und Reaktorsicherheit and Fraunhofer Institut; for the French party Institut de Radioprotection et de Sûreté Nucléaire). The goal of the IWGSTSC is to continue cooperation to improve the analytic capabilities, through information sharing and collaborative research and development plus modelling, to understand the potential adverse public health effects and environmental impacts of radiological sabotage directed at or associated with the transport and storage of civilian nuclear material or other civilian radioactive materials. The Parties may also undertake collaborative research and development in other areas of the physical protection of civilian nuclear materials or other radioactive materials. Since 2000, the IWGSTSC has conducted an extensive test programme for the assessment of the aerosol source term produced in the case of spent fuel transport sabotage by a high energy density device, after having examined several scenarios. The major goal of this programme is to produce an accurate estimate of the so called spent fuel ratio in the domain of respirable, aerosol particles produced. All the reports prepared by Sandia National Laboratories have precisely emphasised the important efforts they have made from the beginning and the amount of work already accomplished. In parallel, the International Atomic Energy Agency (IAEA), assisted by technical experts from different countries, has provided a draft document promised to become guidance for the security of radioactive or nuclear materials during transport. The IAEA document contains general guidance addressed to anyone who intends to implement or improve the security of material transports, but the text is, as of today, limited to rather general recommendations. Based on all the knowledge accumulated from past experiments and also based on the work carried out in Vienna at the IAEA, the IWGSTSC members have decided to work on the development of a method for the evaluation of the vulnerability and the source term. So for doing that, joint projects for the research, development, testing and evaluation of the consequences of the malevolent actions during transport are being pursued and are described in this paper.     

An overview of 20 years' Romanian experience on packaging and components testing according to national and international regulations

Abstract

More than 20 years ago, the Institute for Nuclear Research (INR) Pitesti in Romania, through its Reliability and Testing Laboratory, was licensed by the Romanian Nuclear Regulatory Body – CNCAN to carry out qualification tests for packages intended for the transport and storage of radioactive materials. The radioactive material is placed in packaging which are designed in accordance with national and the International Atomic Energy Agency's (IAEA's) Regulations for safe transport to the disposal centre. A broad range of verification and certification tests are performed at INR on radioactive material packages or component sections, such as packages used for the transport of radioactive sources to be used for industrial or medical purposes. This paper describes some of the various tests, which have been performed, and how they relate to normal conditions and minor mishaps during transport. Quality assurance and quality control measures taken in order to meet technical specification provided by design there are also presented.     

Twenty Years of Experience in Spent Fuel Shipment from German Nuclear Power Plants—A View of the Competent Authority

Abstract

A survey of the transport of spent fuel in and from Germany during the last 20 years is presented. The spent fuel is now transported from the German nuclear power facilities to the reprocessing plants in France and the United Kingdom. In the past, there were also shipments to the former reprocessing plant WAK Karlsruhe (Germany), to the long-term storage facility CLAB (Sweden) and also from the former German Democratic Republic to the USSR. The transport of the spent fuel is carried out in specially built flasks requiring an extensive quality assurance programme. Due to the heavy weight of these packages, the shipments are mostly carried out by rail, but also by road and sea. An overview is given of the following matters: (i) quantities of spent fuel transport, (ii) organisation of transport, (iii) licensing matters, and (iv) reported incidents. In addition, an analysis is included of the radiation exposure for normal conditions of transport, especially of the transport workers. Difficulties and hindrances during transport are also reported.     

Transport of MOX fuel: continuous challenge

Abstract

For 45 years TN International has been involved in the radioactive materials transportation field. Since the beginning the spent nuclear fuel transportation has been its core business. During all these years TN International, now part of AREVA, has been able to anticipate and fulfil the needs for new transport or storage casks design to fit the nuclear industry evolutions. A whole fleet of casks able to transport all the materials of the nuclear fuel cycle has been developed. This paper focuses on the casks used to transport the fresh and used mix oxide (MOX) fuel. To transport the fresh MOX boiling water reactor and pressurised water reactors fuel, TN International has developed two designs of casks: the MX 6 and the MX 8. These casks are and have been used to transport MOX fuel for French, German, Swiss and in a near future Japanese nuclear power plants. A complete set of baskets have been developed to optimise the loading in terms of integrated dose and also of course capacity. Mixed oxide used fuel has now its dedicated cask: the TN 112 which certificate of approval has been obtained in July 2008. This cask is able to transport 12 MOX spent fuel elements with a short cooling time. The first loading of the cask has been performed in September 2008 in the Electricité de France nuclear power plant of Saint-Laurent-des-Eaux. By its continuous involvement in the nuclear transportation field, TN International has been able to face the many challenges linked to the radioactive materials transportation especially talking of MOX fuel. TN International will also have to face the increasing demand linked to the nuclear renaissance.     

Multiple water barriers: alternative to assessment of fuel assemblies during accident conditions of transport

Abstract

Packages for the transport of radioactive material have to comply with national and/or international regulations. These regulations are widely based on the requirements set forth by the International Atomic Energy Agency (IAEA) in the 'Regulations for the safe transport of radioactive material'. In this framework, packages to transport fuel assemblies (including spent fuel assemblies) have to meet the requirements for packages containing fissile material. In accident conditions of transport, the applicant for the package design approval has to show that the package remains subcritical taking due account of the status of the contents in these conditions. In most cases, considering water ingress in the package, it is not possible to assume that the fissile material included in the fuel assemblies is dispersed in the package with the most severe conceivable distribution regarding criticality. In order to alleviate this difficulty, during the last years, we have provided a significant better knowledge of the conditions of the fuel assemblies to be transported. This was part of the Fuel Integrity Project, whose progress was regularly reported during PATRAM 2001 and PATRAM 2004 Symposia. However, for packages which encounter a large g-load during accident conditions of transport and/or which contain spent fuel assemblies with very high burn-up, it can be difficult to demonstrate that the fuel assemblies are not significantly damaged. Then, to make the criticality assessment considering water inleakage into the flask and a large release of fissile material within its cavity will not allow meeting the subcriticality criteria. For that reason, for our package designs, which use a gas and not water as an internal coolant and which fall into that category, the author has decided to take credit of the possibilities provided by the subparagraph 677 (b) of the Regulations. This paragraph allows not taking into account water in the package, provided that the package exhibits 'multiple high standard water barriers'. The paper describes the author's experience with the implementation of this paragraph. Two different cases are considered: either a double vessel, or a double lid. It will be explained when each of these solutions is implemented, and give examples of package designs with such features, as well as the approvals which were granted for these designs in various countries.     

EDF Waste Packages Transport and Compliance with Regulations: Prediction of Retention of Radionuclides by Cementitious Materials

Abstract

Different concrete waste packages have been designed by Electricite de France (EDF) for the long-term storage of radioactive Low Level Waste (LLW). Their main function is to confine radionuclides from the biosphere for three hundred years in a near-surface disposal. According to the transport regulation, a Type B package is needed for some waste like water filters. The water filters from EDF nuclear power plants are encapsulated in mortar and placed in a concrete container. Transport regulations for these containers have required the development of a methodology for safety assessment. The reference scenario of container degradation during transport considers a 9 m drop and a 800°C fire for 30 min. First, the different chemical and physical processes involved in the containment of radionuclides are analysed. In particular, the radionuclide transport mechanisms in cement-based materials have been reviewed. Secondly, the effects of a container drop on the mortar and concrete retention are discussed. Thirdly, in order to prove compliance with the regulations, a simplified model is proposed to predict the radionuclides release with time. It is concluded that cement-based materials offer high performance as a mechanical and chemical barrier to radionuclide releases for Type B packages.     

The Magnitude and Characteristics of Radioactive Material Shipments in Germany

Abstract

A survey has been conducted to determine the type, quantity, and characteristics of radioactive material transport in the Federal Republic of Germany (FRG, not including the former German Democratic Republic). The survey has been extended to all types of material and all modes of transport (road, rail, air, and sea). The survey results indicate that the number of radioactive material consignments totals about 445,000 per year in the FRG. The value is most representative for the later 1980s. Road transport represents the most dominant transport mode with 92% of all consignments and a total of 665,000 shipped packages. Air transport ranks second with a total number of consignments and shipped packages of 19,000 and 240,000, respectively. Most of the radioactive material shipments are related to the use of non-nuclear materials in scientific, medical, and industrial applications. The information acquired in the survey indicates that the average dose rate of packages is clearly below the limit of 0·1 mSv.h^?1 at 1 m from the external package surface by about a factor of 3–20 depending on the origin/end use of the shipped material. The radioactive material transport data bases developed in the study are essential for the evaluation of the adequacy of the Transport Regulations and a useful tool for various other purposes, e.g. safety analysis purposes, by providing factual information, and as input for international data bases, e.g. the IAEA operated data base SHIPTRAM.     

Plutonium Transport: Past,Present and Future

Abstract

The transport of radioactive materials dates back to the beginning of the nuclear industry. The development of nuclear plants and the international trade in fuel cycle services has led to a transport infrastructure to service the industry. Advances in radioactive material package design and technology have been led by increasing emphasis on safety assurance and compliance with transport regulations which in many cases exceed those applied to other dangerous goods. In the case of certain materials security during transport has equal emphasis with safety, and plutoniwn. in its many forms, attracts the most onerous security requirements during transport. BNFL has safely and efficiently transported plutonium both nationally and internationally for 30 years. The Company is committed to the continuation of maintaining such transports in a safe, secure and cost effective manner.     

Compliance Assurance in the Safe Transport of Radioactive Materials in Switzerland

Abstract

Quality Assurance in the transport of radioactive materials (RAM) has been a legal requirement in Switzerland since 1 January 1990. Some four years later, Switzerland is well on the way to having a comprehensive system of Compliance Assurance covering the transport of RAM. By the end of 1994 Compliance Assurance will be fully operational with regard to nuclear fuel cycle shipments which account for over 90% of all radioactivity transported in Switzerland. Compliance Assurance has been delayed in Switzerland for non-fuel-cycle radioactive material shipments. This has been due to the need to modify the legal infrastructure for the relevant supervisory authorities. Nevertheless, it is hoped to have Compliance Assurance related to Radiation Units (large sources in Type B packages) operational before the end of 1994. Systematic progress is being made regarding Compliance Assurance relating to the movement of smaller sources. This involves a very large number of smaller organisations and will take some time to become routine.     

Waste Package and Shipment Aspects in Relation to Transport and Disposal Requirements

Abstract

In the management of radioactive waste, different processes have to be considered such as conditioning, interim storage and final disposal together with transport as the linking process. Attention should be paid to all the relevant steps within these processes, in particular to derive appropriate waste package requirements for a safe waste management system as well as to obtain a consistent regulatory framework. Radioactive waste arising from research and development centres, nuclear power plant operation, decommissioning, the nuclear fuel cycle industry, and applications of radioisotopes in medicine, industry and research, has finally to be shipped to a final disposal site. Therefore waste packages are subject to both the regulatory requirements of transport and the requirements of disposal. Resulting consequences for waste package limitations will be discussed, in particular for low and intermediate level waste taking into account LSA/SCO regulations for transport and waste acceptance criteria for disposal in Germany. Some aspects of different package concepts, like the use of non-reusable or reusable packages, will be considered as well as the application of LSAISCO regulations and further development of LSA/SCO criteria.     

Development of the System for Transporting Radioactive Materials between Chapel Cross and Sellafield

Abstract

The development of the radioactive material transport link between the nuclear power station at Chapelcross in Dumfriesshire and the reprocessing plant and waste management facilities at Sellafield and Drigg in Cumbria is described in relation to the development of the IAEA Regulations and their application in the United Kingdom, from the early days when formal regulations barely existed to the present when detailed regulations and full quality assurance are applied to all aspects of radioactive material transport. The range of transport containers now in use is described, from 50 ton spent fuel flasks to 10 kg sample containers, and these include designs that have interesting possibilities for use elsewhere in the national and international nuclear industry.     

Test Facilities for Radioactive Materials Transport Packages (Sandia National Laboratories,USA)

Abstract

Compliance with regulatory requirements for normal conditions and hypothetical accident environments can be demonstrated by testing packages developed to transport radioactive material. A comprehensive testing capability has been developed at Sandia National Laboratories to simulate the required test conditions and provide response data. Several of the major facilities available to support testing of radioactive material packages are described.     

Evaluation of safety of French type B package designs in severe accident environments other than regulatory

Abstract

Packages used to transport radioactive materials in France must be designed to meet the safety performance requirements when subject to the test conditions set forth in the International Atomic Energy Agency (IAEA) Regulations. During actual use, the packages may be subject to quite different accident conditions. The Institut de Radioprotection et de Sûreté Nucléaire (IRSN) has evaluated the behaviour of typical packages designed to transport spent fuel, high activity waste, fresh mixed oxide (MOX) fuel and plutonium oxide powder under realistic conditions of mechanical impact and fire. The studied designs remain safe after impact onto targets present in the real environment of transport. The energy absorption by the package ancillary equipment (transport frame) compensates for the kinetic energy increase by comparison to the energy expended during the regulatory tests. New software was developed to correctly simulate the thermal behaviour of the neutron shielding materials. The studied package designs exhibit large margins of safety concerning resistance to fire. The results obtained have been used to develop tools in support of the appraisal of emergency situations.     

Demonstration of structural performance of IP-2 packages by advanced analytical simulation and full-scale drop test

Two new types of IP-2 (Industrial Package Type 2) to transport low and intermediate level radioactive waste (LILW) steel drums from nuclear power plants to a disposal facility have been developed in accordance with the IAEA and Korean regulations for radioactive materials. According to the regulations, both packages must preserve their structural performance after they are subjected to 0.9 m free drop tests, which are prescribed as normal conditions.In this study, an advanced analytical simulation and an evaluation process using the finite element (FE) method have been developed for the design assessment of the newly developed IP-2s. Then, analytical simulations for the various drop orientations were performed to evaluate the structural performance of the packages and demonstrate their compliance with the regulatory requirements. Also, full-scale drop tests were carried out to verify the numerical tools and modeling methodology used in the analyses and to confirm the performance of the IP-2s. In addition, parametric studies are carried out to investigate the sensitivity of the analytical variables, such as the material model and modeling methodology.In addition, this paper intends to provide basic guidance on the analytical simulation and evaluation process specifically for Korean types of transport packages, because numerous transport packages must now be developed for the various kinds of LILW that have accumulated in temporary storage facilities in Korea.     

The relevance of IAEA tests to severe accidents in nuclear fuel cycle transport

Abstract

The design and performance standards for packages used for the transport of nuclear fuel cycle materials are defined in the IAEA Regulations for the Safe Transport of Radioactive Materials, TS-R-1, in order to ensure safety under both normal and accident conditions of transport. The underlying philosophy is that safety is vested principally in the package and the design and performance criteria are related to the potential hazard. Type B packages are high-duty packages which are used for the transport of the more radioactive materials, notably spent fuel and vitrified high-level waste (VHLW). Tests are specified in the IAEA regulations to ensure the integrity of these packages in potential transport accidents involving impacts, fires or immersion in water. The mechanical tests for Type B packages include drop tests onto an unyielding surface without giving rise to a significant release of radioactivity. The objects which could impact upon a package in real-life transport accidents, such as concrete roads, bridge abutments and piers, will yield to some extent and absorb some of the energy of the moving package. Impact tests onto an unyielding surface are therefore relevant to impacts onto real-life objects at much higher speeds. The thermal test specifies that Type B packages must be able to withstand a fully engulfing fire of 800°C for 30 min without significant release of radioactivity, and this has to be demonstrated, for example, by analytical studies backed up by experimental tests. The regulations also specify immersion tests for Type B packages of 15 m for 8 h without significant release of radioactivity; and in addition for spent fuel and VHLW packages, 200 m for 1 h without rupture of the containment. There is a large body of evidence to show that the current IAEA Type B test requirements are severe and cover all the situations which can be realistically envisaged in the transport of spent fuel, VHLW and other fuel cycle materials. Any proposals for more severe tests, which have little technical justification, should therefore be treated with caution since this could result in a loss of public confidence in the current regulations, and the ratcheting up of design requirements which could not be justified on quantitative safety grounds.