MOX Packaging: Experience and Development

Abstract

In the back-end of the fuel cycle, several leading countries have chosen the Reprocessing, Conditioning, Recycling (RCR) option. Plutonium recycling in the form of MOX fuel is a mature industry, with successful operational experience and large scale fabrication plants in several European countries. The COGEMA Group has developed the industrialised products to master the RCR operation including transport. The COGEMA subsidiary, Transnucléaire, has been operating MOX fuel transports on an industrial scale for more than 10 years. These transports have been carried out by road between various facilities in Europe: reprocessing plants, manufacturing plants and power plants. Because MOX fuel transport is subject to specific safety, security and fuel integrity requirements, the MOX fuel transport system implemented by Transnucléaire is fully dedicated. Packagings. have been developed, licensed and manufactured in compliance with relevant regulations. A fleet of vehicles qualified according to existing physical protection regulations is operated by Transnucléaire. Further developments are under way to increase the payload of the packagings and to improve the transport conditions. Safety and security remain, of course, top priority.     

Radioactive Waste Transport in the Russian Federation

Abstract

According to the national radwaste management programme, low and intermediate level wastes originating from nuclear power plant (NPP) operation, from the nuclear fuel cycle and from the application of radioisotopes in medicine, industry and research are centrally collected and transported for disposal at 16 special repositories. Packagings and conveyances for these purposes are discussed. A concept of regional repositories and transport of wastes from NPPs and the Navy is also considered together with transport packagings and transport methods.     

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.     

Packaging Design and Qualification: The Experience of the CDTN/CNEN

Abstract

Since 1982 the CDTN, the Nuclear Technology Development Centre, has been designing, testing and qualifying packaging for radioactive materials. These packagings are used for the transport of radioisotopes and disposal of spent sealed sources, wastes generated in the nuclear fuel cycle and the wastes produced in the radiological accident that occurred in the city of Goiânia. For radioactive tracers and medical/industrial radioisotopes, the packagings used are cardboard and wood boxes, while the spent sealed sources are preferably conditioned in metal drums containing lead shielding and a gas absorber material. To condition and transport the wastes from the various nuclear cycle activities, metal drums and boxes are used in Brazil. For the higher active wastes from the nuclear power plant Angra I, a metallic drum in a concrete overpack is used. The wastes generated in the accident were first conditioned in the readily available packaging. Later on, more appropriate packaging was designed by the CDTN staff. CDTN has carried out a programme since 1983 to evaluate the durability of commercial drums used for waste conditioning.     

Type A Packages for Medical Radionuclides and Samples

Abstract

There is a particular need by hospitals and research organisations (e.g. universities) for simple and inexpensive packaging for the transport of Type A quantities (<A₂) of radioactive materials in solid or liquid form. In many cases, these organisations receive radioactive materials from commercial vendors in single-use packagings that are not suitable (and not certified) for use for further shipment. This leaves the hospital or research organisation with the problem of how to ship these materials to laboratories that they support, within packaging compliant with regulatory requirements. A further burden is that the design, testing and procurement of the required transport packaging has to be effected under an ISO 9000 QA programme. Although commercial vendors of radioactive materials find it convenient to use single-use (disposable) packagings, hospitals and research organisations usually find it preferable to use re-usable packagings: this avoids having to dispose of used packaging and enables robust, re-usable packaging to be used economically. Some of the problems encountered in developing simple and inexpensive re-usable Type A packaging are addressed and details are given of a range of packagings developed by Croft specifically to meet these requirements.     

Transport Quality Management

Abstract

Historically, the progression of IAEA Regulation revisions has always resulted in changes mainly for the better, in the way spent fuel is transported. The more recent regulatory changes have had a more pronounced effect on the way NTL transports spent fuel. A Transport Management System has been established which not only ensures the Regulations and Package Approval requirements are met but also demonstrates that they are complied with. The system provides documented procedures for all levels of management. They cover a wide range of disciplines from the simplest of transport administration tasks to the more complex business of transport scheduling, reactor site operations and maintenance of packagings and associated equipment. NTL's Transport Management System is self regulatory. The clearly defined boundaries of responsibilities of the personnel carrying out documented procedures ensures non-conformities are minimised. When non-conformities do arise corrective actions are put into the system to prevent recurrence. The benefits of a formal Quality Management System are easily quantified. NTL have recognised the increased efficiency in spent fuel transport activities alld the snowball effect it has had on other bodies. For example, approved suppliers have responded favourably to demands for better quality and Competent Authorities have expressed satisfaction after completing their compliance checks.     

Instructions to authors

Abstract

The sea transport of fresh MOX fuel from Europe to Japan is under consideration. For the structure and equipment of transport ships for fresh MOX fuels, there is a special safety standard called the INF Code of the IMO. For transport of radioactive materials, there is a safety standard stipulated in the Regulations for the Safe Transport of Radioactive Material issued by the IAEA. Under these, code and standard, fresh MOX fuel will be transported safely by sea. However, a dose assessment has been made by assuming that a fresh MOX fuel package might be sunk from some unexpected cause. In both cases, for a package sunk in the coastal region and for one sunk in the open sea, the evaluated results of the dose equivalent by radiation exposure of the public are far below the dose equivalent limit of the ICRP recommendation (1 mSv.y^?1).     

Letter to the Editor

Abstract

Transport of fresh MOX fuel assemblies for the prototype FBR MONJU initial core started in July 1992 and ended in March 1994. As many as 205 fresh MOX fuel assemblies (109 assemblies for an inner core, 91 assemblies for an outer core and 5 assemblies for testing) were transported in nine transport missions. The packaging for fuel assemblies, which has shielding and shock absorbing material inside, meets IAEA regulatory requirements for Type B(U) packaging including hypothetical accident conditions such as the 9 m drop test, fire test, etc. Moreover, this packaging design features such advanced technologies as high performance neutron shielding material and an automatic hold-down mechanism for the fuel assemblies. Every effort was made to carry out safe transport in conjunction with the cooperation of every competent organisation. This effort includes establishment of the transport control centre, communication training, and accompanying of the radiation monitoring expert. No transport accident occurred during the transport and all the transport missions were successfully completed on schedule.     

Transport of Fresh MOX Fuel Assemblies for the MONJU Initial Core

Abstract

Transport of fresh MOX fuel assemblies for the prototype FBR MONJU initial core started in July 1992 and ended in March 1994. As many as 205 fresh MOX fuel assemblies (109 assemblies for an inner core, 91 assemblies for an outer core and 5 assemblies for testing) were transported in nine transport missions. The packaging for fuel assemblies, which has shielding and shock absorbing material inside, meets IAEA regulatory requirements for Type B(U) packaging including hypothetical accident conditions such as the 9 m drop test, fire test, etc. Moreover, this packaging design features such advanced technologies as high performance neutron shielding material and an automatic hold-down mechanism for the fuel assemblies. Every effort was made to carry out safe transport in conjunction with the cooperation of every competent organisation. This effort includes establishment of, the transport control centre, communication training, and accompanying the radiation monitoring expert. No transport accident occurred during the transport and all the transport missions were successfully completed on schedule.     

LLW Transport by IP-2 Packaging

Abstract

As the Japanese nuclear power plants are located on the sea coast, the optimal system for LLW transport consists of sea and land modes. A special ship ‘Seiei Mam’ was built to transport the LLW from nuclear power plants to the LLW Burial Centre in Rokkasho-mura, Aomori Prefecture, and dedicated trucks were prepared to transfer the LLW from the receiving wharf to the Burial Centre. Containers were developed to transport LLW drums efficiently and were designed and tested to meet the IP-2 packaging requirements. Of such containers 3000 have been used since 1992 and the safe transport of LLW has been demonstrated by means of the IP-2 packagings.     

Dose Assessment for the Public due to Packages Shipping Radioactive Materials Hypothetically Sunk on a Continental Shelf

Abstract

Radioactive materials such as spent fuel (SF), PuO₂ powder, high level wastes (HLW) and fresh mixed oxide (MOX) fuel have been transported by sea between Europe and Japan for many years. Dose assessments for the public have been performed in the past for situations assuming packages shipping radioactive materials are hypothetically sunk on a continental shelf. These studies employed various conditions and methods in their assessments and the results were not always the same. In this study, the dose assessment for all types of package was performed under the same conditions and by the same methods. The effective dose to the members of the public for all materials is lower than previous evaluations due to more realistic assumptions used in this study. These evaluated effective doses are far less than the ICRP recommended limit (1 mSv.year^?1 averaged over 5 years).     

Effect of the New Neutron Quality Factor (ICRP 60) on the Transport of Radioactive Material

Abstract

The ICRP 60 has introduced a new definition of the neutron quality factor. This paper aims to assess the impact of the new neutron quality factor on the transport of radioactive material in France. By using two examples, the transport of fresh mixed oxide (MOX) fuel assemblies and of spent UO₂ fuel assemblies, an overview is given of the technical solutions which could be implemented to meet the new regulatory requirements. The options investigated include the modification of packaging designs and resulting operational changes. The influence of each choice on the amount of transport needed is also addressed.     

Early tests of drum type packagings – the Lewallen report

Abstract

The need for robust packagings for radioactive materials (RAM) was recognised from the earliest days of the nuclear industry. The US Department of Energy Rocky Flats Plant developed a packaging for shipment of plutonium in the early 1960s, which became the US Department of Transportation 6M specification package. The design concepts were employed in other early packagings. Extensive tests of these at Savannah River Laboratory (now Savannah River National Laboratory) were performed in 1969 and 1970. The results of these tests were reported in ‘Drum and board-type insulation overpacks of shipping packages for radioactive materials’, by E. E. Lewallen. The Lewallen report was foundational to design of subsequent drum type RAM packaging. This paper summarises this important early study of drum type packagings for the historical record.     

Assessment for radiological impact of irradiated nuclear fuel package sunk in marine environment

Abstract

To gain the public acceptance for the transport of irradiated nuclear fuel, environmental impact assessments have been made by assuming that a transport package may be sunk into the sea. General circulation models for the Japan Sea and for the world ocean were employed to simulate radionuclide concentration in the ocean near shore and in deep sea areas respectively. Radionuclide concentrations were simulated for the hypothetical release from a submerged transport package of fresh mixed oxide fuel in the Japan Sea and the global ocean by general circulation models. Simulated concentrations were quite small compared to the background concentration by the fallout. The effective doses of radiation exposure to the public for both cases were much less than the effective dose limit (1 mSv year^–1) by the ICRP recommendation.     

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.     

Criticality assessments using polyurethane foam

Abstract

Rolls-Royce has designed a package to transport and store fresh fuel assemblies and anticipates approval from the regulators for the new package design in the near future. The space between the inner and outer steel shells is filled with shaped blocks of rigid polyurethane foam, of two different densities. The criticality safety case for the fresh fuel package had to consider single packages and arrays of packages under routine, normal and accident conditions. IAEA regulatory requirements state that the criticality assessment must include investigations on the effect on the neutron multiplication factor k _eff due to impacts, flooding and fire. Sensitivity studies must also be carried out to determine the effects on the k _eff due to any uncertainties in the composition of the fuel and container materials. An important part of the criticality safety case is the treatment of the foam. The approach adopted to model the polyurethane foam is the subject of this paper. The following were investigated: (1) the effect on the k _eff of varying the elemental composition of the foam, including the removal of hydrogen; (2) the experimental analysis of burnt foam; (3) the effect of addition of water to the foam to simulate water absorption; (4) a simple representation of crushed foam to simulate knock-back in the package; (5) extreme representations of burnt foam, such as replacing foam with solid carbon or as randomly distributed spheres of carbon to represent soot. These investigations were most informative and should be considered in any criticality assessments of transport packages containing large amounts of foam in the future.     

Graded approach to establish QA requirements for type B and fissile material transportation packagings

Abstract

The essence of the graded approach is the establishment of applicable quality assurance (QA) requirements to an extent consistent with the importance to safety of an item, component, system or activity. The genesis of the graded approach is a study conducted by the US Nuclear Regulatory Commission (NRC) for the US Congress in 1987 to assess the effectiveness of QA activities. That study demonstrated the need to improve the application of QA requirements for the nuclear industry in general. The conclusion of the study indicated that a graded approach for establishing QA requirements is the most viable method to satisfy federal safety standards that result in protecting public health and safety. The application of QA requirements for type B and fissile material transportation packagings is not based solely on importance to safety or safety related considerations. The operability of items, components, systems and activities is considered to be equally important. The nuclear industry, along with regulatory agencies, recognises the significance of operability considerations, as well as the evaluation of each item, component, system or activity for safety related considerations. The graded approach for QA requirements for type B and fissile material transportation packagings is based on Title 10, Part 71 of the US Code of Federal Regulations (CFR), ‘Packaging and transportation of radioactive material.’ Guidance for implementation of the QA requirements specified in §71 is provided in NRC Regulatory Guide 7·10, ‘Establishing quality assurance programmes for packaging used in transport of radioactive material,’ and ASME NQA-1, ‘Quality assurance requirements for nuclear facility applications’. The graded approach for QA requirements is based on criteria for containment, shielding and subcriticality specified in 10 CFR Part 71.     

Application of IAEA TECDOC 717 to Packagings and Comparison with Reactor Vessels

Abstract

Brittle fracture evaluation is important for type B(U) packagings and packagings carrying fissile materials in conformity with IAEA Regulations. Packaging materials susceptible to brittle fracture can be evaluated by Linear Elastic Fracture Mechanics (LEFM) or other credible methods as shown in IAEA TECDOC 717. Major similarities and differences between the packagings and reactor pressure vessels are here compared in terms of the brittle fracture evaluation. Examples of brittle fracture evaluations of 100 ton class ductile cast iron (DCI) packagings (casks) under hypothetical accident conditions are discussed.     

The French Nuclear Safety Authority's Experience with Radioactive Transport Inspection

Abstract

About 300,000 radioactive material packages are transported annually in France. Most consist of radioisotopes for medical, pharmaceutical or industrial use, but the nuclear industry deals with the transport of fuel cycle materials (uranium, fuel assemblies, etc.) andwaste from power plants, reprocessing plants and research centres. France is also a transit country for shipments such as spent fuel packages from Switzerland or Germany, which are bound for Sellafield in the United Kingdom. The French nuclear safety authority(DGSNR, Directorate General for Nuclear Safety and Radioprotection) has since 1997 been responsible for the safety of radioactive material transport. This paper presents DGNSR's experience with transport inspection: a feedback of key points based on 300 inspections achieved during the past 5 years is given.