Safety of transport of radioactive Material: 2004 in retrospect

Abstract

There are basically two main technologies for the intermediate storage of spent nuclear fuel in Europe: dry storage in casks or vaults and wet storage in pools. The advantage of casks is their modularity and hence investment can be phased to suit the planned dates of loading individual casks, pools and vaults usually provide longer term capacity and thus require a greater initial investment for operators. Transnucléaire has developed a range of modular dry cask solutions for customers and more than 100 examples of the TN 24 type cask have been licensed for transport and storage in Belgium, Switzerland, Italy, Germany, the United States of America and Japan. This paper compares the requirements for cask licensing in Europe and the USA and shows how two particular BWR cask designs were developed by Transnucléaire. (1) The TN 97 L cask was designed primarily for the European market and the first use is foreseen at the Leibstadt nuclear power station in Switzerland. (2) The TN 68 cask was designed by Transnuclear Inc. and its first use is foreseen at the Philadelphia Electric Company's Peach Bottom Atomic Power Station.     

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.     

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.     

Moving the Largest Capacity PWR Dual-Purpose Cask in the World from Gösgen NPP to the Zwilag Interim Storage Site

Abstract

The Swiss Gösgen nuclear power plant (NPP) has decided to use two different methods for the disposal of its spent fuel. (1) To reprocess some of its spent fuel in dedicated facilities. Some of the vitrified waste from the reprocessing plant will be shipped back to Switzerland using the new COGEMA Logistics, TN81 cask. (2) To ship the other part of its spent fuel to the central interim storage facility at Zwilag (Switzerland) using a COGEMA Logistics dual-purpose TN24G cask. The TN24G is the heaviest and largest dual-purpose cask manufactured so far by COGEMA Logistics in Europe. It is intended for the transport and storage of 37 pressurised water-reactor (PWR) spent fuel assemblies. Four casks were delivered by COGEMA Logistics to Gösgen NPP. Three transports of loaded TN24G casks between Gösgen and Zwilag were successfully pelformed at the beginning of 2002 using the new COGEMA Logistics Q76 wagon specifically designed to transport heavy casks. This article describes the procedure of operations and shipments for the first TN24G casks up to storage at Zwilag. The fourth shipment of loaded TN24G was due to take place in October 2002. The TN24G cask, as part of the TN24 cask family, proved to be a very efficient solution for Kemkraftwerk Gösgen spent fuel management.     

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.     

New Fresh Mox Fuel Packages: From Design to Operation

Abstract

The MX packages developed by COGEMA Logistics according to TS-R-1 requirements will replace older Current packaging to transport fresh pressurised water reactor (PWR) and boiling water reactor (BWR) mixed oxide (MOX) fuels in Europe. Two types of package have been developed: (1) MX8 with a capacity of eight 17 × 17 900 MWe PWR fuel assemblies for dry loading and underwater unloading operations; and (2) MX6 for dry loading and unloading operations. The capacity of the MX6 is six 16 × 16 or 18 × 18 PWR fuel assemblies or sixteen 10 × 10 BWR fuel assemblies. To meet these capacities requirements, an innovative and optimised design has led to ‘mid-weight’ packages with original solutions for the body, the baskets and the fuel restraining system. To cope with both capacity and legal weight transport requirements, a new high-security transport system has been developed simultaneously. The first shipment with MX8 was made in December 2001, and the first use of MX6 packages is scheduled for the end of 2003.     

New Package for the Transport of Fresh MOX Fuel Assemblies in Europe

Abstract

The use of Mixed Oxide Fuels (MOX) in commercial reactors has increased significantly over the past 10 years as an effective way of using stocks of plutonium produced from reprocessing uranium fuels. Now, with advances in fuel design, MOX can give performance approaching that of enriched uranium fuel. To meet demand from European and Japanese utilities, British Nuclear Fuels are in the process of commissioning a large capacity plant at Sellafield to assemble MOX fuels. This has required a new transport package to be developed capable of carrying high specification fuels to customers in Europe whilst complying with the 1996 IAEA ST-1 Transport Regulations. This package is known as Euromox and currently under development to enter service in 2003. Relatively few packages exist for the transport of MOX fuels and Euromoxis the first designed by BNFL for shipments to Europe. Euromox has provided several technical challenges in its development arguably exceeding those typically encountered during the development of new package for irradiated fuel transports.     

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.     

TRANSPORT OF MOX FUEL

Abstract

The regulatory framework which governs the transport of MOX fuel is set out, including packages, transport modes and security requirements. Technical requirements for the packages are reviewed and BNFL's experience in plutonium and MOX fuel transport is described. The safety of such operations and the public perception of safety are described and the question of gaining public acceptance for MOX fuel transport is addressed. The paper concludes by emphasising the need for proactive programmes to improve the public acceptance of these operations.     

Estimation of the Grain Boundary Gas Inventory in MIMAS/AUC MOX Fuel and Consistency with REP-Na Test Results

In the frame of its research activities on fuel safety, the French “Institut de Radioprotection et de Sûreté Nucléaire” performed the REP-Na program in the CABRI reactor devoted to the study of Reactivity Initiated Accidents. Focused on high burn-up UO2 and MOX fuel behaviour, twelve tests (8 UO2 and 4 MOX) were realized from 1993 to 2000. In all these tests, the influence of grain boundary gas was evidenced and it appeared necessary to perform some estimation of its inventory in irradiated fuel. Such evaluations are presented for the MOX MIMAS/AUC fuel, based on two different approaches: “experimental” and “theoretical.” The fission gas amount located at the grain boundaries increases with burn-up in correlation with the production, but also with the initial Pu enrichment, as soon as the agglomerates have reached the full restructuring threshold for the High Burn-up Structure. The consistency with the REP-Na test results is checked, showing that a significant cladding deformation is needed, clearly higher than for UO2 fuel in order to release all the grain boundary gas in RIA. Furthermore, to the fission gas effect, adds the helium's occluded in the irradiated fuel whose amount increases with burn-up, Pu enrichment and ²⁴¹Pu and ²⁴¹Am initial content.     

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).     

An Emergency Response Plan for Transport

Abstract

Transnucl6aire is involved in road and rail transport of nuclear fuel cycle materials. To comply with IAEA recommendations, Transnucl6aire has to master methods of emergency response in the event of a transport accident. Considering the utmost severe situations, Transnucl6aire has studied several cases and focused especially on an accident involving a heavy cask. In France, the sub-prefect of each department is in charge of the organisation of the emergency teams. The sub-prefect may request Transnucl6aire to supply experts, organisation, equipment and technical support. The Transnucleaire Emergency Response Plan covers all possible scenarios of land transport accidents and relies on: (i) an organisation ready for emergency situations, (ii) equipment dedicated to intervention, and (iii) training of its own experts and specialised companies.     

A non destructive technique for determination of U and Pu content in MOX fuel pins for fast reactors

MOX fuel pins containing both U²³³O₂ and PuO₂ have been fabricated for making an experimental subassembly for irradiation in Fast Breeder Test reactor (FBTR) at Kalpakkam, India. This unique composition of the fuel pin is chosen to simulate the thermo-mechanical conditions of the upcoming Prototype Fast Breeder Reactor (PFBR) in the existing Fast Breeder Test Reactor. Since the fertile matrix is natural UO_2, it was difficult to monitor the percentage of U²³³O₂ through chemical methods and neutron assay methods. During the fabrication of MOX fuel pins at Advanced Fuel Fabrication Facility; Bhabha Atomic Research Centre, Tarapur, Passive Gamma Scanning (PGS) was employed as one of the characterisation tools for verifying the fuel composition. PGS was found to be effective in estimating the percentage composition of both U²³³O₂ and PuO₂ and also in ensuring the uniform distribution of the fissile material in MOX fuel pins. PGS is also found effective in monitoring the correct loading of natural UO₂ insulation pellets and MOX fuel pellets in welded MOX pins.     

Development of Long Life FBR Fuels with Particular Emphasis on Cladding Material Improvement and Fuel Fabrication

The development of FBR fuel systems with high reliability and long in-core residence capability is required to make the fast reactor economically competitive with other electrical energy sources. PNC program of fuels and materials development has been primarily focused on mixed uranium/plutonium oxide (MOX) fuel with cold-worked 316 stainless steel for the past 20 years. Modified 316 stainless steel with excellent swelling resistance and high creep rupture strength was obtained for cladding and duct of the fast prototype reactor MONJU. Advanced austenitic alloys and high strength ferritic alloys are also being investigated for high burnup fuel assemblies of a long life core in large scale FBRs.

In MOX fuel fabrication technology, extensive progress has been achieved during driver fuel fabrication for the experimental reactor JOYO. A new MOX production facility PFPF has been completed with fully automatic and remote handling systems. This facility serves for MONJU core fuel production. The improvement of fuel fabrication technologies promotes cost reduction, safety operation and security from a physical protection standpoint.     

COG-OP-30B: A New COGEMA Overpack for Type 30B Cylinders

Abstract

Facing the difficulties encountered in the United States of America in obtaining a durable certificate of approval for the existing overpacks, COGEMA desired to free itself from the constraints imposed by these packagings for the transport of enriched uranium hexafluoride. Transnucl6aire therefore initiated the design of a new Type B(U)F overpack, on behalf of COGEMA, for use with the 30B cylinders containing uranium hexafluoride enriched up to 6% in ²³⁵U, obtained from natural or reprocessed uranium. The external aspect of the new overpack is quite standard (two cylindrical halves closed with ten toggles) and it keeps the same stowage system so that it can be used with the methods of transport which exist already. The main features of COGEMA's overpack are a reinforced internal structure to protect the 30B cylinder's skirt from bending and better absorption of the drop energy to limit the acceleration under impact. The drop tests and a fire test were performed successfully in February and March 1997, the French Certificate of Approval was obtained at the end of 1998, the Swedish validation by mid-1999 and the Canadian validation at the beginning of 2000.     

PATRAM 2004 — Berlin,September 2004

Abstract

Since British Nuclear Fuels plc (BNFL) was formed in 1971 its transport service has safely moved spent light water reactor (LWR) fuel from many locations abroad to its fuel handling plants at Sellafield in the UK. To support this business a number of types of flasks have been designed and used. One of the types used has been the Excellox family of water-filled flasks. To support future business opportunities a new flask, designed to meet the requirements of the new IAEA transport regulations TS-R-1 (ST-1, Revised), has been developed. The flask will be a type B(U)F. This new flask design will maximise fuel carrying capacity to minimise transport costs. The design capacity of the new Excellox 8 flask is to be 12 pressurised water reactor (PWR) or 32 boiling water reactor (BWR) fuel assemblies. The objective of this BNFL project is to provide another economic spent nuclear fuel transport system, in support of BNFL transport business.     

Advanced mixed oxide fuel assemblies with higher plutonium contents for pressurized water reactors

Optimizing fuel cycle costs by increasing the final burnup leads to reduced generation of plutonium. Under properly defined boundary conditions thermal recycling in mixed oxide (MOX) fuel assemblies (FAs) reduces further the amount of plutonium which has to be disposed of in final storage. Increasing the final burnup requires higher initial enrichments of uranium fuel to be matched by an advanced design of MOX FAs with higher plutonium contents. The neutronic design of these MOX FAs has to consider the licensing status of nuclear power plants concerning the use of MOX fuel. The Siemens Nuclear Fuel Cycle Division, with more than 20 years' experience in the production of MOX fuel, has designed several advanced MOX FAs of different types (14 × 14 to 16 × 16) with fissile plutonium contents up to 4.60 w/o.     

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.     

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.