THE DEVELOPMENT OF ADVANCED MANUFACTURING TECHNIQUES IN THE PRODUCTION OF LARGE TRANSPORT OR STORAGE FLASKS FOR RADIOACTIVE MATERIALS

Large Nuclear Transport and Storage Flasks (50 Tonnes +)are constantly being developed in an attempt to optimise designs to suit the particular requirements of a given payload. Flask sizes are also increasing in an effort to reduce frequency of journeys, footprint size for storage and the requirements for multiple handling. These factors are constrained by the capabilities of utilities to handle these increased weights (sometimes in excess of lOOT laden,) and the transportation limitation of road and rail gauges. There are other limitations, not least amongst which are those of the manufacturer and the cost of implementation. Since ultimately any design must follow a manufacturing route it is critically important that the designers follow a whole life least cost solution. The achievement of this methodology is greatly assisted by an involvement from the manufacturers and also their suppliers of major or technically difficult components. This paper will review the history of UK flask design, the applicable manufacturing techniques employed and some areas that were developed during this process. This section will concentrate on three particular designs of flask, cuboid, cylindrical thin walled lead lined and thick walled neutron shielded. The paper will consider various aspects of each design and review the relative difficulty in achieving the desired end result. As a follow up to this, the paper will address the new breed of transport and storage flasks, those above SOT carrying high level vitrified waste or spent fuel. These flasks not only need a design and manufacturing route of the highest integrity but also special requirements due to their size and weights. The paper will consider key areas that have the most significant impact on the \"manufacturability\" of designs both from a cost and technical demand standpoint. Critical areas under consideration will be the welding on the flask, focusing on recent developments that have been undertaken by British Steel Engineering with suggestions being made as to how easier manufacturing routes could have been achieved through earlier collaboration between the designers and manufacturer. Finally the paper will show how a collaborative approach between the ultimate client, designers and manufacturers has resulted in more cost effective, safe end products.