In the course of decommissioning a mixed oxide fuel fabrication plant, the aim of this contract is to select, test and evaluate a range of equipment to minimize operator radiation uptake without incurring the costs or development delays of fully remote operation. The operating philosophy will therefore be for COntact Deployment, Remote Operation (CODRO). It will provide data and experience for the planning and implementation of subsequent plutonium plant decommissioning work in the United Kingdom and elsewhere in the Community.
Particular aspects of the project which will be used to explore plutonium facility decommissioning technologies will include:
alternative inspection and remote surveillance techniques;
investigation of size reduction and dismantling tools and methods;
the development of the remote handling equipment required to carry out a wide range of tasks including dismantling, size reduction, handling of radiometric equipment and cleaning equipment such as vacuum cleaners and transferal of removed components to a packaging facility;
keeping detailed records of machine operations and reliability and of manual intervention for maintenance, redeployment or inadequacies of the remote equipment;
manpower, personal radiation uptake and waste arisings data will also be recorded for comparison with the fully manual operations carried out in the Co-precipitation Plant and other projects.
The plant in question was commissioned in 1975 as a development pilot plant to make mixed oxide (MO2) granules for vibro-compacted fuel manufacture. It was subsequently modified, with additional shielding and a separate control cubicle, as the main production facility for the supply of MO2 feed to the pellet presses of the Fast Reactor fuel element plant. It operated in this form until April 1988.
A decommissioning option study determined the selection of techniques and equipment for the dismantling of plant and equipment. High radiation, due to the ingrowth of americium-241, high plutonium inventory and the statutory requirement to reduce radiation uptake to operators resulted in the recommendation of the use of a mixture of manual and remote operations in line with the contact deployment remote operations (CODRO) philosophy.
A detailed design and engineering study outlined the methodology and procedures for the removal of the plant and equipment in order to maximize the use of the remote handling machine. Parallel planning work included the approval of a preliminary safety report, identification of remote tooling equipment and tool changing requirements and development of plasma arc cutting techniques. Tender specifications have been prepared for the remote handling machine, tool changing equipment and plutonium measurement equipment for cut off pieces and for waste drums.
1. Study of the overall decommissioning scheme
2. Detail design, planning and safety studies
3. Delivery and commissioning of remote equipment
4. Deployment and (active) operation on all appropriate tasks of a range of cutting and dismantling tools
5. Generation of specific data
6. Evaluation of the effectiveness of the CODRO philosophy and of the selected equipment.