The Complex Challenge of Repairing the Gantry Steelwork on the First Generation Magnox Storage Pond at Sellafield: Legacy Waste Storage, First Generation Magnox Storage Pond

This paper puts into context the challenges that were faced when repairing the Gantry Steelwork of the First Generation Magnox Storage Pond (FGMSP). The First Generation Magnox Fuel Storage Pond (FGMSP) provided fuel storage and decanning capability from the early 1960’s until 1986. A significant programme of work has been underway since the completion of operational activities to support the programmes strategic intent of retrieving and storing all legacy wastes, and remediating the structure of the plant to support decommissioning activities. A key enabler to the retrievals programme is the Pond Skip Handler Machine (SHM), removed from service in 2002 following the discovery of significant signs of corrosion and distress, an inevitable consequence of being located in a coastal, salt laden environment. The SHM provides sole capability to access and retrieve the inventory of over 1000 fuel skips. It is also fundamental to future operations and the deployment of desludging equipment to recover significant bulk sludge’s from the pond floor. Failure of the SHM steelwork gantry at worst case could potentially result in the Skip Handler Machine being derailed. This has some potential to damage to the pond structure and at worst case may result in local radiological and environmental consequences. This paper will examine the challenges faced by the team as they successfully defined, planned and executed remedial work to a specific aspect of the civil structure, the SHM gantry rail system, using a purpose built refurbishment platform; the Gantry Refurbishment System. The paper will examine how an “innovative” approach was adopted to resolve the related issues of: • Refurbishing an aged structure to meet extended future operational demands. • The application of pragmatic engineering solutions against current codes and standards including seismic performance. • Provision of safe access for the workforce to undertake the refurbishment work against significant radiological and conventional safety constraints. • The use of off site test facilities to prove work methods. • Engagement of the multiple workforces including supply chain. • Development of challenging safety cases and management control arrangements to undertake the work. The paper will detail the arrangements established to engage all stakeholder groups aligned to a common goal, programme and end position, together with the arrangements put in place for managing the activities of delivery teams, operators and emergency response teams engaged in task execution over the five year period. Finally, the paper will also share the learning from the projects completion, so that the improvement opportunities flowing from this approach can be shared across the industry for the future benefit of all.