Windscale Pile Reactors: Decommissioning Progress on a Fifty Year Legacy

The decommissioning of the Windscale Pile 1 reactor, fifty years after the 1957 fire, is one of the most technically challenging decommissioning projects in the UK, if not the world. This paper presents a summary of the 1957 Windscale Pile 1 accident, its unique challenges and a new technical approach developed to safely and efficiently decommission the two Windscale Pile Reactors. The reactors will be decommissioned using a top down approach that employs an array of light weight, carbon fiber, high payload robotic arms to remove the damaged fuel, the graphite core, activated metals and concrete. This relatively conventional decommissioning approach has been made possible by a recently completed technical assessment of reactor core fire and criticality risk which concluded that these types of events are not credible if relatively simple controls are applied. This paper presents an overview of the design, manufacture and testing of equipment to remove the estimated 15 tons of fire damaged fuel and isotopes from the Pile 1 reactor. The paper also discusses recently conducted characterization activities which have allowed for a refined waste estimate and conditioning strategy. These data and an innovative approach have resulted in a significant reduction in the estimated project cost and schedule.