The demolition of one of Sellafield's tallest structures is under way.
A chimney on top of the oldest reprocessing plant on the nuclear site will be crunched away at a rate of one-metre a week.
The tower will be gone by 2020, resulting in a significant reduction in hazard and risk, and a permanent change to the Sellafield skyline.
ONR permissioned demolition of the First Generation Reprocessing Stack after extensive assessments to ensure Sellafield Limited met legal requirements while progressing safety and security priorities.
Inspectors have engaged with the site licensee during the design, build, testing and commissioning phases of the project.
The 60-year-old structure, which no longer meets modern construction standards, could only be removed once a modern replacement had been built.
The stack sits on top of the First Generation Reprocessing Plant and provided ventilation to a fleet of reprocessing plants.
Conventional demolition techniques like explosives and cranes could not be used due to the congested and hazardous nature of the surrounding area.
Instead, a cutting-edge self-climbing platform has been installed which moves up and down the barrel of the stack and allows workers to carry out demolition using hand held machinery.
Mina Golshan, Director of ONR’s Sellafield, Decommissioning, Fuel and Waste Division, said: "Starting demolition of this redundant stack is a key achievement by Sellafield and another important step towards reducing the risk and hazard posed by legacy facilities on site in order to further enhance safety. This is the focus of our regulatory strategy for the site.
"Our inspectors have engaged with Sellafield Ltd throughout the project and gathered evidence that assured us of the suitability of the proposed demolition activity and Sellafield’s supporting safety case."
Stuart Latham is Head of Remediation at Sellafield Ltd. He said: "Cleaning up our legacy facilities safely, quickly and cost-effectively is our absolute priority, so we are delighted to now see the stack coming down after four years of preparation.
"Given the structural integrity of the stack, its location in the heart of the site and the fact that this new technique has never been used here before, the planning has been comprehensive. The project demonstrates that challenges of decommissioning the Sellafield site.
"We couldn’t move a crumb of this chimney without building a modern replacement first, so this has been a complicated project.
"Safety is the number one priority, so thorough testing has helped us ensure everything works as it should."