The site of Britain’s worst nuclear accident is to be dismantled as part of the wider decommissioning of the Sellafield nuclear plant.
The planned demolition of the 360 foot structure will begin later this year.
A giant crane has been constructed to bring it down.
The 152m crane is the tallest structure ever built at Sellafield, just six metres shorter than the Blackpool Tower.
It will begin work this autumn, removing and lowering chunks of the chimney cut out using diamond wire saws.
Duncan Thompson, the Nuclear Decommissioning Authority’s Sellafield Programme director, said: “The complex task of decommissioning and demolishing the Windscale Pile One Stack has reached an important stage. It is another example of the ingenuity that goes into solving the UK’s decommissioning problems.
“Once demolition begins it will be a very visible demonstration of the work being done to make Sellafield a safer place.”
In 1957, fire broke out in the Windscale Pile One reactor.
The sky-high filters captured an estimated 95% of the radioactive dust created.