A T-25 tractor clears debris on the roof of the Chernobyl Nuclear Power Plant turbine hall.
The tractors were lifted onto the roof of the turbine hall by crane (you can see the lift point on this tractor, just above the cab) where they were used to clear the highly radioactive debris from the explosion.
These agricultural tractors were used because they were light enough not to collapse the roof, unlike the bulldozers and other vehicles used to clear debris elsewhere. They were also more reliable than robotic or remote control systems, which would fail after extended use in radiation fields.
Contextual photo: the area shown in the image above is the lower roof on the right of the photo below. This long building, the turbine hall, houses the enormous turbine generators that created electricity using the steam from the reactors.
