During the operation period, the chimney was used to channel the discharge of gaseous effluents coming from the turbine, the reactor and the Radwaste, all operating in vacuum condition and, thus, requiring a controlled exit point.
The chimney, located near the reactor building, was a truncated cone structure made of reinforced concrete, 95 metres high and with a diameter ranging from 5 metres of the base and 2 metres at the top.
In March 2014, the chimney demolition operations were started. The first stage included preliminary works and verification tests on present systems for the decontamination of the internal surface of the structure, such as: system and machine testing on a 12-metres high chimney mock-up (prototype) in reinforced concrete; waterproofing of areas; the consolidation of support structures.
The internal parts of the chimney were subsequently decontaminated, through scarification. This operation was carried out through a robot, specifically designed by Sogin that progressively moves up and down on the chimney walls to remove the slightly contaminated concrete layers.