Italy’s Societa Gestione Impianti Nucleari SpA (Sogin) on 14 November completed a €10m ($11.8m) project to dismantle the 95-metre-high central chimney at the shutdown Garigliano nuclear power plant in Italy.
Preparations to demolish the stack began in March 2014. It will be replaced by a new, shorter steel chimney to support further decommissioning work at the site.
Sogin used a 12m model for preliminary testing and decided to demolish the chimney using a “controlled crushing technique”. Preparatory work included systems and machinery tests utilising the model, dismantling yard waterproofing and structures reinforcement.
The inside of the chimney was decontaminated by scarification using a specially designed, Italian technology robot which operated inside the stack from top to bottom and removed thin layers of lightly contaminated concrete to a maximum thickness of 1cm. The decontamination work meant Sogin could demolish the chimney as a conventional structure.
The stack was gradually dismantled from the top, with materials falling inside the cone. The demolition work produced about 830t of waste. Contaminated material has been treated and stored in the plant’s interim repository.
Garigliano nuclear plant comprised a 150MWe boiling water reactor that began commercial operation in 1964. It was permanently shut down in 1982 and is currently being decommissioned.
Photo: Garigliano before and after dismantling of the 95m chimney (Credit: Sogin)