By World Nuclear News
An old ventilation stack shared by units 3 and 4 of the Chernobyl nuclear power plant has been dismantled. Its removal will allow a giant protective structure to be installed over the damaged reactor building in Ukraine.Work to remove the 75.5-metre tall stack began on 31 October 2013. Sitting on the roof of the damaged unit 4, the top of the 9-metre diameter stack was 150 metres above ground level. It comprised seven sections weighing a combined 330 tonnes, with each section weighing between 25 and 60 tonnes.
Ukrtransbud Corporation, which was contracted to remove the stack, reported that the final section was removed from the roof on 25 November and that a document confirming completion of the work was signed on 19 December.
The seven sections of the removed stack were placed on a special prepared site where they will be dismantled further, prior to being placed in the turbine hall of unit 3 for temporary storage.
Removal of the old stack, at an estimated cost of UAH94.7 million ($11.5 million), was necessary for the installation of the giant structure that will protect the ruined Chernobyl unit 4. Assembly of the New Safe Confinement - a giant arched structure - on a site adjacent to the reactor is expected to be completed by the end of 2014, while installation of filtering and handling systems will take place during 2014 and 2015. The operation to slide the entire structure over the unit is scheduled before the end of 2015.
A new ventilation stack was commissioned on 22 October 2013 to replace the old stack. This smaller stack - measuring 50 metres in height and 6 metres in diameter - has been built on the eastern wall of the plant building. http://www.world-nuclear-news.org/WR-Chernobyl-ventilation-stack-removed-1001144.html