Work to dismantle the old ventilation stack shared by units 3 and 4 at the Chernobyl nuclear power plant in Ukraine has begun, making way for installation of the giant protective structure over the damaged reactor.
|The top section of the ventilation stack is removed. Once completed, the arched structure in the background will be slid over the damaged reactor building (Image: SSE ChNPP)
The ventilation stack for phase two of the Chernobyl plant (units 3 and 4) is 75.5 metres tall and has a diameter of 9.0 metres. It comprises seven sections weighing a combined 330 tonnes. The top of the stack is 150 metres above ground level.
The top section of the stack was removed on 31 October. The section has been placed on a special prepared site where it will be dismantled further, prior to being placed in the turbine hall of unit 3 for temporary storage.
The plant said that continuous radiation monitoring will be carried out during the dismantling operation. It said that so far radiation parameters "do not exceed the design control levels."
The dismantling work is being carried out by Ukrtransbud Corporation using a giant crane with a load capacity of 1600 tonnes. The operation to remove the entire stack is scheduled to be completed by 10 December.
Another ventilation stack has already been commissioned to replace the old stack. The smaller New Ventilation Stack - measuring 50 metres in height and 6 metres in diameter - has been built on the eastern wall of the plant building.
Removal of the old stack is necessary for the installation of the giant structure that will protect the ruined Chernobyl unit 4. Assembly of the New Safe Confinement on a site adjacent to the reactor is expected to be completed by the end of 2014, while installation of 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.
Researched and written
by World Nuclear News