The works on dismantling of the light roof of the Unit 4 turbine hall are being carried out at the site of the New Safe Confinement (NSC).
Sergei Poplygin, Head of Shop for Object Shelter and New Safe Confinement Operation commented on dismantling methods: “The method itself of dismantling, fragmentation and handling of dismantled roof is the following. The panel is dismantled with size of 12x3 meters. Using the crane, it is descended directly into the body of a special motor vehicle. Subsequently, this vehicle moves the panel to the fragmentation site at the territory of the former assembly area of the NSC arch. At this site, the panels are fragmented to allow their transportation in the body of a KrAZ vehicle”.
Then the fragments removed from the roof will be delivered to "Buryakivka" radioactive waste disposal site.
These works are necessary to install the foam fire extinguishing system. This system will provide permanent fire protection on the roof of the turbine hall at an area of about 72 meters long and 53 meters wide. The total area that can be extinguished is 3800 square meters.
Each foam generator is capable of producing 6,000 liters per minute (100 liters of foam per second). The maximum foam spraying distance is up to 90 meters. In general, the system is designed to extinguish a fire area of one thousand square meters not less than in 15 minutes.
"In case of fire detection, the fire alarm system sends a signal to the foam fire extinguishing control system. Foam will be sprayed by three foam generators installed at the top of three 30-meter towers. The towers are located along the southern side of the turbine hall. The spray nozzles of foam generators are located 10 meters above the turbine hall roof. They can move both automatically and manually in vertical and horizontal planes" — informs Sergei Poplygin about the system.
The contractor's personnel should dismantle the roof more than 1800 square meters in area. As of now, the work is 55% complete — 31 panels of 57 were dismantled from the turbine hall. On average from three to four panels are being dismantled per week.
