JSC RusHydro, in conjunction with the Ministry of Power of the Russian Federation and JSC Lengidroprojekt, has developed a plan of organisational and technical measures for eliminating the consequences of the accident in the turbine room of the Sayano-Shushenskaya HPP and restoring the power station to normal functioning mode.
The plan envisages rapid pumping out of the water from the turbine room, clearing of the destroyed structures and equipment, installation and start-up of a temporary electricity supply scheme, restoration of through traffic of one-legged construction gantry cranes, the thermal contour and heating system of the turbine room, as well as restoration of the functioning of the automated control system for the state of the hydro-engineering structure. Once all the water has been pumped out of the turbine room, the specialists will be able to specify precisely the volume of restoration work required on the generating equipment, including that which is repairable.
For the purpose of ensuring the passage of seasonal high waters and the winter water release while the power station is out of order, it is planned to calculate the water-power balance of the hydro-unit and alternatives for organising the winter release to minimise the effect of icing factors on the building and the territory of the power stations for subsequent agreements in the established manner.
For the purpose of rapid development, expert examination, approval and issue into production of design documentation, a special procedure will be developed for concluding agreements with design, scientific research, repair, construction and installation organisations.
In addition, for restoration of the Sayano-Shushenskaya HPP and accelerated construction of the first stage of the shore spillway, as well as more rapid completion of the Boguchanskaya HPP, which will be capable of partially replacing the lost capacity of the Sayano-Shushenskaya HPP for the time being, JSC RusHydro is to modify its investment programme.
At the time of the accident on 17 August, 2009, 9 of the Sayano-Shushenskaya HPP turbines were in operation (hydro-turbine No. 6 was in reserve). The total active capacity of the turbines amounted to 4400 MW. At 4.15 Moscow Time, a tremendous bang was heard in the turbine room, followed by release of a column of water around 2 hydro-turbines. Light and sound alarms came on at the Central Control Console. Loading was reduced to 0 MW with complete loss of the plant's own needs and flooding of the turbine room building.
At 5.20 Moscow Time, the emergency repair valves on the inflows to the hydro-turbines were closed down by hand from the crest of the dam and water access to the turbine room was cut off from the upper spillway. To replace the passage of the water through the turbines into the spillway dyke, at 7.32 Moscow Time, current was switched on from the mobile diesel generator on the gantry crane on the dam crest. The operation to lift the gates and release the water through free was completed at 7.50 Moscow Time. Throughout the period of the accident, there was no risk of water spilling over the top of the dam and the entire inflow into the HPP's dam was released free through the water release arches.
As a result of external examination, it was discovered that hydro-turbines 2, 7 and 9 had been destroyed, turbines 1 and 3 seriously damaged and hydro-turbines, 4 and 5 slightly damaged, that the metal structure's of the roof of the turbine room has collapsed, that hydro-turbines 8 and 10 were damaged internally and that turbine 6 was in a satisfactory state. Transformers 1 and 2 had been destroyed, while transformers 3, 4 and 5 were in a satisfactory condition. It will be possible to determine the state of the turbines and transformers more precisely after the water has been pumped out of the turbine room and all the debris cleared. The outdoor switchgear-500 was not damaged and is working as normal. No damage was caused to the body of the dam or the spillways.
Intensive rescue and urgent accident restoration work are currently under way.