Hydro power plant engineering

Sayano-Shushenskaya is amongst the world’s biggest hydro energy plants. Years of overloading the turbines and insufficient maintenance were probably behind the main accident during 2009. Could better treatment have actually avoided the catastrophe?

On 17 August 2009, a turbine unit was torn from its anchorage by fluctuating water stress and catapulted into the environment inside Sayano-Shushenskaya hydroelectric power-plant in Russia. Weighing in at around 2, 000 tonnes, the turbine ruined the 27-m-high roofing of this turbine hallway, as well as a number of nearby frameworks and plant components. Propelled because of the force of a 200-m liquid column, an amazing 360 cubic metres of liquid per 2nd shot through the entire turbine hall, such as the reduced flooring, causing numerous brief circuits and immediate failure for the power-plant. Those units which were however in operation suffered various examples of technical and electric damage. All in all, 75 everyone was killed and many more injured.

Clear indicators had been dismissed

The damaged turbine product had been thoroughly overhauled in 2000 and 2005, accompanied by another minor overhaul in the springtime of 2009. At exactly the same time, a control system had been installed so the hydro power plant might be controlled externally consistent with grid demands. This system was not adjusted exactly towards the downloaded turbines.

Following the turbine ended up being recommissioned, the vibrations calculated into the turbine rotor were recently underneath the maximum permitted by the product manufacturer. However, within the following days and months, these oscillations didn't stabilise, but alternatively increased steadily, presumably surpassing the allowed maximum by Summer 2009. Nevertheless, the turbine remained functioning. Fatigue splits starred in the retaining bolts. The bolts sheared the moment water stress had been adequately high resulting in residual forced rupture. The turbine address with turbine rotor and generator weighing around 2, 000 tonnes destroyed its anchorage within the basis and led to the accident.

View of the damaged turbine address and severed yellow turbine rotor shaft.
The holes accommodating the 80 bolts are clearly noticeable all over outer circumference.

Catastrophe court instance

Even today, it's uncertain the reason why neither the plant administration nor the providers halted the turbine which was in fact vibrating highly for all months. Numerous papers are nevertheless in the hands of judiciary. Other people had been reputedly cleaned away by the liquid. Following the liquid had been pumped out of the turbine hallway, 49 for the 80 retaining bolts keeping the turbine address in position were afflicted by metallographic evaluation. Six of these couldn't need a nut. They may were forgotten as soon as the turbine was final serviced. Investigations by the public prosecutor will always be ongoing. Twelve months following the accident, fees had been submitted against the people accountable inside plant running business and in the maintenance businesses. The plant’s operator plans to totally replace all ten turbines between 2011 and 2014.

Improper plant procedure

The catastrophe could have been avoided if the devices was in fact operated in base load mode as specified. Additionally, basic principles ensuring trouble-free operation, such as for example research of the factors resulting in the increase in vibrations, had been disregarded here. Even when the vibrations had increased to five times the permitted level, the machine had not been switched off. More over, required upkeep work ended up being evidently done inadequately or otherwise not whatsoever.