2009 Sayano–Shushenskaya power station accident case study

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1.Introduction
1.1.Brief Dam Description Sayano-Shushenskaya Hydroelectric Power Station was biggest hydroelectric power station ever built in Russia history, and also the sixth biggest in the worth, which is located on the Yenisei River, near Sayanogorsk in Khakassia.[3]The plant operated ten hydro turbines, made total 6,400 MW of output, average annual produced 23.5 TWH,which peaked in 2006 at 26.8TWH. Its arch gravity dam is 246 meters high ,1,066 meters long, and 110 meters of base width. [10]In addition, it was built strong enough to withstand earthquakes of up to 8 on Richter scale.
1.2.Regional Powerhouse Background[3] RusHydro Public Corp, owner of the dam, is the leading power company in Russia as private sector, although most of its shares owned by Russian government. It was first established in December 2004 and become second-largest hydroelectric power company in the world. The energy generated by SSH was about 25% of RusHydro energy production for Russia and Siberia. On top of that,70% of Rushydro energy contribute to aluminum production of the world through United company Rusal’s aluminum smelters.
1.3.Follow The Timeline[3] Accident of august 17 wasn’t first big accident at SSH.From 1978 to 1987,all 10 units of turbine were placed into operation in turn. [10]In March 1979,with Unit 1 and Unit 2 already in operation, a large spring flood overfilled the reservoir and rushed over the running generators and transformers. After 4 months damages were recovered and the units were restarted. There were also two more spring flood attacks in 1985 and 1988 respectively.
2 2.Throughout The Disaster[1] 2.1.Power Plant Operation Before Disaster[3] August 16,2009. As usual generating schedule practices, all possible units at SSH were online and providing the grid with baseload and regulating power, including Unit 2. Meanwhile, Bratsk hydro plant ,which is located 500 miles to the northeast was operating in regulating mode under the control of automactic load-frequency control system(ALFCS), which is overseen by Siberian Unified Dispatching Control Center(UDCC). At 8:31pm,fire alarm tripped at Bratsk plant. Fire compromised communication lines connecting Bratsk and Siberian UDCC and disabled regulating mode.UDCC ordered SSH to replace Bratsk in providing load frequency regulation. SSH staff executed order and put most SSH units under direct control of ALFCS at Siberian UDCC. At 11:14pm UDCC decided to start unit 2 which was originally in reserve state to provide power regulating services. 2.2.The Beginning Of Disaster[3]
On August 17 2009,Units 1,2,4,5,7,and 9 were in regulation mode with Units 3,8,and 10 generating baseload power while Unit 6 was undergoing maintenance and not in operation. Normally 12 operators only staffed the turbine gallery, but this day more than 100 workers present performing repair work. All SSH units were operating with a power setting out of recommended zone as per their turbines specifications, producing excessive vibration. Unit 2 as result of pushed back into service made extraordinarily high level of vibration as well as dangerous level. The technician in shift could feel the vibration of roof, as it grew louder and turned into thunderous roar, who scrambled off the roof immediately. [4]At 8:13am, two massive explosion taken place consecutively and room went black out, according to security guard Aleksandr Kataytsev who was one level below turbine hall. 2.3.During The Disaster
First, the 1860 tons turbine cover was blown off, leaving the Unit 2 turbine in its pit with its wicket gate and head gate opened. At 212 m water head pressure from the dam ejected turbine rotor from the pit as it was continuing to spin and flew across the gallery, further destroyed the surroundings. [4]The penstock water geysered out of vacant shaft at a rate of 67600 gallons per second acted as massive industrial waterjet cut through metal joists ,thus collapsed the roof. The water flood pits of nearby units causing further turbine failures. Electrical short circuits forced all units to emergency shut down along with in house power supply system. Due to power failure ,plant’s automatic safety system failed to shut down Units 7 and 9, for which still operated at full speed ,in excess of 142rpm, triggering the crackling short circuits and explosion in their vicinity. Related scene had been captured into cell phone camera video. 3 2.4.People On The Scene
Water was washing away people form turbine gallery into the Yenisei river. Some of them were later caught and rescued, but unfortunately some were not. [3]The staff later learned that proper emergency exits didn’t exist. Water continued to pour into the hall, flooding lower levels and eventually submerged other Units. As the water lever rose, employees stampeded toward the main entrance. Fearing a total collapse of the dam ,many phoned relatives downstream and urged them to seek shelters. [4]Even among the fleeing workers were supervisors in charge of safety and emergencies, which added to the confusion and chaos. Others led employees to safety using cell phones as flashlights.
Except for Unit 5 gate, the remaining 8 units ‘s wicket and head gates could not be closed remotely. SSH chief engineer later ordered to close all head gates manually. At 9:30 a.m, five men struggled to work in the dark with flashlight, managed to seal all the gates successfully. The work had been toughened where no keys available for head gates control room, so metal doors had to be smashed.
2.5.After The Disaster Within first hours after accident, the Ministry of Russian Federation for Civil Defense directed rescuers from across the country to SSH for finding and rescuing survivors.Withing 24 hours, more than 1500 rescue workers arrived and began working. Fourteen survivors were rescued the operation. Rescue teams also used special chemical by helicopters to congeal industrial oil spread to the river, and removed them from water afterwards. Environmental damage caused by these oil spills was minimized.
4 3.Root Cause Investigation 3.1.Unit 2 Turbine Defects After accident, Russia’s Federal Service for Ecological,Technologica, and Nuclear Supervision (Rostekhnadzor) launched an investigation. [2]Official report was released on Oct.3. According to the report, Unit 2 started having problems shortly after its installation due to defects in its seals and shaft vibrations. The cavities and crack on the turbine wheel were completely reconditioned in 2000. [5]Nevertheless, it continued to have problems and underwent further repairs in 2005 and 2009. [4]From January to March 2009, repairs were conducted and new automatic control system was installed as well. On March 16, the repaired turbine resumed operation but didn’t work right. The amplitude of the machine’s vibrations increased to an unsafe level between April and July. The unit was taken offline until Aug 16 when it was pushed into service again by managers of SSH. Manufacturer of turbine, St.Petersburg metalworks gave the units a 30 years service life. Unit 2 ‘s age on day of disaster was 29 years and 10 month, which almost end its lifespan. 3.2.Unit 2 Anchoring System Failure[3]
Back in operation before the time of accident, log data showed that Unit 2 turbine bearing vibration increased by factor of four within this period. It had been operating for a long period of time with the vibration level far exceeded the maximum acceptable vibration level. Visible cracks showing the propagation of fatigue cracks in attachments points of Unit 2 cover were plainly visible. After all, equipment fatigue, especially in turbine anchor bolts had been formed by excessive vibration from turbine cycling and imbalance over an extended period of time, and lead to catastrophe. 3.3.Poor Management System[6]
3.3.1.Management Team Wrong Judgement Beside technical flaw, management also held responsibility on disaster .Report issued from Russian Federal Service on October 3, 2009 blamed six official who were “conductive to the disaster”, including Anatoly Chubais, former CEO of Unified Energy Systems(UES).According to his statement posted on his website, he went on to say that the plant had been running for more than 20 years when he signed the papers and he was under pressure to make those decisions in 2000 because shutting down equipment while waiting for maintenance funding would have “meant a catastrophe for the economy of Siberia and millions of residents there.” 5
3.3.2.Negligence & Ignoring to Potential Risk From July 2008 until the accident, RusHydro was managed by Vasily Zubakin, who was included in the “List of persons bearing responsibility for accident disaster prevention on Sayano-Shushenskaya” along with 18 other RusHydro executives. They were blamed for made decisions affecting the stability and security of the plant’s operation ,since the accident that were in the making for a long time, was not first time accident ever occurred in SSH. Yet the management didn’t take appropriate action on precaution measure. [3]For example, after repeatedly annual spring floods attack on 1979,1985 and 1998 ,there was a report issued by Russian Emergency Situations Ministry showed that dam walls may not be capable of withstanding pressures result from annual spring floods, yet no significant flood control structures to be constructed upstream to blunt the force of those floods. 3.3.3.No Disaster Drill or Proper Training for Staff
As mentioned above, when disaster happened there was a commotion in among the employees. Most workers were fleeing included the supervisors in charge of safety and emergencies, which added to the confusion. On the fourth floor, shell-shocked midlevel operators telephoned up the chain of command for a contingency plan. All these situations proved that there wasn’t any training or drill had been held before to further staff ‘s knowledge in terms of emergency handling and safety. 3.4. Design Error of Power Plant
As water level rose in turbine gallery ,employees found nowhere to escape but have to rush to main entrance. There were no any emergency exits equipped in turbine gallery. As a result, some were washed away to the river. An order to close all head gates manually by chief engineer were executed by five men. The dangerous task had been delayed and complicated due to no keys available for the room where head gate were located and need to smash the metal doors. 3.5.Financial Problems
Due to budget constraints ,maintenance works couldn’t be carried out and obsolete equipment wasn’t be replaced. For examples, generators breakers were obsolete and not reliable, cracked turbine blades were not repaired or replaced. Unit 2 at the end of useful life was pushed into service again instead of replacement . Insufficient funds made it impossible to have equipment shut down while waiting for maintenance funding, which contributed to management difficulties in making decisions during emergency high demand of power. For the same reason, cost-cutting on safety had been implemented to offset budget deficit. 6 4.The Consequences[8] 4.1.The Dead and Injured
According to official report, the accident led to numerous fatalities ( 75 dead, 13 injured).At the time of the accident in the territory of the SSH there were about 300 people, including repair and hired staff, most of them were workers who were working either on turbine gallery or in the flooded rooms. 4.2.Environmental Impact[8]
A day after the accident, the Natural Resources Ministry of Russia claimed that an industrial oil spillage caused by disaster had spread over 80 km along the Yenisei River. The oil, used as an insulator and coolant in the plant’s transformers was released when one of the transformers exploded. According to Mikhail Kreyndlin, project director at Greenpeace Russia, told Ria Novosti that the transformer oil is low-density distillate which doesn’t sink to the bottom of river but remain as the film on surface, posing severe threat to fish by suffocations. As the matter of fact, more than 100 metric tons of oil were released and killed 400 tons of fish in downstream trout farm. It had made one of the biggest environmental scandal in the news. 4.3.Damages Cost[8] [9] [10]
4.3.1.Equipments damage cost All of the technological systems were flooded and damaged to different degrees. Cable tunnels and galleries of the tailrace in the area of generators 2, 7 ,and 9 collapsed, along with short circuit, air oil tanks displaced, and other materials. The surge of water caused electric and mechanical damage of different extents to all ten units. As per official report, materials ,spare parts and equipment cost 42.76 million rubles, transport services (including flights) was 44.68 million rubles, the collection of oily waste was 70.1 million rubles. Reconstruction of SSH plant with ten new units was expected to take about 4 years and cost about 37 billion rubles. 4.3.2.Economic damage [2] [8]
The disaster had also made great impact on economic ,like contingency business interruption losses for aluminum smelters, which raised the international aluminum supply availability issue. There were approximately 500,000 tons of aluminum output losses due to the power shortage. On top of that, shut down of power plant will push up market prices in Siberia’s grid. 7
In term of energy losses,10% of Russia electricity had gone. Nedootpusk electricity for 2009 had been reduced by 8897.99 million kw.hour and Nedovyrabotka was 8950 million kw.hour. Electricity prices increased after the disaster. On top of that, trading suspended for 2 days at the Moscow Interbank Currency Exchange. Compensation of 1 million rubles paid to each victim’s family and 100,000 rubles to each survivor. The community where most of the workers were housed was flooded and destroyed and being rebuilt. 5.Improvements and Prevention
It’s been over a year since the terrible accident at Russia’s SSH. Based on root cause of the accident ,we can take precautionary measure and do improvement to avoid similar thing happen again in future. 5.1.Emphasize Security Sense
5.1.1.Employees Before accident, most employees showed lack of recognition of hazard, such as ignoring the aging equipment and reluctant to complain or bring up concerns .This phenomenon actually can be overcome by providing training and implementing “reward system”. Through the training , criteria can be set to let employees know when it has crossed the “ need repair “ stage vs “need shutdown” mode. Beside enhance their knowledge on daily use equipments , importance of safety also can be emphasized. For example, operation drill can be carried out from time to time to have them learn what actions need to be taken and what are the impacts if equipment failed. Reward system is like a campaign which encourage employees to take part in maintaining safety. For example, some riddles or mini games with appropriate prizes will do .Reward also given to them who dares to voice out their finding on safety issues, which proved to be helpful. 5.1.2.Management
One of the management mistake found in disaster was the culture that places more value on the economics of power production than on human and plant equipment safety. This should be changed right from top of management to the bottom, start from mindset of directors to the implementation of policy than execution of standard operation procedures. As example, if a director prioritized safety , he will give order to subordinate officers to propose a plan which is safety related, and executed by the rest and so on. Therefore the appointment of top management such as CEO or General manager become very important issue which can’t be underestimated. 8
5.2.Equipment Improvement The plant must also install modern real-time vibration monitoring systems on each unit and have unambiguous rules for their use that do not depend on operator interaction to shut down a malfunctioning unit. Normal and emergency electric supply systems must be separated at all levels to the extent of cable routing. Critical parts list must be updated from time to time.
Conclusion Similar accident is likely to occur again in future, at somewhere people putting economic concerns before human life safety factors. If it is not safe, if there is potential risk of failure, all other benefits , be they economic or environmental or anything else will be gone. As a well trained and vigilant organization which can handle any crisis or disaster in a better way, it must have disaster management plan .Regular drills and training programs ,regular preventive maintenance checks, a list of do’s and don’ts during emergency to be displayed at key locations and etc must be included in plan. A questioning and learning attitude is essential to continue improving the high level of safety standards and their effective implementation.
9 References 1. Sayano-Shushenskaya Hydroelectric Power Station Accident .Available from :http://engineeringfailures.org/?p=703#sthash.DfjpOMJd.dpuf (March 17,2012)
2. (Official Report)The Act of technical investigation into the causes of accidentat the Sayano-Shushenskaya HYDROELECTRIC STATION. Available from: http://engineeringfailures.org/wp-content/uploads/2012/03/Sayano-Shushenskaya-Hydroelectric-Station-Accident-Report.pdf (August 17, 2009) 3. Investigating the Sayano-Shushenskaya Hydro Power Plant Disaster. Available from:http://www.powermag.com/investigating-the-sayano-shushenskaya-hydro-power-plant-disaster/?pagenum=1 (January 12,2010)

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