Sayano-Shushenskaya Dam

Sayano-Shushenskaya Dam

The plant is operated by RusHydro. As of 2009, it was the largest power plant in Russia and the world's sixth-largest hydroelectric plant by average power generation. It provides more than a quarter of RusHydro's generation capacity. The plant operated ten type РО-230/833-0-677 hydro turbines manufactured at the Leningradsky Metallichesky Zavod, each with a capacity of 640 MW at 194-metre (636 ft) head. The total installed capacity of the plant is 6,400 MW; its average annual production is 23.5 TWh, which peaked in 2006 at 26.8 TWh.

The station's constructions include the dam, a power plant building located near the dam, and an additional spillway which is under construction. The arch-gravity dam is 242 metres (794 ft) high. It has a crest length of 1,066 metres (3,497 ft), crest width of 25 metres (82 ft), base width of 105.7 metres (347 ft) and maximum head of 220 metres (720 ft). It consists of a solid left-bank dam 246.1 metres (807 ft) long, a power dam 331.8 metres (1,089 ft) long, a spillway dam 189.6 metres (622 ft) long and a solid right-bank dam 298.5 metres (979 ft) long. It is by far the larger of only two gravity-arch dams in Russia. Water pressure for the dam is approximately 30 million tons, of which 60% is neutralized by the dam's own weight and 40% is carried to rock on the bank
The dam is constructed to "safely" withstand earthquakes up to 8 on the Richter scale, and was recorded by the Guinness Book of World Records for the strongest construction of its type.
The dam supports the Sayano-Shushenskoe reservoir, with a total capacity of 31.34 km³, useful capacity of 15.34 km³ and surface area of 621 km² (240 sq mi).

In 1998, the Russian Emergency Situations Ministry claimed that the "station construction [had] dangerously changed" and that the dam wall might not withstand the repeatedly increasing pressures of the annual spring floods. Since the basement of the dam is weakened, the 30 million tons of water pressure is not divided with 40 % to the shore rocks and 60 % to the dam's own weight as originally designed. Most of the water pressure and probably some of the dam's own weight is driven to the shore rocks since the dam is not constructed to withstand such pressure division.^[
There were also problems with increasing water filtration through dam concrete. In 1993 the French company "Soletanche Bachy" impregnated dam constructions with resins after which the filtration was reduced and situation improved substantially. In later times the impregnation was repeated by Russian companies.
In 1996 the concrete was repaired on the reservoir side at levels from 344 to 388 meters At the same time, the soil under the dam and supporting it from sides, was impregnated to decrease the water filtration.
In 2004, BBC Monitoring quoted a Russian TV news report as saying that the dam operators had been forced to construct an extra water intake wall to alleviate the spring flood pressures.
On 8 September 2009, the Accounts Chamber of the Russian Federation disclosed that the power station was audited in 2007 and that 85% of all technological equipment needed to be replaced. An official notification was sent to the government and the Prosecutor General's Office.
On 11 September 2009, RusHydro made an announcement about the dam's status, saying that the dam is not dangerous as there are around 11,000 sensors in 10 longitudinal galleries in it, and that all dam sections are under continuous monitoring According to RusHydro, displacements of the dam are both seasonally reversible and irreversible. The movements have been reduced in recent years. The maximum displacement (141.5 millimetres (5.57 in)) was recorded in 2006 at dam central section No 33, which however was below the allowed maximum of 145.5 millimetres (5.73 in). According to RusHydro, the scope of displacement between the anchor legs and the machinery hall does not exceed 2.3 millimetres (0.091 in), which is less than the width between them (50 millimetres (2.0 in)), and therefore the dam cannot overwhelm the machinery hall. Also, according to RusHydro the dam is constructed for forces 2.4 times stronger than the actual forces on it are. The spillway is constructed for maximum output 13,600 m³/s, the maximum real water spill can be 7,000–7,500 m³/s as the higher spill will flood villages below the dam.