At 8:13 local time this morning, the largest single hydroelectric dam in Russia experienced a catastrophic failure that destroyed much of the turbine hall and is feared to have killed dozen. As of the most recent reports, at least twelve have been confirmed and seventy two are missing and presumed dead. The incident occurred at the SayanoÃ¢â‚¬â€œShushenskaya hydroelectric power station in Siberia – the largest hydroelectric power station in Russia and the sixth largest in the world. The massive facility is equipped (or was equipped) with ten turbines with a combined output of more than six gigawatts. The dam represents nearly 25% of the current hydroelectric capacity of the Russian Federation.
The accident heavily damaged the dam’s turbine hall and power generating equipment. According to the dam’s operator, RusHydro, two of the turbines have been completely destroyed and at least two others are very heavily damaged. Assessments of the damage continue to be made and at this time, it is too early to know the full extent of the losses, although it is thought to be well into the billions of Rubles. (At least 100 million USD, and possibly far more) Repairs are expected to take years, although officials hope to have some power generation restored within 2-3 months.
It is important to note that at this time, all information indicates that the dam itself has not been damaged and remains structurally sound. The design of this dam has the powerhouse off to the side of the main structure. This is where the accident occurred and thus a dam failure is not of concern. A complete failure of the dam could result in mass casualties well into the tens of thousands. Past reports have indicated concern over the integrity of the dam itself, especially during periods of high flooding, but this incident should not cause any immediate danger of a failure of the dam structure.
There have been local effects, however. The region has experienced power failures due to the shortage of generating capacity. The dam provides power to several large aluminum smelters, some of which have been completely shut down due to blackouts. Although some of the smelters continue to operate on alternate power sources, they have had to reduce their production capacity. These smelters are the region’s largest employer. Additionally, the incident caused a major spill of transformer oil. It is unknown whether PCB’s may have also been released.
The exact cause of the accident remains under investigation. However, it appears that the incident began with the failure of a large oil-filled transformer at the power plant. Reports indicate that there was repair work being done on the system at the time of the incident. Transformer failures are not entirely uncommon and most power plants are equipped to deal with these kind of incidents. However, it appears that the failure of the transformer may have lead to a mechanical failure of the generators at the plant. A sudden loss of load could cause the turbines to over-spin, putting them past their design limits. Loss of phase or sudden loads, such as from a short circuit, can also subject the turbines to enormous mechanical stress.
There are safety systems which should cut the water flow in this circumstance and prevent short circuiting or phase loss on the turbines, but it appears that there was some kind of multiple systems failure in this case. Clearly things went very very wrong.
This is not the first time this kind of thing has happened. In 1949, the much smaller Ocree hydroelectric facility in the US experienced a catastrophic failure which destroyed the turbines and generators at the plant. The event appears to have been triggered by a control problem which caused the turbines to temporarily disconnect from the grid load, causing them to over-spin and drop phase with the power grid. The resulting mechanical forces ripped the turbine-generator units from their mountings send one flying through the powerhouse wall. Plants are equipped with numerous safety systems to avoid such mishaps, but as this event shows, things still go wrong
This entry was posted on Wednesday, August 19th, 2009 at 12:00 am and is filed under Announcements, Enviornment, History, media, Misc, Politics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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