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«The truth about Sayan-Shushensk’s «iceberg»»

Февраля 24, 2010

A giant ice wart, that has formed during the severe frosts on the trestles of the Sayan-Shushenskaya hydroelectric power station (above the dissipating basin) looks menacing, but it poses no threat either to the trestle, and even less for Sayan-Shushensk HPS.

q3_1.jpg The chief of the service of monitoring the hydraulic engineering constructions on Sayan-Shushensk HPS  Nikolay Stefanenko in detail told to the correspondent of Energyland.info about “iceberg”  and about measures on struggle against an icing on Saturday on January, 30th
    - Nikolay Ivanovich, will the dismantling of ice wart above the dissipating basin be made?
    - It will gradually crumble. Accumulated mass of ice would break up, getting into dissipating basin because the temperature of water in the well is +3 C and then it will be calmly washed in the tailrace. It doesn’t constitute a menace to the well. Even if the big piece of an ice cap falls, for example 5 tons, it will not harm the well. In fact the depth of water in well is 18 m. Just think logically: the big piece has a greater area. Is it physically possible for such piece of ice to reach the bottom? (The density of ice is much lower than the density of water.)
    - How does the growth of this ice cap go on?
    -The growth depends on the temperature of external air. Greater warts on trestle had grown during very frosty New Year's holidays. Now the ice wart  has variable height of 20-22 m, and does not increase. Growth – 30-40 sm per day is observed only at low temperatures. In the end of January - the beginning of February the temperature of air in area of Sayan-Shushensk HPS is approximately–13С.
    - Nikolay Ivanovich, will the ice cap stand up to warm temperatures?
    - From the experience that we gain in November and December it is visible, that at temperature –8-10С occurs the descent of ice (in small parts) that accrued on a spillway. The ice is being washed away and on trestle. I am sure that when the spring comes, the bulk of the ice cap will have already been descended, as the water in the dust cloud warm +3 C. It also washes away an ice.
    - What is the weight of an ice cap on trestle?
    - The Trestle was constructed as concrete trucking during the construction of the Sayan-Shushenskaya HPS. Its assumed load is 78 tons today, but according to our estimates  load (with a large margin) does not exceed 22 tons. Our department is monitoring ice formation and monitors structural elements of trestle 2 times a day. I stress again that the ice wart is not only growing, but is also being destructed. Therefore, there is no increasing dynamics of load on trestle. The height of the ice cap is 20 - 22 m. The section and structure of an ice changes, its loading is redistributed, but the general remains approximately to a constant because at formation of cracks occurs natural descend of ice.
    - This is clearly seen from above - the ice cap is "cut design”, which is constantly changing in some areas. At the time when the warming comes, that part of the ice cap, where we can clearly see the crack will fall down.  Water which is being dropped with the zero temperatures manages All these processes.
    - Will the similar situation be next winter?
    -Definetly, it won’t be similar, because the bulk of the water will pass through the culverts of generating units, that will be placed under load by that time.

Taming of the "ice’s pier"
    January 29, 2010 was eliminated ice build-up on the separating pier between the spillway and the engine room. His weight was 250 tons. As told Nicholas Stefanenko, wart "had been overcome" in several ways: a jet of hot water cut the ice, which goes into separate stable from the trestle and the cracks were extended with technology of multifrequency network - pneumatic jack, and that helped to bring down the ice in the tailwater pit. In general mechanical cleaning of an ice is being made with use of specialized techniques, and use of an anti-icing material – beshafit – ecologically pure natural salt.
    - Nikolay Ivanovich, what for has the ice been brought down on a nib of the separating foundation if it does not damage neither a well, nor a machine hall?
    -We don't want situation when on the nib is formed new ice which gives additional loading. For this purpose it is also being removed, though on the nib can has loadings in tens times more, than gives accrued ice. But what for shall we create additional risks if it is possible to avoid them? In general, cleaning of an ice from the nib is being done for the minimization of risks, even hypothetical.
    - How can we determine the density of ice?
    - We cut out cubes and measured their density. It was a variable from 0,6 up to 0,8 . It is interesting, that inside the density was less, than outside.
    - It is evident that people are working on the spillway - what do they do?
    - People are working on the balcony of spillway. They are engaged in mechanical removing of formed snow cap.
    - How is it important?
    - It is necessary that there was no snow and ice, although (by the estimates) balcony can maintain greater loads - 8 m of solid ice. But technological aisles must be clean from ice.
    - Nikolai Ivanovich, what organizations are struggling with the icing on the Sayan-Shushensk HPS?
    - We work with some organizations. For example, organizations which work with de-icing materials – the same beshafit –company " Tehnosgem " which has signed the contract with SH HPS by the  results of the tender works. Their experts had put de-icing tent on the nib and on a right-bank wall.  Chipping of ice makes Open Company "Nature", formed in the settlement "Cheremushki" with the help of  industrial climbers. Cleaning of ice is carried by the company   “SH hydroenergoreparation”. Cut of ice with hot water is carried out by Krasnoyarsk’s scientific research institute of fire safety together with "Nature".

This material was prepared by Andrey Grigoriev, EnergyLand.info
Translation: Mukhametyanov Timur, EnergyLand.info

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