Session K.pdf - Clarkson University

HPP turbines were not operating during that winter, so full discharge passed through thelabyrinth and headwater level variations were equal to few centimetres.Fig. 5. Ice Thickness beside Fusegate No. 3 in January and February 2002When the duration of the thaws (periods of positive temperature) exceeded one week,all the ice from the tail water side melted (Photo A) and the Fusegate drainage systembegan to operate again. A gap filled with free water was formed on the inner side alongthe perimeter of the bucket, due to high heat conductivity of the metal faces. Free sheetsof ice along the upstream side of the Fusegates started moving.Photo A. Hydroplus Fusegates during Thaw of February 2002Throughout the whole monitoring period, no leakage was noticed through the visiblesections of the Fusegate seals. The winter of 2002/2003 happened to be especially cold.During almost the entire period, the temperature fluctuated with substantial variation.Until mid-January, freezing weather became more severe, reaching record temperaturesfor this region, with the lowest being -35 o C (Figure 3, curve 2). The temperature thenrose to ±4 o C but in early February it dropped again to -30 o C. Looking at the plot of averagetemperatures, it is obvious that the first months in 2003 were more severe than the355