Countermeasures for jellyfish attacks at Kashiwazaki Kariwa [Japan] Nuclear Power Station
2005
Takizawa, M.(Tokyo Electric Power Co., Kashiwazaki, Niigata (Japan))
Thermal and nuclear power stations use vast amounts of seawater for the cooling water to condense the steam that drives the turbines and return it as water. Screens are installed to filter the water and keep out trash and other foreign matter. However, since the summer of 1999, large numbers of jellyfish have appeared near Kashiwazaki, and required a great deal of labor to collect, transport, and dispose of those jellyfish. In fact, on July 7,1999, an unusually large flow of jellyfish arrived all at once, shutting down the filtering equipment for reactors 1, 2, and 3. The resulting lack of cooling water forced us to reduce power output. In 1999, we were manually collecting the jellyfish from the screen, but in 2000 we automated this process with a jellyfish conveyor. In addition, we began aerating from the sea floor. By sending air in under the jellyfish and causing them to float up, we now can prevent large numbers of jellyfish from hitting the screen all at once, The jellyfish are transported in a large vacuum car, then stored temporarily in a pipe cleaning pool used during construction. The water is removed and the jellyfish are dried for easu removal.
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