The situation at Sweden's Oskarshamn nuclear power plant in September 2013 was tense. The plant, situated on the Baltic Sea coast, could not get water from the sea to cool its reactors. Its water intake was clogged with jellyfish. OKG, the plant operator, temporarily halted operations at the facility as a precautionary measure.
A similar thing happened at Kansai Electric Power's Ako thermal power plant in Japan's Hyogo Prefecture in August 2012. Seas surrounding the plant were swamped with jellyfish.
Because the thermal power plant could not get cooling water from the sea, it had to be kept offline for a while. The baskets used to pluck jellyfish from the sea reportedly broke under the weight of so many of the blobby sea creatures.