The Oskarshamn nuclear reactors in Sweden were forced to close this week as a cluster of jellyfish invaded the area.
Employees at the facilities scrambled to shut down reactor number three on Sunday after "tons of jellyfish" clogged the pipes that deliver cool water into the plant's turbines.
It took two days for operators to clean the pipes and prepare for a reactor restart. The reactor which generates 1,400 megawatts of output is the largest boiling-water reactor in the world.
All three Oskharshamn reactors are boiling-water types, the same technology that is used at Japan's Fukushima Daiichi plant. As you may recall the Daiichi plant suffered a catastrophic accident in 2011 when a tsunami breached its perimeter and destroyed important equipment at the facility.
Jellyfish are proving to be a headache for nuclear facilities. The California-based Diablo Canyon facility had to shut its reactor down for a short time last year because of sea salp. The California reactor also suffered from clogged intake pipes.
Because nuclear power plants require a constant flow of water to cool their reactor and turbine systems this problem is not likely to end in the near future.
In the meantime Marine giologists warn of the possibility that the jellyfish population may be growing, although no historical data has been provided to that effect.
In the case of the Oskarshamn jellyfish incident the species clogging intake pipes is known as the common moon jellyfish.
Scientists warn that certain types of jellyfish become more prevalent in areas where bad conditions or overfishing have become a reality. Researchers warn that more problems are likely to occur because of those conditions.
Are you surprised that large-scale nuclear plants like Oskarshamn can be damaged by something as simple as a jellyfish invasion?