Jellyfish Contribute to Reactor Shutdown

A swarm of jellyfish.

A swarm of jellyfish.

Early this week operators at a Sweden nuclear power plant reported that a swarm of Aurelia aurita, or moon jellyfish, have invaded reactor number three, Sweden’s largest nuclear reactor, causing the reactor to be shut down.  This particular reactor powers five percent of Oskarshamn, Sweden’s electricity.  Because of the filters the jellyfish are not able to get into the reactor so there is no danger of a nuclear accident but operators say they will not be able to return to full power until some of the jellyfish are cleared out.

Today a spokesperson said that they may be getting ready to start up the reactor again but are unsure of the results.  There are only a few ways for operators to clear the jellyfish out of the inlet.  Many times they drain the pipes forcing the jellyfish to leave.  Sometimes they can also run the water backwards causing the pressure to push the jellyfish away from the filters.  If needed they can also send divers down to clear away the area.

So how many jellyfish does it take to shut down a nuclear power reactor?  Plant operators are unsure exactly how many are clogging the inlet that allows cool water to flow into the reactor, helping the turbines to run properly.  Operators are sure, however, that it has to be a huge amount.  Scott Burell, an NRC spokesman said, “I don’t know that I could quantify the number of jellyfish.”  Because nuclear power plants are often located near big bodies of water this instance does occur from time to time.

In fact, it happened to this plant in Sweden in the year 2005, shutting down a reactor.  In 1999 jellyfish clogged a coal-fired plant in the Philippines during the holidays.  In 2006 moon jellyfish invaded a reactor at a plant in Hamaoka, Japan causing it to have to shut down.  Then in 2008 Diablo Canyon in California had their reactor two shut down from a swarm of jellyfish.  And in 2011 St. Lucie Nuclear Plant in Florida also had a shut down from a massive invasion.  But nuclear power plants aren’t the only plants being invaded by large swarms of jellyfish.  Botched mining operations, beach shut downs and sturgeon extinction can also be contributed to jellyfish invasions.

Why so many problems with moon jellyfish?  Scientists have determined in recent years that the jellyfish population is booming and continues to rise.  Researchers think that it is because of global warming and increased pollution.  Pollution and warmer waters may cause harm to some sea life but not to jellyfish.  Fisherman also do not often catch jellyfish but with the increase in fishing for other types of sea life, the rise in “overfishing” is reducing the amount of predator threats to the moon jellyfish, leaving them to repopulate at will.

While moon jellyfish are considered harmless to humans they obviously pose more of a threat to human productivity than could have been imagined.  As long as they continue to disrupt and invade power plants and other areas their large population will always be a risk to plant operator everywhere.


Written by: Crystal Boulware

National Geographic; New York Times; Discover News; Westcoast Reader


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