Jan 27, 2014

Jellyfish impact on nuclear #Energy: Forget earthquakes and tsunamis: Jellyfish are fast-growing threat

Forget earthquakes and tsunamis: one of the fastest-growing threats to nuclear operations could come from blobby, brainless creatures.

As threats go, the humble jellyfish hardly looks like a formidable opponent.

With a body that is between 95% and 98% water, plus no digestive or nervous system, the average Cnidarian would seem unlikely to imperil mankind's mightiest power generating systems, for example. But you might be surprised.

In September a swarm of moon jellyfish (Aurelia aurita), a species that is not even dangerous to swimmers, took on one of the biggest nuclear plants on the planet… and won.

The umbrella-shaped creatures clogged a cooling water intake at the Oskarshamn nuclear power plant in Sweden and forced operator E.ON Kärnkraft Sverige to shut down the third reactor, cutting off 1,450MW of generation for several days.

Nor was this the first time jellyfish had struck a nuclear power plant. Oskarshamn had experienced the problem previously, in 2005. The following year Chubu Electric Power Co's Hamaoka plant in Japan had to cut its power output while dealing with a jellyfish blockage.

And in 2011, moon jellyfish swarms caused shutdowns at EDF Energy's Torness Power Station in Scotland, UK, and at Florida Power & Light's St. Lucie plant on Hutchinson Island in the US.

Cooling water

EDF Energy had to manually shut down both units at the plant "due to the high volumes of jellyfish fouling the cooling water screens," said the operator, adding that the UK Office of Nuclear Regulation had been briefed on developments.

"Reduced cooling water flows due to ingress from jellyfish, seaweed and other marine debris are considered as part of the station's safety case and are not an unknown phenomenon. At no time was there any danger to the public.

"There are no radiological aspects associated with this event and there has been no impact to the environment."

Three local trawlers ultimately helped clear the jellyfish from the vicinity of the Scottish plant. Meanwhile the Palm Beach Post provided a graphic account of the St. Lucie incident.

"Travelling through the pipes at about 4.6 mph, the jellyfishes' poisonous tentacles broke off," it said. "Trash rakes and large, rotating metal screens that prevent debris from getting into storage tanks could not keep pace with the influx of dying and dead jellyfish."

- See more at: http://analysis.nuclearenergyinsider.com/supply-chain/jellyfish-impact-nuclear-plant-operations