Nuclear plant shut down after jellyfish clog filters

BOTH reactors at a nuclear power station have been shut down after "high volumes" of jellyfish were found on seawater filter screens.

The units at Torness power station, near Dunbar in East Lothian, remained closed last night after they were switched off on Tuesday.

EDF Energy, the plant's operator, said the reactors were shut down as a precautionary measure and there was no danger to the public at any time.

The screens filter out debris in cooling water that enters the plant. An operation is under way to clear the jellyfish from the waters near the power station and the reactors will be restarted once their numbers have fallen.

An EDF spokesman said: "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.

"This was a precautionary action and the shutdown cooling systems performed in a satisfactory manner and both reactors were safely shut down.

"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."

EDF Energy could not comment on when the reactors were likely to be started up again. The Office of Nuclear Regulation has been fully briefed about the incident. Torness power station began generating electricity in 1988.

Conservationists have warned that the increasing number of jellyfish is a global problem that has emerged over the past 15-20 years.

Professor Martin Attrill, a marine ecologist and jellyfish expert at the Marine Institute at the University of Plymouth, said: "It is a complex problem but there are three causes which seem to be playing a major role.

"Firstly, it could be a response to climate change - the seas are getting warmer. CO2 dissolves into the sea and the acidification process favours organisms which don't have to build a skeleton.

"Secondly, the jellyfish are responding to over-fishing. When large numbers of fish are taken from the oceans jellyfish are moving in and filling the gaps.

"There are very few sea creatures which eat jellyfish other than turtles.

"Lastly, fertilisers are ending up in the sea, which again ends up favouring some creatures at the expense of others."

Prof Attrill, who has worked on marine intake problems on the Thames Estuary, added: "Torness could have a series of screens built further away from the present ones to block larger organisms."

Mary Church, Friends of the Earth Scotland campaigner, said: "This is the latest in a number of incidents which demonstrate that nuclear power is fragile, unreliable and potentially very dangerous.

"A few years ago the Torness plant was shut down due to seaweed in nearby waters, the Hunterston B plant has been subject to unplanned shutdowns as a result of power supply problems. While the recent Japanese disaster may have taken place against a backdrop of an earthquake and tsunami, it was a simple power failure caused by these events that triggered the dreadful scenario that we see at Fukushima."