A nuclear power station in eastern Scotland manually shut down its two reactors Tuesday after large mass of jellyfish was found in its seawater filter screens, the operating company said today.

"Both units at Torness power station were manually shut down on 28 June, due to the high volumes of jelly fish fouling the cooling water screens," said a statement from EDF Energy, the French company which operates the power station.

The power station near Dunbar in East Lothian has two advanced gas cooled reactors, but the power plant also draws in water from the North Sea to help cool its nuclear fuel. The filters prevent marine creatures and seaweed from entering the cooling system.

EDF Energy is clearing jellyfish from the waters near the power station and the reactors will be restarted once the numbers have gone down.

An EDF spokeswoman 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," she said, but she was not able to comment on when the reactors might be restarted.

The Office of Nuclear Regulation had been informed of the incident, she said.

A spokesman for the Office for Nuclear Regulation said, "ONR is aware of the situation at Torness and is being kept informed of developments. The licensee reported to ONR that it shut down both reactors in order to maintain the plant within permitted temperature/safety limits."

"ONR's site inspector will follow up on the event with the licensee at the next available opportunity. These situations are not uncommon and are also sometimes caused by fish or seaweed," the ONR spokesman said. "Power stations have a pre-planned course of action which they adopt if such circumstances arise."

The Office for Nuclear Regulation is the United Kingdom's new regulator for the civil nuclear industry. Created on April 1, 2011, the ONR is formed from the merger of the Health and Safety Executive's Nuclear Directorate and, from June 1, 2011, the Department for Transport's Radioactive Materials Transport Team.