This is the second time this year that reactors at Torness in East Lothian have been forced to close because of excessive seaweed. In 2011 it was closed by a swarm of jellyfish.
Reactors need large amounts of water in order to keep them cool, and to prevent them from overheating. Seawater for cooling at Torness is filtered, but when the filters get clogged, reactors have to be shut down as a safety precaution.
The station’s operator, EDF Energy, has said that one of the two 640-megawatt reactors at Torness was shut down in the early hours of this morning. It is expected to remain down for the next seven days.
“We took reactor 2 offline at 02:20 this morning (21 November) due to increased seaweed ingress as a result of the weather conditions in the area,” said the nuclear station’s director, Paul Winkle.
“We are aware that at certain times of year with particular weather conditions in this part of the Forth Estuary, seaweed volumes can increase and enter the station’s cooling water intake system.”
He blamed the blockage on “a high swell and high winds”, saying that large amounts of seaweed were blown into the plant’s intake filters by strong northerly winds. “Seaweed ingress does impact on our electricity generation and we are carrying out work to improve the plant's capability to generate through periods of adverse weather,” he said.
Torness staff were trained to respond to this situation by taking reactors offline if necessary, he said. “In addition, the many-layered safety systems monitor conditions like this and the plant’s inbuilt mechanisms will take the unit offline automatically.”
In a letter to members of the local liaison committee, Winkle stressed that there was “optimum safety at all times”. He added: “Cooling to the reactors was maintained at all times and there were no health or environmental impacts.”
EDF Energy was criticised by the government’s nuclear safety inspectors over a seaweed blockage that closed down a Torness reactor in 2010. Inspectors identified “a number of areas where further enhancement may be possible” in the safety arrangements for dealing with seaweed.
“This latest loss of power at Torness just underlines how unreliable nuclear power is,” said Chas Booth, the green councillor for Leith and a member of the Torness local liaison committee.
“One week it’s seaweed, the next it’s jellyfish – each time it’s a different excuse. It’s absolutely clear that we can’t depend on expensive and unreliable nuclear power to keep the lights on - we need sustained investment in energy saving and renewables instead.”
Although the UK government is pressing ahead with a new nuclear power programme, the Scottish government in Edinburgh is opposed to the building of any more nuclear power stations.