The risk for failure in the security system must be eradicated, said SKI, which presented the results of its investigation into Sweden’s nuclear reactors on Thursday.
“The three (reactors) need to meet a list of measures before we give them official approval to resume operations,” Swedish nuclear power inspectorate (SKI) spokeswoman Maria Svensson told AFP.
The three are the Forsmark 1 and Forsmark 2 reactors and the Oskarshamn 1 reactor.
The shutdown of the nuclear reactors at Forsmark and Oskarshamn after an incident at Forsmark on July 25th has so far cost the plant owners a billion kronor.
Following a blackout caused by a short circuit, two of four backup diesel generators in the Forsmark 1 reactor failed to start automatically, revealing other faults in the power station’s electrical system.
Four reactors – two in Forsmark and two in Oskarshamn – were switched off for safety reasons.
Forsmark personnel reacted correctly in “a unique situation,” according to SKI.
The fourth reactor closed down after the scare, Oskarshamn 2, had made required changes to operating procedures, and was free to resume electricity production, Svensson said.
SKI said the incident was a level-two incident on a scale from zero to seven.
SKI has made a number of demands, including making the battery-powered network more resistant to power surges, which must be met before the two Forsmark reactors can be restarted.
No date was set by the agency for the improvements, but the power stations must adopt the changes before seeking clearance from SKI.
In conjunction with SKI’s announcement on Thursday, the Swedish government said it intended to host an international conference on nuclear safety.
“The aim of the conference will be to exchange Swedish and international experience in nuclear power in the hope of reducing the risk of incidents such as the one at Forsmark,” Swedish environment ministry spokeswoman Lena Berglund told AFP.
“All countries with an interest in nuclear power could be invited, both in Europe and from further afield,” Berglund added.
Sweden has closed two of its original 12 nuclear reactors since 1999 as part of a plan to phase out nuclear power over the next 30 years, or when the reactors’ lifespan expires.
Nuclear power accounts for nearly half of Sweden’s electricity production.