Reactor 3 at the Oskarshamn nuclear plant was disconnected from the grid on Wednesday, Xinhua news agency reported.
“We are troubleshooting and do not yet have any forecast (for when it may be online),” Desiree Ljljevall, communications director for OKG nuclear company, was quoted by the local media as saying.
Reactor 3 has an output of 1,400 megawatts and if the problem persists, it may cause (power supply) problems, said spokesperson for the national grid authority Erik Ek.
“We will then have a problem on really cold days,” he added.
At the end of August, it was reported that another reactor, Ringhals 4 in the southwest of the country, would be inoperable for months due to a damaged pressure vessel.
Later, local media reported that the stoppage of the reactor, which has an output of 1,130 megawatts, was expected to last until January 31 next year.
Christian Holtz, an electricity market analyst at consulting company Merlin & Metis, told the Swedish TT news agency that the stoppage of Reactor 3 would have a major impact.
Electricity prices are likely to soar even higher, as most of Sweden’s electricity is produced in the north, and the reactor stoppage could compound existing problems with the power transmission grid.
According to the Swedish Radiation Safety Authority, nuclear power accounts for approximately 30 per cent of electricity production in the country.
There are six nuclear reactors in operation at three nuclear power plants: Forsmark, Oskarshamn, and Ringhals.