The fire began at the Ringhals plant’s 915-megawatt No. 3 reactor’s transformer at about midnight and was extinguished about two hours later, said Gosta Larsen, the chief public information officer for Vattenfalls at Ringhals, Bloomberg reported. The fire – is as typical for such reactors – triggered an automatic shutdown and there was no danger to the reactor, Larsen said.

“We are now shutting down the plant to a total hold,” Larsen said as quioted by Bloomberg. “We are cooling it down to resting. It will also take some time to restart it, some days at least.”

The Ringhals facility on the Swedish west coast is the Nordic region’s biggest power plant, producing about one-sixth of the electricity used in Sweden. The No. 3 unit is a pressurized water reactor that started commercial operations in 1981, according to the Ringhals plant’s Web site.

The transformer at Ringhals will probably have to be replaced, and Vattenfall doesn’t have a spare one on site, Larsen said.

Ringhals is 70 percent owned by Vattenfall and 30 percent by Germany’s E.ON AG. One reactor at the Vattenfall-operated Forsmark nuclear plant stopped on July 25 because of a fault in the station that sends power from the plant to the high-voltage grid, Bloomberg said. Two of the reactor’s four back-up diesel-generators failed to start automatically and had to be started manually.

The largest power producers active in Sweden are Vattenfall, E.ON and Finnish utility Fortum Oyj, which together control the country’s 10 nuclear reactors and close to 90 percent of total generation capacity, the news agency reported. Sweden, which is Scandinavia’s largest economy, plans to eventually phase out nuclear energy.