A reactor at the nuclear power plant in Forsmark has unexpectedly been taken out of operation on Monday morning, according to a statement from the electricity exchange Nord Pool.
Disruptions to the internal electrical system meant that the pumps regulating the cooling water stopped. However, there has been no danger, says Forsmark's press officer Johanna Blavier.
It is unclear when the fault can be rectified, but it should not take too long.
The reactor, Forsmark 3, normally produces 1,170 MW. The other two reactors at Forsmark are functioning as they should.