A unit of Bulgaria's sole nuclear power plant Kozloduy was shut down on Saturday over a technical problem that has already been fixed and that has caused no radiation leakage, the power plant said on Sunday.
The 1,000 megawatt (MW) Unit Six is expected to be reconnected to the country's power grid on Monday, the power plant said in a statement.
Unit Six was disconnected from the power grid after one of the generator's safety systems in the conventional, non-nuclear part of the unit was automatically activated. The generator's switch-off did not trigger the reactor's emergency safety shutdown system, it added.
On Thursday the plant said it reconnected to the grid the 1,000 MW Unit Five after it underwent routine annual maintenance.
Kozloduy remained with just two 1,000 MW operational reactors after the government closed down four units of 440 MW each to address nuclear safety concerns of the European Union prior to the country's accession to the bloc. Bulgaria joined the EU in 2007.