Nuclear power plant Kozloduy shut down one of its two 1,000-megawatt (MW) units late on April 14 over a technical problem that has caused no radiation leakage, the plant said.
The unit was switched off due to leakage of hydrogen used for cooling the turbine generator located in the non-nuclear part of Unit Five.
The power plant added that it is working to fix the problem and that it is replacing the turbine generator's hydrogen with nitrogen in order to ensure fire safety.
Kozloduy's other 1,000 MW reactor, Unit Six, is operating at 81% of its capacity.
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.