Bulgaria's sole nuclear power plant (NPP) Kozloduy said on Thursday that it has reconnected its 1,000 MW Unit 6 to the grid following a shutdown of about three hours caused by the malfunctioning of two of the main circulation pumps.The reasons for the shutdown have been eliminated and all tests of the unit's systems were completed successfully, the power plant operator said in a statement.Unit 6 was disconnected from the grid earlier on Thursday after two of its main circulation pumps shut down, activating the protection system.NPP Kozloduy's other functioning 1,000 MW Unit 5 is operating at full capacity.