Slovenske Elektrarne said the VVER-440 pressurised water reactor unit had reached 20% of its design output levels before being connected to the grid.
On 13 January, the company received regulatory approval to begin startup procedures for Mochove-3. Power levels would be gradually increased to 100% of the nominal reactor output with testing continuing at various stages of the process.
Mochovce-3 has an installed capacity of 471 MW and is expected to meet about 13% of Slovakia’s electricity consumption, Slovenske Elektrarne said.
A significant portion of the startup process lies ahead with testing to continue at various stages between 35% and 100% of nominal power levels.
Martin Mraz, director of the Mochovce nuclear power station, said the process will include planned short-term shutdowns of the reactor systems.
Mochnovce-3 achieved first criticality on 22 October 2022 after fuel loading a month earlier.
Earlier reports said the unit was expected to enter full commercial operation at the beginning of 2023.
Slovakia operates four commercial nuclear reactors – two at Mochovce and two at Bohunice – all of the Russia-designed VVER-440 type. Together the fleet generated about 52% of the country’s electricity in 2021.
Operation of the new Mochovce-3, Slovakia’s fifth unit, could bring the share of nuclear in the country’s electricity generation to 65%, putting it second behind only France, with 69%.