The power output of unit 3 at the Mochovce nuclear power plant in Slovakia has been increased from 75% to 90% as energy start-up tests continue, Slovenské elektrárne announced. The VVER-440 is expected to enter commercial operation in the coming months.

The Mochovce nuclear power plant (Image: Slovenské elektrárne)

The start-up process involves gradual increases in power, with tests carried out before the level is raised. The unit's power was increased to 55% in March and to 75% in July.

"After successfully performing all the energy start-up tests at a power level of up to 75% of the reactor's nominal power and submitting the test report to the Slovak Nuclear Regulatory Authority, Slovenské elektrárne has increased the power of the reactor of the third unit of the Mochovce nuclear power plant to 90%," the company said.

The unit has so far supplied about 650,000 MWh of electricity to the grid, which Slovenské elektrárne said was equal to the annual consumption of 260,000 households.

"Tests at 75% power level have been completed without delay, which brings us very close to achieving full power at reactor unit 3," said Mochovce plant director Martin Mráz.

Once tests at 90% capacity are completed, the reactor's output will be increased to 100%.

"The complete functionality of the third unit and the achievement of project parameters will be confirmed by a 144-hour demonstration run at 100% power, which will end the energy start-up stage," Slovenské elektrárne said. "This milestone is expected to be reached between September and October".

Construction of the first two VVER-440 units at the four-unit Mochovce plant started in 1982. Work began on units 3 and 4 in 1986, but stalled in 1992. The first two reactors were completed and came into operation in 1998 and 1999, respectively, with a project to complete units 3 and 4 beginning ten years later. Unit 4's schedule has been to follow about one or two years behind unit 3. Each of the units will be able to provide 13% of Slovakia's electricity needs when operating at full capacity.

Slovakia expects to become a net exporter of energy once the two new units at Mochovce are both up and running.