New Slovak reactor reaches full power

26 September 2023

The power output of unit 3 at the Mochovce nuclear power plant in Slovakia has been increased from 90% to 100% as energy start-up tests continue, Slovenské elektrárne announced.

Mochovce units 3 and 4 (Image: Slovenské elektrárne)

The start-up process for the VVER-440 reactor involves gradual increases in power, with tests carried out before the level is raised. The unit's power was increased to 35% in February, 55% in March, 75% in July and 90% in August.

The company now said it completed all the power escalation tests at levels up to 90% in early September. A report on the tests was prepared and submitted to the Slovak Nuclear Regulatory Authority, which confirmed it had fulfilled the conditions to increase reactor output to 100%. Slovenské elektrárne will now perform the final power escalation tests at this power level, followed by a 144-hour trial run.

"After the demanding tests required to prove the safe operation of unit 3, we have reached the final stage," said Peter Farkaš, operations manager at the Mochovce plant. "Full-scale tests are planned for the end of September and the beginning of October, including the 144-hour trial run. All tests so far have confirmed the readiness of the new unit for long-term safe and CO2-free power generation."

Slovenské elektrárne Chairman and General Director Branislav Strýček added: "This is a historic moment for Slovenské elektrárne and Slovakia. Congratulations and thanks to all colleagues, suppliers, regulatory, controlling and partner institutions, who have worked hard towards achieving this important milestone and ensuring that electricity production in Slovakia will be even cleaner and greener for today's and future generations - for at least the next 60 years."

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.

Slovenské elektrárne noted that since being connected to the grid on 31 January this year, Mochovce 3 has, during tests, gradually supplied over 1000 GWh of electricity, sufficient to cover the average annual consumption of about 400,000 Slovak households. It said that at full power, the unit can cover the consumption of up to 1.3 million households per year.

"In terms of electricity production, the country is becoming energy self-sufficient already this year," the company said. Slovakia expects to become a net exporter of energy once the two new units at Mochovce are both up and running.

Researched and written by World Nuclear News