Unit 4 of Slovakia’s Mochovce NPP has begun power generation after receiving the consent of the Nuclear Regulatory Authority (ÚJD SR – Úrad jadrového dozoru Slovenskej republiky). Operator Slovenske elektrárne said this is the last major stage before the unit is put into operation.
The 417 MWe VVER-440/V213 reactor achieved criticality in August after evaluation physical trigger results, the checks carried out and the assessment of the documentation confirmed the readiness of the block for the next stage of the commissioning.
During the power start-up, the reactor power will gradually increase to a nominal level. At each power level, the prescribed operational tests and measurements will be carried out to verify the correct functioning of the technological systems, safety features and the behaviour of the reactor under different operating modes.
“Behind us are successfully mastered stages of loading fuel and physical launch,” said Mochovce Project Director Martin Mráz. “Before us is a series of operational tests, during which we will gradually increase the performance of the block and confirm the readiness of individual devices for long-term operation. The milestone achieved is a confirmation of the high professional level of the project team of Slovenské elektrárne and the quality of work of all those who participated.”
The reactor’s power output will now be gradually increased in stages (5%, 20%, 35%, 55%, 75% and 90%) with checks and tests at each level. It will be phased into Slovakia’s electricity system when it reaches 20%. The final test will be a 144-hour run at 100% power.
“After the successful completion of this phase, Slovakia will gain a new stable source of electricity that will contribute to the country’s energy security and the achievement of its climate goals for decades,” said Branislav Strýček, Chairman and CEO of Slovenske elektrárne.
Mochovce NPP comprises four VVER-440 units. Units 1&2 began operation in 1998 and 1999 and unit 3 began commercial operation in October 2023. Units 3&4 with a design life of some 60 years, will supply some 26% of Slovakia’s total electricity consumption.
Construction of units 3&4 began in 1986 but was suspended in 1992 and resumed only after a lengthy hiatus in 2008. SE puts the value of the entire project at approximately €6.7bn ($7.7bn), up from an estimated €2.8bn in 2008. With the addition of Mochovce 4, Slovakia will have six power reactors in operation. Slovakia also has two VVER-440 units operating at the Jaslovské Bohunice. With all six units in operation, nuclear power should cover approximately 77.5 % of domestic electricity consumption.
