The VVER-440 unit, which was connected to the grid for the first time on 15 October, has now produced about 16.2 GW of electricity, which is equivalent to the annual consumption of about 6,500 households.
It was connected to the grid when its power output was at about 20%, and the power was increased after a series of tests and measurements took place. Similar checks will take place at 35% power, before it is increased in stages to 55%, 75%, 90% and eventually 100% power.
Martin Mráz, Slovenské elektrárne’s project director for the completion of the units, said: “By achieving 35% performance, we are entering the next part of the energy start-up programme. At each performance level, we have a set range of tests, with which we verify the behaviour of the unit in specific operating conditions. Only after their completion and evaluation do we continue with higher performance.”
The final step of the commissioning process for the 471 MWe unit – which is equal to about 13% of Slovakia’s total current consumption – will be a 144-hour trial run at full power.
Background
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 at an estimated cost of EUR6.7 billion (USD7.6 billion). Mochovce 3 entered commercial operation in October 2023. Mochovce 4 reached criticality on 6 August, ahead of its October grid connection.
Slovenské elektrárne’s majority shareholder is Slovak Power Holding BV, which is owned by the Czech energy group Energetický a průmyslový. The second shareholder is the Slovak Republic, which has a 34% stake.
Slovakia already has five nuclear reactors generating more than 60% of its electricity. As well as the other three Mochovce units, there are two at Bohunice, which went into commercial operation in 1984 and 1985, respectively. When the new unit is running at full capacity it will reinforce the Slovak Republic’s position as the country with the highest proportion of its electricity generated by nuclear power. The Slovak government has plans for a new large unit at Bohunice – a Westinghouse AP1000 reactor – and has also been exploring the potential for small modular reactors in the country.
