Plant Operation

Slovakia / Mochovce-3 Reactor Reaches First Criticality, Set For Commercial Operation In 2023

By David Dalton
25 October 2022

Operation of new plant could take nuclear share to 65%
Mochovce-3 Reactor Reaches First Criticality, Set For Commercial Operation In 2023
Slovenske Elektrarne operates four nuclear units at two sites – Bohunice-3 and -4, and Mochovce-1 and -2 (pictured) Courtesy Slovenske Elektrarne.
Unit 3 of the Mochovce nuclear power station in southwest Slovakia reached minimum controlled output on 22 October, marking first criticality for the Russia-designed 440 MW unit.

Utility Slovenske Elektrarne, which owns and operates Slovakia’s four commercial reactors, said Mochovce-3 should reach full capacity and begin commercial operation at the beginning of next year.

The company said that although a controlled fission chain reaction is now taking place in the reactor, the power is close to zero. Station director Martin Mráz said the first startup of the reactor involves “complex tests” during which all the characteristics of the reactor’s active zone are verified.

The next stage will see Unit 3 switch from physical launch to “energy launch”, with heat from the reactor heating water to produce the steam to spin the turbines. The plant will be phased into Slovakia’s electricity system when it reaches 20%, Mr Mráz said.

Slovakia is building two Russia-designed VVER-440 units at Mochovce, about 100 km east of the capital Bratislava. In September Slovenske Elektrarne said the first fuel loading had been completed at Mochove-3, marking the beginning of the reactor startup process.

Slovakia operates four commercial nuclear reactors – two at Mochovce and two in at Bohunice, which together generate 52.3% of the country’s electricity. Slovakia has authorised the operation of Mochovce-3, which is expected to become fully operational by the end of 2022.

Operation of the new unit, Slovakia’s fifth, could bring the share of nuclear in the country’s electricity generation to 65%, putting it second behind only France, with 69%.

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