Plant owner and operator Nucleoeléctrica Argentina said the Candu 6 pressurised heavy-water reactor, which was restarted earlier this year, began operating commercially on 30 May.
The company said the plant, which has been undergoing tests since its initial restart, will operate at a full capacity of 683 MW, 6% more than its previous capacity.
Embalse was shut down in December 2015 for the $1bn project aimed at extending the life of the unit and increasing its 648-MW gross capacity to 683 MW through turbine and generator upgrades.
Argentina has three commercially operational nuclear units, two at Atucha and one at Embalse, all owned and operated by Nucleoeléctrica. According to the International Atomic Energy Agency the plants provided about 4.5% of the country’s electricity generation in 2017.