Spanish energy companies Iberdrola, Endesa and Naturgy have agreed to seek an extension of the Almaraz nuclear plant’s lifespan and are working on a formal request to the energy ministry, reports in Spain have said.

A major blackout in April revived the debate over the need for baseload nuclear power in the country, which plans to close all of its seven commercial nuclear units by 2035.

The move by the three companies could be the first step to Madrid rethinking its plan to shut down the country’s fleet of reactors.