Europe’s largest nuclear fusion energy project, the International Thermonuclear Experimental Reactor (Iter) at Cadarache in southern France, is now in a key phase of machine assembly and is both on budget and on schedule, the head of the project has said.

Iter director general Pietro Barabaschi said that lessons had been learned following multiple delays that set the project back and sent its costs to over €22bn ($25.7bn).

The project’s assembly began in 2020 and was forecast to take five years, but is still ongoing. Iter is targeting 2034 to begin experiments with the tokamak reactor facility.