Nuclear energy is gaining significant momentum in Canada's Ontario province, with new plans to expand an existing plant to become the world’s largest and a pledge to add three small modular reactors to a site where another is already being built.

The news marks a shift for an industry that has been stalled for decades amid fears about safety and cost overruns. It’s also seen as a critical step in modernizing an aging power grid that needs to add capacity without boosting already high electricity costs, or threatening emissions goals.

The 2011 Fukushima No. 1 meltdown — the worst disaster since Chernobyl — slammed the global brakes on nuclear power plans. The Vogtle debacle in the U.S. also provided grist for nuclear’s opponents, in the form of yearslong delays and a price tag $16 billion over budget.