Bruce Power's Life-Extension Program has been ranked the largest infrastructure project in the country for 2017.
The Top 100 Canada's Biggest Infrastructure Projects list puts the $13-billion private investment as the top project on this year's list.
It will ensure the nuclear plant provides 30% of Ontario's electricity for the next two decades.
Bruce Power says the investment will create and sustain 22,000 jobs directly and indirectly, and inject $4-billion into the provincial economy.
The current program invests in the nuclear units to allow them to operate until their scheduled Major Component Replacement Projects begin. That will start with Unit 6 in 2020.
Planning and maintenance investments over the next three years will ensure Bruce Power is ready.