Ontario Power Generation (OPG) can proceed with the refurbishment of Darlington unit 3 after receiving the go-ahead from the province's Ministry of Energy. Refurbishment of Darlington unit 2 has now passed the half-way mark.

OPG celebrates the approval of Darlington 3's refurbishment (Image: OPG)

Darlington 3 will be the second of the plant's Candu units to undergo refurbishment in a project that will enable the 3512 MWe plant to continue operations until 2055. All four units are to be refurbished in a phased CAD 12.8 billion ($9 billion) project which is scheduled for completion by 2026.

"The government took a phased approach to Darlington refurbishment, with each unit requiring individual approval to proceed," OPG president and CEO Jeff Lyash said. "The go-ahead to move forward with the next unit is a testament to the hard work and dedication of the Darlington Refurbishment team."

Ontario's electricity generation was 90% free of greenhouse gas emissions in 2016, and its 2017 long-term energy plan, published in October, recognises the refurbishment of existing nuclear power plants as the most cost-effective option for meeting the province's baseload generation needs. Nuclear power - from OPG's Darlington and Pickering, and Bruce Power's Bruce plant - supply enough power to meet about 60% of the province's electricity needs.

Ten Candu units are to be refurbished between 2016 and 2033 - four at Darlington and six at Bruce. The Pickering nuclear power plant will continue to operate until 2024 to provide baseload electricity during the Darlington and initial Bruce refurbishments. Bruce Power has already begun its Life Extension Project, with the first major component replacements scheduled to begin on unit 6 in 2020.

Bruce Power President and CEO Mike Renchek said the two companies had proved that nuclear refurbishment projects could be delivered efficiently and effectively.

"The two largest infrastructure projects in Canada are the Bruce Power and OPG refurbishments, and both remain on-time and on-budget," he said. The two companies will continue to share resources and implement lessons learned from their projects, he added.

Refurbishment of Darlington unit 2 formally began on 14 October 2016 after six years of planning, and will take some 40 months to complete. The project passed the half-way mark on 15 February and remains on time and on budget, OPG said.

All 960 end fittings from the reactor's fuel channels have now been removed from the reactor core, enabling work to begin on the removal of pressure tubes. This will be achieved using remotely controlled automated retooling platforms. Removal and replacement of the reactor's 480 calandria tubes, 480 pressure tubes and 960 feeder pipes is the largest work package in the refurbishment project.

The planned refurbishment outage sequence at Darlington calls for refurbishment of unit 2 to be completed before the start of work on unit 3, to allow the implementation of lessons learned. OPG's schedule sees work beginning on unit 3 in February 2020, on unit 1 in July 2021 and unit 4 in January 2023.

Glenn Thibeault, Ontario's minister of energy, said the Darlington refurbishment would ensure that "reliable" nuclear energy continued to be the "backbone" of the province's generation fleet.

"This multi-phase project will continue to boost economic activity across Ontario, create jobs and secure a clean supply of affordable electricity for the future," he said.

Investments in refurbishing Ontario's nuclear fleet provide a strategic advantage for the province, Canadian Nuclear Association President and CEO John Barrett said.

"Our nuclear generating stations provide low-cost electricity, paramount to job creation and economic growth, while simultaneously allowing the province to continue to offset harmful greenhouse gas emissions," he said.