"As the year comes to a close and Pickering Unit 4 is removed from service, we extend our gratitude to the thousands of workers who have contributed to its legacy since 1973. For decades, it has played a vital role delivering safe, reliable, and low-carbon electricity for Ontario," the company said on X.

Unit 4 was the last of the four units together known as Pickering A. The four 500 MWe Candu reactors were laid up in 1997. Units 2 and 3 were subsequently retired, but units 1 and 4 were later refurbished to extend their life expectancy, with unit 4 returning to service in 2003 and unit 1 in 2005. Pickering unit 1 was taken offline and out of service on 30 September 2024.

OPG is planning to refurbish Pickering units 5-8 - together known as Pickering B - laying up the reactors in 2026 and aiming for the refurbished reactors to be back in service by the mid-2030s. It is currently refurbishing four Candu units at its Darlington site with completion expected in 2026.