Ontario Power Generation (OPG) reported in its financial and operating results for the second quarter of 2022 that refurbishment of unit 3 of Darlington nuclear generating station was progressing ahead of schedule. Unit 3, the second of four units to undergo a mid-life overhaul, is now expected to return to service by late 2023. “The earlier return to service date reflects OPG’s commitment to incorporating lessons learned from the successful unit 2 refurbishment into the planning and execution of the refurbishment of unit 3 to date, despite the challenges posed by the COVID-19 pandemic,” OPG said.

“Unit 3 is tracking toward safely returning to service several months ahead of schedule, by late 2023,” confirmed OPG President and CEO Ken Hartwick. 

Workers completed fuel channel installation activities on 18 July.

“Fuel channel installation, and the planning and coordination necessary to complete it in an efficient way with quality, is extraordinarily challenging,” said Subo Sinnathamby, OPG Senior Vice President, Nuclear Refurbishment. “We are literally rebuilding a reactor core to the highest safety and quality standards. We could not have done this without a strong and integrated OPG/CanAtom team.”

Fuel channel installation is one of the more complex steps in the project. It requires the precise installation of 480 pressure tubes, 960 end fittings and thousands of other components. Incorporating more than 4,000 lessons learned from unit 2, the critical Retube and Feeder Replacement (RFR) enabled work on the unit 3 reactor and associated systems to progress ahead of schedule.

With fuel channels installed and leak tight, feeder installation continues with the lower segments and connection to each channel. Following this fuel will be loaded later this year. The remainder of the project will focus on bringing systems back into service testing and ensuring the unit is ready to produce power in mid-2023. Sinnathamby said this is “proof that we can, and will, successfully complete refurbishment of the remaining Darlington reactors – units 3, 1 and 4 – by the end of 2026. Unit 1 was removed from service in February to begin its 39-month long refurbishment, marking the first time that two reactors at Darlington will be in refurbishment outages at the same time. 

Image: Reactor face of Darlington Unit 3 (photo courtesy of OPG)