Fuel channel installation has been completed at Darlington unit 3, and the unit is now expected to return to service by late 2023 - several months earlier than planned - Ontario Power Generation (OPG) has announced. The unit is the second of four Darlington units to undergo a mid-life overhaul.

The reactor face of Darlington 3 (Image: OPG)

Workers completed fuel channel installation activities on 18 July, the company said in its quarterly update on the project, meaning the reassembly of the reactor core is complete.

"Fuel channel installation, and the planning and coordination necessary to complete it in an efficient way with quality, is extraordinarily challenging," Subo Sinnathamby, OPG Senior Vice President, Nuclear Refurbishment, said. "We are literally rebuilding a reactor core to the highest safety and quality standards."

The procedure required the precise installation of 480 pressure tubes, 960 end fittings and thousands of other components. Retube and Feeder Replacement - of RFR - work at the unit 3 reactor and its associated systems is progressing ahead of schedule thanks to the incorporation of more than 4000 lessons learned from the previous refurbishment of Darlington unit 2, the first Darlington reactor to be completely refurbished.

"This milestone is not just significant to Darlington Nuclear and OPG", Sinnathamby said. "This is also symbolic for the nuclear industry as a whole. We have again demonstrated our diligent oversight and expertise to complete this job with quality - proof that we can, and will, successfully complete refurbishment of the remaining Darlington reactors … by the end of 2026."

Feeder installation now continues with the lower segments and connection to each channel, and fuel load is expected to take place later this year. The remainder of the project will then focus on bringing systems back into service testing ready to produce power for in mid-2023, the company said.

The Darlington units are being refurbished in a CAD12.8 billion (USD10.1 billion) project that will enable the station to operate for an additional 30 years. Unit 2 returned to service in June 2020 and, following a short delay related to the COVID-19 pandemic, work on unit 3 began in September 2020. The refurbishment of unit 1 began earlier this year and is expected to take 39 months to complete. Work on unit 4, the final unit to be refurbished, is scheduled to begin in the third quarter of 2023.

Researched and written by World Nuclear News