OPG completes defuelling of Darlington reactor

01 December 2020

Ontario Power Generation (OPG) has completed the defuelling of Darlington unit 3 ahead of schedule. It is the second of four units at the site that are being refurbished in a 10-year project that will enable the plant to continue operations until 2055. OPG and its project partner CanAtom Power Group - a joint venture of SNC-Lavalin Nuclear Inc and Aecon Construction Group - have now begun to prepare unit 3 for disassembly.

The turbine hall at Darlington 3 (Image: OPG)

The refurbishment of unit 3 began in September, after a four-month postponement due to the COVID-19 pandemic. The unit's 6240 fuel bundles have now been removed from the reactor using remote-controlled tooling, and placed in water-filled fuel bays where they will be stored for up to 10 years.

Preparing the reactor for disassembly will begin with a process known as islanding, which separates the unit that is being refurbished from the operating units by implementing controls and installing steel bulkheads. This is scheduled to take 55 days to complete.

"Islanding is how we create a safe and defined work area for refurbishment, protecting workers and the plant," Senior Vice President of Nuclear Refurbishment Subo Sinnathamby said.

The experience gained from the refurbishment of the Darlington unit 2, which returned to service in June, will be applied to the ongoing work. "We're making sure to build on our success by applying more than 4000 lessons learned to the plans and preparations for the refurbishments of units 3, 1 and 4. And we've already started to see efficiency gains in schedule and quality performance," he said.

Refurbishment of unit 1 is scheduled to begin in 2022 and unit 4 in 2023. The entire project is scheduled for completion by 2026.

OPG recently announced it is resuming planning activities for building new nuclear generating capacity at Darlington and is considering the construction of a small modular reactor at the site.

Researched and written by World Nuclear News