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Darlington Refurb Project News

Refurbishment of Darlington Nuclear’s Unit 3 now underway

OPG building on the success of Unit 2’s completion

Since the start of execution on the Darlington Refurbishment project nearly four years ago, OPG and its project partners have reached several significant milestones, culminating with the successful reconstruction of the Unit 2 reactor and its return to commercial service this past spring.

A fuel bundle used in CANDU reactors. Darlington's Unit 3 is now underway with defuelling.
A fuel bundle used in CANDU reactors. Darlington's Unit 3 is now underway with defuelling.

Now, following a postponement as a result of the COVID-19 pandemic, the project team is ready to build on its success, starting with defuelling Unit 3, the second reactor scheduled for refurbishment.

The first major work series on the project’s critical path, defuelling, involves the remote-controlled removal of 6,240 fuel bundles from the reactor over the course of 90 days. Workers will place these bundles inside water-filled fuel bays for up to 10 years of safe storage. Once the bundles have been removed, the team will drain heavy water from the unit’s reactor systems.

While the team has already experienced success in previously defuelling Unit 2, the process won’t be identical for Unit 3.

“Continuous learning is the key to success on any project, especially a mega-project like the Darlington Refurbishment,” said Subo Sinnathamby, Senior Vice President, Nuclear Refurbishment. “We have the benefit of having collected more than 4,000 lessons learned during work on Unit 2 and have been applying them to Unit 3 to deliver significantly greater results, including during defuelling.”

Some of those lessons learned have resulted in increased fuel equipment reliability, improved schedule predictability and greater alignment and support between teams.

“Darlington’s fuel handling team has worked very hard to ensure the fuel handling equipment is reliable and our operations, maintenance and engineering groups are trained and ready to execute Unit 3’s defuel campaign,” said Steve Gregoris, Senior Vice President, Darlington Nuclear. “We’re ready to build on Unit 2’s success, as we work as one team to build Darlington for the future.”

Following the completion of Unit 3’s defuelling in late fall, workers will begin islanding, a process that will physically isolate the reactor from Darlington’s three remaining operating units.

The four-unit Darlington Refurbishment project is on track for completion by late 2026.