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Darlington Refurb Project News

Darlington's Unit 3 ready to begin reactor disassembly

Strong performance brings Unit 3 reactor refurbishment ahead of schedule

The Darlington Refurbishment Project has completed a significant milestone with the successful separation of the Unit 3 reactor and its systems from the three remaining operating units at Darlington Nuclear Generating Station.

A reactor vault equipment airlock at Darlington Nuclear Generating Station.
A reactor vault equipment airlock at Darlington Nuclear Generating Station.

On Jan. 6, workers installed the last bulkhead section to complete a physical protective barrier 10 days ahead of the originally planned 44-day schedule. But more significantly, it was done safely.

The installation of the bulkhead, which involved welding together 16 steel panels each weighing more than 5,000 kilograms, is part of ”islanding” – or physically isolating – Unit 3 to create a safe and defined work area for refurbishment and protect workers and the plant.

More than 4,000 lessons learned were captured from the refurbishment of Unit 2, which successfully returned to service in June 2020. Welding techniques and weld quality were identified as areas for improvement, leading to enhanced training and assessment programs.

The bulkheads were sequenced to streamline work flow and gain efficiencies.

To certify islanding is complete, a series of positive and negative pressure tests, called a Containment Pressure Test (CPT), were conducted to verify an airtight seal around the bulkhead.

A successful CPT on Jan. 14 marked the end of the islanding activities on Unit 3 and the start of the next segment of work, the Removal series, which will see the reactor taken apart. The removal series is scheduled to last 311 days.

“We’ve isolated the refurbishment unit from the day-to-day operations of Darlington Nuclear,” said Subo Sinnathamby, Senior Vice President, Nuclear Refurbishment. “This means the other operating units at the power plant will continue producing electricity for the province while we simultaneously remove critical components on Unit 3. I’m most proud that we achieved this milestone safely and ahead of schedule and on budget.”