Criticality achieved Canada’s Darlington 2 following refurb

15 April 2020

Unit 2 at Ontario Power Generation's Darlington nuclear power plant has achieved first criticality following an extensive refurbishment.

The unit will now undergo a series of heat up and low-pressure testing over the coming weeks before bringing the reactor to gradually higher levels of power and then reconnecting the unit to Ontario’s grid.

Darlington 2 is scheduled to return to service this spring, OPG said.

“Achieving first criticality on the unit required an incredibly complex sequence of work that included ensuring that construction was complete, all documentation was in order, and multiple systems were returned to service,” said Mehri Molanaie, key evolution manager. “All this led to approval from the Canadian Nuclear Safety Commission to proceed. We can now move forward and complete the final steps of returning this unit to service.”

Darlington 2 was the first of the plant's four units to be refurbished as part of a CAD12.8 billion ($9bn) project that will extend its operating life for 30 years. The work began in October 2016. Refurbishment, which started in June 2018,  involved the disassembly and reassembly of the reactor.  It was completed in March.

OPG previously announced it is delaying the start of refurbishment at Darlington 3, which had been planned for May, to help ensure stable electricity supplies during the COVID-19 pandemic.

Photo: Darlington 2 has achieved first criticiality (Credit: OPG)

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