The timetable for decommissioning the half century-old Pickering nuclear generating station stands to shift if a new plan from Ontario Power Generation gets approved by Canada's nuclear regulator.

The plan would see four of Pickering's six nuclear reactors operate for an extra year beyond the currently scheduled shut down date at the end of 2024, Ontario Energy Minister Greg Rickford said Tuesday.

Cabinet has given its nod to the proposal from OPG for what Rickford called "optimization" of the timeline for decommissioning Pickering, which is Canada's oldest nuclear power plant, in commission since 1971.

The proposed changes to the operating plan will be put forward for public consultation and would be subject to approval by the Canadian Nuclear Safety Commission (CNSC), Rickford said.

"We're not in a place right this moment to make a comment as to whether that will definitively happen," he told reporters at Queen's Park. "Hopefully we'll be in a position to announce something in the coming months."

The Pickering nuclear power plant leapt unexpectedly into the minds of millions on Sunday morning when a test message from Ontario's emergency operations centre warning of an incident was mistakenly sent live to mobiles phones across the province.

The provincial government took responsibility for an erroneous emergency message sent on Sunday about the Pickering Nuclear Generating Station. (Darren Calabrese/The Canadian Press)

No incident of any kind occurred at Pickering, officials have confirmed. The provincial government took responsibility for the erroneous emergency message, apologized and launched an investigation.

The CNSC renewed Pickering's operating licence last year, approving its shut-down plan and giving it the authority to continue generating power until Dec. 31, 2024.

"The commercial operation of any reactor unit beyond 2024 would require authorization," said the nuclear commission at the time.

OPG proposed the change to the phase-out timeline as a better way of transitioning its workforce, said Rickford. He said keeping one reactor unit operating into 2025 would mean "a certain amount of people will stay on longer."

The Pickering plant provides about 4,500 jobs, according to OPG's website. Many of those workers and their families live in such swing ridings as Pickering-Uxbridge, Ajax and Durham, making the fate of the plant a potential political issue in the 2022 election.

"Just like any energy generation project, the NDP wants to see the business case to determine if it's prudent to extend Pickering beyond its slated lifespan," New Democrat energy critic Peter Tabuns said in a statement. .

Extending the plant into 2025 would see it operating more than a decade past its "best before date," said an official with Greenpeace Canada, long opposed to nuclear energy.

"This secretive decision by the Ford government puts Ontarians at greater risk, said Greenpeace program director Shawn-Patrick Stensil in a statement. "Any transparent economic or risk assessment would opt for replacing this obsolete plant with safe, lower-cost renewable energy."