"New nuclear will not be part of the long-term energy plan which we hope to finalize before the end of this year," Energy Minister Bob Chiarelli told reporters.
"We're in a comfortable surplus position at this point in time, and it's not advisable to make the major investments in new nuclear."
Costs have fallen since the province first paused its plans to build two new reactors in 2009, when the estimated price was said to be as high as $26 billion.
"The costs have come down, but they have not come down enough to justify us building new nuclear when we have a very comfortable surplus," said Chiarelli.
"It is not wise to invest billions and billions of dollars in new nuclear when the power is not needed."
The Progressive Conservatives said backing off on the new reactors was proof the Liberals have given up on getting Ontario's manufacturing sector back on its feet, which would drive up demand for electricity.
"There is no clearer indication that this government has tossed up the white flag to say that the jobs aren't coming back, and that is incredibly concerning to me," said PC energy critic Lisa MacLeod. "We know that if the economy is to pick up, we're going to need those nuclear reactors."
The New Democrats welcomed the decision to kill the new nuclear builds, but said the government should have made it before it gave companies millions to help with applications for the new reactors.
"It's a good development," said NDP energy critic Peter Tabuns, "but I just wish it had come sooner before we spent $26 million giving these nuclear companies cash to prepare their tenders."
The Society of Professional Engineers accused the Liberals of political interference in the long-term energy plan, and said no decision on new nuclear builds should be made until competing options have been examined by the Ontario Energy Board.
"Have we learned nothing from the recent gas plant fiasco," asked the group's president Scott Travers. "When politicians make hasty policy to score political points every Ontarian pays."
Auditor general Bonnie Lysyk reported this week that the total cost of the Liberals' decisions to cancel gas-fired generating stations in Oakville and Mississauga prior to the 2011 election could hit $1.1 billion dollars.
The province will go ahead with the refurbishment of existing nuclear reactors at Bruce Power near Kincardine and the Darlington Nuclear Generating Station in Clarington, added Chiarelli.
"The schedules for those has not been finalized, but they will create probably 8,000 to 10,000 jobs," he said. "The budgets and the procurement have not been completed with respect to refurbishment."
The government also left the door open to building the new nuclear reactors should projected energy demand rise in the future.
"Sometime in the future we might be looking at it, but certainly it's not part of this long term energy plan," said Chiarelli.
Greenpeace Canada applauded Premier Kathleen Wynne for killing the new nuclear reactors, but urged the government to proceed cautiously with refurbishments.
"The Wynne government deserves credit for finally ending the charade that new reactors are needed and cost effective," said Greenpeace spokesman Shawn-Patrick Stensil. "Hopefully the government won't take the industry's cost claims for the refurbishment at face value and require a full public review."
The Canadian Nuclear Association declined to comment Thursday on Chiarelli's announcement.
Ontario currently gets about 50 per cent of its electricity from nuclear generation, and Chiarelli said it will likely be around the 47 per cent mark when the government's long-term energy plan is released later this year.
Last year, Ontario's mix of energy sources was 53 per cent nuclear, 21 per cent hydro, 13 per cent natural gas, five per cent from wind and solar and three per cent from coal, which will be completely phased out by next year.Suggest a correction