TORONTO - Ontario should turn its back on old nuclear reactors in Pickering and reconsider its overall strategy to avoid saddling taxpayers with soaring costs, an environmental group said Wednesday.

Greenpeace energy analyst Shawn-Patrick Stensil is urging the government to re-evaluate its cost targets, saying current estimates to build nuclear plants are "fantasy" based more on the "hopes and prayers" of the nuclear industry than reality.

In a report released Wednesday, the group said the cost of building planned reactors has more than doubled in the last three years -- and taxpayers risk being stuck with the bill.

"If the vendor is AECL (Atomic Energy of Canada Ltd.), there is only one taxpayer," Stensil said. "And the federal government will be on the hook in some way -- thus the federal taxpayer -- for cost overruns and delays."

Ontario currently has three operating nuclear plants: Pickering and Darlington east of Toronto, and Bruce on the shores of Lake Erie.

The province is planning a major expansion of the system over the next two decades that includes building two new reactors at the Darlington site as it aims to generate 50 per cent of the province's electricity with nuclear power. Officials must also decide whether to refurbish the Pickering B reactors or build new ones instead.

Greenpeace wants Energy Minister George Smitherman to shut down Pickering B early next year and replace it with green energy.

Stensil argued that while the actual figures won't be known until the bids come out in the spring, the current financial crisis is making the government's "nuclear cost delusion more of a financial nightmare."

In Finland, Stensil said, the construction of a reactor by one of the Darlington bidders is three years behind schedule and $4 billion over budget.

Smitherman declined to comment Wednesday on the government's plans for Pickering, but said in the legislature that the complex is far from ideal.

"Those are old nuclear plants," he said. "They're small. It's outdated technology.

"It's part and parcel of why we think it's important to renew our nuclear fleet, recognizing that it's providing about 50 per cent of all of the electricity that we're using in the province of Ontario."

New Democrat Leader Howard Hampton asked that any decision about refurbishing Pickering B be submitted to the provincial auditor as well as a legislative committee.

"No matter what (the government) says this nuclear plant will cost, you can pretty much count on it costing double when the final bill comes in, and that's resulting in very expensive electricity in Ontario," Hampton said.

"Very expensive electricity is one of the things that's killing manufacturing jobs in the province."

The Greenpeace report also suggested that under Ontario's current plan, the Liberal government will miss its 2014 greenhouse gas reduction targets by a third.

Smitherman has asked the Ontario Power Authority to review a "modest" portion of the province's power plan and explore the role of renewable energy and conservation. But he's made it clear that Ontario doesn't want to turn away from nuclear altogether.

"Fifty per cent of all the electricity that we use in the province of Ontario -- base-load supply -- comes from nuclear," Smitherman said.

"Having reliable base-load supply is one of the necessary features to have ambitions with respect to renewables, because they do have issues with respect to intermittency."