A group of environmentalists say it's a dangerous precedent to allow 16 radioactive generators to be shipped across the Great Lakes and St. Lawrence River to be recycled overseas.

The Canadian Nuclear Safety Commission will begin its two-day hearing in Ottawa Tuesday afternoon to discuss a plan for Bruce Power to ship the 16 100-tonne generators from the Bruce Power site in Owen Sound to Sweden.

Environmental groups and the mayors of more than 100 communities in the affected area oppose the plan.

Sierra Club Canada says the plan contravenes an environmental assessment approved by the Canadian Nuclear Safety Commission. It added allowing Bruce Power to ship the generators through the region would set a dangerous precedent for more nuclear waste on Canadian waterways.

"Nuclear power is the dumbest mistake Canadians have ever made," John Bennett of Sierra told a news conference Tuesday morning in Ottawa.

Gordon Edwards of the Great Lakes United Task Force on Nuclear Power and Green Energy says his organization is mostly worried about the precedent, rather than the individual shipment by Bruce Power.

"This is just the tip of an enormous iceberg because once they ship these 16 steam generators, they're going to be shipping more and more and more radioactive waste," he said.

Two days of hearing began Tuesday afternoon, with an oral presentation from Bruce Power.

The commission has already said there are no safety concerns to prevent issuing a licence for the shipment.

"By their nature, steam generators are not radioactive," the commission said in a July notice.

"They have become contaminated during their service life. The contamination level is low and confined to the inner parts of the generators. Each and every generator is welded shut and sealed."

Spokespersons for various environmentalist groups accused the Canadian Nuclear Safety Commission of not allowing a full debate on the issue during their Tuesday morning press conference.

Bruce Power is a private nuclear utility that generates about a fifth of Ontario's electricity. Its request to ship the 16 truck-sized generators is part of a plan to refurbish its plant near Lake Huron.

The original plan involved storing the generators in a cement bunker at Bruce Power's site in Tiverton, Ont. Bruce Power now wants to send the generators to Studsvik, a Swedish company that can reprocess the generators and reduce the amount of waste that would need to be stored.

The remaining waste would then be returned the Western Waste Management Facility at the Bruce Power site.

Among the dozens of non-governmental organizations, concerned citizen groups and organizations scheduled to speak at the hearing are Sierra Club Canada, Bruce County Council and the Swedish Environmental Movement's Nuclear Waste Secretariat.

The Great Lakes United Task Force on Nuclear Power and Green Energy says the public has been misinformed on the dangers of the steam generators.

"Our review of Bruce Power's and CNSC's documents have revealed that this hasty, ill-considered proposal has involved little to no planning whatsoever to deal with an emergency involving the sinking of this shipment, containing as it would over 1,400 tons of radioactive steam generators," Terry Lodge, an attorney representing the environmental coalition, said in a statement.

Bruce Power says a person would have to stand next to a generator for a few hours before they were subjected to the same amount of radiation emitted by a chest X-ray.

"The only difference between this shipment and the thousands of other shipments made each year is the size of these components," Bruce Power said in a statement.

"Because they do not fit into the containers traditionally used for shipping low level radioactive material, we require a special arrangement licence from our regulator."

Environmental groups said there are no guarantees what might happen if a boat carrying a generator ran aground or sunk.

With files from The Canadian Press