A pair of new reactors, dubbed MAPLE-1 and MAPLE-2, were to have been put into service in 2000 to take over the job of medical isotope production from the 50-year-old National Research Universal (NRU) reactor, whose shutdown late last year sparked a medical and political crisis.

But now, eight years behind schedule, with a budget that has ballooned from $140-million to $300-million or more and with no prospects of solving the technical hurdles that have bedevilled the project, AECL, with the government's backing, is pulling the plug.

"This is a good business decision. This is the right decision for the Canadian taxpayer, it is the right decision for AECL, and it is the right decision for the medical community," Natural Resources Minister Gary Lunn said in the House of Commons.

An energy industry lobbyist, speaking on condition of anonymity, said the failure of the MAPLEs is a black eye for AECL and will be singled out by its international competitors.

"This is terrible news for Canadian technology," said the lobbyist.

Liberal MP Omar Alghabra agreed: "I think it'll have great impact, negative impact on their reputation."

AECL's chief executive officer Hugh MacDiarmid said he anticipated competitors and critics would say these things about the MAPLE failure, but does not believe it will affect AECL's commercial business, selling CANDU reactors for electricity generation.

"The MAPLEs project was literally at the frontier, the first of its kind," he said. "To suggest that the outcome of this project somehow reflects negatively on our ability to deliver a CANDU reactor ... I don't connect those dots."

The shutdown of the MAPLEs will put new pressure on AECL engineers to find ways to keep the NRU reactor functioning.

The NRU, believed to be the oldest in the world, first went into service in 1957 and now produces most of the medical isotopes used in Canada and half of the global supply. Mr. Lunn said the decision to shutter MAPLE would not threaten isotope production but neither he nor AECL officials could say what project, if any, will succeed MAPLE as a replacement.

MAPLE is an acronym for Multipurpose Applied Physics Lattice Experiment.

"I can't give you anything definitive as to where we're going to be 10 years from now," said Mr. MacDiarmid, who was installed as AECL's chief executive officer in January.

Long-term planning for AECL is difficult right now because it is undergoing a strategic review, ordered by Mr. Lunn, which could lead to partial or complete privatization.

"We are committed to ensure that the medical community has their adequate supply of isotopes," Mr. Lunn said.

"The current reactor will continue to produce them. It's a marvellous piece of technology. And it's operating safer than it ever has been before in its entire history. This decision that we made today is about good governance, good management. It has no impact on the production of isotopes."

But political opponents are not prepared to accept that.

"It's hard to take them at their word," said Mr. Alghabra, the Liberal party's natural resources critic. "I think I'll be forgiven for being skeptical and raising these issues. I think all Canadians ... who suffered because of the shortage earlier this year will join me in raising these questions."