Green Party Leader Elizabeth May called Tuesday for a full public inquiry into the conduct of Atomic Energy of Canada Ltd. after a further shutdown of its nuclear reactor at Chalk River, Ont.

The reactor, which supplies 30 per cent of the world's medical isotopes, was shut down May 15 after inspectors detected a heavy-water leak inside the facility.

AECL ran out of medical isotopes over the weekend and doctors are scrambling to hoard a scarce supply from the world's four other isotope-producing reactors.

AECL said it still doesn't know how long the 52-year-old National Research Universal reactor will be offline, but an official with the operator said it could be a long shutdown.

Speaking in Ottawa, May said Canada has squandered hundreds of millions of taxpayer dollars to build and repair an "uncontrollable" reactor with an untested design.

In the meantime, May said, the Conservative government still doesn't have a long-term solution to the crisis.

"Only 18 months later, here we are again, the Chalk River reactor is shut down," she said.

"Only this time, they don’t quite know what is wrong with it. They’re not sure how long it will take to fix it."

May said Canada "is letting down the world" with its handling of the shortage, and called for an "aggressive global effort" to replace the Chalk River reactor and meet global isotope supply demands.

She also offered advice for the Ontario government not to buy two new reactors from AECL, seeing as it built the two reactors at Chalk River that "simply don't work."

Neil Alexander, president of the Organization of Candu Industries, which represents 140 nuclear-related companies employing more than 30,000 Canadians, took exception to May's claims, calling them "incredibly irresponsible."

"It's a complete lie and it's not actually substantiated by any fact," said Alexander, whose member companies supply parts and build reactors.

"If you look at the projects where AECL has been building power reactors, they have probably one of the best records of any constructor in the world."

'Made in Canada crisis': Liberal critic

May also reiterated her charges that instead of going after AECL during the last shutdown of the reactor in 2007, the government and former natural resources minister Gary Lunn made the "unconscionable" decision to attack the then-head of the Canadian Nuclear Safety Commission, Linda Keen.

Keen, who was in the press gallery for May's news conference, was fired by Lunn in January 2008 for what Lunn said was the government's loss of confidence in her leadership over the way she handled the shutdown.

The two-month closure in 2007 followed the Canadian Nuclear Safety Commission's discovery that the reactor had been operating for 17 months without two cooling pumps hooked up to an additional emergency back-up power system capable of withstanding a severe earthquake.

Facing a crisis, Parliament voted to overrule the commission's safety objections and the reactor was restarted in December 2007 with only one pump connected to the emergency power supply.

May said restoring the independence of the Canadian Nuclear Safety Commission was an "essential first step.”

Medical isotopes — tiny radioactive particles that can be injected into the body — have become the standard treatment for some cancers and have also brought medical imaging to new levels.

During Tuesday's question period, Liberal environment critic David McGuinty accused the government of creating a "made in Canada" crisis in its handling of the reactor over the past two years.

"There is no Plan B," McGuinty told the House. "There is no one left to blame, and there is no one left to fire."

Natural Resources Minister Lisa Raitt, who has previously acknowledged the world supply of isotopes is too dependent on the Chalk River reactor, replied that Canada is taking action by working with international partners in Europe and Australia to counter the shortage.

In the meantime, Health Minister Leona Aglukkaq is working with provinces and territories to stem the shortage for patients and doctors in Canada, Raitt added.

With files from The Canadian Press