The nuclear reactor that produces medical isotopes at the Atomic Energy Canada Limited plant in Chalk River, Ont., was out of commission for more than a year. (Fred Chartrand/Canadian Press)

The nuclear reactor in Chalk River, Ont., can resume production of medical isotopes after a long shutdown, Atomic Energy of Canada Ltd. says.

"The reactor is now operating at high power and can begin to create medical isotopes," AECL said in a statement on its website Tuesday.

AECL is working to get its first shipment of isotopes out this week, said spokesperson Robin Forbes.

The 53-year-old reactor was capable of providing a third of the medical isotopes needed worldwide until AECL shut it down in May 2009 because of a heavy water leak.

The reactor was originally supposed to be down for a month but the outage lasted 15 months.

Doctors and others in the medical community had to look for alternative sources and types of medical isotopes and reschedule patients to deal with periodic shortages during the shutdown.

Medical isotopes are used to diagnose cancer and heart ailments.

Multiple shutdowns

Chalk River's importance first gained worldwide attention in 2007 when the reactor was shut down for maintenance, causing a worldwide shortage of medical isotopes.

It made headlines again in August 2008 when the other four major producers of isotopes — reactors in the Netherlands, Belgium, France and South Africa — all scheduled maintenance and refuelling stops within weeks of each other, forcing doctors to scramble for alternatives.

In November 2009, the expert review panel on medical isotope production established by Natural Resources Canada released its report calling for less reliance on Chalk River by diversifying into other sources of medical isotopes.

"It's been quite difficult," said Dr. Jean-Luc Urbain, head of the Canadian Association of Nuclear Medicine.

"Usually Mondays and Tuesdays we cope quite well. And then Wednesdays, Thursdays and Fridays it's all but abysmal in terms of the number of studies that we're able to do."

Restarting the Chalk River reactor is good news in that it will reduce the strain on the supply of medical isotopes in Canada and around the world, said Dr. Christopher O'Brien, president of the Ontario Association of Nuclear Medicine.

In June, the Canadian Institute of Health Information reported that the latest shortage led to a 22 per cent decrease in cardiac, bone and lung diagnostic tests.

Those findings show "patient care has become more complicated and perhaps not as good," said O'Brien, noting the last outage was less disruptive than the shutdowns in 2007 and 2008 when the medical community first struggled to find alternatives.

The National Research Universal reactor at Chalk River is set to close in 2016.

In April, the Conservative government said it will spend $35 million to find ways to make isotopes without a nuclear reactor. Another $13 million will be spent to find better ways to stretch the existing supply.

But Canada still does not have an alternative plan for after 2016, when rural areas of the country could have trouble getting the isotopes they need, O'Brien said.

With files from The Canadian Press