The Chalk River, Ont., reactor has been shut down since May 2009. That was when inspections uncovered a heavy-water leak and corrosion at the base of the reactor vessel.The Chalk River, Ont., reactor has been shut down since May 2009. That was when inspections uncovered a heavy-water leak and corrosion at the base of the reactor vessel. (Canadian Press)

A nuclear reactor in Chalk River, Ont., where medical isotopes are made has received the green light to restart operations after being shut down for more than a year.

The Canadian Nuclear Safety Commission announced Wednesday afternoon that it was authorizing Atomic Energy of Canada Limited to reload fuel into the National Research Universal reactor.

That means the reactor could begin making medical isotopes again by the end of the month.

The commission regulates the use of nuclear energy and materials in Canada.

The reactor has been shut down since May 2009. That was when inspections uncovered a heavy-water leak and corrosion at the base of the reactor vessel.

The resulting prolonged shutdown led to a worldwide shortage of radioactive isotopes, which are used for medical imaging.

At a one-day hearing on Monday, AECL president and CEO Hugh McDiarmid said he and his colleagues are now confident the reactor is ready to resume safe operation following months of complicated repairs and testing.

Fit for service

Peter Elder, director general of the nuclear safety commission's directorate of nuclear safety and facilities regulation, confirmed the repaired vessel is fit for service.

However, he said as a precaution, the reactor should be run initially for a period of no more than nine months before undergoing inspection to monitor the corrosion rate.

He added that over the long term, the reactor should undergo a planned shutdown each year for further inspections.

McDiarmid said he supports that, and believes it will be easier to carry out the planned shutdowns now that the reactor has been offline for so long.

"There are changes underway in the global supply chain, changes underway in the medical community and so on," he said, "so the dependency of the global supply chain on the NRU is not as great as it was 18 months ago."

Nevertheless, Dr. Christopher O'Brien, president of the Ontario Association of Nuclear Medicine, said the medical community is looking forward to the reactor coming back on line.

"It'd be nice to know once again that that heavy albatross that has been sitting on our shoulders… will be gone."