After undergoing repairs for more than a year, the nuclear facility at Chalk River, Ont., is safe and can begin producing isotopes again, the Canadian Nuclear Safety Commission has said.

The nuclear watchdog made the announcement Wednesday, two days after it heard from Atomic Energy of Canada Ltd. at a hearing regarding the facility.

The 53-year-old reactor will likely restart producing medical isotopes by the end of July, according to officials. It has been shuttered for longer than a year as workers mended a radioactive water leak.

The Chalk River National Research Universal reactor produced a third of the global supply of medical isotopes, which are used in diagnosing cancer and cardiac conditions, before it was temporarily shut down.

To make time for the hearing, the Canadian Nuclear Safety Commission made Chalk River a "priority case."

A small number of 50-year-old nuclear reactors around the world are responsible for producing medical isotopes, and doctors who use isotopes to diagnose medical conditions had expressed frustration at delays in restarting the facility.

"Initially they told us a month before they would have repairs done, then subsequently three months, then after that six months, then we didn't even get any deadlines," the Society of Nuclear Medicine's past president Dr. Robert Atcher said in early June.

Medical tests using technetium isotopes had declined by a fifth last October, compared to a year earlier, the Canadian Institutes for Health Information stated in June. Doctors conducted roughly 12,000 fewer exams using the isotopes.

On Monday, AECL told the commission that the Technical Standards and Safety Authority inspected the repair and found that the reactor was fit to resume production.

Some of the inspections were repeated after a mild earthquake hit southern Ontario in late June, but it wasn't found to have caused any damage.

In a statement, the commission concluded that AECL "is qualified to carry out the activities that will be permitted under its current operating licence and that it will make adequate provision for the protection of the environment, the health and safety of persons, and the maintenance of national security and measures required to implement international obligations to which Canada has agreed."

About $72 million was set aside to pay for the repairs. But in March, Hugh MacDiarmid, president of Atomic Energy of Canada Ltd., said the repairs were costing an additional $11 million per month, factoring in lost revenues.

With files from The Canadian Press