Canada's nuclear watchdog declared the controversial nuclear facility at Chalk River, Ont., safe and authorized its restart after more than a year of repairs.
The announcement came Wednesday after Atomic Energy of Canada Ltd. appeared before the Canadian Nuclear Safety Commission earlier in the week.
Officials expect the reactor will resume medical-isotope production by the end of the month.
The 53-year-old reactor has been offline for more than a year for repair of a radioactive water leak.
Before the shutdown, the National Research Universal reactor supplied one-third of the world's medical isotopes, used to diagnose cancer and heart ailments.
The commission set aside normal hearing rules to deal with what it called a priority case.
The Canadian Institute for Health Information said last month that medical tests using technetium (Tc-99m) isotopes fell 22 per cent in October compared with the previous year - about 12,000 fewer exams.
On Monday, AECL told the commission that detailed inspections of the repair by the Technical Standards and Safety Authority found the reactor fit for service.
"The commission concludes that AECL is qualified to carry out the activities that will be permitted under its current operating licence," the authority said in a release.
The commission said AECL 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."
The Canadian Press