MONTREAL (Reuters) - The Canadian government-owned nuclear reactor at Chalk River, Ontario, was back in service on Sunday morning and expected to begin producing medical isotopes within four days, Atomic Energy of Canada Ltd said.
The National Research Reactor (NRU), which makes more than two-thirds of global supply of the radioisotopes used in cancer tests, was shut down in November for technical reasons, quickly triggering shortages.
On Wednesday, the Canadian government ordered the AECL, the government-owned nuclear technology company that operates the reactor, to restart the plant.
In spearheading the restart, Canadian Prime Minister Stephen Harper criticized Canadian Nuclear Safety Commission boss Linda Keen for not allowing the reactor to restart earlier this month because of what she said were safety concerns.
"NRU provides medical isotopes for about 25 million diagnoses and treatments a year," David Torgerson president of AECL's research and technology division, said in a statement.
"While we recognize the importance of the reliable production of medical isotopes, our first and foremost commitment is to safety. The NRU reactor has operated safely for the past 50 years and is safer now than ever before."
When injected into the body, the isotopes give off radiation that can be seen by a camera to diagnose cancer, heart disease and other medical conditions.
Chalk River produces medical isotopes for Canadian health-care company MDS Inc and its MDS Nordion division, which is responsible for about 50 percent of world supply.
In addition to provoking shortages of medical isotopes in Canada and outside the country, the shutdown of the Chalk River reactor sparked a furious debate in parliament and changes at the AECL.
On Friday, Harper said he accepted the resignation of Michael Burns as AECL's chair of the board, effective December 31.
He also announced the appointment of Glenna Carr as the new chair and Hugh MacDiarmid as chief executive officer.
Reporting by Robert Melnbardis; Editing by Bill Trott