Canada's health minister says the nuclear reactor that produces more than half of the world's supply has returned to service and the shortage of medical isotopes should end soon.

But Tony Clement made no apology for the partisan gamesmanship leading up to an emergency legislation-forced restart at the reactor in Chalk River, Ont., last week.

"Sometimes you gotta fire a couple shots across the bow to make sure the opposition knows that you're serious about the issue," he said.

Clement said Atomic Energy of Canada Ltd., and its nuclear regulator threatened thousands of lives with the closing.

"It appeared to us on the outside as a lot of sound and fury over something that affecting potentially the lives and well-being of many, many Canadians and people around the world," he told CTV's Question Period on Sunday.

The reactor produces radioactive substances used in diagnostic tests for cancer, heart problems, and bone ailments. An extended closure led to an international shortage of the substance and the delay and cancellation of thousands of tests.

The Canadian Nuclear Safety Commission (CNSC) forced the nuclear reactor offline after finding it did not meet safety regulations.

At one point, the Conservative government accused Linda Keen, the "Liberal-appointed" head of the nuclear regulator, of being responsible for the unnecessarily long closure that led to the international shortage of medical isotopes.

Clement said the Conservatives singled out Keen's actions because they thought the Liberals were going to turn the shortage into a partisan issue and delay the reactor's restart.

The nuclear reactor returned to service at 3:44 a.m. on Sunday, AECL announced.

The Chalk River reactor provides enough medical isotopes for about 25 millions tests and treatments each year.

The reactor stopped production for scheduled repairs on Nov. 18 and was expected to restart within five days.

But the CNSC refused to allow the reactor to restart after finding it had been operating without a backup emergency power system for cooling pumps for 17 months.

Emergency legislation passed by Parliament on Wednesday side-stepped the CNSC's objections and allowed AECL to restart the reactor for 120 days in order to alleviate the isotope shortage.

Clement said he was impressed with the how medical professionals reacted to the isotope shortage that threatened many important diagnostic tests.

"The cancer specialists and the nuclear medicine specialists thought up all sorts of ways that they could use the medical isotopes for longer periods of time and use replacement therapies in a pinch," he said.

The AECL said isotopes should be ready for processing and distribution within four days.

The coincidence

Late Friday afternoon, AECL chairman Michael C. Burns resigned suddenly, after one year on the job.

Clement said Burns had been hired as a part-time chairman and that his resignation was just an "interesting coincidence.

"Some times coincidences happen in politics," Clement said. "There was some indication that this might be coming up down the road."

Glenna Carr, a former civil servant in the Ontario government, replaced Burns.

Prime Minister Stephen Harper also announced former rail executive Hugh MacDiarmid was named AECL's chief executive officer. The previous CEO had retired on Nov. 1 and had not yet been replaced.

"Obviously we are disappointed with the way all of this was handled and we're not, our job is not to parse out blame, it was to get the reactor up and running again so that cancer patients and heart patients can get their diagnosis and therapy," Clement said.

With new executives in place, "I think that we're expecting things will run a bit more smoothly,"he said./>

Liberal natural resources critic Omar Alghabra said the resignation by Tory-appointed Burns proved that there was a failure at AECL.