The nuclear reactor responsible for producing more than half of the world's medical isotopes is preparing to come back online, officials said Thursday.

Atomic Energy of Canada Limited (AECL) said in a press release that they has started prcedures to restart the reactor.

"AECL anticipates that it will be producing medical isotopes within seven to eight days," the statement said.

The National Research Universal (NRU) reactor in Chalk River, Ont., was closed on Nov. 18 for repairs. That's when federal nuclear inspectors discovered that the facility had been operating without emergency power backup for its cooling pumps and insisted on upgrades before it could be reopened.

That sparked an international shortage of radioisotopes used in diagnostic tests for cancer, heart problems, and bone ailments.

On Wednesday, emergency legislation was passed by the House of Commons, with support from all parties, approving the restart of the reactor in order to alleviate the shortage of isotopes. The legislation bypasses the Canadian Nuclear Safety Commission and allows AECL to restart operation of the reactor for 120 days, after which it will have to close again for the safety upgrades.

David Torgerson, president of AECL's research and technology, said the NRU reactor is safer now than at any time in its 50-year history.

"We are constantly improving NRU to operate ever more safely. The NRU reactor has operated safely in the past, and is safer now than it has ever been. AECL has an absolute and unwavering commitment to safety," Torgerson said in a press release.

One of two pumps required by recent safety regulations has been installed, and work is proceeding on the other, AECL said. The upgrade has provided the reactor with an additional backup power supply to protect the reactor in the event of an earthquake.

The publicly-owned NRU reactor provides medical isotopes for about 25 million diagnoses and treatments a year.

The reactor was supposed to have been decommissioned in 2005. But a plant designed to replace the aging facility is six years behind schedule and will not produce radioisotopes until late 2008.

Political debate continues

During Question Period on Thursday, Liberal MP Michael Ignatieff, Etobicoke-Lakeshore, accused the Conservatives of responding too slowly to the Chalk River crisis, and questioned their decision not to provide legal council for CNSC during negotiations to reopen the facility.

"Why did the minister of Justice withdraw legal services to the commission," Ignatieff asked. "And what message is this government trying to send to other federal regulators? 'Watch out, or we'll come after you, too?'"

Minister of Justice Rob Nicholson said the government continued to offer legal advice to the watchdog but suggested it seek its own.

"What we did suggest, with respect to the Chalk River reactor, that it might be a good idea that they engage independent legal advice so that there would be no potential for conflict of interest," Nicholson said.

Liberal MP Omar Alghabra, Mississauga-Erindale, accused the government of undermining Canada's nuclear regulator and following the advice of "partisan hacks" in its decision to reopen the reactor.

Prime Minister Stephen Harper rejected the claim and asked why Liberal MPs supported the decision if it was misguided.