Following eleventh-hour talks with the Liberals, the federal government introduced emergency legislation Tuesday evening that will compel Ontario's Chalk River nuclear reactor to restart immediately.

The Liberals had threatened to refuse to give the bill the unanimous support necessary to bypass the legislative process.

But in an unusual sitting of the House of Commons Tuesday evening, all of the political parties agreed to fast-track the legislation through the House and Senate.

MPs passed the vote late Tuesday night, with the NDP and Bloc Quebecois backing it.

The Liberal-dominated Senate, which also agreed to stay late, was expected to put the bill to a vote by early Wednesday.

The Tory bill is an attempt to put a quick end to the critical shortage of medical isotopes that are necessary to diagnose diseases such as cancer.

The new bill will suspend the oversight role of the regulator at the plant for 120 days.

During that time, the reactor's operators will be expected to bring in the changes that CNSC has said are needed.

PM blasted Opposition

The Tory legislation was the topic of heated debate during Tuesday's question period, with Opposition members demanding to know whether it was safe to re-open a facility the country's nuclear watchdog has said does not meet safety standards.

"There will be no nuclear accidents," said Prime Minister Stephen Harper, responding to heckles from Opposition members. What there will be, he said, is a growing medical crisis if all members of the House don't support the legislation.

Harper also accused the Liberals of being part of the problem.

He said past Liberal appointments to the CNCS which overseas the AECL that runs the plant are partly to blame. Harper believes bickering between the AECL and the CNCS has exacerbated issues.

"The continuing actions of the Liberal-appointed nuclear safety commission will jeopardize the health and safety and lives of tens of thousands of Canadians," Harper said.

The Liberals shot back.

"Attacking the regulator -- taking him out of the process -- is going to make the problem worse," charged Liberal deputy leader Michael Ignatieff.

Safety concerns

CNSC director general Barclay Howden refused to get drawn into the political debate. But Howden noted that the commission made its decisions based on advice from scientists and engineers.

He said the Chalk River reactors' main cooling pumps must have access to power at all times so that the core doesn't meltdown in an emergency situation.

The plant has proposed a temporary solution that would have one pump linked to emergency power during repairs. But the CNSC wants to wait for a detailed plan before giving the proposal the go-ahead.

Radioisotope shortages

The National Research Universal (NRU) reactor in Chalk River, Ont. is now 50 years old.

The AECL shut down the reactors for maintenance in November, and then decided to extend the shutdown.

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.

The CNSC extended NRU's operating licence until the problems with the new reactors can be sorted out.

But the commission's director-general, Barclay Howden, said the licence was issued based on assurances from AECL that an emergency power system connected to cooling pumps had been installed.

Safety regulators found out only last month that that those pumps were not installed.

The CNSC has said several new safety standards must be met before the reactor can be reopened.

AECL said in a statement Tuesday that teams of employees and its suppliers "continue to work around the clock on the installation and connection of the upgraded equipment in preparation for return to service.

"AECL employees are in the process of completing the installation of one pump and have secured all necessary components to assemble the second pump."

The company says returning the NRU reactor to service, on an interim basis, using one coolant pump with the emergency backup power connected while work is completed on the second pump will allow the "safe operation of the reactor."

The shutdown has led to radioisotope shortages throughout North America and other parts of the world that have delayed diagnostic testing, therapies and surgeries involving nuclear medicine. AECL has said it is unlikely the reactor will be back to full production until mid-January.

More than two-thirds of the world's medical isotopes are produced at the publicly owned reactor.