The final repairs to the NRU reactor that produces medical isotopes in Chalk River, Ont., are the most difficult, says Atomic Energy of Canada president Hugh MacDiarmid, seen here last June. (Adrian Wyld/Canadian Press)

Medical isotopes from the nuclear reactor in Chalk River, Ont., won't be produced until the end of July, Atomic Energy of Canada Ltd. says.

Hugh MacDiarmid, president and CEO of AECL, told the Commons standing committee on natural resources Tuesday that AECL now estimates Canada's National Research Universal, or NRU, reactor will resume production of isotopes by the end of July.

The final repairs are difficult, but "there is no margin for error," MacDiarmid said.

The cost of the shutdown now runs at $11 million a month for the repairs themselves and lost revenues, MacDiarmid said.

Technicians have had to design new tools and practise each remote-controllled repair before they steer welding torches down to make the patches.

Opposition MPs questioned whether the reactor will actually return to service in July. The NDP's Nathan Cullen said the delays haven't helped AECL's reputation.

"I can understand that observers would have their confidence shaken by the way this has unfolded," MacDiarmid responded. "All we can do is be forthcoming."

A review of the schedule for the remaining work suggests the end-of-July target is feasible, the agency said.

Earlier this month, a panel of welding and reactor experts reviewed AECL's repair plan and confirmed NRU can be repaired, said William Pilkington, AECL's senior vice-president and chief nuclear officer.

"What we're doing has never been done in the history of the nuclear industry," Pilkington stressed.

On March 12, AECL said the reactor wouldn't return to service until late May at the earliest and warned more delays were possible. The reactor went out of service last May after leaking heavy water.

The committee also heard from Stephen Littlejohn, vice-president of Covidien PLC of Dublin, Ireland, a company that sells some medical isotopes to Canada.

Littlejohn said Covidien has formed a "game-changing" partnership with Babcock & Wilcox Technical Services Group that has the potential to supply more than 50 per cent of U.S. demand for molybdenum-99, the parent isotope of technetium-99m (Tc-99m) — the most widely used radio-isotope in the world for molecular imaging and nuclear medicine procedures.

May shortages expected

In the short term, isotope shortages are expected for a few days in May.

"May is going to be a particularly difficult month. It's going to be difficult across the world," Littlejohn said.

Last week, clinicians and the broader health-care community worked a lot of overtime to make the smaller amount of available isotopes go further to minimize the impact on cancer patients, Peter Goodhand, president and CEO of the Canadian Cancer Society, told the meeting.

"My concern, and what we heard through testimony to our committee, is that it's not sustainable," Goodhand said.

There appeared to be a minimum number of cancellations, but these are troubling for patients, said Goodhand, who chaired the Natural Resources Department's expert review panel on medical isotope production.

Ottawa Hospital said dozens of cardiac scanning appointments were cancelled after supplies of the medical isotope thallium ran out. The hospital had been using thallium as a backup during the latest technetium-99m shortage.

Goodhand said experts told his panel that introducing state-of-the-art cameras to current imaging technology could also help by lowering the amount of isotopes needed.

Witnesses also talked about potential ways to meet global and regional demand for medical isotopes.

For example, the addition of the Maria reactor in Poland announced in February can meet 10 per cent of world supply, research continues on using PET, cyclotron and linear accelerators to produce Tc-99m, and some facilities in Europe may be able to run two processing lines at the same time.

With files from The Canadian Press