New Brunswick Health Minister Michael Murphy is now worried about the looming shortage of medical isotopes after he spoke with the federal health minister.

"I'm concerned because this will affect, at some point, the scheduling of nuclear medicine and the tests. There may have to be a rationalization of those tests," Murphy told reporters on Friday after speaking with the federal health minister.

Atomic Energy of Canada Ltd.'s 52-year-old NRU reactor, which supplies 80 per cent of the world's medical isotopes, was shut down May 14 after a power outage in parts of eastern Ontario and western Quebec.

A heavy water leak was detected within the facility the following day, and officials said it would be out of service for more than a month while repair options are considered.

Executives at AECL said Thursday they could not rule out a prolonged shutdown, which has New Brunswick's health minister thinking ahead to next week and beyond about cancer treatments at hospitals in Saint John, Fredericton, Edmundston and Moncton.

"Those cases that are the most pressing and emergent would be dealt with first. The elective ones … or ones that can wait under medical opinion, may very well have to. But Chalk River is going to be down for over a month, without question. The question then is, how long?" he said.

Ellen Snider, a spokeswoman for the Canadian Cancer Society in New Brunswick, said her organization is not happy about the potential for treatment delays.

"When that access is not available it can be a very difficult time for people who are looking for answers, in terms of their medical condition," Snider said.

"Our hope is that the isotope supply will resume as quickly as possible so that the people that are affected can get the answers that they need."

Murphy said he believes it's far from ideal to have to rely on a 52-year-old reactor for such a vital tool.

"We've all placed ourselves in a rather difficult and awkward position by continuing to rely on that aging nuclear plant. So the longer term is going to be such that we're going to have to plan better than this," Murphy said.