Point Lepreau nuclear plant. Photo: NB Power

by John Chilibeck, Local Journalism Initiative Reporter
Source: Telegraph-Jounal
September 18, 2026

The heavy water that leaked last week at a nuclear plant near Saint John is radioactive, NB Power has confirmed.

At just past 5 p.m. on Friday, the public utility responded to questions posed by Brunswick News early Friday morning asking if the leak at the Point Lepreau Generating Station was highly radioactive.

Critics have accused NB Power of downplaying a hazardous spill.

“The heavy water involved is radioactive and contained within the reactor building,” wrote spokesperson Elizabeth Fraser-McAllister, in an email. “The heavy water is at the levels expected in the heat transport system where it circulates.”

Blitzed with follow-up questions from Brunswick News, NB Power said it would respond Monday.

The Canadian Nuclear Safety Commission, which oversees all nuclear plants in the country, said late Friday that as soon as its site inspectors stationed at Point Lepreau found out about the spill on Sept. 10, they acted.

“We are engaged with NB Power as it conducts a thorough assessment of the incident and undertakes the necessary repair activities,” wrote Sarah Dolan, a spokeswoman with the safety commission. “There has been no impact on the safety of workers, the public or the environment, and no workers have been reported to have received radiation doses above regulatory limits.”

She said the commission’s staff would continue to oversee NB Power’s response and review the results of the ongoing assessment of how to repair the leak.

Danger to workers

Gordon Edwards. Photo: NB Media Co-op

Still, the leak raised the alarm for Gordon Edwards, the president of the Canadian Coalition for Nuclear Responsibility.

He said in an interview on Friday the coolant water from a small instrumentation line that was found leaking inside the reactor building has tritium in it.

Tritium is an isotope that is radioactive and unstable.

The heavy water normally circulates through the reactor in a closed-loop system and is used as a coolant.

Edwards said the danger would be to workers if they inhaled the warm vapour of the spilled heavy water.

“When the stuff leaks, like in this case, it’s a genuine problem for the workers, because they’re going to get a brief high exposure to the tritium that they normally wouldn’t be exposed to,” said Edwards, a retired mathematician from Montreal who’s in his eighties and has spent much of his life researching nuclear plants.

“Normally that stuff is in the pipes. It’s not out where they can breathe it. But once it gets out of the pipes, it’s mostly the water vapour that’s a danger.”

NB Power told Brunswick News on Tuesday the leak was contained to the heavy-walled reactor building and there was “no risk to the public, employees or the environment.”

In its earlier news release from Sept. 14, the public utility did not mention the heavy water was radioactive, nor did spokespeople use the word during a subsequent interview and follow up emails, until Friday evening, after Brunswick News posed more questions.

Lack of transparency

Susan O’Donnell

Susan O’Donnell, lead researcher at the Cedar project at St. Thomas University, which pushes for green energy transitions, criticized NB Power for not being more transparent.

“It would have been even more informative to mention that the heavy water that leaked has been in the reactor since 1983 and is now highly radioactive,” she wrote on a reader’s forum. “Interesting that nobody interviewed for the story mentioned that salient fact.”

The union representing most of NB Power’s nuclear employees, the International Brotherhood of Electrical Workers, IBEW local 34, did not immediately reply when Brunswick News sought comment on early Friday afternoon.

The safety commission sets limits on the releases of tritium and requires all Canadian nuclear operators to conduct and report on their environmental monitoring.

Heavy water in and of itself is not radioactive. The special liquid is used in Candu reactors like Point Lepreau so they can run efficiently on cheap, unenriched natural uranium.

The heavy water has two express purposes: a neutron moderator to slow down fast neutrons and a coolant to transfer heat away from the reactor core.

The line that leaked was circulating coolant water, which Edwards said has less tritium, and as result, less radioactivity than what’s in the 360,000 litres of heavy water that just sits in the reactor moderator tank, called the calandria. It builds up radiation over time.

But the coolant is still highly radioactive, he said, estimating it had about 50 billion becquerels per litre.

For comparison, the maximum permissible level of tritium in drinking water is 7,000 becquerels per litre, so the heavy water used as a coolant was millions of times more radioactive than the maximum level of contamination allowed by law, he said.

Repairs could take weeks

It’s still unclear, however, how much water leaked, several litres or just a few drops. And there’s been no indication that the workers were unprotected and exposed to the hazardous vapours.

The commission on its website states that tritium can increase the risk of cancer if consumed in extremely large quantities.

It also states the highest average annual tritium level measured in the drinking water of Canadian communities near nuclear facilities is about 18 becquerels per litre, well below Health Canada’s recommended drinking water limit of 7,000 becquerels per litre.

Edwards said he hoped none of the workers had been exposed.

“Water with tritium generally goes right through the body, but some of it doesn’t go out. It gets absorbed into the organic molecules of the body. It’s called organically bound tritium. And this organically bound tritium stays in the body longer and continues to radiate the sensitive cells. The long-term consequences are mostly cancer.”

NB Power earlier this week said the work to repair the leak was difficult and complex and that multiple shifts of workers had to be used because the reactor building is warmer than most places. Kathleen Duguay, a spokeswoman, said the work could take days or several weeks.

In the meantime, the plant remains offline and won’t produce any electricity.

Workers leaving sensitive areas of the plant are always scanned for radiation levels.

This story was written by John Chilibeck, Local Journalism Initiative Reporter with Brunswick News.