The possibility of a damaging tsunami roaring up the Bay of Fundy represents an extremely low risk to New Brunswick's Point Lepreau nuclear generating station, the plant's director said Tuesday.

Wade Parker said the kind of seismic activity that can lead to tsunamis is rare off the Atlantic coast.

Rare, but not unheard of.

In 1929, an earthquake with a magnitude of 7.2 triggered a submarine landslide and resulting tsunami that crashed into Newfoundland's south coast, killing 27 people in the village of Lord's Cove.

That massive wave, which started its journey on the Grand Banks, had no impact on the Bay of Fundy, said Parker.

"The Bay of Fundy ... has a high degree of protection from any impact of tsunamis, provided by the mainland of Nova Scotia," Parker said in an interview from Point Lepreau, Atlantic Canada's only nuclear power plant.

Analysis of the ocean floor and natural obstacles, such as Sable Island and the shallow Georges Bank, indicate these features would also act as a breakwater for the bay, he said.

However, an outspoken critic of the nuclear industry said Parker's position mirrors that of the Japanese nuclear industry, which was caught off guard last Friday when a tsunami knocked out backup power systems at the Fukushima Dai-ichi nuclear plant.

"The industry will say that everything is good until .... something nasty comes around," said Ronald Babin, a University of Moncton professor and anti-nuclear activist.

"If you would have asked the Japanese people about 10 days ago if there was any danger of that kind, they would have said everything was OK. They had put the (backup) generators behind a wall that was supposed to protect them. They thought they had all the bases covered."

Babin said emergency planners are sometimes overwhelmed by a "compounding of risk," which happens when a cascade of unexpected events confound safety measures.

In northern Japan, the violent shaking Friday caused by the magnitude 9.0 quake prompted a power outage and the automatic shutdown of several nuclear reactors. But the multiple cooling systems at the Fukushima Dai-ichi plant failed when backup diesel generators were flooded by seawater.

Dangerous levels of radiation leaking from the crippled plant forced Japan to order 140,000 people to seal themselves indoors Tuesday.

"All of this added to create this catastrophic situation," said Babin. "It creates new imponderables. Nobody was thinking that would happen in Japan, but it has."

Babin said the dire consequences in Japan should prompt world leaders to consider safer forms of electricity production.

In New Brunswick, Parker said the biggest natural threat to Point Lepreau isn't a tsunami or earthquake, but the possibility of a Category 5 hurricane churning up a 10-metre wall of water in the bay.

Under this worst-case scenario, the plant could weather the storm because it sits 15 metres above mean sea level, even at high tide, he said. As well, the station has four backup diesel generators, two of which are built on large springs to withstand a powerful 6.4 magnitude quake.

The region's largest recorded earthquake hit in 1904 near New Brunswick's Passamaquoddy Bay with an estimated magnitude of 5.7.

"You combine the low seismic activity, the natural protection and the elevation -- this is an extremely low probability event," Parker said.

The plant, which has one Candu reactor, is in the middle of a refurbishment that is running three years behind schedule and $1 billion over the original $1.4-billion budget.

Marc Drolet, a spokesman for the Canadian Nuclear Safety Commission, said reactor sites in Canada are selected to minimize the possibility of flooding.

"These are scenarios that we look at," he said in an interview.

Drolet issued a statement drawing attention to the fact that Candu reactors can be kept cool for several days without power because the water level in so-called dousing tanks is always kept above the steam generators.

Government data analysed by The Canadian Press show that hundreds of small earthquakes have rattled Canada's nuclear power plants over the years with no apparent harm.

Aside from Lepreau, Atomic Energy of Canada Ltd. has Candu reactors at four other power plants, including the Darlington, Pickering and Bruce plants in Ontario, and Gentilly in Quebec.