Doomsday scenarios: Point Lepreau passes tests

Earthquakes, dam failures, shipping disasters, plane wrecks, tsunamis, even meteor strikes were evaluated and found unlikely to cause public safety problems at the Point Lepreau nuclear plant, its licensing hearing heardon Thursday.

"We've conducted a comprehensive safety analysis and it has shown the likelihood of a serious accident remains extremely low," said Michael Hare, Point Lepreau's station director.

The likelihood of a serious accident remains extremely low.- Michael Hare, Point Lepreau station director

NB Power has applied for a five-year licence renewal for the generating station from the Canadian Nuclear Safety Commission, so a group of the utility's top nuclear executives attended a commission hearing in Ottawa on Thursday to make their case for the plant in person.

A good portion of the hearing focused on Lepreau's ability to withstand a significant earthquake event, but NB Power's senior technical adviser, Derek Mullin, said all potential risks to the plant have recently been looked atmany right out of Hollywood disaster movies.

"You look at all of these types of things," said Mullin, who patiently took commissioners through an extensive doomsday list.

"For example a dam failure," said Mullin."The only dam failure that could affect PointLepreauwell there isn't any. You look at things like a random aircraft crash. You look at meteorites and what's the experience of those impacting Earth."

Large earthquakes in past

Mullin said most of those threats were found to be too remote to worry about, but others have been studied in depth, including internal failures that can lead to fires or flooding inside the nuclear facility or a significant earthquake event, which he acknowledged is not as fanciful a danger as space debris.

"The investigation did find evidence of large earthquakes having occurred in the past," said Mullin, who listed three in the Lepreau area in the last 13,000 years, including the most recent sometime during the last 1,200 years.

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He said best estimates put the magnitude of those earthquakes at between 5.5 and 7.0 and centred within at least 30 kilometres of the plant.

Still NB Power told the commission that evaluations of Lepreau show it is robust enough to withstand earthquakes of that size and larger without releasing nuclear material into the environment.

The plant is strong and can be safely shut down and cooled if an earthquake occurs that is greater than our design basis.- Derek Mullin, NB Power technical adviser

"Even when considering extreme earthquake scenarios that lead directly to severe core damage, safety goals for the plant are met," said Mullin.

"Our analysis shows the plant is strong and can be safely shut down and cooled if an earthquake occurs that is greater than our design basis."

Others at the hearing agreed with that assessment, including professional staff members of the safety commission and John Adams, a geological scientist with Natural Resources Canada.

"In general the sizes of earthquakes used are higher than we are using in the national building code," Adams said. "I think that represents a rigorous estimate of the seismic hazard. I was quite happy with the thoroughness of the work."

Reassessed following Fukushima

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Japan continues to deal with repercussions from earthquake and tsunamiLepreau was built more than 30 years ago, but all nuclear plants were required to undergo safety reassessments in the wake of the Fukushima nuclear disaster that was the result of a tsunami in Japan in 2011.

Safety upgrades at Lepreau, including what the utility says is $100 million spent on firefighting improvements at the station over the past five years alone, have increased its ability to withstand a variety of unexpected events, said NB Power officials.

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Based on that and other safety measurements, staff members of the Canadian Nuclear Safety Commission recommended to board members during the hearing that Lepreau's application for a five-year licence renewal, beginningJuly 1 2017, be granted.

A second public hearing by the commission to consider the matter is scheduled forSaint John on May 10 and May 11.