A mid-December leak of heavy water at Canada’s Point Lepreau nuclear power plant is worrying nuclear regulators. As CBC News reported today:
The head of Canada’s Nuclear Safety Commission calls two recent incidents at the Point Lepreau nuclear generating station “unsettling.”
On Dec. 13, there was a radioactive spill. Up to six litres of heavy water splashed to the floor, forcing an evacuation of the reactor building and halt of operations.
Then, on Dec. 14, NB Power issued a news release, admitting there had been another type of spill three weeks earlier. About 23 barrels of water laced with the toxic chemical hydrazine was released into the Bay of Fundy.
Both incidents occurred as part of preparations for restarting the plant, which has been undergoing refurbishments for nearly four years.
“Since this plant is almost finished refurbishing, it’s a bit unsettling to hear about hydrazine and heavy water leak one after the other,” safety commission president Michael Binder said during a regularly scheduled meeting in Ottawa on Dec. 15.
“So that is the discomfort level we all feel about this,” he said.
Another commissioner, Moyra McDill, expressed concern about the fact that the heavy water leak occurred in a piece of machinery that normally handles gases rather than liquids:
“Since machines don’t normally act on their own initiative … something must have been missed somewhere in the system if you have fluid entering a gas zone,” she said. “I’m a little concerned that heavy water ended up in a pump for gas.”
NB Power admitted that small amounts of radiation escaped containment in the heavy water leak:
The heavy water was released into a contained area in the reactor containment building, although NB Power officials told the safety commission that small vapourized particles of radioactive tritium did escape up the station’s ventilation stacks.
There was another disturbing feature in the incident:
In a further complication, safety doors that had closed to contain nuclear particles from further escaping ended up locking in two cleanup crew members for two hours after they had finished their work.
The company also provided details of the hydrogen leak:
A faulty valve in the steam generators was to blame in that case, said (NB Power spokeswoman Kathleen) Duguay. It leaked light water onto the roof of the service building, which made its way to the roof drainage, which connects to a ditch that discharges into the (Bay of Fundy), she said.
Upgrades to the Point Lepreau nuclear power plant have taken longer and cost more than expected:
Point Lepreau, Atlantic Canada’s only nuclear reactor, is undergoing a $1.4-billion refurbishment. It was originally expected to be back generating power by September 2009, but there have been problems, particularly with the calandria tubes.
The tubes, which are about six metres long and 13 centimetres in diameter, contain the reactor’s fuel channels and fuel bundles.
Several of the 380 tubes that were installed were leaking and had to be replaced.
The extended outage at the Canadian nuke is proving to be costly:
It is estimated that NB Power spends $1 million a day to purchase replacement fuel while the reactor is offline.
And, just to add insult to injury, NB Power is asking Canadian regulators for an extension of the plant’s license:
The Canadian Nuclear Safety Commission is currently considering NB Power’s application for a new five-year operating licence for Point Lepreau.
Here’s a link to the article: http://www.cbc.ca/news/canada/new-brunswick/story/2012/01/06/nb-nuclear-commission-lepreau-leaks.html