New Brunswick's Energy Minister Craig Leonard told the legislature Wednesday that he has "no concern" about the radioactive spill at the Point Lepreau Nuclear Generating Station affecting the health of staff at the reactor.

Tuesday's spill involved four to six litres of heavy water, according to Leonard.

"The staff at Point Lepreau did a fantastic job of following the guidelines that they are supposed to — doing everything according to the book and as a result it was an issue that occurred with no impact whatsoever," he said.

Kathleen Duguay, a spokeswoman for NB Power, said on Tuesday that the building was evacuated about 4 p.m., immediately after a radioactive alert was initiated.

'The potential risk posed to the environment was negligible and there are no public health implications resulting from this event.' —Kathleen Duguay, NB Power

The utility was refilling equipment with heavy water as part of preparations for restarting the plant, which has been undergoing refurbishments for nearly four years.

She blames equipment failure for the spill.

"The potential risk posed to the environment was negligible and there are no public health implications resulting from this event," Duguay said in an emailed statement Wednesday.

In previous statements she had said the spill did not pose "any risk," and had "no significant impact to the public or environment."

Work at the reactor building resumed Wednesday morning after officials verified the spill had been cleaned up and it was safe for workers to return, she said.

Cause being investigated

NB Power continues to investigate the cause of the release and will ensure the appropriate measures are put in place to prevent another event, Duguay said.

The Canadian Nuclear Safety Commission issued a statement about the spill. It says site staff are conducting follow-up activities and will provide a status update at the regularly scheduled public commission meeting on Thursday.

NB Power reported the spill to the commission, according to the statement. "All precautions were taken by New Brunswick Power to protect workers.

"The spill did not result in any risk to the public, the environment or the workers."

The heavy water was released into a contained area in the reactor containment building, said Duguay.

"Highly sensitive radiation monitoring equipment alarmed, as per design, alerting workers in the area. Station workers responded quickly and efficiently," she said.

The spill was cleaned up by a team of highly-trained and qualified spill response staff who wore the required personal protective equipment, Duguay said.

Radiation monitoring equipment is designed to alarm immediately in response to any radiation event, she said.

Alarms from the sensitive detectors have been common in the last two weeks, as the reactor equipment is being refilled, Duguay said. This was, however, the first time the reactor building was evacuated, she said.

Environmentalists unhappy

Nuclear opponent David Thompson, of the Conservation Council of New Brunswick, said the spill is one more sign the refurbishment of Point Lepreau is a mistake.

He accused the plant of having "Homer Simpson-type management."

NB Power, however, argues the spill shows how quickly mistakes are caught and fixed.

"We detected it, stopped it, fixed it and cleaned it up," said Duguay.

Derek Lister, the chair in nuclear energy at the University of New Brunswick, agrees.

"They report every little incident that goes on in the plant. I mean, they've been so damaged in the past by allegations of secrecy and keeping the public maybe misinformed that they report every little incident now," he said.

"This is an absolutely minor incident, in my opinion."

The heavy water contains a radioactive hydrogen isotope called tritium that could exchange with natural water in a person's body.

He suspects the spill was mopped up with automated equipment and employees are back to work wearing ventilators.

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 has run into 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 Canadian Nuclear Safety Commission is currently considering NB Power's application for a new five-year operating licence for Point Lepreau.