Senior staff at the Canadian Nuclear Safety Commission say the regulatory body is unable to monitor the refurbishment and pending restart of New Brunswick's Point Lepreau nuclear generating station as closely as it would like.

"We cannot assess everything," said Greg Rzentkowski, director general of power reactor regulation, during a commission hearing on Thursday that was broadcast on the internet.

He was answering questions about a recent heavy water spill at Lepreau, which is located in west Saint John.

"Our resources are limited," said Rzentkowski. "We would like to do it, but it is physically impossible."

About 300 litres of tritiated heavy water spilled on May 21 when a valve opened too soon during pressure testing at the plant.

NB Power crews were testing the system that transfers heat from the reactor up to steam powered turbines as part of preparations to restart the plant when they overpressurized the system.

Poor planning, training led to leak

Rzentkowski said poor planning, training and human error led to the leak, which officials have said was contained in a sealed room and cleaned up without endangering staff or the environment.

"Supervisors were not trained in the operation of the test equipment. Supervisors could not provide active oversight and guidance over the test," said Razentkowski.

"We have to ask ourselves the question — to what level of scrutiny this procedure underwent, how this was implemented in terms of staff training etc. There are many questions we have to follow up."

Paul Thompson, the utility’s manager of regulatory affairs, told the commission an internal review "did find some areas for improvement."

Changes implemented

"These were implemented prior to reinstating the test, which led to a successful test, demonstrating the integrity of the heat transport system, and that was leak-tight, reflecting the overall quality of the work done during the refurbishment project," he said.

In addition, equipment manufacturers provided an onsite demonstration to not only the operators, but also supervisors following the leak, Thompson said.

NB Power continues to evaluate the incident, the commission was told.

There were two previous spills at Lepreau.

On Dec. 13, less than six litres of heavy water splashed to the floor, forcing an evacuation of the building.

The following day, NB Power issued a statement saying that three weeks earlier another spill had occurred. 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.

Point Lepreau has been out of service since March 2008 for a major refurbishment designed to extend the life of the reactor by 25 years.

It is scheduled to reopen this fall, three years behind schedule.

Point Lepreau is Atlantic Canada’s only nuclear reactor.