The Point Lepreau Nuclear Generating Station has operated at an average of just 68 per cent capacity since coming on line last fall new figures show, well below the 93 per cent the utility projected during Energy and Utilities Board hearings last winter.
The shortfall represents about $30 million in lost electricity production.
The New Brunswick System Operator, the organization that schedules use of the province's transmission system, said Point Lepreau put 173,000 megawatt hours of electricity onto the province's electrical grid in March.
That's 35.3 per cent of the reactor's capacity and the least amount its produced since the plant went back into service last November.
NB Power has been running Point Lepreau at partial power for more than a month to preserve fuel and buy time as it works to fix problems with the reactor's new refuelling system.
Kathleen Duguay, a spokesperson with NB Power, said a solution announced last week appears to be working although the reactor will continue to operate at partial power until more fuel channels are replenished.
The fuelling issue is the second significant problem the reactor has dealt with since coming back in service. It was also powered down in December to adjust the chemistry of its boiler water.
Gaëtan Thomas, the president and chief executive officer of NB Power, has said early problems are to be expected, although the utility did not budget for them.
Last year, NB Power filed evidence with the Energy and Utilities Board projecting a 93 per cent operating capacity during its first six months, representing the generation of $150 million worth of electricity
The plan included 13 days of lost production for unexpected events but as of Tuesday, four and a half months into its life, the reactor has already lost 44 days worth of production.
In March, the Energy and Utilities Board approved Point Lepreau's 27-year operational plan, but notified the utility it would review that approval if the reactor strayed too far from its short term performance targets.
"The board will consider the appropriateness of the estimated lifespan of the refurbished plant during each rate case presented by NB Power or, if it deems it appropriate, from time to time in separate proceedings ordered by the Board," the ruling said.
The Point Lepreau reactor returned to commercial service in November 2012 after its problem-plagued refurbishment was completed.
The project was more than three years behind schedule and more than $1 billion over its original budget.
Atlantic Canada's only nuclear reactor had been out of service since March 2008.
The reactor was originally scheduled to come back online in September 2009, but that date was moved to December 2009, January 2011 and then February 2012 as various problems occurred.
The 660-megawatt plant produces enough electricity to power more than 333,000 homes per year, officials have said.