The power generation capacity production at the Point Lepreau nuclear reactor has to 35% due to issues related to refuelling the reactor.
The reduce power generation will allow workers to continue to adjust the process for re-fuelling the reactor.
Work at the plant will take several weeks when spring freshet will create improved conditions for hydro power generation and above-zero temperatures will decrease production at the station.
Point Lepreau operated at 100% capacity in January and February after the reactor was refurbished.
Energie NB Power chief nuclear officer and site vice president Sean Granville said the company reduced the power to refuel the reactor.
"This gives us more time to operate the Station using our current fuel while we make necessary adjustments to our fuelling system," Granville added.
"While the first four months of operations have met our expectations, we now have our first period of reduction while we deal with these adjustments.
"This is not unexpected in the first months of restarting a nuclear plant after a major refurbishment."
Reducing power generation at the plant is an operational action to meet re-fuelling targets and make necessary adjustments to our current equipment, the company stated in a release.