Millstone Power Station in Waterford issued an alert for around three hours on Wednesday after a small fire broke out during some routine maintenance on a diesel generator.
Fire broke out around 11 am. at the Unit 3 diesel generator while crews were testing it after a maintenance outage and quickly burned out within around 10 minutes, according to the company.
Millstone issued the alert at 11:33 a.m., which they said is normal procedure, and lifted it as of 2:46 p.m. No one was injured and employees continued to work through the day, according to the company.
Millstone officials said the station is assessing the damage, investigating the cause of the fire and notified federal, state and local officials.
Millstone Unit 3 is operating at full power, while Millstone Unit 1 is decommissioned and Unit 2 is offline for a routine refueling outage.
The company said backup diesel generators are used to provide power to the station when power is lost and there was no danger and no radioactive materials were released.