Power station call-out.
Cleveland Fire Brigade and police were called to the nuclear power station on Saturday afternoon.
They responded after the automatic fire detection and suppression system was activated in the auxiliary boiler house just after 4pm.
In accordance with normal protocol, the station's response team attended, along with the fire brigade.
They found no sign of a fire and an initial inspection identified that an overheated electrical motor was the likely cause of the fire detection system being activated.
An EDF Energy spokesman said it was declared over at 4.36pm after confirmation that there was no fire. There were no casualties.
EDF say there was no impact on the continued safe operation of the power station.
A Cleveland Police spokeswoman confirmed they were also called out.
said: "Police responded to an incident at the nuclear power plant in Hartlepool at 4.30pm on Saturday.
"There were no off-site implications and police stood down within an hour."
It came a week after firefighters and police were called to deal with a small blaze in a turbine hall.