The fire service confirmed it was called to the site by residents, but a spokesman said its services were not required.
A spokesperson for EDF said: “This steam venting is normal when a reactor comes offline and is no reason for concern.
“Work is underway to establish the cause of the trip and bring the unit back online.”
Heysham 2 went offline over Christmas due to an issue with the high voltage transmission system run by National Grid.
The Lancashire site is the only one in the UK to have two operating nuclear power stations.
Heysham 1 began operating in 1983 and has two advanced gas cooled reactors, scheduled for closure in 2027.
The second plant started generating in 1988 and its two gas cooled reactors are due to close in 2030.
