Supplies to part of the Dounreay complex in Caithness were disrupted during stormy weather on 17 June, it has been reported.
The plant operators said a short loss of power was experienced to the site near Thurso.
Managers confirmed the strike did not directly hit the nuclear power plant.
Back-up supplies also failed as a result of the incident, prompting safety fears to be raised.
It meant that for about one hour there was no power for vital safety systems which monitor radiation and ventilation.
Operators said there had been no risk to people or the environment.
Dounreay is in the process of being decommissioned and the land cleaned up.
The decommissioning work is due to be completed between 2030 and 2033.