On this afternoon at Associated, periodic silence in the room was broken by the loud, throbbing noise of generators in the vicinity--the sound of another outage.

FORBES: Magazine Article

The fire at about 18:30 BST on Saturday led to the venting of steam generators which caused noise and would have been visible to people living nearby.

BBC: Crews tackle fire at Hartlepool nuclear plant

Along with electricity, the diesel generators create heat and noise that can be detected by the enemy.

FORBES: Don't put one of these in your garage just yet.