Gray Hatches (Security Level 0) can be found throughout the Biologic Space Laboratories research station in Metroid Fusion. Initially, these doors are locked; Adam opens them at the beginning of the game once Samus has investigated the Quarantine Bay. Like normal doors in every other Metroid game, they require a beam, missile, or bomb attack of some sort to open.
Interestingly, these are the only security doors not to be displayed as locked or unlocked on the map screen, however they are displayed in the Debug Menu as a door lock that can be turned on and off. Also, during the blackout sequence, the power outage is achieved simply by them turning off security level 0.