How to unlock: go to General Atomics Factory (M7,4) and make it to the "Test Area"
In the building of the General Atomics Factory, there is a quest that does not appear in your journal and for which you will be rewarded with what is in the safe in the quest room. Inside, you find, among others 3 fusion cores.
To start the quest, find on the ground floor the room, where it says "Test Area" on the floor. You can get there by crossing the production hall. Inside, wait for the voice to stop talking and the door to the first room opens. You need to turn off the radio.
In the second room, take up the empty bottle chest of drawers and carry it over to the teddy bear in the cradle. If you have already climbed the first floor and started a fight with robots, there may be a problem here. All sorts of explosions may move the bottle elsewhere in the room.
The third room requires you to remove (take away) three dangerous items. These are spanner in the middle of the room, Abraxo Cleaner from the shelf opposite the tv set, and a machete from the fridge. After you perform all three tasks, the safe will open.
Rewards for completing the quest: Experience points, 3x fusion core