Your base needs a lot of electrical power to keep running, so it is equipped with a high-tech reactor. The downside is that the base has a single major weak point – any damage to the reactor can disable the whole base.
If this Trait is taken, the Gamemaster picks any number of suitable Traits possessed by the base. If the main reactor is damaged or sabotaged, these traits are lost until the reactor is repaired. The main reactor is an obvious target for any attackers, and it is so big and complex that it is hard to defend.