The Gecko's nuclear power plant, a.k.a Poseidon oil reactor № 5, is a large nuclear power plant that once supplied power to Gecko city.
Once the Chosen One enters the plant, he/she is greeted by a guard at the reception area. Jeremy is in the supply room on the PC's left, and the entire section is the living spaces for the ghouls, mainly Gecko's glowing ones. The upper left corner is a checkpoint requiring a card from the guards to pass. Fortunatly for the Chosen One, one of the Ghouls guarding the door has one that can easily be stolen.
This section requires the yellow reactor keycard to gain access, and contains the plant's control center, more living areas, including those of Festus, the Reactor Foreman. He can be pickpocketed for a parts requestion form and a red reactor keycard can be found on him or in his locker.
Hank watches over the control room of the reactor from this point, which also contains a computer with the controls for the maintenance robot, and a link to Poseidonet, which provides the Chosen One access an Enclave security station on the Enclave Oil Rig. The PC can install the needed part by hand or with the robot, or overload the reactor manualy or with the robot. Radiation levels inside the core are very high, and radiation resistant armor, high natural resistance, and plenty of Rad-X and RadAway are recommended.
Gecko's nuclear power plant appears in Fallout 2.