As you can see from this cross-section of one of the wings, very little of the interior of Space Kid Island is devoted to living space — most of it is needed for the infrastructure which makes the station habitable!
Utilities include such things as wiring, plumbing, heating, and ventilation, as well as air and water recycling technology.
Hydroponic algae tanks run below decks all through the rim and wings. The algae grown here is the station’s primary resource for recycling the air — the algae takes in carbon dioxide and releases oxygen. [In case of emergency there is also mechanical air-recycling equipment on the station as back-up.]
Gravity generation is normally difficult in the world of Space Kid! It requires so much energy to run it that most spaceships usually produce gravity for only a small section of the ship [the cockpit], and large structures like the space-cities simulate their gravity by rotating. However, the super-atomic reactor is capable of producing so much power that it can run gravity generators for the entire station, as well as running all the other equipment on Space Kid Island!
Shielding on Space Kid Island serves two functions: not only does it prevent harmful space radiation from reaching inside the station, it also prevents the artificial gravity generated inside from reaching outside. Otherwise, passing meteors etc. might be attracted to Space Kid Island as powerfully as they would be to the Earth!