Reactor at the Megakat Nuclear Plant, located on Level 6. When Dark Kat broke in, his Creeplings attacked the reactor room and shattered the glass surrounding the nuclear fuel rods, stealing them and carting them off in a carrying case. Later, when the queen Ci-Kat-A needed nuclear material to feed off of, Dr. Street put the creature into the back of a van and drove it to the Nuclear Plant, where they broke into the reactor room, knocking aside the technician on duty. The Ci-Kat-A smashed the glass surrounding the fuel rods and ate them, which caused it to grow to gargantuan proportions.
In the unfinished episode The Doctors of Doom, Dr. Viper’s giant scarab and mutant grub worms would’ve breached the reactor as part of Viper’s plan to irradiate Megakat City. The SWAT Kats prevented meltdown by flooding the reactor core with water.