The Kellium energy reactor is an object in the Main Reactor room, located in the Space Pirate base in Metroid Prime 2: Echoes. It was converted by the Space Pirates to process Phazon energy. When Samus first enters the Main Reactor, she can see Dark Samus absorbing a large Phazon crystal in the reactor (though she does not absorb a puddle of Phazon underneath the crystal). Unlike the other structures in the room, the Kellium energy reactor cannot be destroyed by Dark Samus' charge attack during the battle. This is due to its shielding level, which is currently at 220% and holding. It has a wood-like base and after Dark Samus' defeat, shields covering up dozens of miniature reactors explode, revealing them to Samus. Unlike the large version, scanning them will provide her with the Phazon Logbook entry and not the reactor scan. It is unknown what happened to it after the Space Pirates left Aether.
"Structural analysis complete. This is a standard Kellium energy reactor, converted by the Space Pirates to process Phazon energy. Shielding levels at 220% and holding."