The Omega Annihilation Unit is a Emergency Omega System used aboard many of Imperial Starfleet's special classes/types of Warships as a last resort system in an extreme emergency situation. In fact the system is so perfect in function that all last resort weapon and emergency systems are named Omega.
Instead of a basic Self-Destruct System that is typically placed on all Imperial Warships that destroys both ship and crew. The Omega Annihilation Unit instead destroys all organic (and some inorganic) forms of life that both internally and externally surround the ship, leaving the ship itself relatively unharmed. This is also known as an Ultra-Neutron or Corbomite blast. The blast is achieved by directing a super stream of Omega Molecule particle energy through a Nadion Particle energy conduit into the central Corbomite Action/Reaction unit for a accelerated mass absorption process. Then the Corbomite device is automatically programmed to begin a cascade shutdown which creates a self destruction process of the unit only. Afterwards, the energy resonance structure collapses rupturing the Corbomites liquid crystal base releasing all of both of the Corbomites and Omega Molecules combined energy basically turning the ships energy core into a massive weapon of mass destruction.