The fusion reaction creates high-energy plasma at very high temperature and pressure. The products of the reaction (plasma) is contained and directed to the drive cone by magnetic fields to generate the drive thrust. In the event of imminent failure of the magnetic fields, it is safer to completely eject the reaction from the ship via vents. Simply shutting down the reaction by removing the fuel and using shields might take longer and may destroy the reactor and ship when the containment fields fail. The core is normally dumped only when the drive has been heavily damaged and is about to explode and destroy the ship. Such ships have to rely on thrusters until the core is restored. In the best case, the drive can be restored as soon as the magnetic fields are fixed, by restarting the fusion reaction.
Alex dumps the core of the Razorback to destroy missiles that were about to hit the ship. This was an act of desperation.The EMC Ontario was damaged at the Tempest Jovian battle it suffered a reactor breach and was forced to dump core.
When a Belter pirate ship tried to capture the UN transport ship Amberjack the OPAS Tynan was hidden in the transport's shadow. Tynan made itself noticed and target locked the pirate ship. When the pirates fled the Tynan fired its PDCs kocking out the ship. The pirate ship then dumped core whilst the Tynan was behind it forcing the OPA gunship to take evasive action.Spotted by an armed Belter skiff the Razorback being unarmed fled. When a torpedo was fired at them, and the ship could not evade the Razorback dropped its core destroying the torpedo behind. This however left the ship crippled.