5.5 Emergency Shutdown Procedures
Describes the fusion-reactor chamber overload as the most often predicted system emergency, its predicted causes and the auto-shutdown response, the upgraded Starfleet emergency detection subroutines and AI algorithms monitoring thousands of sensor inputs and conditional combinations, the radiative and evaporative cooling responses to a rapid overload, the use of magnetic iris valves to retain EPS power, restart conditions after quenching, and the rapid alerting, evacuation, and manual-shutdown authorization protocols.
The system emergency most often predicted by engineering computer simulations is that of a fusion-reactor chamber overload. If the detonation rate of the deuterium pellet stream rises, the temperature and pressure of the contained plasma rises correspondingly and will lead to an auto-shutdown. The predicted causes include reactor isolinear processor failure, fuel flow imbalances, and sabotage. If the plasma pressure and energy density increase at a rate faster than the EPS conduit system can accept the higher pressures, one or more reaction chambers can suffer total structural failure, effectively destroying the entire fusion-generator section of the station. The current Starfleet computer control codes for the fusion system include upgraded emergency detection subroutines. The artificial intelligence (AI) algorithms monitor 3,470 separate sensor inputs for any out-of-normal values, and the computer can trigger the auto-shutdown of any reactor it deems in danger of failure.
A total of 357,540 conditional combinations have been programmed and include anomalies in temperature, pressure, fuel flow rate, laser detonation timing, EPS conduit constriction, cooling system efficiency, and possible spurious computer impulses. A separate set of 4,556 possible sabotage and external threat problems affecting reactor operation also exist in the fusion system isolinear processors, and will initiate emergency procedures should particular conditional tests prove true.
In the event of a rapid overload, the radiative cooling beds in the lower generator shell will switch to full race mode to attempt to cool the EPS plasma, simultaneously lowering the temperature and pressure. In the worst-case overload, however, the radiator surfaces could be overwhelmed and begin to fail structurally while trying to reduce a chamber temperature of 8.23 x 10⁴ kelvins. The preferred coolant mode, as discussed previously, would be evaporative, where the superheated sodium is allowed to escape into space, followed by the controlled venting of the reactor chamber and EPS system. Magnetic iris valves would be opened and closed by the computer in an effort to retain station EPS power while releasing any overpressure. If the affected reactor can be resupplied with liquid sodium after the overload has been quenched, a restart will be attempted within eight hours of a system inspection.
The emergency detection subroutines will react to avoid a power system incident within 0.00023 seconds and will alert the command personnel and station occupants while the hardware is being safed. Evacuation protocols are invoked, and emergency engineering crews prepare for repair work in environmental suits. In the event of a catastrophic failure, a higher level of emergency response is triggered (see 5.6).
A manual shutdown can be accomplished by command personnel with the proper authorization codes from nearly all Deep Space 9 control consoles or within range of most audio pickups. In a deliberate command decision to shut the system down, the normal emergency programs are placed in standby mode.