FUSION SYSTEM STRUCTURE AND OPERATION

Primary power for all critical station hardware is produced by the fusion generator attached to the -Y end of the Lower Core. The generator section consists of six fusion reaction chambers working in concert to supply energized plasma for distribution throughout Deep Space 12. The original Cardassian term for the EPS translates as ion energy network; however, the Starfleet nomenclature is in effect for all technical discussions. The reaction chamber group is the heart of the generator, potentially capable of producing 790 terawatts of power with all six chambers running. Since the station handover, only four of the chambers have been consistently maintained, the other two of which have been rated as borderline for safety reasons by Starfleet engineers and are usually powered down.
The fusion chambers are housed within the generator shell. This structure also contains the fuel conditioning blocks, fuel transfer conduits, focused nanometer laser detonators, peristaltic and electrohydraulic pump machinery, and radiator beds and coolant loops. The chambers are 25.9 meters in diameter and 30.17 meters tall, constructed of four main layers of rodinium pentacarbide alloy. Each of the wall layers is assembled from six gores that have been gamma welded under a pressure of 203,500 metric tonnes per m2. This results in a large volume chamber that is prestressed against high frequency fusion pressures.
The general operation flow is identical for all reactors. Deuterium fuel is warmed slightly within its storage tanks from a semisolid state of 10.3 Kelvin's to a slush condition of 13.4 Kelvin's The slush is transferred through the Lower Core to a series of six holding tanks and then into neoplesium cavities in the fuel conditioning blocks. The cavities, each a narrowing cone 7.66 centimeters in diameter and 75.9 centimeters in length, with an exit orifice of 11 millimeters, form the fuel into long rods by the use of compression rams. In one continuous process, the rods are further formed into 10.3 millimeter pellets by traveling shaping mandrels and arranged in feed channels for ejection into the reaction chamber.
The laser detonators are focused pulse wave devices capable of converging 26.1 gigajoules of energy on a pinpoint 9.3 millimeters wide, effectively surrounding the target fuel pellet. V'retellium bezenate windows for the twenty nine detonators line the inner wall of the reaction chamber, and the pellet ejector nozzle penetrates the chamber at the +Y or top end. This opening is protected from the nuclear reactions by a cycling force field. A sustained reaction rate of twelve detonations per second is considered normal for benign condition station operations and can be increased to eighty three detonations per second during periods of high energy demand, particularly for EPS-intensive phaser and defensive shield operation. The ignition cycle is similar in principle to that utilized in the station RCS thrusters.
Initial power for the detonators is stored in a large bank of capacitance start up cells. Once the fusion process begins and the released energy overtakes the amount needed to initiate the system, any surplus energy is immediately used to recharge the start up cells. The chamber EPS plasma is directed magnetically through an irised exhaust port and into the station power grid. The exhaust iris and pellet ejector are normally set in one to one firing synchronization, although a ratio of two or three pellets detonated in rapid sequence for each plasma exhaust opening is not unknown. The danger exists that in particular types of hardware or software failures, the plasma density could increase beyond the chamber's rated structural integrity, creating an overload.
When operating at normal rates, the inner chamber wall reaches instantaneous flash temperatures of 560,000 Kelvin's. Eighteen redundant regenerative coolant loops embedded within the three outer layers draw off excess thermal radiation at a rate of 1366 Kelvin's per cubic centimeter per second. Most of the thermal energy is radiated into space, though some may be reintroduced into the EPS plasma or stored in six tanks filled with polykeiyurium dichlorokine, to be converted back into EM current at a later time. When radiated into space, the thermal flow is dumped into a liquid sodium loop and circulated through downward facing louver panels, as well as the large radiator cone at the extreme -Y end of the system. The cone also handles routine and emergency plasma and fuel venting. In emergencies, the coolant method would become exclusively evaporative.

FUEL STORAGE AND TRANSFER

Main power generation for Deep Space 12 relies directly on the storage of large quantities of supercold deuterium, the isotope of hydrogen that also helps power most interstellar vessels in the galaxy. Standard hydrogen atoms possess one proton in the nucleus and one electron in the first orbital shell; deuterium possesses an extra neutron in the nucleus. The form of deuterium stored at Deep Space 12 is a cryogenic semibrittle material maintained at a temperature of -262.35° Celsius, or 10.8 Kelvin's. The densified nature of the fuel allows for increased energy availability per cubic meter than slush deuterium carried on starships, which require some control over tankage balances in a moving structure. While the space station has made one large translational maneuver in its operational lifetime, it does not perform rapid motions with the same frequency as its mobile counterparts.
Six large deuterium tanks and six smaller surge tanks are housed within the Lower Core assembly. The large tanks, which are installed long axis perpendicular to the station's Y-axis in 60 degree intervals, measure 9.44 meters in diameter and 30.17 meters in length. Each rounded cylinder is triple walled kevlinite and hafnium arkenide alternating with plasma expanded insulating foam of polysilica boronite. The gamma welded walls have thickness', from the innermost, of 3.61 centimeters, 2.81 centimeters, and 1.76 centimeters. Five hundred eighty one structural linkages between the tank layers are fabricated from spin cast anodium arkenide with a maximum contact area per link of 2.01 cm2. This reduces the thermal migration to less than 0.000032 Kelvin's/day and is easily countered by diffusion stage vacuum pumps and embedded thermal wicking assemblies. The volume of deuterium stored in each large tank is 2, 111.58 m3, for a total of 12,669.52 m3.
The surge tanks are also rounded cylinders, measuring 6.09 meters in diameter by 20.72 meters in length, and have an internal volume of 603.55 m3. They possess the same structural plan as the larger ones. They are installed inboard of the large tanks in parallel with the station's Y axis. All tank penetrations for supply, purge, vent, and sensor lines have been made by narrow-band Cardassian matter disruption tools. Doubly redundant supply conduits service the main fusion generator system as well as all smaller fusion reactors aboard the station, including the reaction control system (RCS) thrusters.
A single large spherical deuterium tank 30.63 meters in diameter had at one time been mounted partly to the outer shell of the Mid Core and partly to Crossover Bridge 2. This tank held a total volume of 119,000 m3 of deuterium and had suffered a major catastrophic failure prior to the station handover. Remarkably, the structure based overpressure failure was confined to a burst area in the lower one third of the tank, preventing the escaping fuel from impacting other station masses. The tank has not been replaced by Starfleet, and all exposed transfer and sensor conduits have been capped off. It is surmised that this large external tank was installed to relieve Cardassian tanker vehicles from having to make repeated supply runs necessary to maintain the power required for the ore processing and weapons systems. The notion that the destruction of the tank had been an act of sabotage has not escaped either Starfleet Intelligence or the Bajoran security forces, though physical evidence of tampering has yet to be found.

POWER DISTRIBUTION NETWORK

Fusion power produced by the large central generators is distributed through the station over a series of 651 stepped energy EPS conduits feeding all 24 major and 53 minor subsystems. The first stage conduits, formed from multilayer toranium durmanite, measure 1.89 meters in diameter and 1,103.62 meters in length. They emerge from the six fusion energy chambers and are controlled by a set of five one-way plasma flow constrictors. These devices act as baffles to prevent frequent reaction surges in the fusion generators from affecting downstream segments of the system, including the final stage user grid. By the time the plasma has reached the fifth constrictor, the temperature has been stabilized at 215,000 Kelvin's and remains at that level throughout the first three energy steps. Plasma flow controllers and cross feeds link all six first stage conduits in the event of power drains or unbalanced demand, particularly evident in weapon and shield usage.
External to the fusion generator housing, six second stage EPS conduits carry energy outboard of the generator's structural attach point on the Lower Core. They average 1.09 meters in diameter and are 85.23 meters in length. It is known that the individual conduits were spread out in a measure to minimize damage in the event of hostile action or catastrophic failure, which might have jeopardized the entire station had the conduits been clustered together. The second stage conduits are also fabricated from toranium durmanite and are hardened against radiation interference and structural impacts. The main subassemblies of each conduit include an energy polarization bed, emergency venting and cooling jackets, and flow accelerator coils to maintain directional plasma pressure toward critical systems.
The junctions to the third stage conduits split to form eighteen large and twenty seven smaller branches within the Lower Core and up into the Mid Core. Nine of the large EPS branches spread out within the Mid Core and reconverge at the minor crossover bridges to power the weapon sail towers and defensive shield generators directly. Another nine take different paths within the Mid Core to power the ore processing centers in the pylons. The twenty seven smaller branches, moving lower temperature and lower pressure plasma, form the multi use pregrid for the Docking Ring, Habitat Ring, Promenade, and Ops One hundred sixty two fourth stage conduits carry power from the pregrid to plasma circuitry junctions, through embedded wall nets and access tunnels in all areas of the station. The majority of fourth stage conduits terminate in multiphase alternating current taps, and are available for most medium to heavy industrial applications. Induction type user equipment requiring up to 8,192 Kelvin plasma make use of fifth stage step down conduits within residences, laboratories, cargo bays, commercial facilities, and offices. Holosuites are an exception, utilizing higher energy 12,500 Kelvin plasma for their operation.
Starfleet power conditioning equipment was brought in early in the handover process to facilitate most computer, weapon, utility, and spacecraft operations, among other activities requiring stable, transformable energy.
Future upgrades either in work or being considered by Starfleet Command include increased computer control of all major conduits and node branches, improved emergency detection systems applied to high energy junctions, and increased security measures applied to all sensitive power facilities. Work in these areas is usually done in concert with strategic and tactical analysts to further examine all aspects of Cardassian materials science and technology.

Even as one Starfleet engineering team began analyzing exhaustive scans of the fusion power systems, another was compiling operational protocols and documentation on system safety. From the day the first Federation ship docked at the station, it was clear that the fusion reactors were in need of long hours of maintenance and safety checks. Two of the six reactors were completely inactive, and the load was taken up by the remaining four chambers. This is not normally a critical situation, but high Ievel power usage for weapons and full shields would have required at least one other reactor to be operational as backup in case one failed.
Since the power system is purely laser induced fusion, and the multiple chambers allow for maintenance while-active (MWA) procedures, hardware teardown and rebuilding is similar to that of ship installed primary impulse reactors and auxiliary fusion generators. Each reactor is partitioned off into its own sealed housing so crews can, for example, replace the deuterium injector on one reactor,while the two adjacent units are providing EPS power. No starbase class facilities are required for repairs or upgrades to this particular system. Following reactor shutdown and mandatory cold soak thermal energy bleed off of thirty five minutes, a chamber is accessible for internal scans and hardware replacement through a magnetically-sealed inspection port built into the chamber equatorial band. The laser detonators and fuel pellet injector can be reached using extensible boom fixtures built into each generator outer housing. The typical inspection cycle for internal components has been set at 550 operating hours. All inner chamber wall seam melds must be inspected for stress microfractures and resurfaced when voids in the rodinium excelinate reach rates and sizes of greater than two hundred voids 0.02 millimeters in diameter. All chamber pressure surge levels greater than six hundred kilopascals/m2 trigger automatic resurfacing at the earliest available time, since exposure to this amount of force risks multiple fractures of the interior coating.
The other components subject to inspection at 1,200 hour intervals are the fuel conditioning blocks, fuel transfer conduits, peristaltic and electrohydraulic pumps, and external radiator beds. All circulating sodium thermal transfer conduits are inspected at 1,650 hour intervals, and all liquid sodium metal is shunted to catalyst filters for contaminant removal at those times. The neoplesium cavities in the fuel conditioning blocks must be removed to the generator servicing lab and resurfaced with a new flash evaporated neoplesium coating. This coating must be reapplied whenever the optimal surface contour is degraded by 0.31 centimeters.
Chamber power levels higher than 100 percent can be tolerated for short periods, usually less than thirty minutes. Power levels higher than 108 percent are not recommended, though this protocol is waived during crisis situations, when auto shutdown limits can be moved as high as 112 percent, depending on the reactor. Above 108 percent, thermal stresses can be tolerated for an average of five minutes. It should be noted, however, that those five minutes may be crucial to the survival of Deep Space 12, especially during threat attacks. The operational history of the total generator system lists the following limits for each chamber:

Standard safety protocols for the handling of cryogenic fuels are observed in all storage and transfers of slush and liquid deuterium for the fusion system. All pumps and conduits are inspected by NDT means at thirty four hundred hour intervals, and on a rotating basis for reactors and primary fuel tanks. Secondary tanks, vents, and purge lines are inspected every sixty four hundred hours. Microfractures and degraded insulation are repaired as necessary.

EMERGENCY SHUTDOWN PROCEDURES

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 106 Kelvin's. 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. A manual shutdown can be accomplished by command personnel with the proper authorization codes from nearly all Deep Space 12 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.

CATASTROPHIC EMERGENCY PROCEDURES

The catastrophic failure of the fusion power system is predicted to be an energetic event capable of crippling Deep Space 12. The physical effects of one or more reactor chambers explosively dissociating will include gross structural accelerations, EPS energy releases, coolant chemical releases, and major power losses. The probability of large numbers of casualties is high, activating rapid rescue and medical response teams. Once the initial event has occurred, evacuation of all civilians will take place with all available space vehicles. If the severity of the failure is such that the system can be refurbished, engineering crews will perform standard damage control tasks, including safeties all affected systems, assessing any collateral structural and system damage, and sealing off station hull breaches as would be done in the case of a fusion reactor failure aboard a starship.
The engineering teams assigned to EVA tasks would examine the affected areas in standard extravehicular work garments (SEWG) and perform repairs. In hazardous areas where pressure suits would not provide adequate protection, piloted Work Bee craft with remote manipulator arms would engage in repairs and debris clearing. All critical debris required for an incident inquiry would be gathered, stored in a cargo bay, and embargoed, where it would await Starfleet investigators.
If possible, all auxiliary power systems would be brought on-line to make up for all EPS energy lost due to a major reactor failure. In some cases, these smaller fusion devices would aid in the evacuation of Deep Space 12 and would then be shut down. The microfusion reactors powering the station RCS may also provide EPS power for a limited time. If the fusion system suffers a total loss as a result of hostile military action, and all civilians and commercial operators have already been removed to safe locations, all remaining Starfleet and Bajoran assets will depart and the station will likely be forfeit.