Power Systems:
Miharu will likely function on three power sources.
Main Power (70% of total ship power):
2 Matter/Anti-Matter Reactor Assemblies ought to provide most of the power to the ship. Power is then distributed in two fashions:
- Most of the plasma produced is shunted away nearly directly to the sublight engine assembly, where it either feeds it directly or branches off through an accelerator system to head for the faster-than-light subspace distorsion drive. Once there, it can provide power for the distorsion drive or branch off again through another plasma accelerator to feed power to the hyperspace fold drive.
The 'main power grid' effectively feeds the sublight engines first with energy. If the sublight engines aren't used, the power is easily diverted to the distorsion drive and if the ship is to use fold, the power can handily be distributed there instead. While the Himiko-class' power grid tries to provide everything with power and ends up overtaxing itself, the overhaul instead focuses on giving power in an escalating fashion to what needs it.
- The reactor cooling system reuses the waste heat released from the reactor much as a fusion reactor does and uses it to heat heavy water-run generators. The electricity produced goes to the reserve power.
Reserve power (20% of total ship power): Mostly stored through power capacitors, reserve power is used to furnish energy to most of the other ship systems other than the very demanding engine elements and to maintain the power upkeep on the reactor systems in the first place (main power requires electricity to run in the first place, after all). The capacitors will run out of power in long engagements (20 minutes estimate) and may need several minutes (5~10), once depleted, to return to full charge. The charge held may start to decay after more than an hour spent without constant feed from main power.
Emergency power (10% of total ship power): Sturdy batteries close to the bridge and main computer. Emergency power batteries can either be used to maintain survival conditions for a time in case of catastrophic power failure or provide a short spurt of increased power to support the vessel in a dire situation. Unlike reserve power, the emergency batteries take more than half-a-day to recharge, but the charge they hold decays on a yearly scale when left without feed from main power.
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Unlike the Himiko-class, the overhaul's power requirements are expected to go at 35% for standard operation while using the hyperspace fold drive at cruising speed, and 50% at peak military power (assuming only one engine mode is used at a time); it is possible in theory to have the ship running in maximum power consumption up to 80% of the ship's total power output, though it's generally considered wasteful.
End result? The ship should suffer little to no power shortages. Just one of the matter/anti-matter reactors would in fact be sufficient to help the vessel function at peak military power without resorting to emergency power.
The redundancy helps, because it helps the vessel considerably in dealing with damage it might sustain. In an instance where main power cannot be maintained anywhere near ideal conditions, the technicians still have plenty of working room to tweak on the power grid and manage in difficult situations.
Fuel:
The Matter-Anti-Matter reactors function mainly on deuterium (heavy water) obtained through the Matter Collection System of the ship and anti-deuterium, which is stored in special anti-matter pods located close to the ship's main gun.
The anti-matter pods hold the hazardous Anti-Deuterium safely thanks to magnetic containment. In the event of magnetic seal cohesion dropping beyond recovery from the technicians on board (usually due to damage close to the storage units by weapons such as positron cannons, for instance), the pods can be ejected to spare the ship from them exploding. The pods themselves are quite tough and only a direct hit from an anti-ship weapon would be likely to make them detonate - such an event, though, would grievously damage the ship and might cause a chain reaction from the nearby pods making sympathetic explosions, thus resulting in the destruction of the vessel.
So, yeah, pretty heavy armor around those pods. More like plain Yamataium than the composite material - it's not a place anyone wants to be stingy on. ^_^;
The deuterium storage is luckily easier to handle. It's basically a bunch of big pressurized liquid storage tanks. While Anti-deuterium sees use mostly in the power reactors and the ammunition for the ship's main cannon, deuterium has something of a wider, more important use. Not only is it reactant for the matter/anti-matter reaction, but it also serves as coolant.
The ship should have a network of coolant lines going around it beyond the reactor coolant assembly. Parts of the ship, especially in combat conditions, will be prone to overheating and the heavy water will be useable in such instances to 'flush' into problem areas and mitigate the situation.
Not only that, but in emergency situations where anti-deuterium runs out (unlikely, but possible), the ship's M/AM reactors can run only on deuterium much in the fashion of more mundane fusion reactors. They don't run as efficiently as a specialized fusion reactor, though, and it only provides power for limited STL and very limited FTL distorsion speeds seeing the plasma coming from a fusion reaction is much less than what comes out of a controlled anti-matter reaction.
So, while deuterium is more plentiful than anti-deuterium and that it can be collected through the Matter Collection System, good management of that resource remains important.