Fusion Plant

The heart of any ship is its fusion power plant. Without jump drive a starship is trapped in real space, but without its fusion plant it's passengers and crew are at the mercy of the hostile environment of space. Every system on the ship from gravity to life support to propulsion to lighting depends on power from the fusion power plant. Not even a single missile or probe could be launched without power.
All fusion plants have basically the same components. Small craft generally have an integrated power plant, with all major components on a single skid. Even a ship as large as 200 dtons will typically have such a plant. A larger ship, such as a Leviathan, will have several subassemblies dispersed into individual systems.

The fusion reaction takes place in the containment vessel. On most skid mounted fusion plants the containment vessel is mounted horizontally. The Leviathan's containment vessel is mounted vertically. The fusion plant consists of six stacked containment vessel segments. Each vessel segment is an  independent fusion bottle capable of producing the plasma reaction, the tiny captured star, that converts hydrogen into helium releasing energy as heat and radiation.
The reaction is started in the Deuterium Warm Start Reservoir by the Laser Ignition System. Once the fusion reaction has been started it is conveyed to the proper fusion containment bottle by the Cold Start Ignition Manifold.

Once the fusion reaction is fully productive the balance of the hydrogen gas becomes plasma. The plasma is passed through a Magnetohydrodynamic (MHD) Generator that directly produces DC electricity. This power is used by the great majority of high powered components on the vessel, such as the main propulsion Maneuvering Drive, as well as many of the gravitic components aboard ship.
After it passes through the MHD Generator, which greatly cools the plasma, it is sent to one of two 400 Hz AC Generators. One is the main generation unit and the other is a back up. 400 Hz is used by many of the electronic systems on the ship, including sensors and control systems. It is then returned to the containment vessel by the return conduit.

There is a 400 Hz Generator Switchboard which distributes power from the generator room to the ship's 400 Hz Distribution System. There is also a MHD switchboard that distributes power to the ship's DC Distribution System.
Some of the systems in the Fusion Generator room are powered by 400 Hz, so there is a local 400 Hz power panel located there.

Because sometimes the Fusion Generator must be shut down for maintenance there is an Emergency Backup Power Unit. The EBPU consists of a Power Cell Matrix which can store enough power to keep lights, gravity and life support operating for a minimum of 2 hours. It can also keep most control systems on line and provide enough power for Fusion Plant Ignition, to restart the fusion plant after shut down. During normal operation a small amount of DC current is sent through the Matrix Interrupt to maintain a charge on the Power Cell Matrix. When power is lost some DC power is sent back through the charging line to power select DC systems, like the grav plate network.  Other DC power is sent to a DC to 400 Hz converter to supply power to select 400 Hz loads.

On the upper level of the Fusion Power Room is the Thermal Transfer Circuit. The TTC provides cooling to the containment vessels. A Primary Loop is used to transfer heat from the containment vessel. Combined with the magnet bottle system, which prevents the plasma from contacting the containment vessel the TTC prevents the very high temperature plasma from melting the containment vessel and plasma conduit. In the Heat Exchanger the Primary Loop transfers it's heat to the Secondary Loop that transports heat to radiator strips on the hall. Because of the NdN's stealth design excess heat can also be dumped to a thermal transfer matrix that converts the heat to energy which is stored in power cells for later use, or disposal. Thermodynamics limits the amount of heat that can be converted this way, but the ship can under many circumstances simple radiate heat away based on the probable position of observers. It is also possible to play with the specific wavelengths of radiated energy. In almost all cases lower TL sensor can be spoofed by a combination of techniques, allowing the NdN to safely shed excess heat without detection.