Recently updated with new functionality, balance and parts.

This pack contains electrical support parts for generating and storing electricity in the form of Electric Charge: nuclear reactors, additional batteries and capacitors. The electricity generated is quite useful for powering engines in the Near Future Propulsion pack.

Fission Reactors are power generators that run on the EnrichedUranium resource. They are quite heavy and awkward to incorporate into a ship, but rewarding in terms of amount of power generated per mass. There are a few things to make them a little harder to use:

Heat Radiators: Place heat radiators on the surface of the reactors and extend them. Without them, the reactors won't produce much/any power. Match the Thermal Power of the reactor (noted in the VAB) to the Heat Rejection of the radiators you're adding - if the total Heat Rejection is equal to or higher than the Thermal Power listed on the reactor, you'll be fine.
Fuel consumption: Eventually the reactors will run out of fuel. This takes a few years, but also occurs in the background when the ship is unfocused. Refueling can be done when the reactor is shut down by EVAing a Kerbal and selecting Refuel when you right click the reactor. If you have a nuclear fuel container on board, refueling will take place. You can also use the Whirlijig reprocessing plant to recycle some spent fuel from a fuel container.

Capacitors are new parts which store electric charge very efficiently as StoredCharge (they have 8x the electric charge per unit mass). They charge up very slowly from your main Ec reserve but can be triggered to discharge all of their energy into your Ec reserve very rapidly. This lets you run higher power engines for longer time periods. Use the right click menu in the VAB/SPH to vary a capacitor's discharge rate down to 50% of its rated maximum.

There are also larger version of the stock inline battery packs (in 0.625, 1.25 and 2.5m sizes) for storing large amounts of Electric Charge.

For more info check out the KSP Forum Thread.

Installation:

To install, place the included GameData folder inside your Kerbal Space Program folder. If asked to overwrite files, do so.

To use the low-resolution textures, place the contents of the _low folder inside the Kerbal Space Program folder after installation.
Make sure to agree to overwrite all the files if asked.

Known Issues:

Nothing major at the moment

Future Plans:

Improved capacitor management (automation)
Improved reactor panel

Near Future Electrical