Edit: So I discovered something today while discussing numbers with Omicron...looks like my config files generated a little funky (promise, I didn't realize it!), and I'm getting 4x more EU from nuclear fuels than I should have been...so the numbers below are wrong! 
Divide all EU values by 4.
So I saw all these awesome reactors...Tower of Power, Decentralized Distribution of Steam (DDoS), the Official Reactor Design Thread...there's so many creative and interesting builds out there. Well, I wanted to one up them. I wanted to power a nation.
And this is what I came up with. It's nothing fancy, and not really creative...but it's a power horse. Putting out a whopping 6,400eu/t at zero heat, this bad baby is just crying to be abused. And abuse her I did. I pumped her up to 55,500 heat, and with a max heat of 60,000, that placed her at a multiplier of 4.7. Then, when you do the math, that's a reactor putting out over 30,000eu/t. That's no typo! THIRTY THOUSAND! And that's living on the edge, because without cooling, this reactor produces 4,300 heat/second. Given the operating temperature I had her running at, that left me with a 200 heat buffer before exploding...scary.
Anyways, how about you feast your eyes on my beast! She's running a full 6-chamber reactor, as shown in the design above. To maintain a constant cooling temperature, 20 coolant cooling reactors (designed by Someone Else 37) are needed. On top of that, a special (and probably badly designed, but I wasn't looking for efficiency or speed, just something that'd help them cool off a little bit faster) reactor designed to cool Overclocked Heat Vents had to be produced. The whole thing is controlled by a single computer, which monitors the status of the reactor (heat levels, and components) every 8/10ths of a second. This computer forces the reactor to shut down and inserts an Overclocked Heat Vent to cool it off when it exceeds 55,500 heat, removes coolant cells when it's below 54,500 heat to allow the reactor to reach critical levels. It replaces Coolant cells and Heat Vents when they're around 80% broken, so they can be recharged in the cooling reactors. It replaces the fuel when it depletes as well. It does all this using Open Peripherals...other than the ME Interface to keep a supply of fuel rods handy in an "inventory", and exporting coolant cells and heat vents into obsidian chests (vanilla chests kept breaking around the reactor) surrounding the base of the reactor, AE has nothing to do with the actual maintenance of components in the reactor. It does, however, maintain the transfer of components into and out of the cooling reactors.
All this power runs underground via a single glass fibre cable. It goes into 15 EV Transformers, wired in parallel and spaced a meter apart. These transformers output 2048eu/t into two MFSUs wired in a serial fashion. The intent is that the first MFSU remains nearly empty while it keeps the second MFSU charged. Wireless Redstone Transmitters are wired to every first MFSU, and the first MFSU's mode is changed to "Emit when Empty." This in turn is received by a Wireless Redstone Receiver in front of the Computer, which detects that an MFSU is requesting power as part of the conditions required to turn on the reactor.
To test stability, I ran the reactor for a complete cycle before classifying it as "stable enough". You can see the bank of MFSUs I had to place in order to store as much power as that reactor generated. I calculated that the reactor output is in the neighborhood of 3 billion EU per cycle (assuming MOX lasts 5000 seconds, and there's 20 ticks in a second each producing 30,000eu/t). I got a few ideas on how I can tweak around another 1,000 eu out of this reactor, but I wanted to share the progress I made thus far.
Mod List:
Computer Craft
IC2 Experimental (tested in build 299)
Open Peripherals
Applied Energistics
Wireless Redstone
Iron Chests
Some things I learned:
Wireless Redstone doesn't like nuclear explosions...they'll crash your game...or at least they did mine.
ComputerCraft sometimes was listed in the crash logs as well when a reactor I was testing blew on me.
Even if you turn the reactor off while you swap coolant cells, occasionally a reactor tick will get by and add between a few hundred and a thousand heat to the reactor. The control program detects this, immediately shuts off the reactor and places the Overclocked Heat Vent in it to cool it back down to a safer temperature. And it's never anything a Overclocked Heat Vent (or two) can't handle, and it tends to keep the reactor running at the top end of the desired range of temperatures you have set in the Control Program.
If you want to look at the code I used for controlling the reactor...it's sloppy, but it works, and can be found here. Couple that with the following startup program, and you'll be as safe as you can be while completely automating the reactor. And trust me, you want it automated because at the heat levels it obtains, you can't get within 3 blocks of it without starting to take damage, and everything within a block of it will randomly catch fire. Anyways, the startup program:
shell.run("MOXControl")
rs.setOutput("back", false)
sleep(1.1)
os.reboot()
That will run your control program, if you terminate it or it crashes, it'll turn the reactor off instantly, and you have a delay to terminate the startup program before it reboots, running the control program again. This means your control program will almost -always- be running, even if it crashes out for some reason.
Nothing really new or mind blowing in this reactor...other than the massive power output. It takes tried and true concepts, and applies them in a dangerous situation. Living on the edge man, living on the edge. Just wait till you see my ideas on how to tweak around another 1,000 eu out of this girl.
Not that I'm going to build it...with machines unable to take more than 8,192 eu/t, I think less ambitious Mark I reactors would be more advantageous in the long run...or at least, for now.
The reason I didn't use component heat exchangers and more overclocked heat vents to cool it is the ME Network would see those heat vents that are supposed to remain in the reactor and pull them out as well. I know overclocked heat vents will eventually cool off on their own, I was just attempting to speed up the process. Would a setup like this be better: 