I did 8 little 1-block nukes (I guess that would be Mark I) that each put out 120 EU/t and gave me 7 Plutoniums every 5.5 hours from the 16 Depleted Quad Fuel Rods. That's 960 EU/t. I split the 8 reactors into 2 banks of 4 and ran them into MFE's, then into an MFSU. Coupled with my 32 Semifluid Generators at 32 EU/t running on fuel gave me a total of 1984 EU/t which is close enough to the MFSU's output of 2048 EU/t so my power grid was pretty solid and steady.
This is the insides:
http://prntscr.com/84931z
I started with 2, then 4, and ended up using 8 of those little beauties. Just be sure to run a quarry with every 5.5-hour run of the nukes so you have enough Uranium Ore to fuel the next cycle. The quarry will bring in enough ores to easily expand the number of nukes you are running. Turn that 960 EU/t into RF/t using Immersive HV Connections and it's almost 4K RF/t which is plenty to run an Ender Quarry with the bottom speed upgrade.
This is the thread I used:
http://forum.industrial-craft.net/index.php?page=Thread&threadID=11729
It says "
Mark 2-5 reactors:
These reactors produce more heat than they can handle and will explode if left on. This is solved by turning the reactor on and off to give it time to cool down."
So it sounds like the reactor you want is the very last one in Blackpalt's list
On/off reactor with vanilla redstone controle
Mixed design
030303160D0D0D0D0D030303160D0D0D0D0D030216160D0D0D0D0D16160D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D0D
http://prntscr.com/84up0p
Eu/tick: 300 avg (800-1200)
Efficiency: 10,94 (28,8-43,22) [Meu/fuel rod]
Cost: 6 advanced alloy, 595,33 copper, 160 gold, 452 iron, 6 lead, 40 tin, 30 uranium fuel
By: BlackPalt
Runs 10 seconds on, 17 seconds off.
Also, this video seems good for MOX reactors: