Here is the IndustrialCraft2 Nuclear Engineering forum Here is the browser based Reactor Planner by Talonius You will run across many designs on the IC2 forums that link to the Reactor Planner like this: Reactor Plan1 This is a design that I used several months ago. It outputs at 116eu/t on Uranium and 216eu/t on Plutonium. I like this design because of it's relatively low initial cost and the efficiency is fairly high. It's only 3 chambers but it's easy to duplicate and move if needed. I ran a dozen of these in my group's base while we gathered resources for solar panels. Once you have several reactors running you can recover depleted uranium cells in a breeder reactor. Run the re-enriched cells through a centrifuge and you can almost get a self-sustaining system.
these are the 2 I currently use I use x2 of this http://tinyurl.com/pdlt78p 444EU but the are kind of expensive and this is my breeder http://tinyurl.com/bv4tyob and it is 367 EU
I should mention they are 100% safe to run"no local radiation or fire dammage" provided you have all the components in the correct places.