Hey,
I've got a question related to external cooling by water(or air).
I read it's a 3*3sphere or something like that.
And I'm not sure if sphere means cube, since we are in minecraft 
Can you send me a kind of shematic?
...Beeing reactor
MinecraftSlime...Beeing a chamber
...Beeing outsided water?
So for example:
Layer below lowest chamber
Layer with lowest chamber: 
And so one?
I really appreciate your help
It's a cube, only the core reactor's encompassing volume counts. If you picture the 'core' as the center of a 3x3 cube you can see how it takes up 1 of 27 blocks.
You've basically got it right. But it is a 3x3x3 cube, centered on the reactor core. Additional chambers occupy portions of that cube and displace the water in that block - but they offer more cooling than the water would anyhow.
So, for a 6-chamber reactor, it would look like this:
Top level of cube (and bottom level as well):
Middle level of cube:
Also, to be sure your cooling water does not evaporate, set up a ring of water source blocks to flow into the chamber from a couple blocks above (a hot reactor can evaporate water in a 5x5x5 cube centered on the core). I hope this helps.
Thanks, a breeder i wanted to built needed exactly 11 water in his range. With your help i can finally build it 
