with 6 chambers water evaporating starts at 8k but as long as the source block is above the reactor by 2 it will only get the water "flowing" around it and never run out. Granted your mark 1 should never get that high. If you wanted to build a bigger reactor with more chambers and get more out of your Uranium then you are going to have to run cooldowns after or let it melt parts and replace them.
So as far as the construction on your reactor it was fine (minus that you are missing chambers) which you wont need unless you change setup.
Mark I's are good for getting rid of Uranium and completely safe.I would rather get more out of them then just 2.3 eff. Its really personal preference on how much you want to produce / upkeep.
So i run
Mark IV EB
Efficiency 3.67
165 Eu/T
1700ticks before critical. (28mins)
Ment to be used in 10mins intervals with other reactors of same type
(9reactors in 7x7x4)
http://test.vendaria.net/index.php?react…HCHCCHCHCCHCHCH