There are many ways to build a nuclear reactor, some of which are completely safe, and produce plenty of EU.
Some YouTube tutorials:
1180EU/t nuclear reactor completely automated and safe(can't make faster EU than this):
If not taken care of properly, it will most likely explode. A good way to set it up is to have just the reactor put one uraniom cell and the rest vents/coolent
The 1000 EU/t version:
The basic setup tutorial (for beginners):
Example of an alarm system: