A major point is: by the time you have actually gathered enough resources to make a 6 chambered reactor (even with autominers) you will have in excess of 50 uranium
now you can either:
have a safe low powered reactor which uses 4-8 uranium while producing max 80EU/t or
have a not so very safe Mark III reactor which uses 4-12 uranium while producing max 120 EU/t in increments or
have an unsafe Mark V reactor with redstone timers or CASUC producing insane amoutns of EU min 80EU/t max ??? or
Make several Mark II reactors and by that time have over 200 uranium which you will not use for months producing 240 EU/t (for 3)
so the best power/time/resource ratio is to have a single bucket CASUC Reactor with massive power output.
but not very safe...
I am afraid to ask how large is the max explosion radii set to on your server? did you put it way down? or did you put it upwards just for the LULZ?
I set mine to 240 XD