I made this very cheap 80EU/t (40 EU/t calculated) stable design. Usefull for a first reactor.
EDIT: And a new design with 2 less components.
EDIT: And after testing to see how uranium cells distributed heat, a cheaper one.
EDIT: And a bigger reactor I've made. 480 EU/t (240 EU/t calculated) stable.
I made the big reactor better if you were to add the last two chambers
(Yes that is the updated planner, but it's still not complete and is "rough around the edges"