MOX Reactor - Efficient ~1200EU/t no replacements

That's certainly a very unconventional design, good job thinking outside the box. If you heat it up all the way to 9990 degrees, you should be getting 1300 EU/t at efficiency 14.45.

Highest output I have seen so far on internal cooling alone, but efficiency is among the lowest. That's to be expected though, since you can only trade off one for the other if you are limited in how much cooling you have.

If you're looking for other designs, have a look here.