Oh, shit! I've been a full day searching how to solve this, that happens to me too. I thought it was a failure on my setup, but I tested in on creative with a MOX-Fueled Reactor and it was producing 1 mb of UU-Matter per operation. The recipes aren't balanced, to get a diamond it requires full buckets.
I've left a report at the BT.
P.D.: Sorry for my English.