Doing some maths with the fusion reactors. The reactors put out 300k EU @ 30eu/tick, which means they last for 10k ticks. The isotope separator draws 5eu/tick and requires 512 eu for one operation. That means it takes 103ticks per operation of the separator, which translates to a fuel cell every 1030 ticks. This pretty much says that 1 separator can run almost 10 reactors non-stop given an endless supply of tin and an automatic crafting area. This is amazing, because the 10 reactors operations (without scrap) produce 3 uu matter, which makes 5 tin ore, turns into 10 tin, which turns into 40 cells. Which is twice the amount put in. This thing literally doubles it's potential energy every cycle of the reactors. Pretty nifty stuff
(Mind you, it takes either intense micro or automation using buildcraft, as rp2 cannot pull from the empty cell slot of the separator)
I accept your challenge though buildcraft bucketfiller addon and additional pipes will be used