Yeah, you probably want to keep that thing hot all the time with a redstone signal, if you're not already doing it
2/3 of the CESU was consumed just by that thing heating up
If you keep it always 'on' and hot, it eats a little power (I think something like 8 EU/t), but the gain is, every operation doesn't cost you a ton of EU, which is basically wasted on making it warm again.
You can use an AE level emitter to heat it up for you as well, if you get close to wanting to make a bunch more. But that's not much better.
The most efficient setup I found is 3 mark 1 reactors, with a timed power up, so that every 10 minutes a full reactor cycle completes. That basically means spending only 2 'real world' minutes wasting idle energy ticks on a centrifuge, it'll otherwise either be processing more uranium to make fuel rods, or the spent fuel rods.
In fact, one of those isotope generators is perfect for free energy to keep that thing hot, and you probably have enough plutonium by now to make 3 of those pellets, which is all you need for (I believe) 16 EU/t
Now, with these steam boilers, I want them as hot as I can possibly keep them all the time. They only explode if they run out of water and you try putting more water in them (empty) while they're hot, right?
@Arperum The 'i have power' indicator lit up when I gave it one prior to powering it is all, for a moment I thought I tricked it into actually having power.
Now I have to figure out how to automatically mine redstone and lapis that I'm getting from the nether. Thinking ... set up a very small quarry, let it run, then stick some formation planes on the sides of it. If I keep it powered after it finishes, it should see the new blocks and mine them.
Nothing that I can think of requires either in ore form.