Which setups? Don't have any built in my SSP world yet.
With the multi-reactor systems, you can get isotope efficiencies >6 without crippling your EU/t. Let me throw something together after dinner to demonstrate.
Same as in 1.4.7, just without hybrid effects, and slightly less heat (and thorium got halved in runtime). Look it up in my spreadsheet 
Sample 3.07i multi-reactor system - one uranium/plutonium hybrid, one 3x3 thorium sink:
cooling system - 720 heat / tick
http://www.talonfiremage.pwp.b…ovydkz4gvw4bbb961u7t8vqio
ingame setup - 720 heat, +40T/20k, 360 EU/t
http://www.talonfiremage.pwp.b…o2w0unrhtmzv9tetav6ooj11c
cooling system - 572 heat / tick
http://www.talonfiremage.pwp.b…g1879k7e27a0n5hl4ua52zw8w
ingame setup - 550.4 heat, -36T/25k, 204 EU/t
http://www.talonfiremage.pwp.b…bgqhitpiwqtaui1pj892xc000
Total system: 5.573 isotope efficiency, +14T/25k, 564 EU/t
Or: 6.474 isotope efficiency, thorium neutral when running all thorium cycles (either through pausing the plutonium reactor/waiting for fuel, or by building a second thorium sink which runs once every ~3 cycles)
Cooling system on the thorium sink might need some tweaking.
EDIT: For the sake of comparison, here's a singular thorium neutral plutonium/thorium hybrid:
cooling system - 558 heat / tick
http://www.talonfiremage.pwp.b…b8tl8i5r372z12mdth8kmax34
ingame setup - 550.4 heat, 5.06 Isotope efficiency, 254 EU/t
http://www.talonfiremage.pwp.b…lhxmzix6lvgomf7m9vmr904jk
That's more than 1.4 efficiency less than the pair above, and even building 2 of these won't give you as much EU/t.
Nope, plutonium runtime didn't change - it's still 20k seconds, and 25k for thorium, and 10k for uranium.
Basically one plutonium cell equals 5 thorium cells to be neutral (as seen in the last reactor I linked). In 1.4.7 this was 1 to 10 instead.
That total output would be down was a given though, considering the unintended +75% output 'feature' for single plutonium/quad thorium cell pairs was fixed.
Not much of a fan of that metric because it rolls breeding gains into the number, and thus isn't comparable to standard IC2 reactors... you can basically only rate GregTech reactors with that, and then it'll confuse people into thinking they can compare the numbers to pure uranium.
Admittedly isotope efficiency isn't the most straightforward of models, especially with multi-reactor systems, but I wanted to avoid any confusion and keep everything fully comparable. That's why I opted for a metric that exactly returns the reactor planner numbers for pure uranium reactors while also appropriately describing GregTech fuels with the exact same formula. I think that a little complexity is a fair price to pay (but I suppose that as long as there is no automated tool like the reactor planner that reports it, it won't really see widespread adoption).
Just for reference of other readers who may not have seen my previous post, here's how you would calculate isotope efficiency for the multi-reactor system presented in post #364:
First, figure out how many isotopes you require to craft enough fuel for one full cycle. Pick one reactor to start with, usually the plutonium reactor. This example runs one dual uranium cell and 2 quad plutonium cells, and due to lifetime differences, the dual uranium cell must be replaced once per cycle. You effectively have two dual uranium cells, for a total of four uranium and eight plutonium. 1 uranium is 1 isotope, but 1 plutonium is 5 isotopes because the centrifuge turns 5 isotopes into 4 thorium and 1 plutonium. Eight such centrifuge runs thus cost 40 isotopes. Together with the 4 for uranium, that's 44 isotopes to stock the plutonium reactor.
Is this enough to also stock our thorium sink? The runtime for the plutonium reactor is 20,000 seconds, and for each such cycle we have 32 thorium left over. The thorium sink reactor runs for 25,000 seconds, which is one quarter more. During that extra quarter, the plutonium reactor generates an extra 8 excess, for a total of 40. Since we only need 36, we don't need to spend any extra isotopes here.
And now you can also see why explaining things to people is a good thing, because I just noticed that I made a mistake earlier. God dammit why am I so sloppy 
Second, determine the total EU generated for one cycle. 360 EU/t for 20,000 seconds, plus 204 EU/t for 25,000 seconds: 144 million + 102 million = 246 million.
Eight runs of the centrifuge cost 800,000 EU, subtract that: 245.2 million. This is also the point where you would subtract running costs for your reactor if you paid them in UU-matter, but since this is a GregTech reactor and thus subject to GregTech's UU-matter costs, that is a pretty silly proposition, so I'll skip it here.
Finally, divide your EU total (in millions) by your invested isotopes: 245.2 / 44 = 5.5727272727272727...
This number is your isotope efficiency. Or, in other words:
"At what efficiency would you be if you generated this much EU out of this number of isotopes using just a pure uranium reactor."
Third, check if there's anything left: our reactor system only consumes 36 out of 40 thorium every 25,000 seconds. The system is thus "+4T/25k" thorium positive. That thorium is free energy we're not yet taking advantage of, so we might want to do that.
Since 4 thorium is 1/9th of the full 36 load of the thorium sink, we'll just say that these 4 will, at some unkown point in time when we have run many cycles and amassed enough thorium to let the sink run a bonus cycle, give us roughly 1/9th the energy output of a full sink cycle. So 102 million EU / 9 = 11.3333333... million EU. We get to add this number to the total EU yield of the reactor system, which rises from 245.2 to 256.533333...
And then just repeat the division: 256.53333333... / 44 = 5.830830830...
Therefore, by utilizing all the thorium, the final isotope efficiency of the system is 5.831.
Sorry guys, not 6.474, I blame food coma for inventing an extra 10 thorium that wasn't there. 
And people wonder why I don't bother with GregTech...
I'm not ignoring the 3 out of 8 cells returned as depleted isotopes from the centrifuge... I never factor in 8 cells per centrifuge run to begin with.
My math assumes that you insert 5 re-enriched isotopes into the centrifuge and get out 1 plutonium and 4 thorium. True, in practical application you have to insert 8 isotopes and get a side product of 3 depleted ones, but those can be re-bred indefinitely. Therefore you don't actually lose or gain any reactor fuel, and the whole thing can be safely ignored. The only thing that counts is that through some process, the details of which are unimportant, the centrifuge converts exactly 5 isotopes into exactly 5 fuel cells with no loss beyond the cost of 100k EU per centrifuge run.
I'm also not factoring in breeding fuel costs because really, silktouching a single coal vein and throwing the blocks into an indsutrial grinder will give you enough thorium to breed hundreds upon hundreds of isotopes without ever touching your regular reactor fuel at all. Breeding is essentially free of charge beyond the initial build cost of the breeder reactor.
And yeah, that centrifuge recipe is very useful. Together with the fact that the industrial grinder will double uranium output from ore plus guaranteed plutonium dust, and gives guaranteed thorium dust from coal ore (you version's mileage may vary), you can still get a decent amount. You do however invariably end up with uranium cells that you need to run through a regular reactor.
Display MoreI'm not ignoring the 3 out of 8 cells returned as depleted isotopes from the centrifuge... I never factor in 8 cells per centrifuge run to begin with.
My math assumes that you insert 5 re-enriched isotopes into the centrifuge and get out 1 plutonium and 4 thorium. True, in practical application you have to insert 8 isotopes and get a side product of 3 depleted ones, but those can be re-bred indefinitely. Therefore you don't actually lose or gain any reactor fuel, and the whole thing can be safely ignored. The only thing that counts is that through some process, the details of which are unimportant, the centrifuge converts exactly 5 isotopes into exactly 5 fuel cells with no loss beyond the cost of 100k EU per centrifuge run.
I'm also not factoring in breeding fuel costs because really, silktouching a single coal vein and throwing the blocks into an indsutrial grinder will give you enough thorium to breed hundreds upon hundreds of isotopes without ever touching your regular reactor fuel at all. Breeding is essentially free of charge beyond the initial build cost of the breeder reactor.
And yeah, that centrifuge recipe is very useful. Together with the fact that the industrial grinder will double uranium output from ore plus guaranteed plutonium dust, and gives guaranteed thorium dust from coal ore (you version's mileage may vary), you can still get a decent amount. You do however invariably end up with uranium cells that you need to run through a regular reactor.
The grinder is less practical. Maybe with thaumcraft AND redpower (and a shitload of patience trying to get silk touch). You've got to silk touch 32 uranium ore to get enough for a single cycle of that 8 plutonium reactor. It's good for very small reactors, run part time to keep storage full, nothing full size or run full time. (And breeding of course, a single thorium cell isn't going to break anybody's back).
The grinder is less practical. Maybe with thaumcraft AND redpower (and a shitload of patience trying to get silk touch). You've got to silk touch 32 uranium ore to get enough for a single cycle of that 8 plutonium reactor. It's good for very small reactors, run part time to keep storage full, nothing full size or run full time.
Do you know about AS ? It generates tons of Uraninite you don't even have to silktouch since it drop the block itself 
(and it's a bit OP, but I like to assume it's a buff to Nuclear Reactors ^^)
Atomic Science? Last time I messed with UE the whole thing was pretty much unusable.
Some of the UE mods have gotten more usable of late, Atomic Science is one of the ones that has gotten better. I'm considering including Mekanism in the 1.6 release of my mod pack.
It's actually cool but ... it's not the same balance than IC² (I know, BC and its addons are already a bit away from being balanced with IC² but ... with UE addons that's even worse)
UE was never big about game balance in general... :p
