This seems to be slightly more efficient. Cryotheum is very good at moderating the neutrons produced by the cores, meaning that if it's between a core and something that can interact with those neutrons (such as another core or some coolant), the other thing will do so more efficiently. Resonant ender, however, is very good at absorbing moderated radiation outright and producing heat, which can then be turned into power. So you want cryo between and surrounding your cores, and ender outside.
The middle ring of resonant ender in your design absorbs a lot of neutrons that could otherwise fertilize other cores, so replacing it with cryo and filling the corners with ender ups the efficiency to about 67.6 kRF/mB and the raw output to 122.3 kRF/t.
I've gotta wonder, though, if you're putting this much resources into a reactor, if it wouldn't be more worth your time to just install a few of Reika's mods and jump into ReactorCraft.
Side note: If BR's blutonium acted like real-life plutonium in the reactors, cryotheum between cores would be actively bad when using it, since plutonium requires unmoderated neutrons to undergo induced fission. Better to just jam all the cores together in the middle and surround it with cryo and ender in that case.
The middle ring of resonant ender in your design absorbs a lot of neutrons that could otherwise fertilize other cores, so replacing it with cryo and filling the corners with ender ups the efficiency to about 67.6 kRF/mB and the raw output to 122.3 kRF/t.
I've gotta wonder, though, if you're putting this much resources into a reactor, if it wouldn't be more worth your time to just install a few of Reika's mods and jump into ReactorCraft.
Side note: If BR's blutonium acted like real-life plutonium in the reactors, cryotheum between cores would be actively bad when using it, since plutonium requires unmoderated neutrons to undergo induced fission. Better to just jam all the cores together in the middle and surround it with cryo and ender in that case.