First: I KNOW that fusion reactors were discussed and denied, but all proposals were very bad thought stuff, like 2 sentences or less. Pls read it and think about it. Don just say no before taking a look.
I wanted to make a new Suggestion, a new high end reactor for energy needs not even a nuclear reactor can support. The Fusion reactor! Capable of emitting TONS of energy at a not soo high price. The only big negative part, this thing is VERY expensive to build and needs 2 things already achieved:
A working Massfab
a working nuclear reactor/breeder.
You will soon see why. I do not Expect this thing to be like included in the next release or something like this, but I would definitely like to see it released some day.
I once read that you (Alb) wrote that you were thinking about a big collider thing. I don’t know if those plans died with the nuclear reactor consisting of multiple blocks or if it is still a valid option. If it is: This reactor may serve as a realistic way to make a “circle” of blocks.
The theoretical recipe of a reactor should look like this: (I will explain everything like the reactor is just one block big, if you would decide to make it a built circle variations would be great, like varying circle length for varying energy etc.)
To Build and maintain this new reactor we will need a few new items as well as new functionalities.
New Items:
Fuel Parts:
Heavy Water Cell
Uber Heavy Water Cell
Deuterium Cell
Tritium Cell
Fusion Fuel Cell
Lithium Dust
Lithium Ingot
Lithium Plating
Reactor Parts:
Reactor Control unit
Magnetic Mantle
Electronic Magnet
Uncurred Ceramic Plating
Fusion Reactor Plating
New functionalitys for Existing machines:
Nuclear reactor is able to breed heavy water cells => Uber heavy water cells (like isotope cells)
Electrolyzer will need a 3rd slot to input an empty cell which for each electrolyzed water cell will be 1/10 filled with heavy water (thats actually like they do it in RL but we are just much more effective... 
).
Now how does that thing work?
First to the new recipes for stuff:
Reactor:
Electronic magnet:
CCC
III
CCC
C = Copper Cable
I = Adv Iron
Fusion Reactor Plating:
CCC
CAC = U
CCC
C = Carbon plate; A = Advanced Alloy; U = Uncured Ceramic Plating
Sending Uncured Ceramic Plating through a Furnace (preferrably an induction furnace (at 100% heat if programmable)) will create a Ceramic Plate, which can be used for heat shielding on a fusion reactor.
Magnetic Mantle:
MCM
RIR
MCM
M = Electronic Magnet C = Adv Circuit R = Fusion Reactor plating I = Iridium Plating
Control Unit:
FAF
AcLAc
FAF
F = Glass Fiber Cable A = Adv Machine Ac = Adv Circuit L = Lapotron Crystal
Fusion Core:
MMM
MCM
MMM
M = Magnetic Mantle C = control Unit
Lithium Dust:
Obsidian -> Macerator -> Obsidian Dust + Water -> Igneous Solution -> Electrolyzer -> Lithium Dust
Now that you can build yourself a brand new Fusion Reactor you may ask yourself, how the hell does it work? By now it’s just an expensive piece of metal and circuits… You do good asking:
To heat up the reactor (or to be more exactly the plasma) to the needed 150’000’000°K (And yes that is the real temperature you need :P) you will need a lot of power available. (I don’t know whats better to make: Like the teleporter taking energy from a near storage or loading the reactor itself)
The reactor will need 1M Eu to start the little sun inside your brand new reactor! HAYO!
Additionally you need 1 Fusion Fuel cell within the reactor and 1 Lithium Plating (optional), that is placed around the reactor (within GUI) to breed new Trithium. And an empty cell to take the newly bred Trithium. Now you hit an active redstone signal and off we go.
1 Run of the reactor will produce 20Meu Emitted as 2048eu/T that is over 450 seconds of a big POWER load. This reaction is unstoppable and will run through in one shot, if the power is needed or not.
After the fusion within the reactor stopped it will cool down and be ready again for a new run and as you guessed it will need to be heated again after every run! HAYO!
But how do I get my cool Fusion Fuel Cell?
First you need deuterium, which you can get as a residue of electrolyzed water. While electrolyzing water cells you will get 1/10 of a filled heavy water cell as residue.
You will need Tritium and Deuterium mixed 1:1 for the Fuel. To get that stuff initially, since you do not have a running reactor that is breeding your lithium to tritium you will need to breed that thing otherwise. And there comes your nuclear reactor to play.
The breeding of Deuterium (in the form of heavy water cells) => Tritium (in the form of uber heavy water cells) will work the same way as does the breeding of Isotop cells, but heavy water cells do not produce heat unlike Isotop cells.
Now that you got that Heavy or uber heavy water cell, you wont need it liquid as the water it is, but as a Gas, therefore you need to electrolyze it. (heavy water => deuterium, uber heavy water =>tritium)
You now mix 1 Tritium and 1 Deuterium Cell and get 1 Fusion Fuel Cell.
But how do I get lithium platings for easier breeding of tritium? Very easy stuff, you can make it totally realistic out of: Redstone/Iron dust/Tin Dust which gives you 1 Lithium dust which can be smolten into 1 Lithium ingot.
Lithium Platings:
LL
LL
L = Lithium Ingot.
And that is how you get that reactor running. I hope you like the idea at least a bit for the far future. (The whole reactor bases on the best scientific ideas to make a working fusion reactor, the reference for the reactor was this type of reactor: http://en.wikipedia.org/wiki/ITER for nice pictures go here: http://www.iter.org/mach). All numbers are just a shot in the blue a lot of balancing would be needed to implement it.
Oh and there is NO WAY to amplify a nuke with fusion fuel cells so that the devastation will be even bigger.... 
Thx to Irontyger for some good inputs.
you get slowed down all the time for no real reason (for example if running through a small corridor)