A guy is working on a mod called big reactors (big-reactors.net) he is aiming for it to be included in big dig and is designed to compiment big dig nicely. It uses it's own power ore (yellorium) and a couple custom machines, plus the core which is a multiblock for the reactor itself. Currently it's WAY overpowered and has unlimited fuel (it uses yellorium which comes out as a waste item and can be converted into blutonium with the exact same power output as yellorium). It can also generate rediculous amounts of power. Heat isn't coded in yet properly so theres no penalty for making a massive (up to 32x32 by default) reactor including no cooling and generating 100000MJ/t. Plans for later version remove the direct power generation of it (he's wanting to do cooling loops with steam turbines generating power while cooling the system more like an actual nuclear reactor) and include redpower interfaces.
