"Fast breeder reactors the way to go. Generate more fissile material than they consume and can extract (in principle) all of the energy contained in Uranium (vs. the 1% extracted by current light water reactors). More expensive than LWRs, more technically challenging and potential Plutonium proliferation risk, but orders of magnitude less radioactive waste. Much of the research has already been done. Initiatives under way internationally, though not on huge scale. Solving any remaining problems likely to be far easier than solving fusion."
Much more entertaining a post if you imagine it being said by mordin from mass effect.