The problem with current current nuclear technology is that we have no idea what to do with the toxic and long lived waste.  Moreover, the any current design of a reactor produces weapons grade nuclear byproducts (or byproducts that can be easily converted to such).

On the plus side, nuclear energy is abundant, relatively cheap (aside from the high cost of power plant production).  Environmentally, it does not produce any CO2 directly, and provided the Uranium is mined cleanly, it produces little CO2 in the complete fuel cycle.

The Fast Sodium Reactor or Sodium-Cooled Fast Reactor (SFR) promises to eliminate the downsides of nuclear power:

“But if I build a different kind of reactor that uses liquid sodium instead of water to slow things down, I can have a higher neutron speed and that [waste] becomes a fuel. You just mix it in the crucible, put in the transuranics [(ie plutonium etc)], put in some uranium, put in some zirconium, and you cast it into thin rods. That technology’s been developed, it’s easy to do, and you do it in a room about this size.”  — Eric Loewen

(Read more: http://www.esquire.com/features/best-and-brightest-2009/nuclear-waste-disposal-1209-2#ixzz0XBfAzIQV)