Nuclear power is very carbon-efficient (tonnes CO2 emmitted / GWh produced) due to the large quantity of energy produced over the generator lifecycle. It's on par with wind power, and better than solar, according to World Nuclear Org.

  | Lignite | 1054 |
  | Coal | 888 |
  | Oil | 733 |
  | Natural Gas | 499 |
  | SolarPV | 85 |
  | Biomass | 45 |
  | Nuclear | 29 |
  | Hydroelectric | 26 |
  | Wind | 26 |

[1] http://www.world-nuclear.org/our-association/publications/on...