Eh? The lifecycle footprint per kwh of nuclear is comparable or lower than that of wind, with the winner depending on the exact details of any given project.
It is much lower than that of solar.

I am quite aware that decarbonizing electricity is not sufficient, but it is nessesary. If we do not have clean electricity, the electric car merely moves pollution from tailpipe to smokestack. If we do not have clean electricity, highspeed rail becomes a carbon hog. If we do not have clean electricity replacing fossile carbon industrial feedstocks with electrochemical processes is pointless, if we do not have clean electricity, cleaning up home heating is not possible. Virtually every single other ecologically friendly policy or technological solution rests on a unspoken base assumption that electricity production is clean, so making this assumption true as rapidly as possible takes priority over everything else. It is also important to keep in mind that while a lot of these policies will dramatically reduce overall energy use, by virtue of being far more efficient than current praxis, since they all amount to substitution of electrons for gas and oil, they greatly increase electricity demand, so our policy must accomodate this.