I think you're missing my point. I'm saying that nuclear fission is indeed a totally zero carbon process, but the life-cycle emits 12 gCO2-eq/kWh. The term life-cycle is a technical term from the academic concept of Life Cycle Assessment (LCA), which includes all the energy and emissions from the processes of mining, fabrication, construction, operation, and decommissioning.
The life-cycle numbers I give are sourced directly from an IPCC meta-analysis [2]. With nuclear, the entire life-cycle is extraordinarily low carbon even though it requires lots of concrete to build because you get about a billion Watts 90% of the time for 60 years given that much concrete.
As for what's easier, the common answer seems to be that variable renewables are ok for a while but at deep decarbonization, the situation is much easier and cheaper if you include some kind of low-carbon energy that can run 24/7, aka a "firm low-carbon source" [3].
The life-cycle numbers I give are sourced directly from an IPCC meta-analysis [2]. With nuclear, the entire life-cycle is extraordinarily low carbon even though it requires lots of concrete to build because you get about a billion Watts 90% of the time for 60 years given that much concrete.
As for what's easier, the common answer seems to be that variable renewables are ok for a while but at deep decarbonization, the situation is much easier and cheaper if you include some kind of low-carbon energy that can run 24/7, aka a "firm low-carbon source" [3].
[1] https://en.wikipedia.org/wiki/Life-cycle_assessment
[2] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...
[3] https://doi.org/10.1016/j.joule.2018.08.006