Which study are you using to suggest 70? That's on the high end on any study, but not the highest.
The IPCC has min, median, and max estimates on these kinds of things. See Table A.III.2 in [1], 12 being the median.
So worst case by any estimate is that nuclear emits 110 gCO2-eq/kg. Solar PV (utility) max is 180. Hydro is an astounding 2200 (twice as bad as coal, due to biogenic methane associated with large reservoirs). By any estimate, nuclear is a very low-carbon energy source, in a whole different class than fossil fuel and biofuels. In other words, it's one of the few low-carbon options we have.
The minimum for nuclear is not 11 but rather 3.7.
[1] https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...