To qualify your statement I'll claim that nuclear is the only low-carbon energy source we know that can run 24/7 in a wide variety of locations. Hydro can run all night too, but is geographically limited.
This matters because filling in gaps of intermittency requires the production and maintenance of "nonproductive" equipment (like batteries) which takes energy to make, install, maintain, recycle at a scale that may challenge the energy return on investment in many renewable situations.
On the scale of a large solar power plant, pumped water storage has superior durability and much easier maintainability than batteries. Besides, the water that's pumped up hill can actually be "productive", e.g. suppling water to a city or to farms
Hydro also destroys ecosystems since it requires damming rivers and creating a reservoir. It's also quite risky, since when poorly maintained a structural collapse can kill thousands of people downstream. This has happened in China and California came really close to creating a man-made disaster only a few years ago.
Hydro also creates ecosystems, and is capable of supporting existing ones - see California, millions of feet of water were used from reservoirs to ensure sturgeon spawning grounds weren’t dry during a drought.
When you account for construction and decommisioning, a modern combined cycle gas plant emits only a very tiny bit more co2 than a modern nuke plant per MW generated (ignoring the paper designs that haven't actually been built yet). And it does this at significantly less cost and time to first power.
The time for nuclear was 30 years ago, now it's too little far too late.
Citation needed. Nuclear plants emit 12 gCO2/kWh lifecycle vs. 490 for natural gas. Nuclear is at almost 40x better than gas from a climate perspective.
