Nuclear is zero carbon, but not renewable, and is a source of non dispatchable baseload.
Solar and wind are both zero carbon and renewable, but not dispatchable and not a baseload source.
Solar and wind plus storage are zero carbon, renewable, and also a source of dispatchable baseload.
It is very much a practical constraint for current nuclear reactors (whether traditional or SMR) whose uranium supply chains lead straight to problem zones [1].
Using conventionally mined uranium, traditional reactors would only provide 5 years of the world's electricity demand [2].
Seawater-extracted uranium could stretch into the thousands of years, but that is unproven at scale and cost. Similarly unproven are the fast breeder reactors needed to truly make the non-renewability of nuclear moot.
1. https://www.spglobal.com/commodityinsights/en/market-insight...
2. https://phys.org/news/2011-05-nuclear-power-world-energy.htm....