That's a pretty weak argument. Those are once-off building requirements, not something that is repeated. If you compare the cement used by the one nuclear powerplant to the closest city it would be like a drop in the ocean.

There's been large improvement in cements specifically in the past few years. It can be recycled, enforced, and supplanted by other materials.

Concrete sold today can be bought with an advertised lifespan of 100 years. If you replace a coal plant with a nuclear plant how many years would it need to be net carbon negative? What is the grams of CO2 / kWh of nuclear vs coal vs solar?

Concrete resorbs CO2 from the air after you pour it. This carbonation of concrete can cause corrosion to rebar or other re-inforcments. A large portion of that CO2 is eventually reabsorbed back by the concrete. Depending on the mix this process can adsorb 1/3 to 2/3rds of the CO2 produced during production. However, this is a slow process and we keep making new concrete.

https://en.wikipedia.org/wiki/Concrete_degradation#Carbonati...

Also there is the all energy used for processing concrete which a lot times is not from CO2 neutral source.