The carbon dioxide produced by making cement for a nuclear reactor is absolutely insignificant compared to that produced by burning billions of tons of fossil fuels... and keeping on burning that much every year, forever.
This is an effect known as "innumeracy"-- not being clear about the distinction between thousands of tons, millions of tons, and billions of tons,
And that's how we lead to more fossil fuels, someone making a stupid either-or comparison to a one or both problem. Every problem broken down becomes "insignificant". It's all the "insignificant" parts together that make it significant.
Now allow this innumerate to educate you:
The World Nuclear Association estimates the high CO2 emissions as a cost of construction make up 10% of the emission avoidance of shutting down a comparable coal plant. What that means is that not only do you get to spend 25 fucking years building a plant, but you get to wait another 5 years on top of that to just break even its construction emissions (and that assumes you've shut down a coal plant, which ... let's be real here, energy requirements are going up).
Tell me again how achieving nothing for 30 years will help and while your formulate your answer calculate out the total CO2 emissions of a coal plant over a 30 year period for your comparison as opposed to taking fast and realistic action that could reduce emissions *today*.
Let me guess, you're the kind of person standing on a level crossing while the train comes towards you at speed and your only solution is ... "gee I hope the government builds a train line around me in time."