You have put on rosy glasses. Solar begins saving CO2 immediately, while nuclear reactors begin emitting CO2 before they are ready. After a 10-15 year investment in concrete that results in around 4x the CO2 emissions.. they are obsolete by the time they start producing. And additionally they produce still nuclear waste, nobody wants to have them nearby, and they are a strategically high risk in multiple ways (military, financial, environmental). They are vanity projects.