It takes ~10 years to build a new nuclear generator from breaking ground to first kw to the grid, and tens of billions of dollars or euros. Germany deploys ~2GW/month of solar, the US ~4-5GW/month. Total global nuclear generation capacity is ~380GW as of this comment. At current global solar PV deployment rates, even assuming capacity factor delta between solar and nuclear, you could replace total global nuclear generation with ~18 months of solar PV deployment.