Nuclear is very expensive, which means it needs to be run for a long time to make up for the initial investment costs. There are not very many places where you will be able to have enough cooling water for 3 to 5 decades that is not on a coastline. However, if you build on the coast you have to build with 50 years of sea level rise, tsunamis and flooding in mind. All of that adds to the already high costs.
Cover everything with solar, build up on and offshore wind, improve existing hydroelectric and invest in geothermal, make the grid larger with more grid storage, and if you still need more energy sources then add nuclear.