The youngest nuclear power plants in Germany were opened in 1989 after at least six years of built time, with planning going back much further. The last East German opened just weeks before the wall came down and took 13 years to build and closed within the same month. On top of that, you simply can't run a nuclear power plant forever. Germany's nuclear power plants ran an average of 32 years, and I doubt that US power plants will run those 80 years they intend for some https://www.eia.gov/tools/faqs/faq.php?id=228&t=21

To keep a 30 year old nuclear power plant safe you will sure see time of maintenance increasing, thus reducing its output. A 30 year old solar panel? Take it off your roof, recycle the old one, put a new one on and we can be sure it will be more efficient. Just this simplicity when replacing panels makes it a no-brainer. Granted, the blades of wind turbines are still not being recycled, but they slowly get there.