Nuclear power plants are like Wegner chairs: with moderate maintenance, they last for generations.
The design life of the reactors was initially 40 years, a figure slightly taken out of thin air. Today we have become much wiser.
On longevity, the United Nations Economic Commission for Europe (UNECE) [1] writes:
According to the US Department of Energy, the operation of nuclear power plants can be extended to 80 years or more (2). They are updated and serviced continuously, and reactors do not age like humans.
Of the US nuclear power plants, about 90% have had their operating licenses extended, extending operations to 60 years. A subsequent renewal can boost the process to 80 years (3).
There are, therefore, no technical reasons why a nuclear power plant cannot live 80 years or older.
Sources
1. United Nations Economic Commission for Europe (UNECE): https://unece.org/sites/default/files/2021-08/Nuclear%20power%20brief_EN_0.pdf
2. US Department of Energy: https://www.energy.gov/ne/articles/whats-lifespan-nuclear-reactor-much-longer-you-might-think
3. https://www.nrc.gov/images/reading-rm/doc-collections/maps/power-reactors-license-renewals.png
