You may find this interesting, Jack
" ... Many of these plants, though, will likely keep operating, thanks to the Nuclear Regulatory Commission’s practice of granting new licenses to plants that have outlived their original operating licenses.
Most of the 100 nuclear plants now generating power in the U.S. were originally licensed for 35 to 40 years of operation; now the NRC is issuing new permits, in 20-year increments, that will allow them to keep running for 60 or even 80 years. Eighty reactors (many plants comprise more than one reactor) have already had their licenses renewed, and many of the remaining ones are likely to come up for renewal in the next decade.
Operating aging nuclear plants far beyond their original design lifetimes raises the specter of system failures, leaks, and accidents. Environmental groups, for example, have opposed a license extension for the Davis-Besse station, a nuclear plant operated by utility FirstEnergy in northern Ohio, because of extensive cracking in the exterior of the plant’s containment building. FirstEnergy “should retire Davis-Besse as planned,” Pat Marida of the Ohio Sierra Club’s Nuclear-Free Committee told reporters in September, “on Earth Day, 2017, rather than continuing to play radioactive Russian roulette on the Lake Erie shore for 20 more years.”
Last year the commissioners rejected a recommendation from their own technical staff that the existing rules for relicensing should be revised to reflect increased concerns around going from 60 years to 80. The ruling cleared the way for companies to apply for a second renewal of operating licenses under the existing regulatory scheme. ... "
https://www.technologyreview.com/s/544211/how-old-is-too-old-for-a-nuclear-reactor/
