Oldest Reactor Ready for 60 Years of Operation After Makeover

Swiss utility Axpo Holding AG restarted the world’s oldest nuclear reactor after halting it since 2015 to carry out works that will allow it to operate for at least a dozen more years.

Connected to the grid for the first time in July 1969, the Beznau-1 reactor on its own river island in northeast Switzerland is the world’s oldest still in operation. After the Swiss Federal Nuclear Safety Inspectorate found irregularities in 2015, the unit underwent an extensive modernization upgrade to extend its expected lifespan to 60 years.

At left, Beznau 1, in Switzerland, with the second unit under construction to the right, on Aug. 6, 1969

During the last three years, an additional earthquake and flood-proof emergency ...