11 percent of the total electricity output worldwide, was produced by 450 nuclear reactors. A source from the International Atomic Energy Agency delivered some details about the number of nuclear reactors by age in years and combined capacity.
The United States is currently running 99 reactors, making it the country with the most units online. France was in the second position with 58 units of reactors. Most reactors were connected to the grid in the 1980s, now 29 to 38 years old.
The government decided to shut down all nuclear plants by the end of 2022, in Germany. The 7 still running reactors were built in the 1980s. The reactor at Beznau power plant in Switzerland which has been delivering electricity since July 1969. It was 49 years old.
The age of a reactor is determined by its first grid connection. Reactors connected in the current year are assigned with the age of 0 years. As of April 2015, this data was collected.
Image source: https://www.statista.com/chart/13656/number-of-nuclear-reactors-by-age/
Image license: CC-BY-ND