lifespan

I'm not arguing about how many years is the lifespan of reactors, but insisting at the time of constructing reactors in late 1960s people were told the life span of reactors is 10 years because it can't endure strong radiation for more than ten years even if it were made in think steel.   So they had understood they need to decommission it after ten years.
In 1981 after constructing No1 reactors in Fukushima Dai'ichi, people argured whether to decommission it in National Diet and decided not to. Instead they called for help from GE, and GE dispatched tens of workers to keep on maintaining it. 
Probably you would like to point out that the lifespan of nuclear reactors is at least 30 - 40 years.   Our recognition to lifespan of reactors changed around 1981.