How?
Because of improved uptime. The whole problem with the previous generation of nukes has been lack of a standardized design. If every car were handmade to slightly different specifications, how much would it cost to keep a fleet running? Today we have standardized designs, like the AN-1000, with interchangeable parts.
Yankee Vernon (Vernon Vt.) an old early 1970's GE plant owned by Entergy Corp., recently started doing this, running at 20% over design capacity, and had to be shut down a couple of times due to a 'shakes' problem. Of the 103 nuclear power plants in America, how's the one in your region being operated?