Economy of scales. PG&E's Diablo Canyon site with both Units, was originally estimated to cost $689 million in 1968. When it finally got approved and entered into the Rate Base in 1985, it was valued at $5.1 Billion.
Recently anti-nuke groups wanted PG&E to abandon the Tertiary sea water cooling system and retrofit it with another new cooling system. That estimate came out at $13 billion for the retrofit alone
. That's why PG&E said fawk it, and agreed to shut the plant down at the end of its operating license in 2025 & 2026. Gov Brylcreme saw the writing on the wall on power shortfalls due to this generation loss, and rallied PG&E to keep it operating....