Nuclear power plants are always good money pits. My personal favorite is Marble Hill that went from an estimated $1.4B to $7B and was abandoned after spending $2.5B. Not quite the same thing because it was never finished. Are you still paying for the Washington Public Power Supply System nuclear abandonments from 1982?
Well, Hanford Cleanup still continues to this day... with infrequent moments of true panic... Footnote: An ex-girlfriend's grandfather was rehired a few years ago to go back out to the site and try to retrace his late-night nuclear-waste-burying escapades. Apparently his bosses would get him up in the middle of the night, put him in the backhoe, then they'd drive randomly out into the desert, dig a hole, drop some barrels in, cover it up all nice and pretty (and hard to see), and leave. They now have him on salary again, going out and trying to recreate those late night unmapped trips from 40 years ago...