That's budgeted as part of the (still remarkably low) operating costs. In the US at least, anybody operating a nuclear plant has to pay a certain amount yearly

That's budgeted as part of the (still remarkably low) operating costs. In the US at least, anybody operating a nuclear plant has to pay a certain amount yearly into a fund for its eventual decommissioning. (The same sort of situation applies to insurance, in case anybody was wondering.)