Building, dismantling and taking care of waste all costs money and generates no revenue. (Building a nuclear power plant at least brings with it potential future revenue. Power companies have no interest in dismantling plants or taking care of waste, it doesn't make them money.) Running the plant also costs money but also generates revenue. Especially old nuclear power plants (which are already written off) are profitable as hell. Why do you think are power companies interested in keeping them running as long as possible?
Every additional day those nuclear power plants run decreases their cost/kWh.
They are interested in keeping them running as long as possible because that is where their pay checks come from. Every additional day they run increases the risk of catastrophic failure, that is the point I am making. I don't see them as a valid or viable enterprise. The cost/revenue model of accounting is really stretched when it comes to dealing with the timelines necessary for proper nuclear disposal. I see what you are saying about how it is a tiny cost over that huge 30000 year period. Taking that period as given, do you agree that the years where the plant is operational are the most risky?
Every additional day those nuclear power plants run decreases their cost/kWh.