I saw a DW Planet A documentary about decommissioning a nuclear plant in Germany. They walked around the plant in some safety gear, but with their faces fully exposed and no breathing apparatus. They said the project was decades behind schedule and it was costing ten times as much as expected. The decommissioning process involved spraying water and gels on slightly radioactive materials from the factory to reduce their radioactivity to effectively zero. The process created much more radioactive material than there was in the first place, which then itself had to be dealt with. The cost of decommissioning is determined by the lobbyists for the companies that do the decommissioning. Voters have no idea what decommissioning should cost, and no one will ever question going over budget. It's a great business.
https://www.youtube.com/watch?v=QKIaRg3SdTw