https://ifp.org/nuclear-power-plant-construction-costs:
> To sum up, since the early 1970s, the cost of constructing nuclear power plants in the U.S. has been steadily rising. This can be traced to a constantly shifting regulatory environment, which has continuously changed plant design requirements, and added more and more safety features, which often were required to be implemented on plants under construction. The regulatory environment is partially a reflection of the fact that nuclear power and the risks of radiation had become increasingly controversial, and that early understanding of the likelihood of a nuclear plant accident was often inadequate.