Since the dawn of the nuclear era, more than two dozen nuclear power reactors have been permanently shut down in the United States. At some point, the remaining 100 nuclear power reactors currently operating in the United States also must be permanently shut down. But after a reactor is no longer generating power, how will the next step, known as decommissioning, be accomplished? In theory, the process is straightforward. The Nuclear Regulatory Commission requires that after a nuclear facility is retired, it be decontaminated, with all its nuclear fuel, coolants, and radioactive wastes removed. Once this is completed, the owner’s license is terminated, and the site is considered to be freely available for other uses—with some restrictions, as needed, on a case-by-case basis. But if recent history is any guide, owners of a nuclear power plant that is no longer operating can take a range of approaches to accomplishing the end goal of "greenfield" status, in which the site is in the same pristine condition it was before the plant was built. There are three main approaches in real life: "do it yourself," "wait and see," and "calling in the decommissioning cavalry." A few case studies give an idea of what to expect based on the experiences so far. They do not cover every factor in decommissioning decision making but reveal some of the potential pitfalls, problems, and dangers that could accompany the upcoming wave of decommissionings.