The nuclear option will always remain ‘open’, in the sense that the technology is understood. Also, records can be maintained even if no more stations are built and existing ones end operation over, say, a 50-year period. To restart the nuclear industry, however, would be a major and lengthy under taking, and problems in the energy field can emerge rapidly. The uncertainties, and the size of the challenges, associated with the issue of energy and the environment over the next decades are large. Thus, it can be argued that action should be taken today to ensure that nuclear power is available as a practical option.