[en] Over the past several years, Congress has directed the Department of Energy (DOE), the Nuclear Regulatory Commission (NRC), and the Environmental Protection Agency (EPA) to abandon their efforts to assess an array of potential candidate geologic repository sites for the permanent disposal of spent nuclear reactor fuel and high level radioactive waste, to develop generally applicable requirements for licensing geologic repositories, and to develop generally applicable radiation protection standards for geologic repositories, and instead to focus their efforts to determine whether a single site located at Yucca Mountain, Nevada can be developed as a geologic repository which providing reasonable assurance that public health and safety and the environment will be adequately protected. If the Yucca Mountain site is found to be suitable for development as a geologic repository, then at each stage of development DOE will have to provide the NRC with progressively more detailed information regarding repository design and long-term performance. NRC regulations reflect the fact that it will not be until the repository has been operated for a number of years that the NRC will be able to make a final determination as to long-term repository performance. Nevertheless, the NRC will be able to allow DOE to construct and operate a repository, provided that the NRC believes that the documented results of existing studies, together with the anticipated results from continuing and future studies, will enable the NRC to make a final determination that it has reasonable assurance that the repository system's long-term performance will not cause undue risk to the public. Thus, in its efforts to revise its current regulations to assure that the technical criteria are specifically applicable to the Yucca Mountain site, the NRC should also make sure that it preserves and clarifies the concept of staged repository development