The DOE began studying Yucca Mountain in 1978 to determine whether it would be suitable for the nation's first long-term geologic repository for over (150 million pounds) of spent nuclear fuel and high-level radioactive waste as of 2015 stored at 121 sites around the nation. An estimated of the waste would be from America's military nuclear programs. On December 19, 1984, the DOE selected ten locations in six states for consideration as potential repository sites, based on data collected for nearly ten years. The ten sites were studied and results of these preliminary studies were reported in 1985. Based on these reports, President Ronald Reagan approved three sites for intensive scientific study called site characterization. The three sites were Hanford, Washington; Deaf Smith County, Texas; and Yucca Mountain. In 1987, Congress amended the Nuclear Waste Policy Act and directed DOE to study only Yucca Mountain, which is adjacent to the former nuclear test site. The Act provided that if during site characterization Yucca Mountain was found unsuitable, studies would stop immediately. This option expired when Reagan actually recommended the site.