Not later than 64 months after January 7, 1983, the Secretary is authorized to, to the extent practicable, begin at a site evaluated under section
10194 of this title, as part of and as an extension of siting research activities of such site under such section, the mining and construction of a test and evaluation facility. Prior to the mining and construction of such facility, the Secretary shall prepare an environmental assessment. The purpose of such facility shall be—