In this report, the U.S. Nuclear Waste Technical Review Board (Board) summarizes its major activities in calendar year 2000. During 2000, the Board identified four priority areas for evaluating the potential repository at Yucca Mountain. The areas are the following: (1) meaningful quantification of conservatisms and uncertainties in the U.S. Department of Energy's (DOE) performance assessments; (2) progress in understanding the underlying fundamental processes involved in predicting the rate of waste package corrosion; (3) an evaluation and a comparison of the base-case repository design with a low-temperature design; (4) development of multiple lines of evidence to support the safety case of the proposed repository, the lines of evidence being derived independently of performance assessment and thus not being subject to the limitations of performance assessment. Finally, the report summarizes the Board's views on each priority area. A more detailed discussion of the priorities can be found in letters to the DOE included among the appendices to the report.