We present a reactor-by-reactor analysis of historical busbar costs for 99 nuclear reactors in the United States, and compare those costs with recent projections for next-generation US reactors. We argue that cost projections far different from median historical costs require more justification than estimates that lie close to those medians. Our analysis suggests that some recent projections of capital costs, construction duration, and total operations and maintenance costs are quite low-far enough from the historical medians that additional scrutiny may be required to justify using such estimates in current policy discussions and planning. (C) 2007 Elsevier Ltd. All rights reserved.