What history can teach us about the future costs of U.S. nuclear power.

I n response to energy security and environmental concerns, the U.S. is collaborating with nine other countries to develop fourth-generation nuclear reactor technology, which is intended to be safer than current reactors, be available at lower total cost, and incur financial risks no greater than those for other energy technologies. In this article, we discuss the financial risks for new nuclear power to achieve its cost objectives, from a threedecade historical database of delivered costs from each of 99 individual U.S. nuclear reactors. We argue that past technology development patterns indicate the importance of including high-cost surprises in the planning process. One hundred and four nuclear reactors provided 19.3% of U.S. electricity generation in 2005, but no new reactors have been approved for construction by the U.S. Nuclear Regulatory Commission (NRC) ju p it er im a g es