Nuclear Reactors: Status and Challenges in Development and Deployment of New Commercial Concepts [open pdf - 3MB]
From the Highlights: "Energy demand in the United States is expected to continue to grow over the coming decades, and DOE considers nuclear energy to be one way to help meet this increased demand without producing air pollution. However, the current domestic commercial nuclear reactor fleet, consisting of 99 large LWRs [Light Weight Reactors] that provide about 20 percent of U.S. electricity, is aging, and some reactors have shut down in recent years. LWRs use light, or ordinary, water to cool the reactor. New reactor concepts are under development as alternative energy options. Light water SMRs [Small Modular Reactors] have some similarities, including the coolant used, to the existing large LWRs, and advanced reactors differ more from the large LWRs. Both new reactor concepts differ from the existing large LWRs in potential applications."
Government Accountability Office: http://www.gao.gov/