The dominant type of new nuclear power plant, light-water reactors (LWRs), proved unfinanceable in the robust 2005–2008 capital market, despite new U.S. subsidies approaching or exceeding their total construction cost. New LWRs are now so costly and slow that they save 2–20× less carbon, 20–40× slower, than micropower and efficient end-use. As this becomes evident, other kinds of reactors are being proposed instead—novel designs that are claimed to solve LWRs’ problems of economics, proliferation, and waste. But on closer examination, the two kinds most often promoted—Integral Fast Reactors (IFRs) and thorium reactors—reveal no economic, environmental, or security rationale, and the thesis is unsound for any nuclear reactor.