Last week's official dedication of the National Ignition Facility, the massive experiment in nuclear fusion, has set some physicists to plotting ways in which nuclear fusion could be put to work in a new generation of nuclear power plants. Although doubters say that NIF may not even be able to produce a controlled fusion reaction, the same reaction that occurs in the heart of the sun and in thermonuclear weapons, boosters such as U.S. Energy Secretary Steven Chu are already discussing how fusion energy could best be harnessed. Chu notes that the Obama administration's decision to halt construction of the Yucca Mountain repository for nuclear waste has renewed interest in reactors that could actually reduce the nuclear waste produced by traditional nuclear power plants. There are