(Audio of alarms going off.)  It's only a drill at a nuclear reactor. Such simulations train operators to prevent meltdowns. Such constant training has ensured no repeat of the near disaster at Three Mile Island. But real problems still happen several times a month at the 104 nuclear reactors in the U.S. And with plans to build as many as 29 new reactors, that sound may become ever more common. A nuclear renaissance is under way in the U.S. and abroad as governments look for reliable, secure and climate-friendly means of generating electricity. Reliable in that nuclear reactors can generate electricity nearly 90 percent of the time. Secure in that such power plants rely on fuel found in Australia, Canada and the U.S. And climate-friendly in that generating electricity from uranium produces less greenhouse gases than burning fossil fuels. But questions remain, including what to do with the waste. In addition to being radioactive, it contains materials suitable for nuclear weapons. It remains to be seen whether nuclear is a bright--some might say glowing—hope or a false alarm. For more on the new nuclear energy, check out www.sciam.com this week. (See www.tinyurl.com/2pb4bc)