In the absence of a clear picture from the Japanese government of what is happening at the Fukushima Daiichi nuclear plant, a number of experts have stepped in to offer their take on what is currently unfolding and the worst-case scenarios that might occur. Tennessee State University's Dr. Michael Allen spent his early career at Sandia National Labs performing simulations of the world's worst nuclear-reactor accidents, including what happens when nuclear fuel is no longer submerged in water. (Yesterday, U.S. authorities in Japan said the pools of water in Unit 4 containing spent fuel rods, which are different from the reactor cores, had boiled dry.) Allen told the Knoxville News Sentinel that he's unsure whether a full-scale meltdown is inevitable, but he explained how it might occur.
