Reply #12: The storage pools are vastly more dangerous than the vessels.

[snagglepuss]

snip


Sharon Begley, the science columnist and science editor of Newsweek, has a good write-up of the call, “The Japan Nuke Problem No One’s Talking About,” which I’ll excerpt:

To the growing list of worries at the Fukushima Daiichi nuclear-power plant … add this: could the spent nuclear fuel sitting in a nearby storage pool pose an even bigger threat to people and the environment? The spent fuel produced by reactors has been a challenge since the dawn of the nuclear industry, with most reactor operators opting to store it in pools of cooling water on site. At the 40-year-old Fukushima plant, which was built by General Electric, the fuel rods are stored at a pool about three stories up, next to the reactor (a schematic is here). Satellite photos raise concerns that the roof of the building housing the pool has been blown off, says Robert Alvarez, a senior scholar at the Institute for Policy Studies and a senior policy adviser to the secretary of energy and deputy assistant secretary for national security and the environment from 1993 to 1999. He and other experts are now warning that any release of radioactivity from the spent-fuel pool could make the releases from the reactors themselves pale in comparison.

The spent-fuel pools are rectangular basins about 40 feet deep, made of four- to five-foot-thick reinforced concrete lined with stainless steel. That was thought to be sufficient to prevent a breach. But the disastrous combination of an earthquake (which knocked out power form the electricity grid) and a tsunami (which swamped the diesel generators serving as backup power) forced the power-plant operators to turn to batteries for core cooling.When battery-powered cooling failed, hydrogen in two of the units exploded, damaging the reactor buildings—and, apparently, the spent-fuel area as well. Satellite photos appear to show that two cranes used to move spent fuel into the pool “are both gone,” Alvarez told a press conference organized by Friends of the Earth, a nonprofit environmental group that opposes nuclear power. “There has definitely been damage to the pool area.”

The pools “contain very large concentrations of radioactivity, can catch fire, and are in much more vulnerable buildings,” he warns. If the pools lose their inflow of circulating cooling water, the water in the pools will evaporate. If the level of water drops to five or six feet above the spent fuel, Alvarez calculates, the release of radioactivity “could be life-threatening near the reactor building.” Since the total amount of long-lived radioactivity in the pool is at least five times that in the reactor core, a catastrophic release would mean “all bets are off,” he says.

Of particular concern: cesium-137 in the pool, at levels Alvarez estimates at 20 million to 50 million curies. The 1986 Chernobyl accident released about 40 percent of the reactor core’s 6 million curies. In a 1997 report for the Nuclear Regulatory Commission, scientists at Brookhaven National Laboratory estimated that a severe pool fire—made possible by the loss of cooling water—could leave about 188 square miles uninhabitable and cause up to 28,000 cancer deaths


read more at

http://climateprogress.org/2011/03/14/third-explosion-r...