*SCALPSWINGSTRADDLE*

[mikeg]

http://ecocentric.blogs.time.com/2011/03/15/a-new-threat-in-japan-radioactive-spent-fuel/#ixzz1GiG5zs13

Would a spent fuel fire be worse than a meltdown of the reactor core?

Pick your poison. Fresh fuel is hotter and more radioactive, but is only one fuel assembly. A pool of spent fuel will have dozens of assemblies. One report from Sankei News said that there are over 700 fuel assemblies stored in one pool at Fukushima. If they all caught fire, radioactive particles—including those lasting for as long as a decade—would be released into the air and eventually contaminate the land or, worse, be inhaled by people. "To me, the spent fuel is scarier. All those spent fuel assemblies are still extremely radioactive," Dalnoki-Veress says.

Why hasn't there been concern over spent fuel safety in the past?

There has been. The spent fuel is related to a nagging issue for the nuclear industry: what to do with nuclear waste. Right now, there is no approved long-term storage of spent fuel. Storage in certain geological structures would safely house spent fuel for centuries, but it's difficult to get nearby communities to accept such geological repositories. So, as an interim measure, nuclear power companies are storing more spent fuel assemblies in pools.

Interestingly, the people who have raised the most concern about this is nuclear terrorism experts, rather than nuclear safety campaigners. That's because combustion of spent fuel was something that most people only thought could be possible following sabotage by terrorists. "This is the worst case scenario that '[terrorism experts] thought about happening. We envisaged scenarios such as terrorists stopping the cooling at a spent fuel pond. And now it seems to be happening without terrorists," Dalnoki-Veress says.

Perhaps the most troubling warning about the dangers of spent fuel came in a 2003 article in the journal "Science and Global Security" by Robert Alvarez, Senior Scholar, Institute for Policy Studies, called "Reducing the Hazards from Stored Spent Power-Reactor Fuel in the United States." Its first paragraph reads:

Because of the unavailability of off-site storage for spent power-reactor fuel, the U.S Nuclear Regulatory Commission has allowed high-density storage of spent fuel in pools originally designed to hold much smaller inventories....It has been known for more than two decades that, in case of a loss of water in the pool, convective air cooling would be relatively ineffective in such a “dense-packed” pool. Spent fuel recently discharged from a reactor could heat up relatively rapidly to temperatures at which the zircaloy fuel cladding could catch fire and the fuel's volatile fission product, including 30-year half-life Cs, would be released. The fire could well spread to older spent fuel. The long-term land-contamination consequences of such an event could be significantly worse than those from Chernobyl.