http://www.counterpunch.org/lindorff03152011.htmlfrom the article:
There is a worse problem though. Probably in an effort to keep the problem of nuclear waste hidden from the public, these plants feature huge pools of water up in the higher level of the containment building above the reactors, which hold and store the spent fuel rods from the reactor. These rods are still "hot" but besides the uranium fuel pellets, they also contain the highly radioactive and potentially biologically active decay products of the fission process--particularly radioactive Cesium 137, Iodine 131 and Strontium 90. (Some of GE's plants in the US feature this same design. The two GE Peach Bottom reactors near me, for example, each have two spent fuel tanks sitting above their reactors.)
As Robert Alvarez, a former nuclear energy adviser to President Bill Clinton, has written,
if these waste containers, euphemistically called "ponds," were to be damaged in an explosion and lose their cooling and radiation-shielding water, they could burst into flame from the resulting burning of the highly flammable zirconium cladding of the fuel rods, blasting perhaps three to nine times as much of these materials into the air as was released by the Chernobyl reactor disaster. (And that's if just one reactor blows!) Each pool, Alvarez says, generally contains five to ten times as much nuclear material as the reactors themselves. Alvarez cites a 1997 Nuclear Regulatory Commission study that predicted that a waste pool fire could render a 188-square-mile area "uninhabitable" and do $59 billion worth of damage (but that was 13 years ago).
