Reproduced verbatim from the Fairewinds Associates website: "In this Fairewinds’ feature, Fairewinds Associates Chief Engineer Arnie Gundersen [pictured, left] analyzes a US government national laboratory simulation video that shows nuclear spent fuel rods do catch fire when exposed to air. This simulation video proves Fairewinds’ assertions that nuclear fuel rods can catch fire when exposed to air, and Arnie discusses the ramifications of this phenomena if the Fukushima Daiichi Unit 4 spent fuel pool were to lose cooling water.
The Sandia National Laboratories video in its entirety can be seen here."
As Arnie explains in the video, the U.S. has 23 operating (and 1 permanently closed, at Millstone Unit 1) General Electric Mark I Boiling Water Reactors, which hold significantly more irradiated nuclear fuel in their storage pools than does Fukushima Daiichi Unit 4. Beyond Nuclear has published a fact sheet on the risks of GE BWR Mark I high-level radioactive waste storage pool risks.