On Tue, 14 Jan 2014 13:44:19 -0500, "Mr. Luddite"
wrote:

What *can* happen is that the fuel rods can produce an abundance of
hydrogen when exposed to regular water. Hydrogen can explode if there's
an ignition source but it isn't a "nuclear explosion" as reported.

===

I believe you can also get steam explosions if the rods come into
contact with pockets of water.