Bent Water Rod in Spent Fuel at TEPCO's Kashiwazaki-Kariwa Nuke Plant, No One Knows Why or How

Engineers, care to comment?

During the regular maintenance, TEPCO found a bent water rod in one of the spent fuel assemblies in the Reactor 5 Spent Fuel Pool at Kashiwazaki-Kariwa. In another assembly, the company found a bit of cotton-like fiber caught in the spacer.

From TEPCO's press release (Japanese) on October 17, 2012:

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Fuel rod configuration, from "Nuclide Composition and Neutron Multiplication Factor
of BWR Spent Fuel Assembly", Japan Atomic Energy Research Institute (November 1999):

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