TEPCO was ordered by the newly installed Nuclear Regulatory Agency to check the inside of the Spent Fuel Pool of Reactor 3 using the video camera, after a piece of steel frame fell into the pool on September 22, 2012. So the company did, on September 24, and released the videos the same day. (For the video of the debris sliding into the pool, see my previous post.)
TEPCO says they didn't find a piece of metal on top of the fuel assemblies in the pool (1st video), so they looked at the bottom of the pool (2nd video). They did find a piece of metal, but they say they are not sure whether that was the one that dropped into the pool on September 22 or that had been there since the explosion in March last year.
Lots of concrete fragments on top of the fuel assemblies:
Metal debris, but TEPCO is not sure if that's the one that fell on September 22:
Unlike the Reactor 4 Spent Fuel Pool (with 1331 spent fuel assemblies and 204 new fuel asssemblies), the Reactor 3 Spent Fuel Pool has only 566 fuel assemblies (514 spent, 52 new, and there was no MOX fuel in SFP) with the capacity of 1220. Since the metal slid from the edge of the pool and likely went down straight from there, there was probably no fuel stored where it fell. Hopefully.
For your information, from Ministry of Economy, Trade and Industry (3/17/2011), number of fuel assemblies in Spent Fuel Pools at Fukushima I Nuclear Power Plant (I added the labels). From left, the columns are: Reactors, Storage capacity in the pool, Spent Fuel, New Fuel:
In addition, there are 6375 spent fuel assemblies in the Common Spent Fuel Pool.