You’ve listened to experts say that – unless the rods are removed from the fuel pools before a major earthquake strikes (using special equipment which keeps the rods submerged in water the whole time) – they will likely catch fire and release huge amounts of radioactivity. See this and this – starting at 4 minutes into the video.
You’ve read that – after reviewing photos from several different angles – the Nuclear Regulatory Commission’s initial impressions were that spent fuel pool number 3 might not be there at all, and that nuclear engineer Arnie Gundersen said a couple of days ago:
Unit 3 is worse [than No. 4]. It’s mechanically its rubble, the pool is rubble. It’s got less fuel in it. It faces the same problem. Structurally the pool has been dramatically weakened. And, god nobody has even gotten near it yet.
And you may caught the recent headline that a 35-ton machine fell into spent fuel pool 3. As Kyodo News reports:
The operator of the crippled Fukushima Daiichi nuclear power plant on Friday found that a 35-ton machine had dropped inside the spent fuel pool of the No. 3 unit, possibly because of a hydrogen explosion that occurred in the early stage of plant’s nuclear accident last year.
Tokyo Electric Power Co., commonly known as TEPCO, reported the finding after placing a camera inside the water-filled pool the same day to prepare for removing, as part of the decommissioning process, the nuclear fuel stored there.
One photo showed part of the machine, originally located above the pool and used to insert and remove fuel, appeared to have dropped onto the nuclear fuel storage racks.
But – until you see pictures – it is hard to get a sense of what all this means.
Here’s a picture just released by Tepco of the giant machine in the fuel pool :
And another new Tepco photo showing other tangled wreckage inside the pool:
The following graphics from Ashai news show how the crane is normally used to move spent fuel rods in and out of the pool. Here’s the crane bringing in a special container to hold the rods:
Loading spent fuel rods into the container:
The crane then lifts the rod-carrying container up: