Without anywhere to go with their spent fuel rods, the Fukushima plant has accumulated quite a collection over the years.
Japan, like the United States, has kept ever larger numbers of spent fuel rods in temporary storage pools at the power plants, where they can be guarded with the same security provided for the power plant.
Figures provided by Tokyo Electric Power on Thursday show that most of the dangerous uranium at the power plant is actually in the spent fuel rods, not the reactor cores themselves. The electric utility said that a total of 11,195 spent fuel rod assemblies were stored at the site.
And, according to the same NYT article, the water cannon and helicopters aren't doing a very good job of cooling off the containment tanks. Engineers are also worried that nuclear fission will resume in the rods -- a process known as "recriticality." If that happens, they won't be able to dump water onto the rods because the water would actually speed up the fission process. Then an explosion would fling molten uranium everywhere.
I have a strong feeling that new information from this point forward is going to become very difficult to receive. The radiation has obviously risen to astronomical levels by now, and it's likely that the Japanese government, say nothing of Tokyo Electric, will want to mitigate widespread panic.
(Incidentally, I've written about a wide variety of political topics for the Huffington Post, and I've never witnessed such vocal support for anything as I've seen for nuclear energy in the comments. Commenters evidently just love it, love it, love it. Almost like they're hired trolls shilling for the industry. Hmm.)