Thursday, March 17, 2011

Too Little, Too Late - Spent Fuel May Pose Greatest Risk In Japan

Tokyo Electric was planning to build an off-site storage facility for spent fuel rods from its reactors.  Unfortunately those plans were not finished before the situation at Fukushima Daiichi deteriorated into what it is now.

The pools containing the spent fuel rods have lost a lot of water and the rods may be exposed to air. This means they will heat, a lot.  If the zirconium shielding around the fuel oxidizes or catches fire the fuel will be exposed to the open air and that is a bad thing.

According to experts from Tokyo Electric there is a chance the rods may reach “recriticality”.  This means fission may start again, in the open air!  Should that occur, the fuel would likely melt down and eventually contact water causing an explosion that would send molten uranium into the atmosphere.  The other problem may be that just pouring water on them might not help, it would take large quantities of water laced with boron to absorb the neutrons being radiated and stop the chain reaction.

There probably won't be a Hiroshima style explosion, but a steam explosion that shoots radioactive material into the atmosphere would be devastating.  Call me a pessimist, but I don't see a happy ending on this one.

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