Spent fuel rods stored on top of the damaged reactors are using up the water meant to keep the cool. At least one pool is boiling.
Is it common practice to store spent fuel rods on top of a reactor? Apparently, there were some inside the buildings housing the containment chamber. Since two of these have exploded, it would appear they have been scattered about.
Does anybody else store spent nuclear fuel on top of reactors?
James Pilant
“It’s worse than a meltdown,” said David A. Lochbaum, a nuclear engineer at the Union of Concerned Scientists who worked as an instructor on the kinds of General Electric reactors used in Japan. “The reactor is inside thick walls, and the spent fuel of Reactors 1 and 3 is out in the open.”
A spokesman for the Japanese company that runs the stricken reactors said in an interview on Monday that the spent fuel at the Fukushima Daiichi and Daini plants had been left uncooled since shortly after the quake.
The company, Tokyo Electric, has not been able to cool the spent fuel pools because power has been knocked out, said Johei Shiomi, the spokesman. “There may be some heating up,” he said.
Even as workers race to prevent the radioactive cores of the damaged nuclear reactors in Japan from melting down, concerns are growing that nearby pools holding spent fuel rods could pose an even greater danger.
The pools, which sit on the top level of the reactor buildings and keep spent fuel submerged in water, have lost their cooling systems and the Japanese have been unable to take emergency steps because of the multiplying crises.
By late Tuesday, the water meant to cool spent fuel rods in the No. 4 reactor was boiling, Japan’s nuclear watchdog said. If the water evaporates and the rods run dry, they could overheat and catch fire, potentially spreading radioactive materials in dangerous clouds.
Pilant's Business Ethics Blog 
Its pretty much common practice to store the spent fuel rods in close proximity to the reactor during their cool down phase. When the rods come out of the reactor, they are still very hot and very radioactive and must be cooled down. So they put them in these pools to cool them down.
In most nuclear plants in the US, the cool down period for these rods is about 6 months before they are capable of being transported to a long term storage facility. However, in reality those spent rods can spend years in the cool down pools before being transported. This is, of course, the problem with nuclear energy…. i.e. what to do with the waste permanently.
Another danger they face is the spent rods coming too close together. Should they come too close together (due to structural failure or any other failure caused by the earthquake and tsunami), then the mass can become super critical.
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Thanks for the information. However, you will note, that storage decision complicates problems at the plant. I will probably post your comments as a blog entry later today. I have to teach a class in a bit.
James Pilant
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Oh I agree. It definitely does complicate this problem. In the US, the spent rods are kept in proximity to the reactor but I dont believe they are kept right above the reactor.
Unfortunately, when they design and build these reactors, they try and over-engineer it so much that the chances of catastrophic failure are minimized. My bet is that the designers of that reactor system didnt anticipate this scenario. Its a tragedy, but its one that, I’m sure, the nuclear community around the world will learn from.
No matter what we plan for, mother nature always seems to do what she wants. This tragedy is a sobering reminder of the forces that REALLY govern this world.
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