I'm not a total expert on this specific topic, but I do have a degree in physics. I had a sudden realization moments ago as to an extremely dire
consequence of the spent fuel pool going dry, which I haven't seen discussed anywhere.
I'm assuming that there are other physicists out there who are involved in managing this disaster who have thought of this. At least, I really hope
there are otherwise the workers might make a dire mistake.
If so, then they are keeping the phenomenon that I'm about to describe a secret.
To keep things simple, water is intended to serve a very different purpose in a reactor core than in the spent fuel pool.
Water is pretty good at absorbing dangerous gamma radiation, so by keeping the used fuel rods under many feet of water, workers in the plant are
shielded from the gamma radiation they are emitting. The water of course also keeps the rods from getting too hot.
In the reactor core, water actually serves to make the nuclear reaction go critical. I won't go into all the technical details (see the article
below for them - it seems pretty well written), but water serves to make the fuel rods go into critical reaction. Without the water in most (maybe
all) modern reactor designs, criticality simply won't happen (the rods might still get hot enough to melt down without water, of course).
The water does this by slowing down neutrons emitted as the nuclear fuel undergoes its normal radioactive decay. Because of some very complex quantum
mechanics, these slower moving neutrons are more likely to interact/collide with other radioactive atoms in adjacent fuel rods, as opposed to just
"flying through" adjacent fuel rods. This collision/interaction causes radioactive decay that results in more neutrons being emitted. Because
these new neutrons are also slowed by the water, they are also more likely to result in additional fission, etc, etc. This is what is referred to as
the chain reaction of nuclear fission. Because of this phenomenon of slowing the neutrons, water in the reactor is necessary in order for the fuel to
reach criticality, where the fission reaction is stable at a certain level.
Now we get to the problem that might be happening now that the spent fuel pool has gone dry.
In addition to slowing down neutrons and hence making them more likely to cause fission, water also absorbs/blocks neutrons. These two things result
in the opposite effect. In the reactor core, the fuel rods are configured to be very close together that few neutrons get absorbed by the water
before reaching a neighboring fuel rod. This makes the effect of slowing the neutrons outweigh the effect of absorbing them, and hence we get
criticality and a nice chain reaction of fission.
Normally in the pool, the spent rods are stored far enough apart so that the effect from slowing down the neutrons is far outweighed by the amount of
neutrons that are absorbed before they reach a neighboring used fuel rod, since the neutrons have to travel so far to reach a neighboring rod.
With no water in the pool, the outside casing of the fuel rods will have begun to burn and also to oxidize with the air. This can cause it to become
very brittle and crack, and the fuel pellets might be falling out and collecting on the bottom of the pool. A bunch of pellets might be collecting in
piles which are geometrically more favorable for criticality. There could also be puddles of molten fuel collecting, which might have a geometry more
favorable for criticality. Additionally, the force of the explosions likely knocked the fuel rods around, and some might have been knocked closer
together. In this case, if water is added back to the pool it could cause things to go into a critical reaction that would generate huge amounts of
heat and radiation and be extremely, extremely bad.
So, I'm afraid that we might have a chicken-and-egg problem on our hands. Without adding water the used fuel will burn and melt, and release insane
amounts of radioactive material into the atmosphere. Adding water could cause the fuel to go critical - which would be a whole other level of
The extreme and sudden radiation spike that forced all workers to temporarily evaporate may have been due to used fuel that was submerged under the
last of the water in the pool going critical. The heat of the critical reaction would have very quickly turned the last of the water to steam, and
then the chain reaction would have ended without the presence of water. So, that spike seems like evidence that my above theory is correct.
Sorry for the bad news…
Why are the officials keeping this secret? Is it possible that no other physicists have thought of this!!! If so, somebody should warn the
authorities NOW that they need to be VERY CAREFUL if adding water to the used fuel pool.
I'm tempted to call the white house, but I doubt that whoever I talk to will know enough about nuclear physics take me seriously and actually connect
me to someone in charge.
What should we do to get this information out there???