Doing nothing regarding the storage pools could be an incredibly bad
suggestion, though it may be the only option if serious radiation
leaks begin to occur and evacuation is necessary. What to do depends
on whether neutron absorber slabs were actually placed between *all*
fuel assembly storage positions. It is my recollection that storage
pools did not have neutron absorber slabs when originally constructed
decades ago because there was no intent to store for long periods.
Separation geometry alone was used to prevent criticality. When
storage pools began to run out of room, the unused portions of
storage pools were later modified to accommodate closer storage by
adding neutron absorber slabs between fuel assemblies, and storing
them closer together.
If the neutron absorbers used can burn, decompose or rubblize at
lower temperatures than the fuel rod assemblies, then even they may
not prevent criticality in the volumes in which they exist, because
they will not still be located appropriately in the rubble. If there
are volumes where do not exist then it is essential to fill those
volumes with a solid which will prevent critical mass, either by
preserving the geometry or by absorbing neutrons.
One key thing to do immediately is to situate a number of neutron
counters in the vicinity of each pool. This could be done by
lowering an asbestos insulated cable with one or more neutron
counters on it through the roof by crane, or to lower through the
roof a water cooled metal pipe with neutron counters located within it.
Time is of the essence. Putting water on the storage pools seems to
have provided some calm for a while, just no permanent solution.
It seems possible to use a crane (one is on site, but maybe not big
enough) to lift a fire hose or cement hose with a steel pipe on the
end up over the top of the building structure and to lower the pipe
down into the building at the spent fuel pool location, which is
right under the roof. It should then be possible to pump a coolant
into the cooling pond through the hose and pipe.
For a reactor with the roof intact, a shaped charge should be
sufficient to blow a sufficient sized hole in the roof.
One idea for a coolant is to use a boron carbide pellet with water
(or boric acid) slurry. That way, if the water evaporates, the boron
carbide remains to reduce the degree of criticality. If there is
sufficient boron carbide then water loss may actually further reduce
the degree of criticality, though the temperature would rise and the
fuel rod cladding may oxidize. Still, when a rubble pile forms, it
will be full of boron carbide, which can withstand very high
temperatures, and prevent criticality, eliminating the china syndrome
possibility.
It may be feasible to use a cement pumper truck to pump such a slurry.
The main problem with this idea may be locating the tons of boron
carbide pellets needed. Boron carbide should be around a many forms,
including the form of industrial abrasives. A mix of boron carbide
powders, granules and pellets in a slurry may be very effective due
to the high packing coefficient, but might eliminate any prospect of
water cooling.
Another problem could be that there is a big crack or hole that is
letting the water out. If the crack is too big, then the pellets
should leak out also. However, enough might remain inside to be
effective for most of the fuel rods, especially if the pellets etc.
sinter together in the process.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
