As the Japanese Reactor Crisis continues I was recently struck with a radical thought. They've had several fires, especially with the stored pools of spent fuel which are kept in water to keep it cool. As was expertly explained here by Rachel.
Simply putting more and more water into the situation is simply not going to work in the long run, if there are now leaks caused by the earthquake that water will gradually seep away and re-expose the rods to open air. As the rods are exposed the heat up and give of hydrogen (which has already ignited causing two explosions), as it also create radioactive steam.
When a reactor is shutdown and not in use the atomic reaction is retarded by surrounding the rods of uranium pellets with Control Rods Made of Cadmium & Graphite. Since the source of our problem is a run-away reaction we need to think about ways of not just cooling the exposed rods but also slowing down the reaction that is causing them to be heated and consider infusing the coolant water with Cadmium, Graphite or some other substance which is water soluble and can retard the reaction keep the spent fuel rods from re-heating and re-igniting as they've already done twice.
Essentially it would become "Control Water" which would tend not to simply boil away, but not just cool the rods, but keep them from reacting and generating heat in the first place in the same way that the Control Rods work. It's essentially the same idea as using anti-freeze in your car radiator rather than pure water because water has a boiling point of just 212 degrees Fahrenheit, while the liquids used in anti-freeze boil at a much higher temperature.
There risks to do this, as Cadmium is poisonous and if there are leaks it could get into the water table - but that risk is only a great as the risk of radioactive water doing the same thing.
In for a pound, in for a penny extra. They've already attempted to use Boric Acid (which is flame retardant) why not this?
Another issue is the holes which have form in the ceilings of several of the buildings and particularly the containment vessels - one rapid way to seal those holes and keep radiation from escaping into the atmosphere is to seal those holes with polyurethane foam as shown here during an episode of Dirty Jobs where they were sealing the entrance to abondoned mines.
These plugs could be placed quickly and seal any leaks which are allowing radioactivity to escape into the atmosphere.
We may be past the point where techniques like this can be used due to high levels of radiation - but at this point, something clearly has to be done and maybe it's time to start looking at solutions that are somewhat off the beaten path.
My half a cent.
Vyan