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jpsb said: Only a tiny fraction of the fissional material is “used up”

I guess we could argue over whether 2% is a tiny fraction or not. Certainly there was enough used up to destroy both Hiroshima and Nagasaki. That which wasn't used up was wasted and modern weapon design attempts to maximize that percentage.

Perhaps you can help by providing an estimate of how much plutonium exists today at Fukishima. If I am correct that at least one of the reactors was plutonium based, and given that spent fuel from that reactor may also have been on site, how much plutonium is there and how does it compare to the amount of plutonium used in the Nagasaki bomb?

I would be very surprised if the amount of plutonium present at Fukishima isn't much greater than that used in the Nagasaki bomb. Perhaps you will surprise me.

I will certainly admit that the internet today has much, much more detailed information about these subjects than when I was in college in the sixties.

The bomb dropped in Hiroshima was a U238 bomb and contained less then 300lbs of Uranium. The bomb dropped on Nagasaki was a plutonium bomb and contained a few Kilos of plutonium. I would be surprised to learn 2% of either the P or the U was converted into energy my thinking is maybe 0.5% at best.

I would have to do the math to determine how much plutonium is present at Fukishima and I don't have the data that would allow me to so. How many fuel rods, how old they are and what % was plutonium when new.

I think only one reactor was a plutonium reactor the other three are enriched uranium.

My main point was that in an air blast only the bomb parts (mostly) become fallout. Air blasts are much cleaner then ground blasts where tons and tons of dirt interact with the fissionable materials and become radioactive. Now perhaps the total radiation release is the same but ground blasts produce more much fallout.

Personally I think the article is greatly overstating the dangers. Spent fuel rods will over time cool down, so without knowing how long the rods have been in the pool it is difficult to know how great the danger. But if the rods are capable of melting the pool then the danger from those rods is very real. They are still pretty hot and there are hundreds of tons of them, not a few hundred pounds. And they will be reacting with the ground (dirt) not the atmosphere at 1500 feet.

I have read that the water temp in the pool is under 100C if so the rods are not all that hot. However that could change if all the rods wind up in a pile under the pool. The reactors are still very hot and still a big problem.