"Little Boy" had 64kg of HEU. A basketball is 25cm in diameter, and has a volume of 8181 cm^3. U has a density of 19.1 g/cm^3, so this U basketball weighs 156kg (~350#), or about 2.5x Little Boy. Little Boy's yield was ~15ktons, so Perry's basketball might yield 35-40 ktons. https://en.wikipedia.org/wiki/Little_Boy It is my understanding that the "problem" with the Little Boy design is that it is incredibly inefficient in its use of fissile material. On the other hand, it is also my understanding that the design is almost trivial. Perry obviously gave himself a much larger mass to enable an even more incredibly inefficient design to still "work". However, if you're in a position to make your own material, you will have plenty of time (while it's being processed) to investigate more efficient designs. At 05:42 PM 5/19/2016, Thane Plambeck wrote:

From an email I just received that was signed by the governor of California and William J Perry

"A quantity of HEU the size of a basketball would be sufficient to make an improvised nuclear bomb that had the explosive power of the Hiroshima bomb and was small enough to fit into a delivery van. Such a bomb, delivered by van (or fishing boat) and detonated in one of our cities, could essentially destroy that city, causing hundreds of thousands of casualties, as well as major social, political, and economic disruptions."

My question: is this really true? I mean, supposing a small group of people accomplished getting that much HEU, is it really just a matter of "improvisation" to detonate it? I was under the perhaps mistaken impression that detonating it involved some serious engineering chops, especially if you dont want to kill or fatally irradiate yourself in the attempt.

-- Thane Plambeck tplambeck@gmail.com http://counterwave.com/