Yet again you demonstrate your stupidity. First, as mentioned SEVERAL TIMES TO YOU IN THE EARLIER THREAD, the theory calls for a 5km ball, not an 80km ball.
Were did you read that? Both of the articles that I read had dimentions of 25-50 miles and 31-62 miles. ( see POPULAR SCIENCE.)
Second, you need 1E38 J, not 4E32 J.
What makes you think it takes that much energy to blow up a planet? There are several compeeting theories and the better ones come up with much less energy than that, generated by the overcomeing gravity model.
Third, this "uranium droplet" would not be composed of 100% fissile material, you moron, or it would have gone off already!
Of course not I would expect it to be 99.3% U-238, just like all the rest of the U we have found anywere else on the planet.
How fucking stupid can you be? Don't you realize that most uranium is useless for that purpose, which is why uranium in which the fissile isotope has been removed is called DEPLETED uranium and considered garbage?
You have just proven your ignorance beyond all shadow of a dought!
Several isotopes of Thorium and U-238 (Depleated Urainium.) all fission when struck by fast nutrons like those generated in D-D and D-T reactions in thermonuclear weapons. That is why all larger Thermonuclear weapons get 50% or more from the Depleated Urainium sleeve that is placed around the thermonuclear "Secondary". At least one isotope of Thorium, U-233, U-235 and all the isotopes of plutonium that I can remember will all fission when struck by so-called slow "thermal" nutrons which is why they are used to make small Fission bombs. It is easy to get slow nutrons but hard to make fast ones.
I recomend that you read Richard Rhodes's THE MAKING OF THE ATOMIC BOMB and DARK SUN. They are probably the best un-clasified works on the subject and after you have read them you will not be so ignorant on the subject.