Sunday, February 26, 2012
This fun little simulation shows the detonation of any nuclear device of standard design (no enhanced radiation weapons that I can see) from a list of preset warheads, or any arbitrary yield. While I doubt the information here is perfect, since detonation altitude and conditions would greatly alter the results, it does seem to scale fairly well to at least 100 Mt devices.
The simulation above shows a small Davy Crockett nuclear device of 20 tons yield. One should note that while this is tiny for a nuclear device, and near the minimum yield possible before you get a fizzle, it is still an exceptionally powerful bomb. In explosive power alone, this bomb would be several times more damaging than even a large conventional bomb like the GBU-43/B MOAB. The explosive yield is twice that of a GBU-43, but I also think there would be a hotter fireball and an explosion with very high brissance. Even more significant, as you can see above, is the radiation damage. Very small nuclear bombs do the most damage by radiation when used against humans. Those a few blocks away would survive the blast (as long a flying debris did not hit them) and probably would not even see much of a thermal exposure at all, as buildings would block most of that, but the radiation exposure would be profound indeed. (Unless again buildings could be expected to stop most radiation, something that I do not know much about.) One would have to be 10 blocks away, or about half a mile, to be safe from severe radiation exposure if unshielded by buildings. There is no doubt that this particular target, the Empire State Building, would be completely destroyed and rendered radioactive in the process. A tiny bomb like this would, if used by terrorists, cause billions of dollars in damage and kill thousands of people.
For fun, I also tried huge detonations like a 10 Gt device:
Now I have been told that devices of 100 Mt and higher have limited use as atmospheric detonations, simply because blast is shot upward into space, and because heating is limited with the curvature of the Earth and the atmosphere blocking most of it. Any giant nuclear device must necessarily detonated at high altitudes of miles or more to help spread the heat around. But if they are, the amount of thermal heating can be profound indeed. The Tsar Bomb demonstrated this.
This 10 Gt device above has a large fireball about 20 miles in diameter (enough to utterly destroy and even crater most of New York, the place of detonation.) The blast is also massive, killing most people indoors half way out on Long Island, and killing many people out to the end of Long Island. But far more shocking is the amount of thermal energy that this bomb would produce under ideal conditions. This simulation shows 3rd degree burns as far north as Montreal and as far south as South Carolina. Clearly such a bomb would be very difficult to build, and would only be deployable on a large ship. Detonating at sea level from a ship would ruin the point of using such a large bomb in the first place for the reasons I discussed above. Only fallout would be enhanced with a sea level detonation, and the fallout from a 10 Gt blast in New York would be severe enough to harm millions of people as far as Russia, though at a time of nuclear war, the fallout from distant detonations would not be a priority. Far more economical is to simply use many smaller warheads of 200 - 900 Kt yield as is the case here: