Are They Useless? VII (of X). Another Elided Effect
The awful heat produced by a nuclear weapon usually goes unmentioned when the yield of a nuclear weapon is expressed, as it almost always is, in tons of TNT equivalent.
Another effect almost always elided is that of the ionizing radiation a nuclear bomb releases.
At the instant of the detonation, a dose of ionizing radiation is “promptly” fired off—at the speed of light—that is strong enough to kill anyone within range who gets hit with it. A hundred percent of the time. Even though they won’t feel anything when it hits them.
TNT does not release ionizing radiation.
The extent of the harm caused by the prompt radiation can be represented more or less accurately—as with the blast and heat damage—by a circle drawn around ground zero. Bigger yields will give you bigger circles.
But here’s a wrinkle. The circle within which the prompt radiation will be strong enough always or almost always to kill you is usually smaller than the circle within which a nuclear weapon’s blast or heat will kill you. That means that if the prompt radiation from a nuclear detonation is powerful enough to kill you, you will probably have been killed also by heat or blast. “Overkill” that came to be called.
In any case, when we are hit with ionizing radiation, we don’t sense it in any way. Think back to when you last got an x-ray. X-rays are a kind of ionizing radiation. One of the many kinds released in nuclear explosions.
After the detonation, more ionizing radiation will be released, over time, in the form of what weapons effects experts came to call “fallout.” Fallout is fission products that have been generated by the detonation of the bomb. Detonations on the ground or on or just under water—"surface bursts”—will produce much more radioactive fallout than “air bursts.”
This fallout will fall and its ionizing radiation will do its work in unpredictable places and spans of time and may or may not kill you in the end. The same amount of fallout will kill some people and not others. But it will kill some people who would not otherwise have died yet. Though not a “causal certainty,” this is now recognized to be a “statistical certainty.”
It’s spooky stuff.
Detonations underground or in space--if they are detonated far enough underground or far enough out in space--won’t produce fallout. Not on the surface of the earth anyway.
The particles of radioactive fallout are not going to come down inside a circle. They will be carried off by the winds and deposited…well…somewhere, depending on wind and weather and other things impossible to predict with certainty. If you want to draw a picture of where fallout would likely be harmful to people, you will have to draw long smears going off in the direction of the prevailing winds at the site.1
Which may or may not be the direction the wind is blowing that day.
For many years after the bombs fell on Hiroshima and Nagasaki, our military leaders and the civilian Atomic Energy Commission of the time denied or downplayed the harm that can be caused by fallout. Even after 1946, when we started testing nuclear weapons in the Marshall Islands at our proving ground in our Pacific Trust Territories the Pacific Ocean, and after 1951, when we started testing nuclear weapons in Nevada inside the continental United States, our officials denied and downplayed it. Perhaps they thought “national security” required them to lie to us and to the people harmed.
If a specific person gets cancer, you can rarely show conclusively that it was directly caused by radioactive fallout. But as time went by, the evidence became undeniable—some earlier-than-expected deaths from fallout were a statistical certainty.
As our recent history has demonstrated, however, nothing is undeniable, no matter how strong the evidence for it.
The generation of fallout by our testing of nuclear weapons in the atmosphere means that after World War II, most of the people killed by our atomic bombs were Americans. Because of our testing. Not only us though. Fallout doesn’t stop at borders. Any more than global warming does.
Since the harm radioactive fallout causes cannot be restricted to military targets, it adds to the uselessness of nuclear weapons for military purposes.
Next: Here’s a New (Better?) Idea for a Nuclear Weapon
If you would like to see what the fallout smears might look like if, say, the B-61 bomb currently in the U.S. arsenal were detonated on the surface in a particular city of interest, visit Alex Wellerstein’s Nukemap. You get to choose the spot. Anywhere on earth. You can choose the yield of the bomb too.