how long does radiation from an atomic bomb last?

Like the atomic bomb dropped in Japan in the 1940’s during World War 2

How long does nuclear radiation last?

All radioactive substances decay over time. Some take fractions of seconds, others many thousands of years.

In theory all radio active substances stay slightly radio active and are never completely inert. That’s why it is more appropriate to use the ‘half-life’ of a radio active substance to indicate its level of radio activity. Its half life is the time it takes for its radio activity to fall by half.

For example, if the radioactivity of a radioactive substance fell by half every two years, its half life would be two years. You notice that it takes much longer for its radio activity to fall to very low levels and that after six years it would have dropped to one-eight of its radio activity.

At every step of its decay the radio active substance transforms into another substance as the composition of the nuclei in its atoms changes.

The half-life of uranium 238 is 4.5 billion years. That means that within that time half of the remaining uranium 238 will have decayed.

Your previous answers are correct for the radioactive material that the bomb was made of (those atoms that survived the explosion) and the radioactive elements that were created during the explosion. Since these were air blasts, there was not a tremendous amount of soil, concrete, rock, etc that was vaporized by the explosion.

The larger amount of radiation was the radiation created by the actual nuclear reaction. This radiation lasted only an instant but it was very intense. It was a fission bomb so some mass of U or Pt (depending on which bomb you are talking about) was converted into energy according to E=mC^2 and that energy was in the form of radiation, and lots of it. This radiation covered most of the electromagnetic spectrum and included visible light, an electromagnetic pulse, IR, UV, alpha and beta particles, gamma rays, x-rays, etc. Most of these forms of radiation travelled away from the blast at the speed of light and, those that have not bumped into something or have not been absorbed by something are still travelling. There is a pulse of gamma rays produced by that bomb still travelling thru space and, by now, about 65 light years away.

Of the nuclear tests that have been conducted by the US, Britain, France, and the Soviet Union, (and more recently by India, Pakistan, and N Korea), many of these were ground or unground or underwater tests so the actual explosion consumed (vaporized) a lot of whatever was around (soil, rocks, water, etc). In addition, many of these tests were of hydrogen bombs (fusion bombs which are detonated by atomic bombs) and, therefore, were much more powerful than the two atomic bombs used on Japan. The radioactive elements used and created by these explosions decay according to the half life and, therefore, will be around for a long time. Any radiation that escaped into space is still out there travelling away from earth at the speed of light.

How Long Does Radiation Last

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how long does radiation from an atomic bomb last?
Like the atomic bomb dropped in Japan in the 1940’s during World War 2

I heard the radiation levels would be hazardous for about 50 years, but it really depends on where the bomb is detonated

More or less forever. It just gets diluted as the stuff spreads out. Eventually the mass decays, but there will always be something left there.

It all depends on the radioactive element.Radon for instance can be found in our own homes.


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