Why does some nuclear radiation take thousands of years to decay and some only a decade or so?

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I’ve been researching nuclear energy and radiation in an effort to understand it. I don’t understand why I’m seeing a lot of info saying a nuclear bomb’s radiation dies out in about 10 years, but a nuclear reactor explosion like Chernobyl will take thousands of years. What’s the difference?

EDIT: Okay, so what I’m seeing is I didn’t account for the differences in types and sheer amounts of fuel for each kind of reaction. I’m not a chemist or physicist or anything. I just like learning stuff. 😁

These explanations make a lot of sense, so to those of you who didn’t answer the wrongway and provided helpful and educational responses, thank you.

In: Chemistry

7 Answers

Anonymous 0 Comments

Different radioactive isotopes have different half-lives. Some have half-lives that are fractions of a second and some have half-lives that are billions of years. Nuclear weapons and nuclear reactors produce some of the same isotopes, but some are different, and in different amounts.

Specifically in regards to the radioactivity produced by bombs vs reactors, the real factor is the amount of radioactive material. Nuclear bombs have a very small amount of radioactive material – only a few kg. Reactors on the other hand can have *thousands* of kg of nuclear fuel inside. So reactor meltdowns can spread much more radioactive material around.

In other words, Hiroshima and Nagasaki are safe because there was very little radioactive material to begin with. The Chernobyl reactor, on the other hand, had almost 200 tons of nuclear fuel inside, so it’s starting with a much higher amount of dangerous radioactive isotopes contaminating the environment.

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