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
A radioactive substance is just that, one that releases radio frequency radiation on its own. Different substances have different characteristics but the one that you’re asking about is half-life or the amount of time it takes the element to break down so as to be half as radioactive as it currently is.
The key thing to understand about half life is that it is inversely proportionate to the intensity of the radiation so the nuclear material involved in a bomb, designed to instantaneously generate an enormous amount of energy has a relatively short half life while the nuclear material in a power plant like Chernobyl that was designed to produce constant, regulated heat for long long periods of time has a much longer half life
That having been said, the radioactive material leaked in Chernobyl was a complex blend of elements the most dangerous of which had short enough half life that even now a person could more or less safely go actually see the “elephants foot” with their own eyes for a few minutes and only soak up as much radiation as a couple dozen chest x rays.
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.
2 factors –
One is different types of radioactive atoms are more radioactive and so decay faster.
Two is reactors use a lot more radioactive material – a bomb might contain tens of kgs while Chernobyl had 192 tons of nuclear fuel in it.
The nucluear bomb is a fision explosion and the stuff left behind are atoms resulting from uranium split in two. So these smaller atoms are usually less radioactive.
A nuclear reactor explosion is usually partial fision combined with other explosive materials such as hydrogen gas, and high energy particles from nuclear reactions. The stuff left behind contain a lot of the original nuclear fuel with is enrichted uranium. Radioactive decay of uranium involves many nuclear reactions that gradually result in smaller and smaller atoms left behind. This is a process that can take thousands of years.
Why do some animals live 2 years and some live 200 ?
Because they are different things.
in terms of safety, it’s not only duration of the radioactive substance, but also whether the chemical element gets absorbed and concentrated into certain parts of the body and thus bombarding some organs causing mutations of cells and the like some short half-life stuff are the worst. Iodine – many 8 days or a month or so half-life concentrate in thyroid, and easily generated in nuclear reactor accidents. Strontium 90 is something like 30 year half-life, comes from bombs, but because chemically similar to calcium, gets absorbed into the bones. Caesium is also 30-year scale, and also problematic. Bismuth (as in pepto-bismol) is naturally radioactive, with half-life in billions of years, but it is very weak so no problems. media often focused on nuclear reactor wastes – tons of it – and talks about the thousands / millions of years to decay. but that is really more a quantity / concentration problem. there are naturally-occurring nuclear reactions for millions of years in certain spots on earth (in africa, for instance), but they aren’t that toxic to us or much other life. we are actually more resilient to natural radiation than is portrayed (because we evolved with it). man-made concentrated stuff, including constant high altitude flying, we are not so well adapted.
The reason lies in the very word used to describe it . . . RADIATION.
For some atoms, they radiate a LOT, which means they decay quickly.
Others radiate more slowly, and so take longer to decay.
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