Why is fresh uranium fuel safe to handle with standard PPE while “spent” fuel is so hazardous?

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My uninitiated mind would think that it would be the other way around.

I was watching a video about nuclear power. The guy being interviewed was wearing safety glasses and nitrile gloves while holding a uranium fuel pellet. Then the camera pans to a screen showing the robot handling spent fuel in the bottom of a 40-foot deep pool of heavy water. The pool is in a room behind a big red door with every “do not enter” warning imaginable. I would think the fuel would be less radioactive coming out than going in.

In: Chemistry

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Anonymous 0 Comments

Basically it works like this. When something’s radioactive, it means that it is actively changing into something else. If you left a block of uranium around long enough, it wouldn’t be uranium anymore. Meanwhile, if you left a block of iron sitting around until the end of time, it would still be iron.

Uranium is actually pretty stable. If it wasn’t, we wouldn’t have any. You have to think that almost all the radioactive stuff on Earth has been here for a very, very long time. When a radioactive material breaks down into other materials, it tends to form very unstable stuff that is breaking down rapidly (perhaps only a decade).

Because the whole point of radioactive power generation is to promote more fission, you want more radioactivity. To this end, they look for naturally findable uranium-235 which is much less stable than uranium-238 which is most uranium. Taking a big pile of uranium and extracting as pure a 235 batch as possible is called enrichment.

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