Trying to understand causes and effects of nuclear reactions and radioactivity

cshum00

I have been reading a lot about nuclear plants and how when things go wrong the whole area becomes inhabitable. I have been trying to understand certain things but i am not sure. I hope my understanding of it are not filled with self-inflicted misconceptions.

1) Uranium crystals found in nature in general are only slightly radioactive. Does it mean that the uranium radiation is usually not high enough to cause health problems?

2) Is it true that what's actually highly radioactive are the resulting elements uranium's nuclear fission; not uranium itself?

3) Is it true that the radiation of the unstable elements doesn't spread themselves very far? Is it the coolant liquid/gas' spills from the reactor; that carry the radioactive particles far from the source?

4) When people check sites years after radioactive spills have happened, they find that the nearby vegetation and/or objects have become radioactive as well. Does it mean that by leaving a highly radioactive element next to a stable element, the stable element becomes radioactive with time too?

5) Are there chemical reactions to make unstable isotopes of elements to become stable?

6) Isn't there any convert the radioactivity of radioactive wastes into electricity? And therefore at the same time accelerating the process of radioactive decay?

mfb

Uranium can be bad for your health if you eat/drink/inhale something with uranium. Uranium outside your body is usually unproblematic - it emits mainly alpha radiation, which does not reach living cells in your body.
Right
Gamma radiation is the most penetrating, but even that can be shielded in a reactor (or some kilometers of air).
Or fission material direcly boiling in the reactor, which happened at Chernobyl.
No, the plants get some fraction of the radioactive nuclei, or radioactive dust spreads over the area.
No. Radioactivity is not influenced by chemistry - with electron capture (a possible mode of decay of some isotopes) as an exception, as this depends on nearby electrons.
Nuclear reactors do that all the time with a part of their waste. There are ideas to transmute the remaining problematic radioactive waste into other elements.

cshum00

So, if i pick up a rock from a radioactive site. Then I clean up the radioactive dust from using a vacuum cleaner. Then the rock will be back to normal?

This has brought an interesting perspective which i ignored completely: transmutation of elements. Nuclear reactions is pretty much the alchemist dreams from centuries ago of transmuting elements. Except currently we don't have total control of the resulting elements of the transmutation. And we can only do fission reactions. Maybe in the future, humanity will able to do fusion reactions too. And also have control over what elements to transmute. Then transmuting iron to gold will no longer be just be a concept of the past.

mfb

Probably. Neutron activation is possible, but I would not expect any significant radioactivity based on that unless the rock was in the power plant itself.

Controlled fusion reactions are possible. You can transmute elements into other elements, but it is extremely expensive for extremely small quantities. It is used to produce some radioactive isotopes like Fluorine-18.