Is Pu Impossible to Mine in Nature Due to Its Short Half-Life?

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Discussion Overview

The discussion revolves around the possibility of naturally occurring plutonium (Pu) and whether it can be mined from natural sources, particularly in comparison to uranium (U). Participants explore the conditions under which plutonium might exist in nature, its production in nuclear reactors, and the implications of its short half-life on its natural abundance.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether plutonium can be found in nature, noting that while uranium can be mined, plutonium cannot be found in significant quantities.
  • Another participant suggests that plutonium can indeed be found in nature, referencing the existence of natural nuclear reactors that may produce it.
  • A third participant agrees with the notion that plutonium exists in nature but speculates that it has not been discovered and likely exists only in trace amounts.
  • A fourth participant provides detailed information about the rarity of natural reactors and the low concentration of uranium in natural ores, arguing that the short half-lives of plutonium isotopes would result in minimal amounts remaining over geological timescales, making mining economically unfeasible.

Areas of Agreement / Disagreement

Participants express differing views on the existence and mineability of plutonium in nature. While some acknowledge the potential for natural plutonium due to natural reactors, others emphasize the challenges posed by its short half-life and low concentrations, leading to an unresolved discussion.

Contextual Notes

The discussion highlights the dependence on specific definitions of "natural" and the implications of half-lives on the presence of plutonium over geological timescales. There are unresolved assumptions regarding the economic viability of mining trace quantities of plutonium.

jimmyy
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Is it correct that Pu cannot be found in nature?
What I mean acctually is that while Uranium can be mined, Pu from what I have searchd on wikipedia cannot be mined.

I know that Pu is produced in nuclear reactors(or other facilities) from Uranium.
 
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jimmyy said:
I know that Pu is produced in nuclear reactors(or other facilities) from Uranium.
The question is difficult to answer, because there are plenty of "natural" reactor out there. So yes, you can find Pu which has not been produced by a human reaction.
 


I think humanino is probably right but it hasn't been discovered yet and I would assume that there are only tiny quantities of it.
 


Oklo: Natural Nuclear Reactors
http://www.ocrwm.doe.gov/factsheets/doeymp0010.shtml
http://www.ans.org/pi/np/oklo/

There are very few 'natural reactors' or deposits of U ores that went critical. Natural U is about 99.3% U-238 and ~0.7% U-235. But the U oxide content of U-bearing ores is very low - at most a few %.

The half-lives of the fissile or fissionable Pu-isotopes are relatively short, so if they do form by neutron capture in U-238 (with subsequent beta decay U-239 -> Np-239 -> Pu-239), there will be very little Pu remaining after millions or billions of years, i.e. trace quantities (ppm levels) that would not be economical to mine.

Pu 239, T1/2 = 24110 y
Pu 240, T1/2 = 6561 y
Pu 241, T1/2 = 14.29 y
Pu 242, T1/2 = 3.75E+5 y

U 238, T1/2 = 4.468E9 y
 
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