Talk:Natural nuclear fission reactor

Moved from Oklo during merge

"since there is no physical reason why it should be exactly constant" is not well phrased. It is expected that the fine-structure constant is, exactly that - constant. Controversy arises from the fact that certain measurements described in the fine-structure constant article indicate it may have shifted over time. I have changed it to ", as new evidence suggests is possible". --JoeMeyerowitz 1/2/06

This is misleading for two reasons. First there is a long tradition of theoretical physics speculation about models where the so-called "fine structure constant", and/or other parameters, actually change very slowly with time. Theoretical models date back to Dirac in the 1930's. The original statement that there is no reason why it must be exactly constant is quite correct: these are parameters which a priori are continuously variable. Second, what has happened recently is the appearance of claimed signals of nonzero variation in astrophysical spectra, which is an experimental result. The new evidence does not "suggest that change is possible" since that was known all along; it suggests that change may actually have occurred. --Tdent 12:00, 20 September 2006 (UTC)

"A key to the creation was that at the time, the abundance of fissionable U-235 was about 3%, which is comparable to the amount used in today's reactors. Due to U-235's shorter half life than U-238, the current abundance of U-235 in natural uranium is about 0.7%. Therefore a natural nuclear reactor is no longer possible on Earth."

3% of what? I assume the 3% in the first sentence means 3% of natural uranium, as in the second sentence. This is ambiguous. --Jsnow 03:20, 22 August 2005 (UTC)

What about James Lovelock's claims that the Uranium was concentrated by bacteria? See his book The Ages of Gaia (1988).

I removed the "nuclear skullduggery" or whatever it was. If anyone knowledgeable can replace it with something comprehensible, it would be greatly appreciated.

I believe that the definition is wrong. A natural nuclear fission rector is a exactly that. Such a thing could occur at any time or place. The definiton limits it to the past. That is logically wrong. —Preceding unsigned comment added by 124.197.15.138 (talk) 21:52, 4 December 2010 (UTC)

Question

Are there any other sites than Oklo? thx.

So far no other sites have been found --21:26, 28 March 2006 (UTC)

Then why not replace 'best known location' with 'only known location?' 'best known' implies that there are other, more obscure ones. 69.249.92.211 16:25, 30 June 2006 (UTC)

Pending any clarification from an expert, I'll make that edit myself. 69.249.92.211 14:50, 11 July 2006 (UTC)

From:jjf I have another reference: Scientific American, July 1976 p.36 George A Cowan A Natural Fission Reactor —Preceding unsigned comment added by Foxjj (talk • contribs) 13:04, 11 October 2007 (UTC)

Timing

At one point the article states that the reactions occurred 1.5 billion years ago, while at another point it says the reactions took place over 2 billion years ago. Can someone clarify and/or correct this? How long did the reactors operate? Paul D. Anderson 06:28, 1 September 2006 (UTC)

omg

This is incredible. 67.183.178.23 02:53, 8 June 2007 (UTC)

Well put! I look forward to this article growing over time, as it is a darn neat topic. Dxco (talk) 22:44, 27 February 2008 (UTC)

I believe I read somewhere, years ago, that mutations due to natural fission were considered a contributory factor to evolution. Is there any truth in that ... any citations? Delverie (talk) 17:00, 27 July 2009 (UTC)

There is a recent article in GSA oday suggesting that isolated oxygen producing photosyntheses-driven biological communities in the mostly reducing environment of the Archean contributed to the formation of natural nuclear reactors. However, as a negative feedback, this reactors may prevented the spread of oxidising life forms. See article: Did natural reactors form as a consequence of the emergence of oxygenic photosynthesis during the Archean?Geomartin (talk) 06:28, 16 October 2009 (UTC)

IIRC Isaac Asimov's Foundation series speculated that there was a relationship. I think it was in Edge of Foundation or Foundation and Earth, from the 1980s. Given he was a biochemist, and almost got assigned to the Manhattan Project during WWII, it's not too wild to suppose this idea was kicked around among colleagues and friends. He died in 1992.

4.249.63.191 (talk) 21:45, 31 October 2011 (UTC)

Iron

As the most stable nucleus, Iron very well may serve in critical background processes in both stellar and terrestrial nuclear formations. 74.195.28.79 (talk) 09:25, 30 September 2008 (UTC)

Impossibilty of natural reactors under current conditions

I undid the change regarding the possibility of natural reactors by ID 98.210.108.122 . It is true that Magnox and CANDU reactors use natural uranium instead of enriched uranium, however the conditions in these reactors are so special that they are not compareable to nature. For instance, CANDU reactors use heavy water as moderator, which does not occur in nature in concentrated form. Therefore the statement in the article remains true that natural fission reactors are not possible anymore on earth.Geomartin (talk) 04:51, 16 November 2009 (UTC)

Mechanism of the reactors

This part sounded very suspicious:

After cooling of the mineral deposit, short-lived fission product poisons decayed

So I checked out the citation () and found that it wasn't in there. In fact, this is what the paper says:

"Interestingly enough, the 30 min pulses of natural
nuclear reactor activity and 2:5 h dormant periods re-
corded in the Oklo Al phosphate resemble a typical geyser
operation. Similar time scales suggest similar processes.
This similarity suggests that 0.5 h after the onset of the
chain reaction, unbounded water was converted to steam,
decreasing the thermal neutron flux and making the
reactor subcritical. It took at least 2.5 h for the reactor
to cool down until fission Xe began to retain. Then the
water returned to the reactor zone, providing neutron
moderation and once again establishing a self-sustaining
chain."

My guess? Some editor added "poisons" to describe the (biologically nasty) short-lived fission products for some reason, and another interpreted that as neutron poisons. So unless someone sources that statement, I'm removing it. Kolbasz (talk) 13:35, 29 October 2011 (UTC)

Done. Kolbasz (talk) 12:23, 1 November 2011 (UTC)

would be nice

The diagram is nice; a map would be nice too. I don't read coordinates very well. 4.249.63.191 (talk) 21:36, 31 October 2011 (UTC)

Is 'reactor' correct terminology?

I admit I don't know much about school-level physics (& nothing at all about geology) beyond what any vaguely scientifically interested person might pick up in adulthood, but is it correct to describe it as a reactor anyway? Is it only a reactor if it's actually *doing* something with the reaction - such as generating electricity - rather than simply existing? Would a more accurate title be 'natural nuclear fission phenomenon' or something? Note that I'm asking to seek knowledge, rather than asking as a rhetorical device to make a point! Star-one (talk) 16:12, 13 April 2012 (UTC)

A nuclear reactor doesn't have to do anything, power-wise. For example, the Hanford production-reactors in the Manhattan project just sat there and generated heat (had to be cooled with water) but generated no electricity. Their job was to fission U-235 and make Pu-239 out of U-238 with the neutrons produced. The better question is whether the word "reactor" itself demands an artifact-- something made by humans. Most people writing about this have tended to take the view that if you qualify the word by writing "natural reactor" it's okay. Or rather is a permitted conceit, like writing of certain stalactites as natural chandeliers, and so on. SBHarris 17:21, 13 April 2012 (UTC)

Comment

Quote: "Oklo is the only known location for this in the world". I thought Morro do Ferro?, Poços de Caldas, Minas Gerais, Brasil had a natural nuclear fission reactor as well.

I hope it's the right reference: Natural analogues for the transuranic actinide elements: An investigation in Minas Gerais, Brazil (1984), Environmental Geology and Water Sciences, Springer, Volume 6, Issue 1, pp 1-9.

Proc. Technical Committee Meeting on Natural Fission Reactors (1978), IAEA Tech. Rep., STI/PUB/475, IAEA, Vienna, Austria.

or Gancarz, A. J. (1977). Technical Committee Meeting on Natural Fission Reactors, December 19-21, 1977 Paris, France.

W. Miller, R. Alexander, N. Chapman, John C McKinley, J.A.T. Smellie (2000) Geological Disposal of Radioactive Wastes and Natural Analogues, Elsevier, pp. 328

Chapman, N.A., McKinley, I.G. Shea, M.E. and Smellie, J.A. (1990): The Poços de Caldas Project: Summary and Implications for Radioactive Waste Management, SKB Tech. Rep., TR 84-16, SKB, Stockholm, Sweden.

But I can't confirm that it was a natural fission reactor. Regards --Chris.urs-o (talk) 10:19, 12 January 2013 (UTC)