> only known natural nuclear reactor
um, stars?
Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
31–40 of 124 posts
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#32> All natural uranium today contains 0.720% of U-235. That's related to the material of our solar system all coming from the same supernova explosion or similar, right? Does this apply to our entire milky way or just the solar system? What if parts collided with material of _other_ origins and some of that is on Earth, then there could be different mixes, right?
It's related to how long ago the uranium was formed: https://world-nuclear.org/information-library/nuclear-fuel-c... We can calculate the abundances of U-235 and U-238 at the time the Earth was formed. Knowing further that the production ratio of U-235 to U-238 in a supernova is about 1.65, we can calculate that if all of the uranium now in the solar system were made in a single supernova, this event must have occurr…
I read GP's question really as: "did all Uranium on Earth come from the same source?" and your answer implies "yes". I think that's right.
The fact that everywhere we see the same U-235/U-238 ratio or very close (Oklo) strongly implies either a single source (supernova) or that if it was more than one source they were all at roughly the same time (6.5 billion years ago), with the latter seeming [to me] less likely, so a single source at 6.5 billion years ago is what makes sense. Unless there were many supernovae and their remnants mixed quite well in our corner of the galaxy where our sun was born.
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#33Earlier quoted context omitted.
Grok says: At Earth's formation ~4.5 billion years ago, natural uranium contained approximately 23.2% U-235 These numbers are probably only for the local corner of the galaxy. It depends on when the supernova(s) that created the uranium exploded.
We all have access to Grok and other AI models, and we will ask it if we want it's bullshit hallucinations. There is no point polluting HN with this trash.
Anyone can look it up, yet I was the only one who did.
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#34> All natural uranium today contains 0.720% of U-235. If you were to extract it from the Earth’s crust, or from rocks from the moon or in meteorites, that’s what you would find. But that bit of rock from Oklo contained only 0.717%. Heh. The garbage web software developer me would have just called it good enough Would be really interesting to know what the error bars on those figures look like
I think it would've been good enough for the miners too, if not for the fact that nuclear arms control treaties require every gram of U-235 to be accounted for. When they were digging it out of the ground and found it was less enriched than it should've been, this needed to be explained. It has always fascinated me to think that this natural phenomenon could and probably would have remained unknown forever if not for these treaties and agreements.
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#35Earlier quoted context omitted.
Grok says: At Earth's formation ~4.5 billion years ago, natural uranium contained approximately 23.2% U-235 These numbers are probably only for the local corner of the galaxy. It depends on when the supernova(s) that created the uranium exploded.
We all have access to Grok and other AI models, and we will ask it if we want it's bullshit hallucinations. There is no point polluting HN with this trash.
Is it wrong?
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#36> All natural uranium today contains 0.720% of U-235. If you were to extract it from the Earth’s crust, or from rocks from the moon or in meteorites, that’s what you would find. But that bit of rock from Oklo contained only 0.717%. Heh. The garbage web software developer me would have just called it good enough Would be really interesting to know what the error bars on those figures look like
You have me wondering about that as well. If the uranium was going to be enriched for use in a light-water reactor (I would guess it was), maybe the difference translates into needing more stages of enrichment to reach the required level?
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#37> only known natural nuclear reactor um, stars?
the word "fission" is missing
https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#38Richard Rhodes brought this up in an interview. He made it a point for critics who say nuclear waste can't be safely disposed of through burial. Well, we have pretty good natural evidence that nuclear fission products can remain buried and undisturbed for a pretty long time!
I don't disagree that nuclear waste can be disposed of safely under good conditions[1].
But I think a fallacy to claim that natural phenomena should inherently be considered "environmentally safe" in human terms. There are coal seam fires that have been going on for centuries and the pollution of these is just as bad as the pollution generated by human created coal mine fires (and that's truly awful, a significant source of carbon pollution).
[1] The problem with nuclear reactors isn't that their pollution couldn't disposed of with ideal methods but that when they run by for-profit corporations, you will always have the company skirting the edge of what's safe 'cause corporations just go bankrupt with catastrophic events and so their risk-reward behavior isn't the risk-reward optima for humanity.
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#39Richard Rhodes brought this up in an interview. He made it a point for critics who say nuclear waste can't be safely disposed of through burial. Well, we have pretty good natural evidence that nuclear fission products can remain buried and undisturbed for a pretty long time!
I don't disagree that nuclear waste can be disposed of safely under good conditions[1]. But I think a fallacy to claim that natural phenomena should inherently be considered "environmentally safe" in human terms. There are coal seam fires that have been going on for centuries and the pollution of these is just as bad as the pollution generated by human created coal mine fires (and that's truly awful, a significant so…
What are the conditions under which nuclear waste buried a mile deep in bedrock will post a risk to society?
Re: Oklo, the Earth's Two-billion-year-old only Known Natural Nuclear Reactor (2018)
#40Maybe it’s a remnant from a nuclear ancient civilization.
Maybe it's a sign of a future time travelling civilization with nuclear power but poor navigation, warped straight into the mantle Earth's crust :D
I thought where you were going with his was "that realized the best way to dispose of their nuclear waste was to dump it in the deep past." I’d read that novel.