OPEN THREAD 20191219

Basically, all legal free speech is allowed. We will assist the authorities in dealing with illegal speech. You are each other’s moderators. Have fun. And don’t forget to MAGA at nuclear levels.

Citizen U

Day 43 – TECHNETIUM.

3 thoughts on “OPEN THREAD 20191219

  1. Well, technetium has a perfectly nice article in wikipedia — https://en.wikipedia.org/wiki/Technetium — and, for somewhat obvious reasons, neither me nor anyone I know has an good anecdotes about technetium….

    So, instead, I’ll go off on a tangent about the earliest nuclear reactor. This is generally considered to have been Chicago Pile-1, constructed under the direction of Enrico Fermi, and first run on December 2, 1942. https://en.wikipedia.org/wiki/Chicago_Pile-1

    That this crude reactor was operating in the middle of a large city with no radiation shielding or cooling system seems a bit unusual today, but its initial run was only about four-and-a-half minutes producing about half a watt of power, so this was not considered a problem. Subsequent runs reached 200W, but this tended to irradiate the experimenters, so most of the time it ran throttled back to half a watt.

    In 1943, they moved and reconfigured the reactor into Chicago Pile-2. They even put up a nice boulder as a monument to this.

    Unfortunately, the boulder contains a glaring inaccuracy. Chicago Pile-1 was NOT “the world’s first nuclear reactor”. Not by a ways…..

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  2. As it turns out, there was a previous nuclear reactor that significantly predates CP1. It was postulated to potentially exist in 1956 by Paul Kazuo Karuda, and a location was subsequently discovered in 1972 with sixteen different reactor sites. The location was a region known as Oklo, near a town named Franceville, in Gabon, Central Africa.

    Self-sustaining nuclear reactions occurred approximately 1.7 billion years ago in what are today uranium mines. Each may have lasted for up to a few hundred thousand years. A key factor in its operation was that U(235) was approximately 3.1% of natural uranium at the time — the major difference in half-lives has lowered that to about 0.72% today.

    Of course, this sort of begs the question of why the reactors didn’t run earlier, when the 235 level would have been even higher……and the reason is that water had to concentrate the uranium ores and also moderate the reaction. Groundwater couldn’t concentrate the ores until about 1.7 billion years ago because uranium compounds generally aren’t soluble in water in a low-oxygen atmosphere. Plants didn’t put enough oxygen into the atmosphere until about 1.7b years ago. There’s tons more detail at https://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor

    So, we have sixteen light-water nuclear reactors running about 1.7 billion years ago initiated by plants, followed about 1.7 billion years later by a lower-power graphite reactor initiated by Enrico Fermi. Fermi got his Nobel in 1938, and the plants ended up as coal. Funny old world, that…..

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  3. Actually there are plenty of people who have had an encounter with technetium.

    It is used in imaging of muscles when a heart attack is suspected.

    A sample of molybdenum 99 (radioactive as hell) is shipped to the hospital. It has (if I recall) a 60 hour or so half life. It decays to technetium 99m. This is a less-stable (or more energetic) form of Tc-99. It’s “milked” off of the molybdenum cow and injected into the patient as part of a chemical compound. (The doctor arrives with a metal box, pulls out a syringe with a lead jacket on it, and injects it into you. Yes, something he won’t handle without a lead shield is now inside you. That’s not as bad as it sounds; he’s exposed to it a lot, you’re exposed to it once).

    Technetium 99m has a six hour half life. It gives off relatively weak gamma rays and drops into a less excited state without actually changing into another element (or changing atomic weight). So now, with this stuff inside you, you are a gamma ray source.

    They take pictures, and image your heart muscle, even having you walk on a treadmill then hitting you with another shot of the stuff.

    Within 24 hours it’s all out of your system. And sewer rats get exposed to the much-less-radioactive technetium 99-without-the-m, which has something like a 200,000 year half life.

    By the way, with a 200,000 year half life, NONE of it that might have been around when the earth was formed is still around. The earth is some 23,000 times as old as this half life; each of these half lives represents a halving of what was there before. Ten half lives reduces the amount to 1/1024th (a fraction that should be named a “Warren”), and that has happened, cumulatively, 2300 times, so imagine 1/1024 multiplied by itself 2300 times. That’s far, far, far, far too small a fraction for even one atom of Tc-99 to remain after 4.6 billion years–even if the ENTIRE FUCKING UNIVERSE had started out made of the stuff and solid from end to end rather than mostly space with scattered hydrogen and helium. (On average the universe has about one atom per cubic meter, if memory serves.)

    The fact of the matter is that ALL short lived isotopes are either long gone, or we can demonstrate they are being created by some process today (like with carbon-14). There MAY be vanishingly small amount of original plutonium 244 in the earth–it has gone through something like 50 half lives.

    That’s pretty damn good evidence that the earth is old. (Six thousand years is ignorant twaddle close to the level of flat-earthism, for a host of very good reasons this only being one of them.)

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