As bizarre as it is, Karameru's weird shorts probably brought a lot of attention to the Demon Core seeing as they're rather popular (even just that one is currently at 4.1M views.)
I'd wager this is the weirdest thing I've ever found an excuse to link to on HN.
I've always found the Tokaimura accidents to be a little "creepier." A vat of liquid can end up in a state of mixture and configuration that causes it suddenly become critical. [0]
Wow what an interesting article, especially the part about the plutonium liquid vortex reaching criticality. Fascinating (but sad) stuff. Shame how his widow was treated afterwards.
Gallows humor is a popular go-to for multiple popular internet fora. The topic was also brought up by a few influential YouTube science explainers (here's Kyle Hill semi-apologizing for popularizing the meme: https://www.youtube.com/watch?v=z497lu4t5XI, although I don't think the Google Search history suggests his 2017 video was the primary mover of the popularity spike).
In addition to the aspect of its horror that you highlighted, radiation is also a go-to science bogeyman because how how cause and effect are perceptually disjoint. You can feel absolutely fine absorbing way past an LD50 of radiation at the moment it happens; the suffering comes later, from hours to days later. Like firing up a computer with an already-damaged hard drive, you won't have a problem until the OS needs that data and loads garbage instead of useful routines.
Yes, it's a bit surprising how much of a meme the demon core is on Twitter. Some other popular radiation memes: "drop and run", LANL plutonium rods, "3.6 Roentgen not great not terrible" and "This is not a place of honor". Am I missing any?
It’s not exactly safe to handle, it’s just not acutely fatal until it’s supercritical. Plutonium forms an oxide that easily flakes off so handling any sized demon core is full of danger. Bump it against something, scratch it, or even if the environment is particularly humid the powder will get everywhere.
Ingesting or inhaling any of that oxide would result in a slow and very painful death.
What are they doing? Besides being obviously stupid, how is anything useful coming out of that? It doesn't look like anybody is actually measuring anything useful.
He's randomly wiggling that screwdriver back and forth, but what for? Is somebody collecting data for a table or a graph? Shouldn't the separation distance, or angle, or something being carefully measured and controlled?
One of the things I noticed with the experiments I participated in was that while the drama was very real for me, to an outside observer, its actually kind of dull. To keep the pacing tight and keep the audience interested, they have to spice it up a bit.
As I understand it, Slotin was demonstrating to another colleague how to test the distance dependence of criticality, so the data collected was less valuable to the demonstration than the procedure. I think the creative license here was the second screw driver to make it look more sciencey. Holding one half of the beryllium sphere with a bare hand (as was part of the approved procedure) probably felt a little too slap-dash, and the fact that Slotin's procedure involving a screw-driver was unapproved in the first place undermines the role of the scene to call out the government's lack of care for Cusack's American-everyman character. If there's a (tenuous) moral to be extracted from the incident, its that Slotin apparently believed in the cowboy persona he projected, and it cost him his life.
I want to be very clear here that I don't actually think there's much moral to this story. They had an idea of how bad criticality could be, but there was no real deterrent other than Fermi telling Slotin and others that if they kept up the procedure, they'd be "dead within a year". That tells me that everybody, from Oppenheimer on down, did not understand just how dangerous this sort of demonstration could be. Given the era, that's pretty understandable.
During the incident, he was demonstrating the technique necessary to Graves, not performing an actual experiment. He was a bit of a show-off and was doing the demonstration without shims that would have prevented criticality.
The more you contain the plutonium core within something that reflects neutrons, the closer it gets to going critical. In this case, they used two half spheres of beryllium as reflectors. The screwdriver was used to adjust the amount of neutrons reflected, and the results were measurable on a Geiger counter. I believe the goal of this technique was to compare their calculations to the real thing.
Right, but there's no actual measurement being done, nor it could be done, unless there was some guy there measuring the separation with calipers or something.
So what's the point, simply to practically demonstrate that less distance = more radiation? I guess that makes some sense, but it seems too trivial of a thing to demonstrate to people in a high level, secret operation.
I'm just imagining that for this to actually produce some sort of useful result there needs to be some sort of precise measuring happening. Maybe moving half the sphere with a screw and having a dial indicator there, or something.
As I understand it, this was just a demonstration of the technique. The actual experiment called for metal shims between the cores, which I assume were of known thicknesses. Also, from the American Physical Society's writeup:
"Nine days after the accident, Slotin died after “a total disintegration of bodily functions.” Ironically, he had become disillusioned with the postwar atomic tests, and one reason for that ill-fated experiment was to train a replacement, so Slotin could resume his prewar research in biophysics and radiobiology at the University of Chicago. He never got that chance.
In response to his death, Los Alamos ceased all hands-on experiments with critical assemblies, using remote controlled machines to protect the operators. As for the killer “demon core,” it was used in one of the first postwar atomic bomb tests at Bikini Atoll, a mere five weeks after Slotin’s death. The test went off without a hitch."
If the actual experiment needs precisely sized shims, then any demo should be done with shims. Because you'd want to show people what shims, how they're placed, and what's supposed to happen.
The experiment setup seems accurate, but sustained (prompt) criticality for several seconds, as evidenced by the continuous blue glow, wouldn't leave the building standing, let alone any surviving witnesses to tell the story, would it?
I thought it was a high-energy pulse over a few milli- or even nanoseconds, stopped by thermal expansion of the core or reflectors. Oscillation between supercriticality and subcriticality seems possible, but that would probably also look different.
Since the time scale of the exponential term in the equation for prompt criticality is on the order of nanoseconds, any sustained (i.e. non-oscillating/somehow naturally moderated) event, in a configuration as simple as a few geometric neutron reflectors, would either be over after less than a few of these, or leave a crater, and what was pictured in the clip seems sustained to me.
Witnesses reported blue light, so hollywood did blue light. It's a movie not a documentary.
Regardless we know from the witnesses in the room the criticality at least lasted long enough for Louis to need to use his hand to separate the cores, which is clearly not nanosecond scale, so I'm not sure what exactly you're expecting or criticizing here. The only difference I can find googling is that he apparently used one hand one screwdriver, not two.
"Under Slotin's own unapproved protocol, the shims were not used and the only thing preventing the closure was the blade of a standard flat-tipped screwdriver manipulated in Slotin's other hand. Slotin, who was given to bravado, became the local expert, performing the test on almost a dozen occasions, often in his trademark blue jeans and cowboy boots, in front of a roomful of observers."
play stupid games, win stupid prizes. his only salvation was that he sacrificed himself to save his colleagues.
there were also other, safer ways to do it
"Enrico Fermi reportedly told Slotin and others they would be "dead within a year" if they continued performing the test in that manner."
It's an interesting topic, what would be the most unnatural way to die.
At some point, I got in a conversation about what would happen if you drank nothing but heavy water. The short answer is that yes, this would kill you; the differing molecular weight between molecules built with heavy hydrogen and regular hydrogen will eventually add up to disruption of metabolic processes in ways that we haven't even researched. But we haven't researched them because it would cost an absolute fortune to get enough of the stuff to do yourself in.
This would be a suicide reserved for billionaires.
Heavy water's only about $1000 a litre in bulk. Certainly cheap enough to run experiments on rats and small plants. Such experiments have been done. That's how we know it'll kill you.
Its toxicity profile is kind of interesting. In almost all eukaryotes (plants, animals, fungi) low concentrations (1 - 10%) seem to have no obvious effect at all, while around 25% it seems to cause temporary sterility - the gametes seem particularly sensitive. As it approaches 50%, cell reproduction stops and death is rapid. Very few eukaryotes can survive >50% heavy water in their cells. Though a few types of yeast and single-celled plants seem to be able to survive in conditions like many bacteria can - up to 95% or more heavy water. But all kinds of life die at 100% heavy water, as far as I know.
Surely not that much. The LD50 of heavy water is really high at 30% of body weight[1] but it's only about $10,000 per kg. So even the most obese millionaire should be able to kill themselves this way if they really want to.
That's part of why thermonuclear weapons have such a disturbingly high "bang for the buck." The enriched uranium or plutonium primary is really expensive. So is the rocket that gets it where it's going. But the lithium deuteride that makes up the fusion fuel is comparatively dirt cheap.
> That's part of why thermonuclear weapons have such a disturbingly high "bang for the buck." The enriched uranium or plutonium primary is really expensive. So is the rocket that gets it where it's going. But the lithium deuteride that makes up the fusion fuel is comparatively dirt cheap.
No idea what the cost of enriched U, Pu, or lithium deuteride is, but I'll note that A) current day thermonuclear warheads deliver an estimated 50% of the total output through fission of enriched U (casing) and Pu (primary) B) the lithium in lithium deuteride, as well as the deuterium, need to be enriched, so probably not quite dirt cheap (depends on your definition of dirt cheap I guess)?
I was under the impression that the difference in mass results in slowing down metabolic processes (mainly because it takes more energy per unit time to move a more massive molecule). I wouldn't expect the hydrogen bond strength to be affected because hydrogen bonds are electromagnetic bonds, and the electromagnetic properties of deuterium and (H1) water are the same (other than the mass-effected ones; heavy hydrogen in an electric field will accelerate more slowly than light hydrogen, but that's because it's more massive, not because it's more weakly coupled to the electric field).
Heavy water hydrogen bonds are a couple percent stronger because the molecules themselves are very slightly smaller. Smaller molecules result in a shorter range of vibration at a given temperature, hence less inherent "fighting" of the hydrogen bond.
The fact that Daghlian and Slotin died in the same hospital bed has always been a sobering thought. "Well, that does it" are harrowing words.
There are famous engineering incidents that are good to study -- the Challenger disaster, the Minnesota Bridge collapse, the Therac 25... But compared with the LANL Criticality incident, there's something different. The former are all technical failure analysis.
This incident is almost existential in it's implications, like Shelly's Frankenstein. A discussion on the nature of humanity.
