The Demon Core 1945

The Demon Core was the nickname given to a 6.2-kilogram (14 lb) subcritical mass of plutonium that accidentally went critical on two separate instances at the Los Alamos laboratory in 1945 and 1946. Each incident resulted in the acute radiation poisoning and subsequent death of a scientist. After these incidents the mass of plutonium was referred to as the Demon Core.

The Slotin and Daghlian incidents were combined and fictionalized in the film Fat Man and Little Boy.

[cloudstreets]

This is a great demonstration how flat head screwdrivers have 1000 different uses, none of which include driving a screw.

[fletchermoore]

In irl instead of, "I'm dead." The moment it happened he calmly said, "Well that does it." Much more chilling to me.

[as]

there's something uniquely horrifying about radiation poisoning like this - a mistake that doesn't result in a sudden traumatic injury, or instantaneous death, but rather a realization that you may have 12, 24 or 72 hours, but you are going to die imminently and there is absolutely nothing you can do about it.

[CodaMission]

Things of note:
- What's going on here is a criticality experiment. Reactivity in nuclear fuel is phrased in three terms. Subcritical, meaning that reactivity is slowing down.
Critical, meaning reacitivity is steady
And Supercritical, meaning reacitivity is speeding up on its own.
The experiment is to place a spherical sample of fuel, the core of the bomb, and surround it with a neutron-reflecting beryllium shield, formed in two parts, each a hemisphere. The bottom is already on, and the top is lowered into place. As the core becomes surrounded, the neutrons it emits have nowhere to go, and so keep bouncing around and smashing into each other. Reactivity increases and the core becomes supercritical.
-There was no coffee. Slotin's hand slipped for no other reason than it happened to slip. The film adjusted this to make his own death seem less like his fault
-Slotin was known, and repeatedly warned, for violating safety procedures. He removed the spacers inserted to prevent this very thing. He often gave demonstrations to people who didn't need to be present for the experiments
-The blue tint is real. Its radiation particles giving off flashes of light as they ionize in the air. What they can't show is the intense heat wave they all felt.
To be clear though, yes, it was his fault, but it also wasn't. We have the benefit of hindsight to tell us that he was making a mistake. This was a new field of physics. NO ONE knew just how to approach the safety procedures. The authorship of sound safety protocols is built on the blood of those who didn't know at the time.
Nowadays we build criticality experiments to be fail-safe. This means that a failure in a mechanism results in the experiment lapsing into a safe state. In this case, a fail-safe experiment would be one where the Beryllium cap is raised onto the core rather than lowered, so that a slip in the mechanism causes it to fall away and not on the core

[josephdillard]

When dealing with plutonium in a criticality experiment, a good rule of thumb would be "If your life depends on handling a screwdriver the right way, you're not doing it right".

[IonOtter]

The reason he told everyone to take off everything metal, was so it could be analyzed. When gold, silver and copper are exposed to high radiation, they produce isotopes that can be measured to determine how high a dose was given.

[PTS]

It’s crazy…. He was literally a dead man walking. His body, his cells were dead but he was still fully conscious and able to say “fuck I’m dead” or “well that does it”

[_Matsimus_]

It’s as if he’s back in room 1408 and this is another nightmare

[ocsrc]

If I've said it once I've said it a thousand times

No food or drink around the atomic bomb

[sceaux]

The radiation damaged one man so badly that he turned into a lawyer.

[NightRunner]

From the Wiki:

The standard protocol was to use shims between the halves, as allowing them to close completely could result in the instantaneous formation of a critical mass and a lethal power excursion. Under Slotin's own unapproved protocol, the shims were not used and the only thing preventing the closure was the blade of a standard straight 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. Enrico Fermi reportedly told Slotin and others they would be "dead within a year" if they continued performing the test in that manner. Scientists referred to this flirting with the possibility of a nuclear chain reaction as "tickling the dragon's tail", based on a remark by physicist Richard Feynman, who compared the experiments to "tickling the tail of a sleeping dragon". On the day of the accident, Slotin's screwdriver slipped outward a fraction of an inch while he was lowering the top reflector, allowing the reflector to fall into place around the core. Instantly there was a flash of blue light and a wave of heat across Slotin's skin; the core had become supercritical, releasing an intense burst of neutron radiation estimated to have lasted about a half second. Slotin quickly twisted his wrist, flipping the top shell to the floor.

[crumdoggy]

“Enrico Fermi reportedly told Slotin and others they would be "dead within a year" if they continued performing the test in that manner.” Fermi was right. Extremely reckless and needless deaths.

[opsimathics]

Please explain to comrade Shcherbina how a screwdriver isn't a safe laboratory instrument

[BluntForceTrauma]

What blows me away is that such smart scientists would set up an experiment such that they were always trying to prevent the upper-half of the sphere from falling down onto the lower one.  Why on earth would they not have made their apparatus such that they were lifting the lower-half _UP_, towards the *stationary* upper-half?  In engineering we would call this "fail safe."  The way they were doing it was NOT...

[Colin-khkp]

Fun fact, Slotin did some math after the incident and correctly figured that he would die in 9 days. He was an incredibly smart guy, book smart, obviously, not in the common sense kind of way...

[monster]

The blue light was perfect, it felt so real. No big flashy noises or effects, just a sudden blue light, like a chemical reaction.

[Otaku]

The NRC actually no longer allows this experiment to be performed by humans anymore. It can only be performed in a glove box by robotic means.

[FreGZile]

If I'm not mistaken, in this movie they mixed the two incidents into one, the first would have been when Daghlian dropped a berrilyium brick on the core, the second was Slotin manipulating two hemispherical reflectors wrapping the plutonium core with his hand and a screwdriver. So, In that later one, there were no brick reflectors as depicted in that scene and he actually held the berrilym sphere with his bare hand. Clever.

[gnjjqhw]

One of the scariest story I've ever heard. You see the bluish flash, you're done in a fraction of a seconds. But you feel completely normal (or a little bit sick, I've heard) at least for a while. The worst part of this story is the man who got this can calculate how much damage he've already got. He's 100% sure he's already dead and he ain't got nothing to do about it.

[Choronzon]

Richard Feynman called it tickling the tail of the dragon.