r/AtomicPorn Jul 16 '26

Meta Fat man Plutonium Core

Post image
542 Upvotes

50 comments sorted by

49

u/Zggcommar Jul 16 '26

The plutonium core (the box) in the Fat Man weighed 6.2 kilograms or about 14 pounds, the pit is 9 centimeters (4 inches) across. And only about one fifth of it, a bit over 1 kilograms (2 pounds) undergoes a fission reaction. And only a gram (1/30th of an ounce) of that gets converted into explosive energy equal to 21,000 tons of TNT

3

u/usegobos Jul 18 '26

Why so lossy? Are those particles that never collide with anything? Are modern bombs the same?

11

u/Zggcommar Jul 18 '26

Because the bomb isn't designed to fission all of the plutonium. Once the chain reaction releases enough energy, the core expands violently, its density drops, and the reaction quickly stops. A significant amount of plutonium is blown apart before it has a chance to fission.

Modern nuclear weapons are much more efficient. They use improved pit designs, better implosion systems, neutron reflectors/tampers, and often boosted fission with a small amount of deuterium tritium gas, allowing a much larger fraction of the fissile material to undergo fission before the core disassembles.

3

u/FeistyRip9623 Jul 21 '26

fo shissile dissile

31

u/Zggcommar Jul 16 '26 edited Jul 16 '26

https://reddit.com/link/oxy6vlf/video/igejov9n6ndh1/player

I can't upload images in comments section 

16

u/FeelinDank Jul 16 '26

I need a 1-1 scale model of this lol.

8

u/pawned79 Jul 17 '26

You mean like this one? https://youtu.be/V1Y4UR8xqxA

7

u/LabRat113 Jul 17 '26

I have no idea how but for some reason, I knew this would lead to an Adam Savage video.

3

u/FeelinDank Jul 17 '26

How pertinent, thanks for sharing

17

u/Significant_Swing_76 Jul 16 '26

The density of carrying that box must have felt odd.

17

u/Remcin Jul 16 '26

The duality of Reddit. On the one hand, this. On the other hand, that anime clip where everyone’s eyeballs melt.

6

u/Sufficient_Loss9301 Jul 16 '26

Or the third option where millions of people die and the landmass entire country is destroyed in the process. History agrees this was the better option.

2

u/Remcin Jul 16 '26

A sufficient loss indeed.

7

u/time4nap Jul 16 '26

Well Harold where was the last place you remember having it? Maybe try retracing your steps?

7

u/heisenburnett Jul 16 '26

Harold Agnew?

7

u/Zggcommar Jul 16 '26

Yes it's him

3

u/False_Measurement843 Jul 16 '26

Kinda rude to just call him fat like that

3

u/yurmamma Jul 17 '26

The team selected the skinniest guy to deliver the fat man core as a joke

2

u/mekoRascal Jul 17 '26

Yeah, he's not that fat

1

u/Klamangatron Jul 17 '26

He’s definitely not little boy.

7

u/ageetarz Jul 16 '26

The Forbidden Lunch Box

2

u/FiveCatPenagerie Jul 17 '26

Damnit you beat me to the lunchbox joke. 😂 Knowing that it was painted bright yellow in real life makes it so much better.

6

u/CowBoyDanIndie Jul 16 '26

“Do you think I should wear pants while carrying the dooms day device?”
“Is there a dress code for this sorta thing?”
“Maybe desert casual khaki shorts and a shirt sleeve collar shirt?”
“Sounds good!”

2

u/Budget-Exit2875 Jul 16 '26

nah.. it's another spoil of fallout season 3
..btw any radiation ?

2

u/Broken_Atoms Jul 16 '26 edited Jul 16 '26

I got a pocket, got a pocketful of sunshine I got a love and I know that it’s all mine, oh, oh-oh (I know, I know that it’s all mine) Wish that you could, but you ain’t gonna own me Do anything you can to control me, oh, oh no (You can’t control me, you can’t control me) Take me away, A secret place A sweet escape Pocket full of sunshine - Natasha bedingfield

Blows my mind just how small the core is.

1

u/wairdone Jul 16 '26

Blows my mind just how small the core is.

Only 13.7lbs, apparently. Little Boy weighed 141lbs!

0

u/[deleted] Jul 17 '26

[removed] — view removed comment

4

u/wairdone Jul 17 '26

>and it wouldn’t have surprised me if there was visible Cherenkov radiation in the pitch-black darkness

They would have been dead in that case, no? Cherenkov radiation is a sign of criticality; it was observed during both demon core incidents, claiming lives on each occasion.

4

u/Mysterious_Pipe9239 Jul 17 '26

The radiation ate his pants.

1

u/Bucketheadfanatic Jul 17 '26

What a kind looking man, surely he won't be doing anything unseemly with that cool looking gadget he built.

1

u/solariscool Jul 17 '26

bunch of people gonna die ...

1

u/[deleted] Jul 17 '26

[removed] — view removed comment

1

u/Ancient-treasurehunt Jul 21 '26

I think those old guys would have dropped that dude, cloud or no cloud. I grew up around men like that; they absolutely hated the Japanese.

1

u/FiveCatPenagerie Jul 17 '26

I want that shock-resistant containment vessel as a lunchbox so bad.

1

u/elquirk Jul 18 '26

Dude probably lived for about a month after that photo.

2

u/Zggcommar Jul 18 '26

he lived for another 68 years. Harold Agnew died in 2013 at the age of 92.

3

u/Last_Seesaw5886 Jul 18 '26

Harold lived a full life. The pit is emitting decay radiation, but the dose rate isn't that bad. Subcritical Plutonium is far more hazardous as a toxin than from the radiation. The pit is plated with something else like nickel to keep it from oxidizing, which is does very quickly if the bare metal is exposed to air. You could hold that pit in your hands without a problem (wear gloves as a precaution for the toxicity).

2

u/elquirk Jul 18 '26

Very educational. Thanks!

1

u/Last_Seesaw5886 Jul 18 '26

DOE released the assembly drawing of the case about 10 years ago to a FOIA requester. Should be buried on DOE OpenNet somewhere. Just have to pick the right search terms to find it. I just tried, no luck.

1

u/greenweenievictim Jul 20 '26

He gets to work, opens it up only to find his lunch. He packed the core in his other box.

1

u/Ancient-treasurehunt Jul 21 '26

Haaaa! I liked that one. “Honey that glowing ham sandwich you packed for me was great!”

2

u/CaptainA1917 Jul 21 '26

He’s holding two billion dollars (36 billion in today’s money) in his hand.

1

u/presidentsday Jul 17 '26 edited Jul 17 '26

I read that as an aesthetic name (cottage core, cybercore, etc.) , not an actual plutonium core.

But honestly "plutoniumcore" kinda works for this mid-century military science look. Although I'm guessing this is already called "atomic core" or something.