Going Nuclear - The Science Of Nuclear Weapons - Part 2 - Chain Reactions

The evil proliferator is Khan the father of the Pakistani Bomb , a true spy and thief of secrets , the Islamic Bomb . Sold the technology to anyone who had the money . North Korea was helped most effectively

When a second of time became an eternity

1. Tungsten Carbide ? I don't believe WC was used because the density is only 15.6 g/cc whereas up to 18 g/cc is available with HeavyMet alloys of Tungsten (which can be machined at room temperature) . In addition WC is rather more brittle and if you are not going to test the device why would you not go with a material with high impact resistance ? 2. The correct core topology is a male cylindrical target , a hollow annulus project and three toroidal outer cores held concentrically around the target. This enabled a 2.8 or 2.9 factor on critical mass to be achieved. The trick is that there is an air gap between the male target and the encircling toroids. This would reduce the number of neutrons per cm2 of internal bore of the toroids, in terms of receipt of spontaneous neutrons from the target. (It works the other way from toroid to target of course). 3. I have a strong suspicion that there was something novel about the securing bolt that holds the target. Specifically it might have been boron steel with a sheer pin on the contact face and the Big Nut at the far end so it could be punched out of the core at assembly time (and through the nose of the bomb case or into a recess) and in fact the wafers that make up the target are held in place by say 6mm diameter high tensile bolts or similar. The three outer toroids were flown out to Tinian, one per each of three C54 a/craft , I would guess because there was only enough U235 metal to make up the target and projectile in say June 45 and the last three components had to be site fitted, which would have been a nervous job. My guess would be that just two outer toroids would have been required to get at least 6kT out of the bomb. Little boy HAD to be dropped first because its yield was unknown and for psychological effect Fat Man had to have a bigger explosion or at least be equal to Little Boy in destructive output. Otherwise the Japanese army and emperor might try to call the bluff of the US. Effectively the did that anyway. They gambled 100 000 lives and a whole city that the US would not follow up quickly with a second bomb. 4. The Abner initiator was likely flat given how it was going to be crushed but beyond that I'll say no more. Another poster has provided data on initiators below. All the above information is already in the Public Domain (except for my guess that there might be something fishy, as in neutron absorbing, about the centre bolt of the assembly.) By the way, there is such thing as an absolute critical mass. There is a critical mass for a sold sphere, there is a critical mass for a solid cylinder of a given aspect ratio.. and so on. It is all about the surface area (neutron loss ) to mass ratio.

There was only enough U235 to build one gun-barrel weapon, so it was decided that since the design was probably going to work, it would be dropped untested.
This was a result of production and scheduling difficulties at Oak Ridge (fantastic place to see, if only by photograph).

I have absolutely no idea what this guy talking about but the way he tells its is amazing in such detail and very smart.

Later uranium type devices moved the rings, not the projectile. They were also surrounded by beryllium to reflect the neutrons. A small black powder charge propelled the rings up a tube into which the projectile was mounted. When the top ring of the stack neared the end it struck two neutron generators that initiated the main fission sequence and the weapon exploded. Moving the rings has an advantage that the generators can be placed further apart yielding a superior neutron spread and higher yield.
Your analysis of the little boy, AKA thin man is correct. It was primitive compared to the ones designed in the fifties.

Best thing here: where you put your mic. Took me ages to catch.. i hope you meant to do that xD

"North Korea liked this"

Good info

Scott's got the bad men out there on Amazon ordering all the U-235 up now! Awesome series mate, wish young me had this thirst for understanding physics!

Nicely done, Scott! Thanks!

Where did they get the HUGE quantities of graphite? I’ve toured the “B” reactor at Richland Washington...

J. Robert Oppenheimer i got that fissle material

There is a really wonderful book about nuclear weapons: "The Making of the Atomic Bomb" by Richard Rhodes, a fantastic book, he even won the Pulitzer price. A second book describes the development of the hydrogen bomb: "Dark Sun". The neutron generator is described in the first book as beeng a foil of alpha emitter on one 235U body and a foil of beryllium on the other. The yield of an A-bomb is statistical in nature as it depends on the number of neutrons in the first generation, thus the n-source was added to assure a sound first generation, which is not given by the 235U-neutrons.

There is another wonderful "nuclear" book about Saddam Hussein's bomb project: "The bomb in my garden" by Mahdi Obeidi!

I’m from Oak Ridge, TN home of the plants that enriched the uranium for the Manhattan Project.

The uranium design was also not tested because the sheer amount time it took to acquire fissile uranium. They were literally separating the U-235 from the U-238 by mere atoms at a time. It took years to enrich enough for just the little boy weapon. That's why the reactors were needed for plutonium production.

Y does it feel like someone is looking over my shoulder?

what is good about your talk is that you recall numbers time distances and for example cross sections and time that I cannot recall

In the book "To Hell and Back" the author talks about the concept of the Little Boy bomb being a primitive particle accelerator, essentially shooting a beam through the planet. What do you think?

IF YOU ARE READING THIS, PLEASE SPREAD THIS MESSAGE TO EVERYONE TO SAVE HUMANITY. THE MUTUALLY ASSURED DESTRUCTION OF THE WORLD IS NOT JUST A NIGHTMARE, IT IS REAL AND CAN HAPPEN IN OUR LIFETIME. CONTACT YOUR POLITICIANS, YOUR CONGRESSMEN, AND OTHER LEADERS AND TELL THEM THIS IS NOT ACCEPTABLE. BRING AN END TO NUCLEAR BOMBS BEFORE IT ENDS US ALL. WE ARE AT A POINT WHERE ONE DETONATION CAN SET OFF OTHER DETONATIONS WHICH WILL MAKE OUR PLANET TURN INTO A PLANET WIDE NUCLEAR CREMATORIUM. DON'T LET THIS HAPPEN, SPREAD THE WORD AND STOP THIS FROM HAPPENING PEOPLE. PLEASE I BEG YOU DO NOT TAKE THIS LIGHTLY OR AS A JOKE. THIS SHIT IS REAL.

I have often wondered how efficient neutron generators are and how much energy they can impart into a generated neutron.

The first graph of the little boy was backwards too lol 😆. I love this series and would love to see more videos on the going nuclear ☢️ playlist.

It always susrprised me that you can have such a simple way to detonate a nuke,

K I’m officially lost lol. I think my tiny brain was able to understand about 75% of the first video and maybe half the first half of this one.

Coming back to this with a question. You talked about "Non-natural nuclear reactor" when describing the first critical pile. What's a natural nuclear reactor?

Scot I love this series so much

please no more ominous base notes behind the narrative

It must have been fun to be a scientist in the early 1900's, breakthrough discoveries almost everyday.

nice

keeping Keff very close to 1 does not require control rod motion. That would take way, way too much time. Moderator temp works much better.

very excellent description of delayed neutrons! And also a subtle description of what happened at Chernobyl.

Thank you, Scott.
Still so mind-boggling that so much energy can be released in mere fractions of a second; that a chain reaction can happen so fast.
Just imagining megatons of energy being released in the blink of an eye, and covering so much area, is scarily amazing.

Fool proof

A constant

More bang for the buck

A scientist should use SI values, not antique imperial values! WTF is a short tonne? How many teaspoons does a short ton have?

Good stuff, thanks.

Another reason the Little Boy/Hiroshima bomb wasn’t tested was because they only had enough near-pure U235 for the bomb itself. The enrichment process was so time- and energy-intensive that it took a year or so to get enough for one bomb. The Nagasaki bomb used plutonium, which could be made in a nuclear reactor but required a more complex firing mechanism, hence the test in Nevada.

"1.01" "milliseconds"
Carefulling... carefulling...

Is there any difference between nuclear blast and explosion as per controversy over indian authorities afterwards getting the 74 trial?

Hello, Scott...thanks so much for your videos (they're fascinating and enlightening...). Please note that the court under the stands of Stagg Field at the University of Chicago was a Squash Court! (Racquetball had not yet been invented:)

Kind of hard to believe they deployed little boy without ever testing gun type bomb. The risk would have been too high for the bomb to fall into the Japs hands.

Hi, you skipped over the point about avoiding pre detonation in the gun type weapon. Was that intentional because it's secret?