I get to listen to a lecture from one of the most prestigious universities in the world for free, and I can pause and rewind it at my whim. Think about that for a second...!
I am a chemist and this guy has no clue what is going on. Kinetic energy of fission products? Really? No mention of mass defect and the actual physics that is going on? This is disinformation pure and simple. I mean , he is an associate professor of public policy, associate! It shows. This man is in no way qualified to speak on this subject.
Every American is on the NSA list. The Government is scared of us and collects all our data. Thank you Snowden. So if your hard drive crashes, just ask Obama for the back up. ;)
im not american im australian but i bet the NSA is still spying on me also i think il have to purchase the backup from trump obama would give it to me but trump would probably try to make me pay
Never though I would get the basic understanding, well taught, not locked in explaining in complicated terms at all, so well delivered. Was always wondering how they can be sooo powerful, now that guessing can rest :P
"All the energy and matter that has existed still exists. Matter does not create energy of itself. The actions of matter enable energy to become manifest".
I personally loved this lecture, and the lecturer did a fantastic job explaining everything, I spend hours a day watching and listening to lectures about nuclear physics and explosives etc because they interest me alot, I wish New Zealand universities would offer a degree or diploma in nuclear physics or pyrotechnics and explosives, or even an online course, if they did do this I would be there first student
SuperBking1340 Now that I think about it more, using the mass of the two given particles and the angle of recoil from the charged particle, it could be determined what direction the neutral particle rebounded in.
+SuperBking1340 good question, but unfortunately I don't know the answer to that, you would need to ask the people that assemble nuclear weapons for the answer to that
56:35 Minor detail about hot air rising. I think he is mixing up cause and effect. You do not start with hot air rising and then colder air rushing in below to "prevent a vacuum". The hotter lighter air causes a lower pressure above the colder heavier air. This causes the cold air to be pushed up from its sides (as the side pressure around the cold air is higher than the pressure from above), which then in turn pushes the hot and lighter air upwards. Think about an air bubble under water. Water on the top of the bubble flows down on its sides and fills up the bottom of the bubble. The permanent movement of water from the top to the bottom makes the air rise up. There is no water rushing in from below to fill up any vacuum.
I'm building a bomb for my dad for his birthday and I want it to be big. However my yield seems to be consistently below the 50 kiloton mark even when I use enough material for a 100k or so bomb. I've got the hollow sphere and the air gap and the explosive lenses mostly dialled in, but still I end up with this figure "8" blast pattern that is not very optimal Can you please help? I only have enough fissile material for two more bombs so I can really have only one more test before I make the present.
You've got enough material for a 100kt explosion? Is that assuming the impossible efficiency of 100%, are are you assuming maximum possible efficiency of 33, but only getting 16%? 16% is pretty good. Are you using uranium or plutonium? Boosted or unboosted? Reflected or unreflected? Tamped or untamped? How precise is your neutron injection timing?
I was at Trinity in 2007 - tourists took the last of the Trinitite glass from the ground a while back but you can still get some from collectors online.
I grew up in the '60's and '70's, and while I missed the Civil Defense drills in schools, I had found a lot of books by the agencies in a landfill in the valley below our house, across the river from the US Naval Academy. Those books, plus reading "Triumph" by Philip Wylie, had me watching every contrail in the sky. Those neurosis-inducing nukes...... Test pilots would occasionally issue a sonic boom over the area, and one day a Harrier dropped in to hover over a parking lot at the Academy. The initial sonic boom and the subsequent roar had us running for cover..... like that does ANY good within ten miles of a nuke. Thanks for sharing this extremely well-done lecture.
@39:38 are you referring to gamma ray detection only? If so, are you stating that cat litter emits a higher count rate (combined Th, U, and P) than *unshielded* enriched Uranium?
Interestingly you can enrich uranium using photo activated uranium salt decomposition. You’ll have to guess the salts that this would work with. This approach relies on the minute differences in the chemical properties of 238 and 235. It only needs recrystallisation equipment. It’s not an economically viable method though.
Dr. William Penney, the British scientist who developed the British nuclear weapons, had a permanent grin on. Look up a photo (any) of Dr. Penney and you can be sure he is flashing his toothy grin. Maybe he was Stanley Kubrick's model for Dr. Strangelove. Penney was knighted for his contribution to the nuclear arms race.
Great lecture! Except the actual process where the energy is transferred from the primary to the secondary (31:00) is not exactly right. The actual process is the ablation of the surface of the secondary, from high energy X-rays filling the bomb case, exploding it inward. It's not the radiation pressure. The surface is rapidly heated and ablates away, propelling the material inward to compress the secondary.
Bryan Carter Even if you assert that what you said is correct, the radiation pressure is what starts the main reaction in the secondary. A distinction without a difference.
False. radiation pressure results from the kinetic energy of the photons (yes, photons, despite having mass, have an energy associated with them). Ablation pressure is a different mechanism.
So I starting watching this a couple of days ago and heard him suggest The Making of the Atomic Bomb by Richard Rhodes. I finished it and yes it is a page turner. and yes it is very good. If you are interested in history of science you will enjoy this book. the book tells the history of nuclear physics not just an account of los alamos.
Amazing video. Though obviously a very complex and chemistry / physics topic, professor Bunn does a fantastic job of explaining things clearly and in a simplified manner.
Fantastic very interesting. This speaker is well worth the effort to listen to. And is so close to perfect as far as keeping every sentence riveting If he can just drop the habit of saying O.K , OK , OK , It's to many oks . He is so interesting I had to persevere, but please play it back and note how often you say ok. Then note how the flow sounds so more interesting when you use far less ok. This is in no way intended to offend, you are well worth the time. In fact I will both like and share. Keep it up you are great , in fact so riveting and interesting , you don't need the ok , ok. Thank you I found your technical explanation perfect OK. Warm regards Grant
If that whole putting the dueterium into the pit to cause a fusion reaction at the same time as the fission isn't the classified part, I wanna know what the classified part is.
Miniaturisation. The smallest fission bombs in the US arsenal are literally the size of a football. The smallest high-yield fusion bombs are smaller than the fission bombs other nations have.
At 15:00 when he's talking about 2/3s critical mass inriched uramium. Is he talking about uranium that's being compressed by an explosion making it completely hypothetical? Or is he saying that if you swing 2 pieces of uranium 235 at each other that there will be a small deadly explosion even before you could hit them together?! Fascinating and good to know if your ever handling nuclear bomb cores.
This level of understanding of the thermonuke is trivial. However, it was only arrived at after 40 years of experimentation and testing, which might lead you to the clue that a lot is unsaid here. Go read Clancy's "The Sum of All Fears" to put yourself to sleep.
Anyone familiar with the phenomena of the Ocean water around a Nuclear detonation turning temporarily black? .... I read about it years ago but am unable to find any info anywhere on the net, .... would greatly appreciate any help ... cheers
+getorfmalawn Its called a "slick". I think it does not actually turn black. When the hyper-sonic shock wave travels thru the water the surface becomes a little smoother thus not reflecting light as well. Right behind that shock wave is the one traveling slightly slower thru the air. Where the air wave meets the surface of the water it creates an effect call "cracking". It disturbs the surface of the "slick" and causes it to then appear white.
Cheers Tyler ...I since posting found the term "slick" mentioned in Wiki of all places .... Ive been thinking the phenomena is connected to the property of water to form a temporary "Lattice" through its H-bond network,... acting similar to a Black Body type absorber .....temporarily negating reflection ... you're explanation is not entirely excluded in that process, ( speculative as it is) with the tremendous energy compressing the molecules into forming the lattice .... interesting stuff thanks again for your reply mate
+getorfmalawn It looks like i spoke too soon on the "cracking" too. It appears that the cracking happens before the air pressure gets there. I assume the cracking is the result of the "slick energy" being released from the lattice as it decompresses. Can you expand on that?
31:07 According to en.wikipedia.org/wiki/Thermonuclear_weapon#Compression_of_the_secondary there are three proposed theories of how the energy is transferred to the secondary: - radiation pressure exerted by the X-rays - X-rays creating a plasma in the radiation case's filler (a polystyrene or "FOGBANK" plastic foam) - Tamper/Pusher ablation
The x-rays cause the tamper surrounding the secondary spark plug to ablate so explosively that it causes a rocket effect. The tamper blasts cylindrically inward from all sides, compressing the spark plug to fission pressure + temperature. Ignition of the spark plug then pushes the tamper back out again, which kills the reaction before it even leaves the bomb casing. It happens so fast that they had to load the first H-bombs with paraffin to slow the neutrons from the primary down so they wouldn't reach the spark plug before it had compressed all the way.
Great information, very informative. Lecture is off the chain, you know you are in the presence of a expert. On the other hand what horrible reality these devices have created. So sad and depressing. So much engineering in the wrong direction. One love y'all.
awesome video , i love learning about things like this im gona look into seeing if you have any other lectures on different subject's this kind of stuff is so fascinating to me honestly had no idea it was so complicated and i enjoyed learning about how they use this type of thing to produce regular power for people to use, or factory's ect. agin awesome video !! thanks
We hear about other countries who we don't want to have them, but the truth is the knowledge on how to is easily available, and is taught to students in school....yes even students from other countries no restrictions other than the general admission to the school.
I wonder what kind of informations in this video are intentionally placed misinformations. But all in all, as far as i can evaluate that, a very good video. Thanks.
That photograph at 2:20 is of the - Badger shot of Operation Upshot-Knothole in 1953 and NOT of the Trinity Test as Bunn suggests! Just look the pictures up yourself, if you don't believe me.
You're correct... Plutonium 238 is used as a heat source in very long-range exploring spacecraft (Voyager, etc). There's a special material that gives off electricity if one side is cold and the other hot, so one side is heated by the Pu -238, and the other side radiates heat off into outer space, at around 400 below zero F.
Thanks profe. I like how easy you made me understand. Profe stay calm I won't make bombs :-). I'll make a new material none nuclear explosive much said a very steady material I just want to be able to flow out and absorb the energy from this type of reaction. I'll keep watching your videos please keep us learning.
Fission > fusion > fission > fusion > fission and in the end = huge boom and giant fireball and whole city gone in just one second. Amazing. Its just amazing how smart are some people.
1:00:20 not precisely true. The US tested its weapons primarily in a desert. Under such condition you don't get a lot of fallout with an airburst. But there _was_ fallout in Hiroshima, an airburst, in the form of the "black rain". Fallout is certainly possible with an airburst if the humidity is high enough to form precipitation after the event.
It is true enough for real world purposes. Measurements in black rain areas indicate that doses could have been as high as 44 rads (0.44 Sv for gammas) at the top range of estimates. This is between nothing and fuck-all in terms of serious injury from radiation. Modern nuclear weapons are larger. Most are in the few hundred kT range. Which gives a larger fireball that rises more rapidly, giving less, not more local fallout from an air burst.
A one gigawat coal plant needs eighty cars of coal trains a day to power. A one gigawat nuclear plant you need about half of these cars of coal a year to power it. So if Target sold nuclear energy, "More for less."
Modern Nuclear Chemistry by Seaborg ... is very useful also ... shake at 10ns is essentially one fission cycle ... 12 ns is one k-meson time ... if you have a doubling every shake ... it does not take long to release a lot of energy ...
well done ,now everyone got ideas about how to made accelerated nuclear bomb , please continue your favor and give more ideas where to get the materials from ! i think we can buy it from the black market of weapons ready rockets with nu warhead !
Just the fact that you underestimate yourself is a sign of a higher IQ. Plus I don't think average IQ blokes Care about this stuff. They are watching Britney Spears videos.
Loved this lecture; going on to watch part two. I really want to formally study this myself at an actual institution rather than on my own during my free time but I don't have the funds to do this. I was surprised to see just how much of this I already knew even though I never had a chance to take a physics class when I was still in high school. A majority of it was more of review for me, but a fair bit of it was completely new to me. I personally have always been interested in the prospect of building a working efficient fusion reactor.
So it sounds like just having Uranium-235 sitting around, it starts to break down? How do you contain it then without it automatically starting nuclear fission - or is that kinda the idea? Just thinking about the pellets used in fuel rods. Does the nuclear reaction automatically happen just by having it close together in pellets in the fuel rods, or do you have to have some catalyst to get it going?
If you are talking about nuclear fuel rods, that is a lot different from fuel for a bomb. Nuclear weapons have uranium enriched to close to 100%, while nuclear power plants are generally less than 5%. That means less fissionable U235, and is also the reason a reactor could never lead to a nuclear explosion.
Arnold maybe the reactor couldn't explode but there can still be fallout radiation for miles, also even tho reactor rods aren't the weapons grade choice , they can still be made into a crude / effective substitute. Which is what Mr. Harvard man said.
Just look carefully at the video.. All neutrons have to be captured by a U235 core and cause another fission.. Most will be leaking or not be captured..
Jonas Carlsson Yeah I get it for a powerplant, but what about in a bomb where you have a core of fuel sitting there? Seems like fission would spontaneously occur.
Watching this and repeatedly hearing about the astronomical orders of magnitude of heat and pressure that is released in these reactions, I wonder if we could harness this power to mimic the natural processes which create petroleum. Any thoughts about that?
The graphite control rods in a reactor are what control the neutron reflections right? Pulling out the control rods causes the reaction to accelerate, while inserting them blocks the netrons, slowing the reaction? In the case of Chernobyl the control rods were all pulled out over accelerating the reaction, neutrons everywhere, then all control rods were quickly inserted back in, in a state of panic, but doing so caused the control rods to actually become reflectors, there were too many neutrons already about that, then excessive hydrogen gas was created, and thus only making the meltdown of the reactor, also explode. Can anyone comment on my understanding?
+SwingingChoke No. Graphite is a good moderator, better than water. Control rods are made of materials like cadmium and hafnium that have large cross sections for absorbing neutrons at desired energies. Inserting them blocks neutrons. Inserting graphite rods, which are not control rods, moderates the neutrons (slows them down without absorbing them), slow neutrons fission uranium-235 or Pu-239 more readily, which speeds up the reaction. Chernobyl was a graphite-moderated reactor with light water cooling. Water is also a decent moderator a poor neutron absorber. If it ever gets hot enough that steam bubbles form in the reactor, neutrons zip across those steam bubbles and hit graphite, which is a better moderator than regular light water in that it doesn't absorb as many neutrons; that means, if it boils in the reactor, the reactivity increases. The water is operating as a "liquid control rod" that is never supposed to be removed. Among the fission products, there are isotopes which absorb neutrons readily. The most important one of these is xenon-135. This isotope is a neutron-hungry monster. When you start a reactor up, there is no xenon-135 because it has all decayed. Over a few hours it will build up in the reactor, decreasing the reactivity. It reaches an equilibrium when it is being destroyed as fast as it is created. In the Chernobyl reactor they had been operating at full power, creating a lot of iodine-135, which decays into xenon-135. As they ramped the power down, they eventually had trouble maintaining the right level of reactivity because xenon-135 was being formed from decaying iodine-135 faster than they were burning it off, so they manually removed control rods to maintain the reactor to keep it running. Eventually the xenon-135 burned off, which increased reactivity, which increased power, which burned off xenon-135 faster, which increased reactivity. When they noticed the power unexpectedly and rapidly increasing; from low levels towards normal levels; they SCRAMed the reactor to shut it down. The control rods were tipped with graphite, which is not a control rod, but prevents water from entering the channels were the control rods are withdrawn, giving even more control. The control rods had been withdrawn so far, manually, that water had entered these channels. The water is essentially acting like a weak, liquid control rod in these channels when present. As they insert the control rods graphite tip first to try to shut down the reaction, they push this water out of the channel with the graphite tip, replacing water with an excellent graphite moderator. This made the power increase rapidly far beyond what the reactor could take. Things overheated, broke, warped and they could not get the control rods more than about a third of the way in before they got stuck. From mathematical simulation and witness accounts it is believed that the power was about 30 GW thermal when the first steam explosion happened (ten times normal; 3 GW thermal -> 1 GW electric), lifting a 2000 ton steel plate, and after that the excursion continued (less water) until the second more serious explosion dispersed the core so that it was no longer critical. The second explosion can have been caused by several different candidates, e.g. hydrogen from hot zirconium in steam, or hydrogen and carbon monoxide from hot graphite or prompt criticality, equaling about 10 tonnes of TNT in explosive force.
Basically he's saying, "We've discovered a few really easy ways to achieve criticality, but of course i can't talk about those...". Knowing it's possible is half the battle.
They initially used a beryllium reflector and a U-238 tamper in the primary. I think they eventually said fuck it and just use a U-238 tamper/reflector to save space and weight in the primary. I also don't believe they use explosive lenses any more. The problem with explosive lenses is that they have a long aspect ratio to turn an expanding spherical wave into a converging wave because the difference in detonation velocity between the two explosives isn't that great. In the Swan test they used an "air lens", which looked like a prolate spheroid (two pointy sides of an egg) surrounded by high explosives. The explosives would be initiated at two points and as the detonation proceeded from the "poles" towards the "equator" of the metal plate it would be launched at subsonic speeds and be reshaped into a sphere. This impacted on and ignited a high explosive surrounding the pit and a tamper; this high explosive pushed off of the metal plate and compressed the primary. If you get the microsecond timing of the detonators wrong, the plutonium pit is squeezed into a peanut shape and criticality is prevented; therefor you shouldn't get a nuclear yield if you drop the device and the high explosive goes off (one point safety). This design is smaller, lighter, but probably not as efficient as a high explosive lenses. In a thermonuclear weapon that goes ontop of an ICBM you don't care if the primary is very efficient as you'd rather save a half a tonne of weight than half a kilogram of plutonium. The goal was to put say 6 decoys, a bunch of shaff and 3 real warheads ontop of one ICBM that can be launched from anywhere and to anywhere on the surface of the Earth; and super expensive plutonium became not that super-expensive.
I get to listen to a lecture from one of the most prestigious universities in the world for free, and I can pause and rewind it at my whim. Think about that for a second...!
I am a physicist and this is one of the clearest and well organised explanation to the layman and scientist on this topic - excellent presentation.
I am a chemist and this guy has no clue what is going on. Kinetic energy of fission products? Really? No mention of mass defect and the actual physics that is going on? This is disinformation pure and simple. I mean , he is an associate professor of public policy, associate! It shows. This man is in no way qualified to speak on this subject.
thanks for putting me on the NSA watchlist
MWB Gaming lol
Every American is on the NSA list. The Government is scared of us and collects all our data. Thank you Snowden. So if your hard drive crashes, just ask Obama for the back up. ;)
im not american im australian but i bet the NSA is still spying on me
also i think il have to purchase the backup from trump
obama would give it to me but trump would probably try to make me pay
MWB Gaming oh, Obama would make you pay, but TRUMP will make you pay with your daughter...
sorry for the bad joke if you actually HAVE a daughter....
lol no offense taken
trump would make me pay with both lol
This professor is such a great speaker. Easy to understand even if you are not physics major.
Black SUV just pulled up next to my house.
Why am I mesmerized by this deadly apocalyptic subject?
my father was at Castle Bravo in 1954.
Thanks James Cameron for an excellent 101 lecture.
No budget to steep, no sea to deep. That's who? It's him, James Cameron.
!?
Michael Corcoran Explains why his movies are loaded with bombs.
@Dan Kelly: It's a joke. Michael is saying Professor Bunn appears similar to James Cameron - and indeed there is a vague resemblance.
Dan Kelly:
A nuclear bomb took down the Titanic, and James Cameron attempted to tell the story with DiCaprio.
kim was lit when his boys found this
What?..
A good portion of this info was in my course of study for a power reactor operator's license. Nice refresher.
Trinity Slide @ 2:15 is not a picture of Trinity, but a picture of Shot Badger from the Upshot-Knothole series in 1953.
Can you imagine going back in time to WWII and telling people "you know that super secret tech you're all working on? Yeah... we call this RUclips"
Never though I would get the basic understanding, well taught, not locked in explaining in complicated terms at all, so well delivered. Was always wondering how they can be sooo powerful, now that guessing can rest :P
"All the energy and matter that has existed still exists. Matter does not create energy
of itself. The actions of matter enable energy to become manifest".
I personally loved this lecture, and the lecturer did a fantastic job explaining everything, I spend hours a day watching and listening to lectures about nuclear physics and explosives etc because they interest me alot, I wish New Zealand universities would offer a degree or diploma in nuclear physics or pyrotechnics and explosives, or even an online course, if they did do this I would be there first student
+SuperBking1340 One method is to observe the path of a charged particle as it collides with a neutral particle.
SuperBking1340 Good question, I'm not entirely sure.
SuperBking1340 Now that I think about it more, using the mass of the two given particles and the angle of recoil from the charged particle, it could be determined what direction the neutral particle rebounded in.
+SuperBking1340 good question, but unfortunately I don't know the answer to that, you would need to ask the people that assemble nuclear weapons for the answer to that
+mark lister Im from new zealand too and really enjoyed this lecture
56:35 Minor detail about hot air rising. I think he is mixing up cause and effect. You do not start with hot air rising and then colder air rushing in below to "prevent a vacuum". The hotter lighter air causes a lower pressure above the colder heavier air. This causes the cold air to be pushed up from its sides (as the side pressure around the cold air is higher than the pressure from above), which then in turn pushes the hot and lighter air upwards.
Think about an air bubble under water. Water on the top of the bubble flows down on its sides and fills up the bottom of the bubble. The permanent movement of water from the top to the bottom makes the air rise up. There is no water rushing in from below to fill up any vacuum.
I'm building a bomb for my dad for his birthday and I want it to be big. However my yield seems to be consistently below the 50 kiloton mark even when I use enough material for a 100k or so bomb. I've got the hollow sphere and the air gap and the explosive lenses mostly dialled in, but still I end up with this figure "8" blast pattern that is not very optimal Can you please help? I only have enough fissile material for two more bombs so I can really have only one more test before I make the present.
Use the fissile material for the remaining 2 bombs for 1 bomb.
You've got enough material for a 100kt explosion? Is that assuming the impossible efficiency of 100%, are are you assuming maximum possible efficiency of 33, but only getting 16%?
16% is pretty good. Are you using uranium or plutonium? Boosted or unboosted? Reflected or unreflected? Tamped or untamped? How precise is your neutron injection timing?
Some speculate that the yield of a nuclear bomb is dictated by the by its position in celestial space. So, it may fizzle or it may go BOOM.
Very good lecture. Easy to understand.The science to make it explode is well known. Not exactly top secret. The means to do it is the hard part.
I was at Trinity in 2007 - tourists took the last of the Trinitite glass from the ground a while back but you can still get some from collectors online.
I grew up in the '60's and '70's, and while I missed the Civil Defense drills in schools, I had found a lot of books by the agencies in a landfill in the valley below our house, across the river from the US Naval Academy. Those books, plus reading "Triumph" by Philip Wylie, had me watching every contrail in the sky. Those neurosis-inducing nukes......
Test pilots would occasionally issue a sonic boom over the area, and one day a Harrier dropped in to hover over a parking lot at the Academy. The initial sonic boom and the subsequent roar had us running for cover..... like that does ANY good within ten miles of a nuke.
Thanks for sharing this extremely well-done lecture.
@39:38 are you referring to gamma ray detection only? If so, are you stating that cat litter emits a higher count rate (combined Th, U, and P) than *unshielded* enriched Uranium?
Interestingly you can enrich uranium using photo activated uranium salt decomposition. You’ll have to guess the salts that this would work with.
This approach relies on the minute differences in the chemical properties of 238 and 235. It only needs recrystallisation equipment.
It’s not an economically viable method though.
If I wasn't on a list from all the other cap I watch.....I definitely am now
some dude haha yup. I’m a Feynman fan so naturally this pops in my feed.
Fascinating. Great presentation.
Dr. William Penney, the British scientist who developed the British nuclear weapons, had a permanent grin on. Look up a photo (any) of Dr. Penney and you can be sure he is flashing his toothy grin.
Maybe he was Stanley Kubrick's model for Dr. Strangelove. Penney was knighted for his contribution to the nuclear arms race.
Outstanding lecture.
this vid just auto played when i was napping, just saying whomever might be spying on me lol
so fascinating!!! i love learning about nuclear bombs!!
Great lecture! Except the actual process where the energy is transferred from the primary to the secondary (31:00) is not exactly right. The actual process is the ablation of the surface of the secondary, from high energy X-rays filling the bomb case, exploding it inward. It's not the radiation pressure. The surface is rapidly heated and ablates away, propelling the material inward to compress the secondary.
If you want to get technical, wouldn't it be the mass and radiation transferred from the primary to the secondary?
Eric Wesson tellar-ulam
Bryan Carter Even if you assert that what you said is correct, the radiation pressure is what starts the main reaction in the secondary. A distinction without a difference.
if we are getting technical, it was radiation pressure. all momentum is carried by photons
False. radiation pressure results from the kinetic energy of the photons (yes, photons, despite having mass, have an energy associated with them). Ablation pressure is a different mechanism.
So I starting watching this a couple of days ago and heard him suggest The Making of the Atomic Bomb by Richard Rhodes. I finished it and yes it is a page turner. and yes it is very good. If you are interested in history of science you will enjoy this book. the book tells the history of nuclear physics not just an account of los alamos.
I was looking at, like, a LEGO set for Nuclear Weapons on Amazon, but I couldn't find any. Do you think I'll have better luck on Craigs List?
I am just interested in how everything works together
21:15 it's so badass when someone says "that's classified" one day I hope to be able to say it.
Amazing video. Though obviously a very complex and chemistry / physics topic, professor Bunn does a fantastic job of explaining things clearly and in a simplified manner.
Gone fission...
Fantastic very interesting. This speaker is well worth the effort to listen to. And is so close to perfect as far as keeping every sentence riveting
If he can just drop the habit of saying O.K , OK , OK , It's to many oks .
He is so interesting I had to persevere, but please play it back and note how often you say ok.
Then note how the flow sounds so more interesting when you use far less ok.
This is in no way intended to offend, you are well worth the time.
In fact I will both like and share.
Keep it up you are great , in fact so riveting and interesting , you don't need the ok , ok.
Thank you I found your technical explanation perfect
OK.
Warm regards Grant
This is a great professor.
He leaves the fun stuff out but a nice rendition of basics of old nuclear weapons design
Great video. Great lecture. Is there a similar on nuclear power?
If that whole putting the dueterium into the pit to cause a fusion reaction at the same time as the fission isn't the classified part, I wanna know what the classified part is.
Miniaturisation. The smallest fission bombs in the US arsenal are literally the size of a football. The smallest high-yield fusion bombs are smaller than the fission bombs other nations have.
Well done sir.
and don't forget to watch the 1963 movie "Dr Strangelove, or ..." Still a great and important story.
At 15:00 when he's talking about 2/3s critical mass inriched uramium. Is he talking about uranium that's being compressed by an explosion making it completely hypothetical? Or is he saying that if you swing 2 pieces of uranium 235 at each other that there will be a small deadly explosion even before you could hit them together?! Fascinating and good to know if your ever handling nuclear bomb cores.
About 28:00 he says the core heats to "billions of degrees". Is this correct? I thought even fusion bombs don't get hotter than 40M degrees or so
Well, I guess he knows what he's talking about, he sure seems smart enough... But, it'd be kinda hard to measure, don't you think?
A Fission reaction is used to trigger a Fusion Reaction.
Yes, it happens for an extremely small period of time though.
Good question! Amazing how you get confident answers that don’t answer your question at all.
It’s ok to not know the answer folks.
Fissile cores do not reach billions of degrees. In kelvin, we're talk around tens of millions. Maybe 70 million max.
Did they invite Iranian nuclear scientists and reps of the Guards of Islamic Revolution to this exciting lecture?
+Al Johnson Da.
No but your racism was
This level of understanding of the thermonuke is trivial. However, it was only arrived at after 40 years of experimentation and testing, which might lead you to the clue that a lot is unsaid here. Go read Clancy's "The Sum of All Fears" to put yourself to sleep.
+YELLING ARNOLD (IS EVERYWHERE) Got anything better than that?
eatenbytheweasel americans
21:00 Anyone have any idea what these "simpler" approaches might be he is referring too? (Asking for Iran)
Anyone familiar with the phenomena of the Ocean water around a Nuclear detonation turning temporarily black? .... I read about it years ago but am unable to find any info anywhere on the net, .... would greatly appreciate any help ... cheers
+getorfmalawn Its called a "slick". I think it does not actually turn black. When the hyper-sonic shock wave travels thru the water the surface becomes a little smoother thus not reflecting light as well. Right behind that shock wave is the one traveling slightly slower thru the air. Where the air wave meets the surface of the water it creates an effect call "cracking". It disturbs the surface of the "slick" and causes it to then appear white.
Cheers Tyler ...I since posting found the term "slick" mentioned in Wiki of all places .... Ive been thinking the phenomena is connected to the property of water to form a temporary "Lattice" through its H-bond network,... acting similar to a Black Body type absorber .....temporarily negating reflection ... you're explanation is not entirely excluded in that process, ( speculative as it is) with the tremendous energy compressing the molecules into forming the lattice .... interesting stuff thanks again for your reply mate
+getorfmalawn It looks like i spoke too soon on the "cracking" too. It appears that the cracking happens before the air pressure gets there. I assume the cracking is the result of the "slick energy" being released from the lattice as it decompresses. Can you expand on that?
31:07 According to en.wikipedia.org/wiki/Thermonuclear_weapon#Compression_of_the_secondary
there are three proposed theories of how the energy is transferred to the secondary:
- radiation pressure exerted by the X-rays
- X-rays creating a plasma in the radiation case's filler (a polystyrene or "FOGBANK" plastic foam)
- Tamper/Pusher ablation
It's obviously not radiation pressure because that's a piss-weak effect compared to ablation pressure.
The x-rays cause the tamper surrounding the secondary spark plug to ablate so explosively that it causes a rocket effect. The tamper blasts cylindrically inward from all sides, compressing the spark plug to fission pressure + temperature. Ignition of the spark plug then pushes the tamper back out again, which kills the reaction before it even leaves the bomb casing. It happens so fast that they had to load the first H-bombs with paraffin to slow the neutrons from the primary down so they wouldn't reach the spark plug before it had compressed all the way.
Great information, very informative. Lecture is off the chain, you know you are in the presence of a expert. On the other hand what horrible reality these devices have created. So sad and depressing. So much engineering in the wrong direction. One love y'all.
CVbeats to be fair more people wouldve died if they didnt bomb hiroshima and nagasaki vs an invasion of japan, the lesser of two evils if you will
awesome video , i love learning about things like this
im gona look into seeing if you have any other lectures on different subject's
this kind of stuff is so fascinating to me
honestly had no idea it was so complicated and i enjoyed learning about how they use
this type of thing to produce regular power for people to use, or factory's ect.
agin awesome video !! thanks
Love it when he said "people" instead of scientists.
Makes us feel like we belong to the same human beings.
We hear about other countries who we don't want to have them, but the truth is the knowledge on how to is easily available, and is taught to students in school....yes even students from other countries no restrictions other than the general admission to the school.
Thanks a lot for the video. Very informative. That is one morbidly fascinating device
I wonder what kind of informations in this video are intentionally placed misinformations.
But all in all, as far as i can evaluate that, a very good video. Thanks.
OpenGL4ever Sketches of the bomb structures are not correct. The explanation of the function is correct.
dieselscience
How do you know? Have you ever developed a nuclear bomb for a country?
Do you know what Y-12 is?
dieselscience
Now i know. But what is about you?
"But what is about you?" - If English is not your native language, that's OK but I don't understand what you are asking..
Where can we download the blueprints for 3D printing?
Great explanation. I enjoyed a lot, thank You. God Bless peaceful countries and lovely people.
54:28 that looks like a soap bubble.
That photograph at 2:20 is of the - Badger shot of Operation Upshot-Knothole in 1953 and NOT of the Trinity Test as Bunn suggests! Just look the pictures up yourself, if you don't believe me.
Wouldn't plutonium 238 be great for nuclear powerplants since it generates heat and therefore be great in a steam turbine?
You're correct... Plutonium 238 is used as a heat source in very long-range exploring spacecraft (Voyager, etc). There's a special material that gives off electricity if one side is cold and the other hot, so one side is heated by the Pu -238, and the other side radiates heat off into outer space, at around 400 below zero F.
Many thanks for the lecture though I cannot imagine a situation where I'd need that type of knowledge. :)
Why is the CIA following me
Thanks profe. I like how easy you made me understand. Profe stay calm I won't make bombs :-). I'll make a new material none nuclear explosive much said a very steady material I just want to be able to flow out and absorb the energy from this type of reaction. I'll keep watching your videos please keep us learning.
Great lecture
21:01 what are they?!?! Now im curious... Very much so
Very Interesting, i like your class online, i send you greetings!
Fission > fusion > fission > fusion > fission and in the end = huge boom and giant fireball and whole city gone in just one second.
Amazing. Its just amazing how smart are some people.
1:00:20 not precisely true. The US tested its weapons primarily in a desert. Under such condition you don't get a lot of fallout with an airburst. But there _was_ fallout in Hiroshima, an airburst, in the form of the "black rain". Fallout is certainly possible with an airburst if the humidity is high enough to form precipitation after the event.
It is true enough for real world purposes. Measurements in black rain areas indicate that doses could have been as high as 44 rads (0.44 Sv for gammas) at the top range of estimates. This is between nothing and fuck-all in terms of serious injury from radiation.
Modern nuclear weapons are larger. Most are in the few hundred kT range. Which gives a larger fireball that rises more rapidly, giving less, not more local fallout from an air burst.
Wonderful, it's absolutely right of what I was searching for. Thanks alot
A one gigawat coal plant needs eighty cars of coal trains a day to power.
A one gigawat nuclear plant you need about half of these cars of coal a year to power it.
So if Target sold nuclear energy, "More for less."
great video! thanks for sharing!
This science made 1sec an eternity of time
This lecturer is brilliant. I'd bet he could make "how paint dries" an interesting topic :) Thanks for the video Belfer Center.
Thanks for the upload
Nothing new really, except the breakdown on what's hardest to achieve.
is it me or he make it sound simple? even i would of used bigger words :/ this man as a gift
Modern Nuclear Chemistry by Seaborg ... is very useful also ... shake at 10ns is essentially one fission cycle ... 12 ns is one k-meson time ... if you have a doubling every shake ... it does not take long to release a lot of energy ...
well done ,now everyone got ideas about how to made accelerated nuclear bomb , please continue your favor and give more ideas where to get the materials from ! i think we can buy it from the black market of weapons ready rockets with nu warhead !
thanks for sharing this. very clear explanation and it was very useful for me to understand.
IIRC, the heavy metal Beryllium is used as the tamper.
Beryllium is not a heavy metal, it's the second lightest metal. Also it's not used as a tamper, but as a neutron scatterer.
Great video+speaker...even for an average IQ guy like me-
Just the fact that you underestimate yourself is a sign of a higher IQ. Plus I don't think average IQ blokes Care about this stuff. They are watching Britney Spears videos.
Not to mention look how many people have watched pt 1 vs pt 2. I bet most of the numbers who started pt1 never finished Pt1 let alone pt2.
Loved this lecture; going on to watch part two. I really want to formally study this myself at an actual institution rather than on my own during my free time but I don't have the funds to do this. I was surprised to see just how much of this I already knew even though I never had a chance to take a physics class when I was still in high school. A majority of it was more of review for me, but a fair bit of it was completely new to me.
I personally have always been interested in the prospect of building a working efficient fusion reactor.
So it sounds like just having Uranium-235 sitting around, it starts to break down? How do you contain it then without it automatically starting nuclear fission - or is that kinda the idea? Just thinking about the pellets used in fuel rods. Does the nuclear reaction automatically happen just by having it close together in pellets in the fuel rods, or do you have to have some catalyst to get it going?
If you are talking about nuclear fuel rods, that is a lot different from fuel for a bomb. Nuclear weapons have uranium enriched to close to 100%, while nuclear power plants are generally less than 5%. That means less fissionable U235, and is also the reason a reactor could never lead to a nuclear explosion.
Arnold maybe the reactor couldn't explode but there can still be fallout radiation for miles, also even tho reactor rods aren't the weapons grade choice , they can still be made into a crude / effective substitute. Which is what Mr. Harvard man said.
Just look carefully at the video.. All neutrons have to be captured by a U235 core and cause another fission.. Most will be leaking or not be captured..
And the powerplant also features control rods that absorb enough neutrons so that the chain reaction never goes logarithmic.
Jonas Carlsson
Yeah I get it for a powerplant, but what about in a bomb where you have a core of fuel sitting there? Seems like fission would spontaneously occur.
Fascinating and wonderfully presented. Thanks.
Watching this and repeatedly hearing about the astronomical orders of magnitude of heat and pressure that is released in these reactions, I wonder if we could harness this power to mimic the natural processes which create petroleum. Any thoughts about that?
I know someone who has 125 MG of 55% enriched Uranium and want to know what YIELD that would have?
thanks
I bet he's fun at party's
Makes me wish i went to college... Great talk. Very interesting!
Wrong image for trinity test 2:21
The graphite control rods in a reactor are what control the neutron reflections right? Pulling out the control rods causes the reaction to accelerate, while inserting them blocks the netrons, slowing the reaction? In the case of Chernobyl the control rods were all pulled out over accelerating the reaction, neutrons everywhere, then all control rods were quickly inserted back in, in a state of panic, but doing so caused the control rods to actually become reflectors, there were too many neutrons already about that, then excessive hydrogen gas was created, and thus only making the meltdown of the reactor, also explode. Can anyone comment on my understanding?
+SwingingChoke No. Graphite is a good moderator, better than water. Control rods are made of materials like cadmium and hafnium that have large cross sections for absorbing neutrons at desired energies. Inserting them blocks neutrons. Inserting graphite rods, which are not control rods, moderates the neutrons (slows them down without absorbing them), slow neutrons fission uranium-235 or Pu-239 more readily, which speeds up the reaction.
Chernobyl was a graphite-moderated reactor with light water cooling. Water is also a decent moderator a poor neutron absorber. If it ever gets hot enough that steam bubbles form in the reactor, neutrons zip across those steam bubbles and hit graphite, which is a better moderator than regular light water in that it doesn't absorb as many neutrons; that means, if it boils in the reactor, the reactivity increases. The water is operating as a "liquid control rod" that is never supposed to be removed.
Among the fission products, there are isotopes which absorb neutrons readily. The most important one of these is xenon-135. This isotope is a neutron-hungry monster. When you start a reactor up, there is no xenon-135 because it has all decayed. Over a few hours it will build up in the reactor, decreasing the reactivity. It reaches an equilibrium when it is being destroyed as fast as it is created.
In the Chernobyl reactor they had been operating at full power, creating a lot of iodine-135, which decays into xenon-135.
As they ramped the power down, they eventually had trouble maintaining the right level of reactivity because xenon-135 was being formed from decaying iodine-135 faster than they were burning it off, so they manually removed control rods to maintain the reactor to keep it running. Eventually the xenon-135 burned off, which increased reactivity, which increased power, which burned off xenon-135 faster, which increased reactivity. When they noticed the power unexpectedly and rapidly increasing; from low levels towards normal levels; they SCRAMed the reactor to shut it down.
The control rods were tipped with graphite, which is not a control rod, but prevents water from entering the channels were the control rods are withdrawn, giving even more control. The control rods had been withdrawn so far, manually, that water had entered these channels. The water is essentially acting like a weak, liquid control rod in these channels when present. As they insert the control rods graphite tip first to try to shut down the reaction, they push this water out of the channel with the graphite tip, replacing water with an excellent graphite moderator. This made the power increase rapidly far beyond what the reactor could take. Things overheated, broke, warped and they could not get the control rods more than about a third of the way in before they got stuck.
From mathematical simulation and witness accounts it is believed that the power was about 30 GW thermal when the first steam explosion happened (ten times normal; 3 GW thermal -> 1 GW electric), lifting a 2000 ton steel plate, and after that the excursion continued (less water) until the second more serious explosion dispersed the core so that it was no longer critical. The second explosion can have been caused by several different candidates, e.g. hydrogen from hot zirconium in steam, or hydrogen and carbon monoxide from hot graphite or prompt criticality, equaling about 10 tonnes of TNT in explosive force.
Thank you, I appreciate the clarification for me. I have a great understanding now.
Outstanding. Thank you.
That first slide is not a picture of the Trinity test. It is from a Nevada Test Site test in the 1950's.
Go back to 51:00 minutes....sounds like a major concern if you ask me....
And then read his background and tell me this really shouldn't be a concern
Basically he's saying, "We've discovered a few really easy ways to achieve criticality, but of course i can't talk about those...".
Knowing it's possible is half the battle.
Fascinating! Thanks for the clear explanation.
well presented
The Frugal Gourmet know a lot about nuclear physics.
I thought shampoo was involved in the mechanism somewhere. I guess the A-team were not a good source of technical information.
what kind of material did they use to deflect neutrons?
They initially used a beryllium reflector and a U-238 tamper in the primary. I think they eventually said fuck it and just use a U-238 tamper/reflector to save space and weight in the primary.
I also don't believe they use explosive lenses any more. The problem with explosive lenses is that they have a long aspect ratio to turn an expanding spherical wave into a converging wave because the difference in detonation velocity between the two explosives isn't that great. In the Swan test they used an "air lens", which looked like a prolate spheroid (two pointy sides of an egg) surrounded by high explosives. The explosives would be initiated at two points and as the detonation proceeded from the "poles" towards the "equator" of the metal plate it would be launched at subsonic speeds and be reshaped into a sphere. This impacted on and ignited a high explosive surrounding the pit and a tamper; this high explosive pushed off of the metal plate and compressed the primary. If you get the microsecond timing of the detonators wrong, the plutonium pit is squeezed into a peanut shape and criticality is prevented; therefor you shouldn't get a nuclear yield if you drop the device and the high explosive goes off (one point safety).
This design is smaller, lighter, but probably not as efficient as a high explosive lenses. In a thermonuclear weapon that goes ontop of an ICBM you don't care if the primary is very efficient as you'd rather save a half a tonne of weight than half a kilogram of plutonium. The goal was to put say 6 decoys, a bunch of shaff and 3 real warheads ontop of one ICBM that can be launched from anywhere and to anywhere on the surface of the Earth; and super expensive plutonium became not that super-expensive.
Little boy used tungsten carbide, fat man used natural uranium. In more modern weapons, beryllium and beryllium oxide are used.
Modern thermonuclear primaries don't use natural or depleted uranium tampers. Fusion boosted weapons don't really need tamping.
M'kay?
He sounds like Christopher Walken talking about building a nuclear bomb. Awesome.
Nic Lewis haha I thought that too.
Imagine if we put all this amazing effort and ingenuity into things that would help people instead of to kill as many as possible at the same time...