@badmoth242xl3 1 year ago Actually, I disagree regarding the origin of the Los Angeles Detonations.
For one, despite being relatively tightly packed, for a countervalue strike on an urban center they are rather dispersed. In order to achieve an adequate Damage Expectancy (DE) on a soft target like a city, 5-10psi is generally the ballpark that strike planners use in order to cause medium damage. The detonations here appear to be too far apart for it to have that level of DE across the entire city. It could potentially be explained by the US degrading China's nuclear capability by conventional means, however after over a century of unconstrained nuclear buildup I doubt that Chinese planners would even begin to transfer warheads slated for Los Angeles against other targets.
I disagree that it's a MIRV. Rather, I believe the missile carrying these warheads was only equipped with a MRV, the MIRV's unguided predecessor. Given the POD for the Fallout universe occurs in the early 1950s before the development of the Minuteman Missile and the world is less digitally advanced, the payload busses for the missiles in Fallout may simply lack the ability to independently target their warheads. The Chinese SLBMs may be less like a Trident and more like a Polaris A3. Regarding the Polaris A3, it initially carried a unitary 600kt W47 warhead for the A1-A2 variants, but adopted a trio of 200kt W58 warheads in the A3 model. This resulted in an overall increase in total DE, since the trio of detonations would be roughly equivalent to a single 1MT detonation, but with the added benefit of being more survivable against Ballistic Missile Defense systems. However, this came at a significant cost to the missile's CEP, relegating it only for use against countervalue targets.
Consequently, this explains the timing, yield, and dispersion of the detonations better than with a MIRV. With a MIRV, the detonations would have been much more tightly packed, and there would've been less time between the detonations assuming such a dispersion profile. Fallout's nukes are already small, but the need to cram multiple (presumably pure fission) warheads in a single missile would have reduced the yield even further, hence the detonation yield shown.
One other thing too, the fact that Los Angeles and most other US cities were hit by SLBMs rather than by bombers (be it gravity bombs or standoff missiles), suggests that China had little confidence in the ability of their bombers to successfully penetrate US airspace. Prior to the adoption of later SLBMs that enabled Boomers to engage in hard-target Counterforce operations, SLBMs were meant to be used against soft targets in a second-strike role. The comparatively less advanced technology in Fallout might mean that this remained true up until 2077. This either implies that the US had either already degraded China's ICBM force via conventional or nuclear attack and this is the Chinese second strike, or China threw everything into a single "Sunday Punch" that left little nuclear forces in reserve. 3
Aren't nukes in the Fallout universe supposed to be less "destructive ... www.reddit.com › falloutlore › comments › arent_nukes_in_the_fallout_u... Jan 13, 2026 · From the explosions seen in the TV series, they lack the distinct double flash of a hydrogen bomb or fission-fusion device. These give you much ...
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Anonymous2026-04-03 5:21
Gyrgir • 9mo ago
Based on a discussion I had many years back on the subject with a nuclear engineer, the main limiting factor in building arbitrarily large multistage Teller-Ulam bombs is the extreme difficulty of modelling designs, as the dominant activity that needs modelling is turbulent radiation hydrodynamics, and turbulent hydrodynamics without radiation is already a major unsolved research problem which is suspected to be potentially unsolvable.
He went on to say that you can probably develop designs empirically by testing them and analyzing the data, but he expressed a preference that any such tests be conducted on a planet he doesn't live on.
That said, he thinks the practical limit, without additional testing and given full access to detailed info from the Tsar Bomba test, would probably be around 500 MT, about 5x the projected yield of the Tsar Bomba design had the Soviets included the U-238 tamper (an additional fission stage which was left out of the test bomb to reduce fallout). 21 Pristine-Bridge8129 • 9mo ago
Thank you for this fascinating insight. 2 weeOriginal • 9mo ago
Interesting! How much larger is each stage than the previous? Typically, I mean. 3 u/Phssthp0kThePak avatar Phssthp0kThePak • 9mo ago
That is such a great book. 2 Famous-Opposite8958 • 9mo ago
I read a book years ago in which a scientist pointed out that after a certain point, all one would accomplish with a bigger bomb is to propel a section of atmosphere above the bomb faster and faster into space. I may be mistaken but I recall that the “practical” limit to be around 100MT.
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Anonymous2026-04-03 6:43
Profile photo for Peter Webb Peter Webb Lives in Far North Queensland (2023–present)Author has 17.5K answers and 36.2M answer views2y
The Tsar Bomba design was for a fission bomb, but only the fusion stage was tested.
It is probably helpful to explain the various types of nuclear weapons, and how they work. Spoiler alert: there are no pure fission of pure fusion bombs ay more; and this is no longer a useful classification.
Fission Bombs
The first three atomic bombs - detonated at Los Alamos, Hiroshima and Nagasaki - were pure fission devices, as were all nuclear weapons until the mid 1950s.
In the early 1950s, computer simulation showed that a mixture of tritium (an isotope of hydrogen) and lithium could be “fused” by the heat and pressure a fission bomb.
This created two new classes of nuclear weapons:
Enhanced Fission bombs
A very small amount of tritium and lithium massively increases the yield of fission bombs. It does this by increasing the percentage of the Uranium or Plutonium that fissions - up from less than 20% of the Plutonium to almost 100% of it fissioning, a 5 or 10 times bigger bang. Almost zero of this is directly from the fusion reaction, what the fusion reaction does is expose the Plutonium to very high speed neutrons which can trigger lots of fission events.
So these could still be considered fission bombs, even though they rely on fusion in their operation.
Fission-fusion bombs, aka “Hydrogen” bombs
If instead of just adding a little tritium and lithium to enhance the fission reaction, you add lots, so the energy it releases is much more than the fission stage, you get a Hydrogen bomb. These can be easily tuned to different yields by moving the fusion products closer to or further away from the fission stage.
The first test of this idea was at Bikini atoll, and the blast was double that which had been predicted. Whoops.
Fission-fusion-fission bombs
Now we get to the Tsar Bomba. It turns out that the fast neutrons emitted by fusion reactions can not only split plutonium atoms, they can cause good old uranium 238 - depleted uranium, cheap as chips - to fission. So the plan was to build a huge Hydrogen bomb, then wrap the entire thing in tons of depleted uranium. Used this way, it is a giant “enhanced fission bomb”; the purpose of the fusion stage is to supply the neutrons for the DU to fission, which would produce the bulk of the energy.
But the Russians chickened out. They covered the outside with several tons of lead, rather than uranium. So the actual test explosion was only that of the largest ever hydrogen bomb - 50 megatons. After the miscalculation at Bikini Atoll, they concluded that detonating a bomb with a predicted yield of maybe 200 megatons which could potentially be 500 megatons spraying tons of fallout into the upper atmosphere probably wasn’t a great idea.
TL;DR
Technically, the actual Tsar Bomba was a regular H bomb, but the concept they were testing was a fission-fusion-fission bomb, which technically is an enhanced fission device.
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Anonymous2026-04-03 7:04
Profile photo for Scott Carter Scott Carter BSEE, >40 Years Aerospace, Medical, and Industrial (1980–present)Author has 961 answers and 549.1K answer views · 2y
Assuming you mean an unboosted weapon (since boosting does involve some fusion, even though the direct contribution of the D-T fusion energy to total yield of a boosted fission weapon is usually very very small), I suspect it might be the US’ 160 kT Mk 6. I can’t find a definitive statement whether the 500 kT Mk 18 was or was not boosted (the 700 kT Orange Herald definitely was).
edit - see better answer from Evan Bell[1]; Ivy Mike/Mk 18 was not boosted.
[1] Profile photo for Evan Bell Evan Bell · 2y What is the most powerful fission nuke? I've checked Google but it keeps telling me Tsar Bomba but that's a fusion one. Mk-18 Super Oralloy Bomb, tested in Operation Ivy, shot Mike, reported as 500 or 540kt. There's also Orange Herald, 720kt boosted fission device. The highest yield single stage device. The fusion burn is thought to have failed in this shot, so it may have been a pure fission explosion, but it's not known for certain. Profile photo for Ernest Montague Ernest Montague NopeAuthor has 8.6K answers and 6.8M answer views · 2y
That would be Ted Taylor’s device, IIRC around 700 kilotons. Ted was the most prolific and brightest of the fission device designers.
Oops, wait. Orange Herald, a British device was 700 kt. Ivy King, Taylor’s device was 500kt. Ted said that he thought he could get a megaton out of a fission device. He also designed the smallest, the dial a yield backpack device. Profile photo for Evan Bell Evan Bell Several thousand hours of nuclear weapons research. Author has 964 answers and 300.1K answer views2y
Mk-18 Super Oralloy Bomb, tested in Operation Ivy, shot Mike, reported as 500 or 540kt.
There's also Orange Herald, 720kt boosted fission device. The highest yield single stage device. The fusion burn is thought to have failed in this shot, so it may have been a pure fission explosion, but it's not known for certain.
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I decided that I should finally finish my initial hypothesis about Edward Teller's Sundial and Gnomon this year, 2025. Christmas is a good occasion for such a gift, isn't it? :)
So. Last time (see the first part) I suggested that the Sundial itself is simply a very large (15 m in diameter) spherical tank filled with heavy water. I chose heavy water because Dyson mentioned it in a secret report from 1962 and because it is the most reasonable choice. Although, during the discussion, another, possibly decisive, argument emerged, which I initially overlooked. The density of deuterium in heavy water is 1.3 times higher than in liquid deuterium (in lithium deuteride, the density of deuterium is only a quarter, 1.25 times higher than in liquid deuterium). This, strangely enough, may turn out to be an important argument. Lately, I've been trying to do some numerical analysis, I even thought of posting it here before this message about the Gnomon, but I realized that I need to work on it some more, not rush things. But the overall picture is interesting. Not everything is as simple as I thought, but not everything is as terrible as it could be. In particular, I discovered that Edward Teller didn't need to achieve unlimited burning from the heavy water tank. A "amplification" mode (damped combustion of fuel) is possible, where the initial explosion of the Gnomon will be amplified 10 times by the uncompressed layer of heavy water. That is, the 10 Gt Sundial bomb would be a simple amplifier of the 1 Gt Gnomon core.
However, my calculations show that to ignite uncompressed heavy water (with an initial burnup of 80%, which is possible because the adjacent gigaton ignition device can provide such afterburning) at an ignition temperature of 8.9 keV, you would need an ignition device of ~600 Mt, and the burning would not be unlimited, but rather decaying, but with a gain factor "at infinity" of 9.8. With such a minimum ignition device, you could get up to 6 Gt. But if the ignition device in the center is made to be 1 Gt (as planned), then we are guaranteed to get 10 Gt by placing the Gnomon in the center of a spherical tank with the appropriate amount of heavy water.
So, everything now converges to a nuclear yield of 1 Gt for the Gnomon. How was this key part of the Sundial supposed to be constructed? This is where the whole intrigue of the investigation lies.
The idea that Edward Teller didn't overcomplicate things and simply proposed building a multi-stage Teller-Ulam scheme seemed completely pathetic and implausible to me from the very beginning. If I had even the slightest doubt about this, I wouldn't have participated in this investigation.
Yes, it could be done that way. You take a fission bomb of, for example, 100 kt, then with a "typical" interstage amplification of 100 times, you get a "dirty" 10 Mt on the second stage (W-53), then on the third stage, again, a "dirty" 1 Gt. Only three steps! Maybe you would need four stages, that is, a "matryoshka" of four bombs nested inside each other, but those are just details. The important thing is that it's real. Perhaps this is why Dyson, in a secret report from 1962, warned the US government that any nation capable of creating a 1 Mt bomb, that is, having mastered the secret of the Teller-Ulam design, could also figure out how to make a 10 Gt ocean mine and flood the US coast, covering their tracks and claiming they had nothing to do with it!
And indeed, look: the Russians, having just tested the RDS-37, were planning to achieve 1 Gt (1 kt/kg, a 1000-ton device) in precisely this simple way. But can you really compare our wonderful Hungarian "Martian" (the Great Lame One) Edward Teller with some unfortunate, barefoot and ragged, perpetually lagging behind Russians [deep irony]?
When Teller first proposed the concepts of the Sundial and Gnomon super-bombs in 1954, he couldn't have been offering such a simple, crude imitation. Teller knew that this wouldn't interest the peacemakers, who were firmly entrenched in their comfortable positions on the Atomic Energy Commission. He knew that the peacemakers would be horrified by the power of the bombs he envisioned, and that they would react negatively to his idea of such gigantic explosive devices, especially ones so ineptly and simply designed. He was already "at odds" with them and knew them inside and out. It would have been foolish to come forward with a simple set of ideas. And the Sundial was simple. Therefore, the Gnomon idea had to be sophisticated and complex, just like the recent Teller-Ulam scheme, which simply begged to be tested, which would captivate with its beauty and boldness! That was Teller's calculation (which failed).
So what was the Gnomon if not a simple three- or four-stage extension of the Teller-Ulam scheme?
We have two clues. Even three.
Firstly, in the available descriptions, it is mentioned that the device is single-stage. However, we don't quite understand what device is being referred to? Perhaps only the Sundial. Yes, it looks like a "Super" and it is a single stage. There is no compression stage. There is only an ignition stage. Instead of compression, there is simply a very large mass.
But what if the same applied to the Gnomon?
Here the second clue emerges. That "all this" (what exactly?) resembles a "Sloyka" or "Alarm Clock". A single-stage layered structure. Since there is no need for a layered structure in the heavy water tank itself (at least in our investigation so far) (although it cannot be completely ruled out), I am inclined to attribute the "layered structure" specifically to the Gnomon device.
So, the Gnomon is a single-stage layered structure of the "Alarm Clock" type.
And finally, the third clue that I (hopefully) recently found.
A strange phrase, a short paragraph in the transcript about "light cases".
Returning to the subject of light cases, Dr. Teller mentioned a "wild ideal" of using no case at all, just air. [.....]
Although the subreddit "fathers" did not share my enthusiasm, I stubbornly want to "add" this to the topic of Sundials and Gnomon, because this "wild idea" seemed to precede the report on super-bombs, and this topic itself was out of place there (if not explained further). I designated the "light case" (hohlraum casing) with the letter "B", the "air" (hohlraum space) with the letter C, A - primary, D - secondary, tamper. How to make it so that only "air" C remains and there is no "light case" B left? Surround the primary A with the tamper D. Topologically, there is simply no other solution for "no case at all, just air"! This is my deciphering of this mysterious "wild idea" of Edward Teller. And this puts everything in its place. The concept of the Gnomon is finally taking shape.
The Gnomon is a virtually non-scalable (non-reducible) layered spherical structure with a very large cavity at its center (I assumed a minimum of 2 meters in diameter, see the drawing) which houses the primary (and only, therefore the entire device is single-stage) source of nuclear energy: a bomb. Initially, I considered a two-stage thermonuclear bomb of at least a megaton for this role, but a simple calculation showed that if the initial temperature of the photon gas in this two-meter cavity is 2 keV, then a fission bomb of 84.2 kt would be sufficient (assuming that half of the energy is in the form of matter energy, and the other half, 42.1 kt, is in the form of photon gas). If, of course, we need a temperature of 5 keV, then a 3.3 megaton ignition device would be required (which somewhat detracts from the elegance of the idea). As soon as the central initiator explodes, the photon gas begins to press on the spherical wall of the cavity (there is no "radiation case"!) and compress the first layer of the "Sloyka".
And this is where the first difficulties begin. On the right in the picture, I showed the stages of compression of a small section of the first layer, assuming that if everything works as it should with the first layer, then it will work with the second, third... and so on, as many layers as needed (I assumed 10 here).
In the diagram, I showed with numbers: 1 - the inner cavity (before the explosion of the central bomb), 2 - the first layer of U-238, the tamper and also the liner. 3 - a layer of lithium deuteride, 4 - the next layer of tamper (liner) from U-238. When the central bomb explodes, equilibrium is established in the hohlraum and the temperature of the photon gas is about 2 keV (I assumed that it might be more, up to 5 keV), and this leads to the well-known radiation ablation (number 5 and arrow), our tamper begins to move flat (actually outwards) compressing the deuterium layer (a shock wave arises, number 6). Reaching the opposite wall, the wave will reflect (and intensify, number 7) and thus, reflecting, the reflected wave will compress the fuel until the remaining part of the compressing tamper reaches 100-200 times compression of lithium deuteride (number 8). This is not drawn to scale, only the general idea. I assumed that if the diameter of the Gnomon is 7 meters, then the thickness of one compressed layer (7-2=5/2=2.5; 10 layers, one layer 25 cm, 5 cm - U-238, 20 cm - lithium deuteride) initially 200 mm should be compressed to 1 mm. And this is the MOST DIFFICULT part (the peak of complexity).
We have achieved compression (essentially flat compression, that's the idea). But how do we ignite it now? Here in the diagram, I've assumed the simplest, "naive" case, that the tamper burned through uniformly and completely (the Marshak wave caught up with the multiply reflected, oscillating shock wave in the deuterium layer) and thus simply ignited the already compressed layer of thermonuclear fuel (this is indicated by the number 9 in the diagram). If this is possible, we are the winners. Of course, we will need something like a tritium initiator here (DD ignites at 9 keV, and DT only at 2.4 keV). But these are just "minor details." It's worse if the "burning tamper" concept is untenable and we need some additional ignition mechanism, and that too across the entire compressed surface (the surface of a sphere with a radius of 1 meter and a thickness of 1 mm). I suspect that Taylor himself, when he first presented this proposal in 1954, didn't quite understand what mechanism should be used. Perhaps he had a whole set of possible solutions, and it was the search for and testing of this mechanism that he intended to carry out in his laboratory, for which he requested permission and a test plan from the high commission. To test not 1 Gt (that's madness) but the idea of flat compression. As we know from the Gnomon project, they worked for a little over a year, and there are a number of reports from which it follows that a large number of options were proposed. And I believe that all this work was aimed at implementing this flat compression in a small, experimental "flat" device (a whole series of different devices). They were looking for a mechanism for flat compression and ignition of a single layer from the compression side, which they would then implement in a huge device in the form of a "superlayer." Or they wouldn't implement it in practice, but they would possess the secret of a new, unique flat compression technology.
You cannot miniaturize this technology. In any case, it will be megatons. But if, during testing, you can flatten and ignite even just a fragment of a layer (let's say a megaton), then it becomes obvious that the same thing will happen with the next layer, and the next, in a large gigaton Gnomon... And this will happen as many times as you need! And no "light cases"! There are no cases here at all!
This is the alluring beauty of the idea that Edward Teller advertised to the respected commission of highly intelligent men. He was tempting them with "beautiful physics"! But the learned men said that Teller had completely gone mad with his gigaton projects!
However, the work wasn't actually banned. And for about a year, theoretical research on the topic continued. Did Teller find a loophole to implement the idea? We don't know. But perhaps that's not so important now. What's important is to understand what he wanted to do? It's important for us to admire the flight of thought. Right? And here, a captivating flight of thought, novelty, is clearly present!
In conclusion, I want to say that I would have continued to ponder this set of ideas for a long time if, a month ago, I hadn't accidentally stumbled upon a previously overlooked (or perhaps not immediately understood?) message from Carey Sublette, published here two years ago:
If you make an uncompressed fuel tank large enough it can be bigger than the mean free path of the photon anyway, accomplishing the same end as super-compression.
The problem with this is that you now have to heat an enormous volume to heat to very high temperature, requiring enormous amounts of energy for the igniter.
In 1955 anything they were attempting to design had to be something that did not require highly refined datasets or massive computation as they had neither. Like the great simplification of physics that the equilibrium burn of T-U provided, this had to be based on easy to calculate design principles.
Possibly this was something like a Sloika but with no external compression - an internal driving bomb compressing successive layers of fuel to high density as it expands outward. Each layer is larger in volume, providing more energy to compress the next even larger layer. In the very last layer the system radius, and accumulated explosion energy might be enough to drive an uncompressed fusion reaction.
That is, the scheme I described above was essentially described by Carey Sublette here two years ago. I'm simply following his line of thought! Therefore, it's time to bring this idea to light and try to refine its details!
reddit say 4mo ago Beneficial-Wasabi749 Reverse engineering of AN602. My version is 2025. r/nuclearweapons - Reverse engineering of AN602. My version is 2025.
The bomb was three-stage (not to be confused with three-phase), bifilar, meaning two "primaries" compressed one "secondary." The bomb's calculated yield was 51.5 megatons. 50 megatons is the "round" thermonuclear yield of the final spherical (the Russians didn't make any other kind at the time) third stage (half of 100 megatons; if you replace the lead tamper with a U-238 tamper, the bomb will become dirty and its yield will at least double). Therefore, 1.5 megatons is the "primary" stage. That is, the design interstage gain here is 50/1.5 = 33.3... times (quite common, no more than 50 times). Obviously, 1.5 megaton fission devices don't exist, so it would have been a thermonuclear device in any case (and thus the bomb had three stages). But since the device was bifilar, two 750 kt bombs were used instead of one 1.5 Mt bomb. This is discussed in one of Trutnev's interviews.
Let's calculate the main stage. Using the lithium deuteride density of 820 kg/m³ and the (very high) fuel burnup coefficient of 0.5, we obtain a lithium sphere diameter of 1.67 m. Considering the thickness of the tamper, hohlraum, and ballistic casing, all of several centimeters, we can assume a gap of 15 cm between the hohlraum wall and the sphere. Although proportionally to two meters, this seems small, it is sufficient. However, this was apparently the limit. If the fuel burnup in the final stage had been set to the usual 0.3 or 0.25, the device would not have produced the required yield.
When designing the device, I initially drew a simple hohlraum shaped like a "pill" (a cylinder with spherical ends), like the primary stages, but then decided to minimize its volume. The volume of the hohlraum as I've drawn it (two truncated cones, a central cylinder, minus the volume of a sphere, minus the two built-in bifilar "pills," excluding their rear hemispheres) is ~4 m³. At a power of 1.5 Mt (half of which will be in the form of photon gas), the photon gas temperature (E = 4 * sigma/c * T^4 * V) in such a hohlraum will be 18 million Kelvin, or 1.6 keV. This is very close to the temperature required for compression. If a higher temperature is needed (say, 2 keV), the hohlraum volume will have to be further reduced.
I also calculated the 750-kt bifilar charges, assuming these were "dirty" two-stage devices, where only 375 kt would be obtained from nuclear fusion (the rest from fission of a U-238 tamper, possibly enriched U-235). For these devices, I assumed a typical, modest burnup of 0.25 (1/4), and ultimately found that each "pellet" secondary contained 30 kg of lithium deuteride. This is a sphere with a diameter of 412 mm. Having measured the hohlraum shown, calculated its empty volume, and assumed the temperature in the small hohlraums to be the same as in the large one (1.6 keV), I obtained a photon gas energy of 3.5 kt, considering that this is only half (the rest is in matter), the total minimum yield of the primary is at least 7 kt. Thus, each of the two primary devices was 7-10 kt. This agrees well with the typical gain of 375/10 = 37.5. It's quite possible that the primary was actually more powerful, 10-15 kt.
Regarding the synchronization of two explosions for a bifilar design, if the fission devices have a neutron initiator in the form of a neutron gun (or betatron), then using electronics it's relatively simple to synchronize their pulses with nanosecond precision, thereby initiating the chain reaction in both devices simultaneously.
All spherical thermonuclear stages had a fission spark plug in the center. But in the case of a sphere, it takes up so little space that I didn't calculate a correction for their volume. I also showed very large shadow lenses, which ensured the sphere's shading from direct radiation rays that would appear (by the Marshak wave) on the surface of the primary hohlraums. Where were those famous lead rings that Sakharov added on his last night located? I can only guess, but I suspect this was an attempt to address the problem (concern) associated with radiation propagation in the main hohlraum. Please note. All lenses are positioned as close as possible to the primary source because they also act as an inertial buffer, slowing the expansion of the explosion plasma. It is claimed that the body of this "lens" barrier contains boron-10, which maximally attenuates the neutron flux.
Regarding the center of gravity. It's known that the AN602's center of gravity had to be shifted compared to the AN202. I assumed the shift was rearward because, despite the same general design, the AN202 used spherical bifilar primaries, while the AN202 used elongated thermonuclear "pellets." As a result, the hohlraum inevitably lengthened, shifting the center of the sphere rearward. The entire mass of the bomb shifted rearward toward the tail. And perhaps that's why the bomb's nose was slightly extended forward.
Another subtlety. People like to think that the nose sphere (I also drew it here), clearly depicted in the secret film, is one of the primaries. This can't be true (since it's under the double hohlraum). In the film, you see some kind of electronics unit (connected by cables to the nose antennas), made in the shape of a sphere. In the film (if you look closely), we see the preparation of an EMPTY bomb casing. I have little doubt of this. This is a typical technique of the Soviet multi-level secrecy system. The film was shot for clueless party officials. They could be shown the empty casing. And if the film gets to the West, they shouldn't see anything they shouldn't (the physical packaging of the device).
The main question: Was there some technological secret to the bomb, beyond its bifilarity, three stages, and enormous yield? At first glance, no. For example, the interstage gain factors are quite standard for the 1950s. The only thing that looks suspicious is the high REQUIRED fuel burnup in the final stage, over 50%. There's a hypothesis that this was the design's key feature. Perhaps the compression of the large sphere in AH602 occurred not in a single shock wave, as before, but in a series (possibly two for now). Moreover, I assume that the double compression shock was achieved by a two-layer tamper (an ablate with a medium Z created one wave, then an ablate with a high Z—lead—created a second). Perhaps (I've marked it with a dotted line) a reflective layer was introduced into the sphere, amplifying the incident and reflected waves. These techniques have been known since the "Zababakhin Soys." In short, it's entirely possible that they used a simplified solution to what we later saw in all its glory in the "Golden TIS" (three shock waves, which the Russians considered sufficient for a quaddiabatic approximation), where they achieved supercompression and ignition without a spark plug. This was already in 1962. But here, in 1961, the spark plug was still present, but the compression was apparently not quite typical. Hence the high burnout rate.
The latter hypothesis explains well the unpleasant story of how the super-powerful bomb was being developed at Chelyabinsk-70, but almost at the final stage, the project was taken over and reassigned to Arzamas-16, where they did everything slightly differently (with the same dimensions and weight, but much more powerful). In the memoirs, one can read about the resentment of the people from Chelyabinsk-70 towards their more senior colleagues, saying they had crossed them! And yes, there was apparently some petty palace intrigue involved. The people from Arzamas-16 apparently promised Khrushchev that they would guarantee a 50-megaton nuclear yield (and Nikita had even promised this in advance from the podium of the Congress, which greatly displeased Sakharov). The people from Chelyabinsk-70 were also designing something similar, but they hadn't yet risked doing it on such a scale and were playing it safe. But the veterans, for some reason, went all-in, seizing the initiative and helping Nikiya stage a worldwide spectacle. That's why there was so much anxiety "the night before the premiere." That's why Sakharov sat on a stool in front of the already assembled bomb all night, debating whether to add those rings or not. This episode illustrates how precarious everything was. Everyone was terrified that the new idea with super-high compression wouldn't work, that the burnup would be "normal" (0.25-0.3), and that ultimately, the 50 megatons Khrushchev had already promised wouldn't tear up the Antarctic skies. But everything worked as planned. And the joy knew no bounds.
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Anonymous2026-04-06 17:14
And then we see the legacy of this breakthrough in the super-powerful Soviet warheads of 25, 20, 18 Mt. Although they differ greatly in appearance, they are clearly more advanced than the B-53, which is the "swan song" of the fading 1950s era, when people in Los Alamos thought, "That's it, we've reached the Taylor Limit" (and many said, "Thank God!"). Yes, the US could have created equally good, or even better, super-bombs than the Russians, but Kennedy, McNamara, and their successors managed to turn the course of nuclear weapons development 180 degrees – towards miniaturization. Yes, America didn't surpass the Russians in this (my gentle irony lies precisely in the fact that Americans cannot accept that someone might surpass them in anything), because the US deviated from the course of creating super-powerful bombs earlier than the Russians. And this historical fact will have to be accepted. Especially since, in any case, it's now pure history. The Russians, a little later, followed the Americans and there, in miniaturization, they were again catching up, with their tongues hanging out.
Three outer layers. Low-Z (7), medium-Z (6), and high-Z (5). This means that during radiation ablation, there will be three shock waves instead of one (by the way, I suspect that in the US, this is what they call an "exploding case," although that's just another hypothesis of mine). When the first shock wave quickly passes through the low-Z layer (4) and reflects off the "central core" (3,2,1) (beginning to compress it), the reflected portion of the wave travels back and meets the next (second) shock wave at the boundary (4-5), thus amplifying it. And this happens again, when the second amplified wave hits the "core," it is reflected again, reaches the boundary (4-5), and again meets the third wave, amplifying it again. That's the beauty of the idea.
This is the Russian answer to RIPPLE (declassified many years later, apparently because the Russians wanted to show that we weren't just slackers in 1962). And keep in mind that RIPPLE, while it generally implemented the same idea (quasiadiabatic compression), I believe the mechanism was completely different. There, the radiation current from the primary to the secondary was generated by a special mechanism. Here, the temperature in the hohlraum remained constant, but three ejecta waves (which approximated the Poisson adiabat) were formed by three layers of the ablating shell liner.
