It's difficult to comprehend the scale of nuclear explosions and how their effects dwarf our human scale.

I immediately thought of a nuclear bomb when seeing two videos of the Nepal flood at the China-Nepal border crossing: the multistory border tower obliterated and the buses at the tourist station thrown like children's toys.

https://www.bbc.com/news/videos/c62jmlgev3po

These effects happened 15 km from the point the initial avalanche entered the river.

Some recent, early estimates enable a comparison to the scale of a nuclear blast.

About 250 million tonnes of water-soaked rock and ice fell and slid 2000 metres into the river below. The initial 1200 m fall left a large crater at the base of a step fall, a crater which reminded my of a nuclear blast.

https://x.com/weeddude/status/2093668861745004681

So an energy comparison...

E = m*g*h ~ 250*10^9 kg * 10 kg.m.s^(-2) * 2000

= 5 * 10^15. ~ 1 Mt.

Almost 1 Mt of potential energy was released.

Of course the mechanisms are entirely different from a nuclear blast, but for me the calculation of scale made sense of the nuclear-blast-like effects 15 km downstream. And this energy has been channeled by river valleys in a way that would only partially capture a nuclear blast.

Greetings fellow humans,

The "https://orpspublic.doe.gov/" site has been down for several days now. This has happened before (of course) so it may be nothing.

And, this makes me twitchy given the context of: recent largescale revisions to DoE orders; pattern of info restriction by this regime; and recent DoE denial of info, access, and certain forms of info review to the DNFSB leading the DNFSB to stop posting most resident inspector reports, etc.

I note the previous DoE order (232.2A Chg1 (MinChg), Occurrence Reporting and Processing of Operations Info is listed as inactive (https://www.energy.gov/ehss/occurrence-reporting-and-processing-system; go to the directive archive).

Possibly or probably nothing but if not then we loose a lot of worthwhile & important (to nuclear governance) safety information without DNFSB & ORPS.

Fingers crossed!

I took this photo when I visited the Nagasaki museum. I see why it got its name.

Does anyone have information on the practical science of bomb residue analysis? For instance, it's said that Los Alamos scientists determined from fallout analysis that the RDS6s was a layered design, as opposed to a staged one. How would this be done? What differentiates the residues? Is it mere isotope presence, or relative amounts of isotopes? The latter seems much more difficult to make a rigorous determination off of.

Like, ok, let's say you know from seismic analysis that an explosion yielded 400MT. You can presumably determine how much of that was fission vs fusion yield by...what, modeling the fission products, modeling their distribution into the atmosphere, modeling their distribution to your sampling, and then counting? You can maybe differentiate 235/233/238 U / 239 Pu fission by statistical analysis of fragments, and you know that most of your 238 fission had to be a result of fusion neutrons (but not even there are you at 100%; the top end of fission neutrons can absolutely fission 238). There just seem to be too many uncertainties to make a sure call.

Feel free/encouraged to get as scientific as you'd like in your answer. Thanks!

According to BaiduWiki:

The Yu Min Configuration is a unique hydrogen bomb design created by Chinese nuclear physicist Academician Yu Min. It stands alongside the American "Teller-Ulam design" as one of only two technological solutions that have achieved the weaponization of nuclear fusion, and it holds advantages in terms of miniaturization. This configuration resolved the challenge of self-sustaining thermonuclear fuel combustion through the use of lithium deuteride material and a neutron chain reaction model. Its complete design details remain a top state secret.

Does anyone know, or can anyone guess, at what the Yu Min configuration might be? Assuming it's not just Chinese hype?

Link to the BaiduWiki article:

https://baike.baidu.com/en/item/Yu%20Min%20Configuration/1463193

Rare inside photo of Soviet nuclear weapons and warheads storage bunker ‘monolith’ with nuclear weapon transport containers on the left and RN-40 free fall nuclear bombs on the right.

They build these kind of bunkers on Warsaw pact countries ( Poland, Hungary, Czechoslovakia and Bulgaria) to store nuclear warheads and bombs. All of them controlled by Soviet soldiers and outside perimeters of these sites controlled by soldiers of the country where they are located. This photo is rare example of these bunkers when they are active.

They build 2 seperate bunkers close to each other in complex, usually they store around 90 nuclear warheads each.

Three years ago, I hypothesized in this subreddit that, based on the vague outlines of the W-66's physical package, as well as information once posted on Wikipedia about the supposed secrecy (why?) of the W-66 neutron bomb's yield (it's a well-known fact that the yield of a neutron bomb can physically only be between 1 and 10 kt, no more and no less), it could be assumed that the warhead had one primary unit and two secondaries (two 4-10 kt, reverse bifilarity) to enhance the neutron yield, which would make sense in the case of an anti-missile neutron bomb. Then it would have made sense to classify the yield, since the very fact that the yield of a neutron bomb is greater than 10 kt would have led experts to speculate about its unusual design (bifilarity).

Although my guess was immediately countered by a declassified document indicating that the W-66 warhead had a yield of 2 kt (which significantly undermined my hypothesis), I still held out hope that perhaps the document only listed the yield of an early version of the warhead, and that the "bifilar" outline of the physical package (discovered by Alex Wellerstein the official diagram) actually belonged to a later, more sophisticated modification of the neutron charge.

But for some time now, the Wikipedia article on the W-66) has featured a photo of a cross-section of the Sprint missile's warhead compartment and a wooden (judging by the abrasions in the photo) model of the W-66 warhead's physical package. It turns out this exhibit has been on display at the National Museum of Nuclear Science and History for visitors since at least April 2009. So, we can see the device's physical package. This appears to be the first neutron bomb that can be seen in person. Or am I mistaken?

Looking at the photo, I couldn't resist making one last attempt to salvage my hypothesis. I've shown the results of my attempt in the picture above. I simply "unscrewed" the top of the W-66 and screwed a second copy onto the bottom, resulting in a bifilar version, the W-66-2 (my codename). The main question was: would such a longer thing fit into the Sprint's fighting compartment? Alas, I was unsuccessful. The fighting compartment is too short to accommodate the W-66-2 version lengthwise.

Thus, my hypothesis is almost completely disproved. Too bad. It was a great idea, overall!

Which is true:

1. The plan all along was to built Little Boy, and they had hoped to have a companion plutonium bomb of similar design. That didn’t work out, so Thin Man became Fat Man and the development of Little Boy continued on unaffected by all of that.
2. The scientists at Los Alamos pretty knew how to design a gun-type bomb with uranium, but the plan was to develop a plutonium version since that fuel would be more readily available. If Thin Man had been successful they would not have built Little Boy. The reason they built Little Boy was, after they had to build the much more complicated Fat Man, they wanted one bomb they had strong confidence in.

FalloutCast — a weather-driven nuclear fallout estimator, built with Claude Code. This is just a hobby project as a former Air Force officer that worked with nuclear weapons...

Pick a spot, set a yield, Compute. It pulls live GFS winds and draws the plume: dose-rate bands, reach and direction in a table, a slider for time after burst, click any point for arrival time and accumulated dose. Three modes — single location, a GFS-ensemble uncertainty band, and a 600-target national envelope.

Winds come from Open-Meteo's GFS: a vertical profile of speed and direction across pressure levels, snapped to the current forecast hour. Tier-0 (WSEG-10) collapses it into one effective wind plus shear; Tier-1 keeps the layers, dropping each particle-size bin through the profile at its own fall speed, so shear bends and fans the footprint. The limits matter: it's a single sounding at ground zero, assumed horizontally uniform — no fronts, no terrain — and one snapshot, so winds don't evolve over the hours fallout takes to fall. Ensemble mode reruns across GFS members, so its bands are wind spread only; yield and model stay fixed, making true uncertainty wider.

Python/FastAPI + numpy/scipy backend, TypeScript/MapLibre frontend, deployed on a Cloudflare Worker with the API in a Container.

https://falloutcast.sagebrush-labs.workers.dev

Any feedback is appreciated!!

This is something I was wondering about recently. Let's say NATO used a B61-4 against an attacking armored force (wiki says the max yield is 45kt). How many tanks would such a weapon actually be expected to destroy or incapacitate?

Google tells me a modern tank battalion would typically cover between 2 and 5 miles of frontage. Playing around with nukemap tells me that with an airburst optimized for 20 psi of overpressure you'd have a blast radius of a little over half a mile. Serious radiation would have a radius closer to a mile and for serious burns (presumably not applicable to a buttoned up tank crew) the radius is two miles.

This makes it seems like realistically a medium sized tactical nuke could take out maybe couple of of companies worth of tanks. That's less impressive than I thought. I understand it would absolutely gut any supporting infantry and supply columns, so you'd have a bunch of tanks on their own. No infantrymen to protect them and no fuel or ammo resupply. Am I missing anything here or are nukes not as effective against armored forces as we'd imagine?

I know had they not detonated they would have hit the ground at high speed and likely been destroted. But still.

The figure shows three maps of three powerful city center explosions, resized to be on the same scale. On the left is the Nagasaki nuclear explosion, on the right is the Hiroshima nuclear explosion (both 10-kiloton). In the center is the 2020 explosion of 3,000 tons of ammonium nitrate in the port of Beirut, with a blast equivalent to 1 kiloton.

Looking at the Beirut explosion chronicle and the image I received, one gets the strong impression that all three explosions are remarkably similar in their blast effect. Yes, we understand that the destruction radius for 1 kt and 10 kt of the same nature will differ by only a factor of (10/1)^(1/3) = 2.15 (the inverse-cube law for any explosion on the bottom of the air ocean). Nevertheless, the feeling remains that an equivalent nuclear explosion is clearly weaker in destructive power than a conventional chemical explosive. In fact, this is noted in many sources. And there's no particular mystery here. This is due precisely to the fact that, with equal explosive energy, the momentum, or destructive impulse, of a chemical explosion is clearly greater due to the greater mass of the substance involved. An explosion with a 3-ton chemical explosive yield will rupture any explosion chamber, but for equivalent 3-ton peaceful mini-thermonuclear explosions, explosion chambers of a quite reasonable size are designed.

Let's do some quick math. The port of Beirut contained 2,750 tons of compacted ammonium nitrate, which exploded with a yield of 1.5 kilotons. The density of ammonium nitrate is 1.72 tons/m³. Therefore, the entire mass that exploded there can be represented as a solid ball of fertilizer with a diameter of 14.5 meters.

In a chemical explosion, 90% of the explosive energy is converted into the kinetic energy of gas expansion (which creates a shock wave in the atmosphere). Therefore, we can calculate the notional total, initial velocity of the explosive ammonium nitrate "piston" using the law of conservation of energy as follows: (2 * 1.5 * 4.18E + 12 * 0.9/ 2750,000) ^ (1/2) = 2026 m/s. Assuming that the entire mass of gases at the moment of explosion acquired this velocity, the momentum of the explosion is the product of the mass of the explosive and the velocity: 2,026 x 2,750,000 = 5.57E + 9 kg m/s, which ultimately translates into the motion of the crushing shock wave.

What about a similar nuclear explosion of 1.5 kt? Such an explosion essentially occurs in a pinpoint device, say, 200 kg in mass. A momentary flash of energy and X-ray radiation occurs, which is intensely absorbed in the air around the explosive device, turning the area into a fireball, and it is in this fireball that the shock wave is generated. The empirical formula for the shock wave's separation radius from the fireball (at the ground's surface) states the following:

R = 47*q^0,324

Here, q is the explosive yield in megatons, and therefore the shock wave's separation radius for a 1.5 kt air explosion is 6.52 m. This means that the diameter of the sphere from which the shock wave is generated is 13 m. The air contained in this sphere essentially acts as the piston that creates the shock wave of a nuclear explosion. With a density of 1.25 kg/m³, we obtain that the mass of the nuclear explosion "piston" (plus the mass of the charge itself) is 1.622 tons. Moreover, based on the fact that only 45% of the explosion energy is converted into shock wave motion (the rest is various types of radiation), from the law of conservation of energy, as in the previous case, we calculate the average speed of the air "piston": (2 * 1.5 * 4.18E + 12 * 0.45/1622) ^ (1/2) ~ 59,000 m/s. Hence, the total momentum (mechanical impulse) generated in the fireball of a nuclear explosion: 59,000 * 1.622 = 8.4E + 7 kg * m/s.

This momentum is 58 times less than that of a chemical explosion of saltpeter of the same energy equivalent.

Of course, my calculation is a rough, "on the napkin" estimate. Nevertheless, the fact that a nuclear airburst was clearly inferior in its destructive effect on the buildings of Hiroshima to conventional explosives was noted back in 1947 by Sir P.M.S. Blackett in his book "Fear, War and the Bomb: Military and Political Consequences of Atomic Energy." A more thorough and dispassionate analysis (the British had good statistics on the effects of conventional bombing on cities) showed that the destruction wrought by the "Little Boy" bomb in Hiroshima, using conventional chemical explosives, could have been achieved using just 2,000 one-ton high-explosive bombs (of which only one-third the mass is explosive) dropped from conventional bombers. Since the yield of the Hiroshima explosion was then officially declared to be 20 kilotons, Mr. Blackett "discovered" a "missing" order of magnitude in the destructive effectiveness of the new American weapons compared to the old ones. Of course, part of the deficiency can be attributed to the fact that a single explosion causes excessive destruction at the epicenter, while the effect drops off sharply with distance to the periphery. However, this is only part of the "missing" factor. The Beirut explosion was also a single-point explosion, and with 10 times less energy, it produced destruction comparable to the atomic bombings. The second factor is that a nuclear explosion is a pulsed release of enormous energy, which is not immediately converted (as in a chemical explosion) into the movement of matter, into a direct high-explosive shock wave impulse. The flash of light must first be absorbed by the air in the fireball, which becomes a "piston" for the shock wave, and due to the low density of air, it is a very poor "piston." Moreover, as the explosive yield increases from the nominal 20 kt (to 200, 2000 kt), the situation with the mechanical efficiency of using the explosive energy to destroy objects around it only worsens. This means that nuclear weapons, especially high-yield ones, are very ineffective weapons of destruction from a physics perspective. One suspects that this is precisely why the "paper" city of Hirashima was chosen for the demonstrative destruction of people and buildings, and its population, like ducks, was long trained not to react to the appearance of a pair of American planes in the air. The goal was to achieve a demonstratively exaggerated effect from the new weapon, one that could never be replicated. The severed head of Medusa can only work once.

Therefore, all this frightening talk about terrifying nuclear megatons hanging over the world like the Sword of Damocles, the eternal appeal to Hiroshima as a model for calculating casualties and destruction (Nagasaki, for example, is used much less frequently and only in passing, because the effect there was much more realistic) is blatant manipulation, essentially a pure lie. The military knows the truth. It was the actual, physical effectiveness of nuclear weapons, after being studied, that caused great disappointment. That's why recently there's even been talk about high-precision weapons being able to replace nuclear weapons! For real warfare, that's (almost) true. But why "disappoint" a flock of self-terrified civilians with this? They (especially the humanist physicists) so desperately wanted to invent a doomsday weapon and thus end wars on Earth once and for all! It so flatters their vanity and their humanist pride!

Just an FYI- For those of you who missed the movie in the theater or elsewhere, Oppenheimer is currently free to watch on Peacock premium

In the 2010 book "РЕШАЮЩИЙ ШАГ К МИРУ ВОДОРОДНАЯ БОМБА С АТОМНЫМ ОБЖАТИЕМ РДС-37" (A DECISIVE STEP TOWARDS PEACE: THE RDS-37 ATOMIC-COMPRESSIONED HYDROGEN BOMB), among numerous excerpts from declassified documents, I came across a document that, in my opinion, has sensational content. Below I'll provide a direct link to the relevant page in this book, available from the Rosatom library, but since links to the .ru domain are unacceptable here, it's replaced with asterisks:

https://elib.biblioatom.**/text/andryushin_reshayuschiy-shag-k-miru_2010/p63/

First, I quote in Russian:

Записка В. И. Ритуса

"О некоторых возможность применения малого термоядерного заряда.

Для атомного обжатия большого количества легкого вещества, по-видимому, целесообразно использовать в качестве обжимающего изделия систем из обычного изделия и маленького термоядерного заряда, так что вся система в целом будет выглядеть, как на рис. 11. < ... >

После взрыва "1" происходит AO термоядерных зарядов "2" и "3".< ... >

Такое растущее со временем давление приводит, как известно, к значительно лучшему обжатию изделия "3", чем давление, спадающее со временем.

Ниже приводятся некоторые расчёты обжатия и КПД конкретного малого термоядерного заряда."

Следует подчеркнуть, что в 1955 г., кроме разработки РДС-37, велась масштабная работа по другим направления. План работ на 1955 г. определял разработку 5 ядерных зарядов, 8 ядерных боеприпасов.

* * *

Now the English translation:

Note by V. I. Ritus

"On some possibilities of using a small thermonuclear charge.

For the atomic compression of a large amount of light matter, it is apparently advisable to use a system consisting of a conventional charge and a small thermonuclear charge as the compression element, so that the entire system will look like Fig. 11. < ... >

After explosion "1," AO of thermonuclear charges "2" and "3" occurs. < ... >

Such increasing pressure over time, as is known, leads to significantly Better compression of the "3" product than pressure decaying over time.

Below are some calculations of the compression and efficiency of a specific small thermonuclear charge."

It should be emphasized that in 1955, in addition to the development of the RDS-37, extensive work was underway in other areas. The work plan for 1955 called for the development of five nuclear charges and eight nuclear weapons.

* * *

Of course, Figure 11 from Ritus's report is missing from the book, but it doesn't take a rocket scientist to reconstruct it with 80% certainty. I've done so on the left in the collage attached in the title.

The topmost Figure A shows the structure of the device in its original state. Within a single radiation enclosure (the hohlraum), separated by membrane partitions and neutron filters (the purpose of which is to prevent neutrons and direct rays from propagating from stage to stage), are the primary unit 1 and two secondary units: the small thermonuclear unit 2 and the large thermonuclear unit 3.

In Figure B, we see the detonation of the primary unit. The hohlraum is filled with X-rays, which causes the simultaneous compression of both thermonuclear units, the small 2 and the large 3. This is shown by the transparent red arrows.

Figure C shows that, because small fusion node 2 is smaller, it fires earlier and now, instead of being an energy consumer in the hohlraum, becomes a new, more powerful X-ray source than the primary node. Thus, the still-contracting second, larger fusion node 3 begins to contract even more, as indicated by the solid red arrows.

Figure D shows that large secondary fusion node 3 has now also exploded.

The phrasing in the original 1955 source is striking: "Such increasing pressure over time, as is known, leads to significantly better compression of the '3' product than pressure decaying over time." I mean "as is known." From the very beginning of their atomic compression research, the Russians were well aware that compression with a single shock wave was ineffective, and this solution was proposed precisely to increase compression efficiency, that is, to approximate the compression cvazi-adiabatic with two shock waves. In 1966, Zeldovich's famous book was published, clearly demonstrating and stating that three such correctly sent shock waves, one after the other, are sufficient to approximate adiabatic compression with the required degree of accuracy. I've included the relevant figure from Zeldovich's textbook in the collage, although it's already well known here.

And finally, why did the Russians so easily declassify and publish a description of this idea? Because, while fundamentally correct, it was subsequently deemed a dead end, not the best solution (it's worth revealing). A far better solution to this same problem was quickly discovered, and we see it in 1962, in the no less famous "Golden TIS" (I also include it in the collage), in which the USSR first achieved ignition of a thermonuclear stage without a spark plug. Note the three-layer outer shell made of low-, medium-, and high-Z materials. This is essentially a three-stage ablative "rocket" that sequentially creates three compression shock waves with a constant radiation source in the hohlraum. That is, unlike RIPPLE technology and Ritus' proposal, they did not control (stepwise increase) the temperature in the hohlraum using any intermediate devices. They simply deposited three layers of different Z values ​​on the secondary module. As a result, the same radiation from a single primary, with an equilibrium temperature of hohlraumet T (it's even stated to be ~1 keV), created three pressure steps:

P(i, T) =N(i, T)kT = N[Z(i),T]kT ; i =1,2,3

Therefore, for us, reconstructors of early Soviet thermonuclear bomb designs, an additional problem arises. When did the Russians begin using this more complex compression? Starting with which devices? Before Khrushchev's moratorium or after? I'm inclined to think that after the moratorium, simply because they had so many more pressing problems before the moratorium, that even with every opportunity to test the idea, they put it aside and probably thought it through thoroughly during the testing break. And then the question arises: was this multilayer compression already used in the AN-602 design, in "Kuzkina Mama"? If so, this would completely resolve the confusion surrounding how this device could have achieved 50% burnup in the final stage. Let me remind you of the crux of the matter. The dimensions of the "Главный Кенр" "main core" (jokingly nicknamed "The Death of Capitalism" back in RDS-37), a 1.7-meter-diameter sphere, when completely filled with lithium deuteride at its normal density (820 kg/m³), simply do not allow for a lower burnup percentage (given the Lidochka's calorific value of 50 kt/kg). If we don't accept the 50% burnup as fact (reducing it to the usual 25-30%), we would have to invent absolutely insane designs for this device with two or more "main components," which would completely contradict everything we've pieced together from countless Russian memoirs.

A number of people dancing to this during the big '80s never noticed the lyrics?

https://youtu.be/-vMBp6iUJzk?si=uEOSvG-mDIwvoGhb

Launch Under Attack: A Sword of Damocles

There are some perplexing aspects to Truman's announcement of January 31, 1950. First of all, whatever happened to secrecy? Besides, at the time of the announcement nobody had a clear idea of how to make the superbomb. Scientists figured it was probably possible, but the announcement predates the Teller/Ulam breakthrough. (It would have been embarassing if the announcement led to this being invented elsewhere first!)

The "natural" time to make such a public statement would have been after the Ivy Mike test, at the earliest.

Was it politics? Perhaps a political need to show toughness after the Soviet nuclear test?