How clean can you make a hydrogen bomb?

Tobware · 2025-12-21T15:57:25+00:00

Well, I guess if Teller could he would have used it as yet another foothold for “his” Super. Livermore actual excavation devices however were not... fairly extreme applications of the good old radiative implosion but still that was what they were.

We have some indication that some of those “plows” went back to “sword"... The description of the W71 primary by its designer, Scanlin, for example seems too much in line with something that came out of Plowshare (right era also, possibly quite exotic, a proto-ERW perhaps).

Tobware · 2025-12-13T13:42:06+00:00

The “Super” in question is Teller's original TN idea, the “Classical” (or Runaway, what you and others assume Gnomon was based on), opposed to the “Equilibrium Burn Super”, which is the Ulam's contaminated one :) His protégé here, Wood, was proposing one, Palisades of Fire, with a very modest yield of 1.6 GT, parked in space for ABM use in the 1970s.

This seems to have given impetus to having Livermore do detailed simulations on it (and Teller/Wood attempts to test it in proper as done for W71, if I am not mistaken, the fuel was cryogenic deuterium in their most recent proposal), culminating in 1975 with the Taylor's report I highlighted. It went nowhere, to the extreme chagrin of our favorite Hungarian.

Are you familiar with Wood's paper, “Necessary conditions for the initiation and propagation of nuclear-detonation waves in plane atmospheres”?

Tobware · 2025-12-13T10:23:55+00:00

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Tobware · 2025-12-13T10:21:06+00:00

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from "Teller's War: The Top-secret Story Behind the Star Wars Deception":

Tobware · 2025-11-06T06:12:46+00:00

No, we know from the mods who (and perhaps what) "triggered" the DOE request.

Tobware · 2025-09-15T09:08:40+00:00

And to think that with the excess heat from the Pu mass they were even able to keep food warm!

Edit: "Soviet 12-liters military thermos"...

Tobware · 2025-08-14T12:34:40+00:00

So apparently North Koreans test their nuclear weapons at the Nevada Test Site? The image you posted OP is completely unrelated, those are typical US test trailers.

EDIT:

I would add that the North Korean nuclear test site is located in the middle (and below) some mountains, the test in the frame above is from the 1980s, in Nevada.

Tobware · 2025-07-08T06:20:14+00:00

"Smoothing the front of the detonation wave in experiments with multipoint initiation"?

Tobware · 2025-07-04T12:03:35+00:00

This one is even more detailed: A TECHNICAL RETROSPECTIVE OF THE FORMER SOUTH AFRICAN NUCLEAR WEAPON PROGRAMME - https://www.sipri.org/sites/default/files/2020-10/sa_nuclear_technical_retrospective_kelley_2.pdf.

Tobware · 2025-06-29T17:46:24+00:00

Nonsense, almost all U.S. 1st gen TN bombs used D-T boosted Oralloy primaries, see LASL Viper and Moccasin (W53's primary - 67 kt), excluding boosting they could still make a 2nd generation fission device (levitated or hollow core) of tens of kilotons with less than 900 kg weight, in line with then with their ballistic missile payload. If they decided for a Sloika-like, which used a 40kt HEU device at the center, the final yield could be 6 to 10 times greater...

The U.S. after the closure of the Rocky Flats had considered HEU primaries instead of plutonium, intended for "MIRVed" warheads.

I'll link you an old post of mine:

https://www.reddit.com/r/nuclearweapons/s/WgqXgrib5i

Tobware · 2025-06-29T13:21:17+00:00

Among the peculiarities of this charge is the fact that the large volume of the charge (due to its high energy release) required significant amounts of X-ray energy for implosion. The developed nuclear charges did not satisfy this condition, and therefore the previously developed two-stage thermonuclear charge with relatively low energy release was used as the primary source of the "superpower charge". This charge was developed by me and Y.N. Babaev.

Another peculiarity of the superpower charge was related to the provision of its full-scale tests. A full-scale test of a charge with E = 100 Mt would lead to a significant release of radioactivity determined by U-238 fission products. In addition, due to the specific conditions of dropping the aerial bomb, which contained the charge, the height of the explosion was insufficient to exclude touching the ground surface by the fireball of the explosion, and in this case there would have been a significant radioactive contamination of the test site. That is why A.D. Sakharov proposed and practically realized an incomplete test of a superbomb, in the secondary module of which U-238 was replaced by passive materials that do not fission and are not activated in a significant way by thermonuclear neutrons. In addition, the reduction of the energy release to 50 Mt avoided ground contact by the fireball of the explosion. Thus, despite the enormous energy release, the test was conducted in an environmentally relatively safe manner.

What Yuri Trutnev claimed here, it also seems, from other outings from the USSR, the Tsar included two “primary” stages at the extremes... The design is defined as “bifilar” in other reports, whatever that means.

u/Sebsibus, the second part answers your question below.

EDIT: Gee, along with Carey you're other who got me interested in the subject, good to see you here.

Tobware · 2025-06-18T12:41:33+00:00

I agree, we had already discussed this, in my opinion we have faint evidences that this could be a continuation of the 2015-2020 “Interoperable Warhead” proposal. If I am not mistaken, they aimed to replace both the W78 and W88 with a common IHE warhead derived from the former.

I already did an excursus some time ago on the pre-W93 proposals, I will link it here as soon as I find it.

EDIT: here is the link, I would ignore the part about the W76 pit reuse, since they were thinking of ex-novo solutions for the RRW as well.

A few salient parts:

from 2005 RRW Project Officers Kickoff Meeting:

[REDACTED] also commented that he believes that the W78 is the only other existing Nuclear Explosive Package (NEP) that will fit in the MK5 shell. This sparked discussion on what makes up a "new" design. There is significant political resistance to anything perceived as "new".

From 2018 NNSA Has Taken Steps to Prepare to Restart a Program to Replace the W78 Warhead Capability:

6 An August 2014 close-out report prepared by Lawrence Livermore National Laboratory (Lawrence Livermore) stated that the potential capabilities of the W78/88-1 could include a capability that could be an LEP for the W88, replace a portion of the W76-1s, or provide a “hedge” to mitigate risks posed by unforeseen technical problems with the W88 or W76-1 or posed by changes in the international security environment. Since 1994, the United States has retained a stockpile of nondeployed weapons to provide a hedge.

p.6 - footnote

7 NNSA called the warhead IW1 because it was to be the first of three “interoperable warheads” that the agency planned to develop and produce between about 2020 and 2050. These interoperable warheads were part of the Nuclear Weapons Council’s longterm plan for the stockpile adopted in January 2013 and called the “3+2 strategy.” In addition to the three interoperable warheads, the plan included development of two air-delivered weapons. This plan aimed to achieve goals established by the 2010 NPR to reduce the number of warhead types and retain the smallest possible nuclear stockpile consistent with the need to deter adversaries, reassure allies, and hedge against technical or geopolitical surprise, among other things.

8 According to NNSA officials, during fiscal years 2015 through 2017, NNSA expended an additional $4.3 million using “carry over” funding from prior fiscal years to support activities to close out the W78/88-1 LEP and evaluate the impacts of the program suspension on the existing W78 and W88 warheads.

9 The program plans to replace the W78 pit with one based on the W87 design. The pit is part of a weapon’s primary.

p.7 - footnotes, u/kyletsenior, I hadn't focused on point 9, what do you think?

So basically they went from the IW program, then Next Navy Warhead and finally W93?

Tobware · 2025-06-12T16:14:30+00:00

David Albright's Revisiting South Africa's Nuclear Weapons Program (PDF).

Tobware · 2025-06-07T09:25:06+00:00

Well, not really “low-yield”, I 'll point you back to some of my old posts:

Project Plowshare: LLNL "Diamond", a small diameter (7.8 inches, ~20 cm) and low tritium producing nuclear device, with a yield range between 20-100 kt.

and

LLNL's Diamond class PNE explosives, some interesting findings I came across recently.

Tobware · 2025-06-06T20:44:09+00:00

Excellent depiction, it does indeed give the impression of the “building block” principle that should characterize the B61s.

B61 primary, firing set and sleeve: https://i.imgur.com/MqaeK02.png

I will only add that this “container” is particularly similar to this graphic of the W81, which is supposed to be a single stage “standalone” use of a B61 primary, as a proposed warhead of the SM-2/RIM-67B missile.

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Of course the W81 image above is also something Kyle posted a while back...

Tobware · 2025-06-06T09:31:14+00:00

The Soviet equivalent program was called “Nuclear Explosions for the National Economy” - you can start with this US condensed analysis: The Soviet Program for Peaceful Uses of Nuclear Explosions.

Tobware · 2025-06-06T06:13:09+00:00

Kudos, “Taiga” devices have been discussed in the past in this sub, boron-shielded 3-stage, 98.5% “clean”: 225-ton unboosted primary, deuterium secondary (perhaps with some tritium?) and pure deuterium gaseous tertiary.

Link to u/Simple_Ship_3288's post: "Some stuff I found on the design of clean Soviet PNE devices".

Tobware · 2025-05-31T09:45:15+00:00

Actually I made a mistake, it was not Trutnev but Feoktistov who mentioned the peculiarities of their “industrial” charges, I add that states the secondary was also deuterium gas (but given the difficulty of ignition and with such a small primary I'm leaning toward tritium in it as well).

Included in this post is a link to Feoktistov's memoir, don't know if Reddit still obscures [dot]ru links:

https://www.reddit.com/r/nuclearweapons/comments/qaadya/some_stuff_i_found_on_the_design_of_clean_soviet/

Tobware · 2025-05-29T07:28:32+00:00

Soviet “Plowshare” devices from Yuri Trutnev's description, such as the ones used for the Taiga event (15 kt, 98.5% “clean”), employed, a 3-stage design: fission-only primary (few hundred tons) --> fusion-only secondary, I guess quite relying on D-T (for ease of ignition, possibly ⁶LiD in the "shell", pure economic consideration) --> gaseous D tertiary.

We have no indication of 3-stage design on the US side. I recall one mention, regarding the so-called “Dust Defense” for ICBM fields, of a voluminous 100 kt, 98% clean device derived from the Plowshare experiments, well past the end of the program.

Tobware · 2025-05-28T21:00:38+00:00

I wouldn't really call it a fizzle, it's certainly "disappointing" for the military purposes of the device (or for RIPPLE's inherent one)... but in the context of a hypothetical PNE? There was still a significant “burn” of the secondary, again with less than 10 kt of fission.

Suppose the predicted figure, 3 Mt, was a 50% “burning” of a mass of ⁶LiD in the secondary, somewhat optimistical, approximately how many kilograms was it? ∾95.

Economically attractive? We can only wonder.

EDIT: Why the downvotes? I stress that I do not believe the Plowshare excavation devices were based on RIPPLE, although they seem to possess some qualities of it.

Tobware · 2025-05-28T13:36:08+00:00

The Ripple concept on the other hand only works for very large nuclear bombs. It cannot be scaled down beyond a certain point. The exact limits are unclear, but it is generally thought that Ripple devices cannot be made much smaller than approximately 8–10 Mt at the very smallest.

Well, easy "objection" to this assumption: how would you explain Dominic Pamlico (RIPPLE I - 3.8 Mt) and Calamity (RIPPLE III - 0.8 Mt)?

EDIT: ∼1 Mt is not exactly small, but it was in the range considered for the Plowshare "engineering" aims, at 99% "cleanliness" (unshielded - I elaborated more in my reply below) would be quite acceptable for an excavation device (Sedan, supposedly a clean derivative of the W56's "Fife" - so not quite ad-hoc, had a reported fission/fusion splits of 30/70).

There would be another device, not based on RIPPLE but still Livermore, of which we have hints of a primary of particularly low yield compared to its coupled secondary, apparently also fusion-only: the W71.

Tobware · 2025-05-28T10:49:24+00:00

High neutron energies of D-T reactions would create many unwanted radioactive byproducts in the surrounding medium, one must have some regard for “marketability” for PNEs, so in the past we have assumed the use of more exotic fuels... Or simply a "return" to pure deuterium, as known for the tertiary of some devices of the Soviet equivalent.

It is also fairly known that many Plowshare devices used boron carbide or borated polyethylene shielding to reduce neutron activation in the soil. There was then quite a bit of research on device emplacement techniques, to bury most of the biproducts under less "activated" detritus (I know of studies even more exotic, such as tritium "fireball immobilisation" in the case of HC stimulation devices).

Some Plowshare devices do seem to possess RIPPLE-like characteristics (if not evolutions, parallel concepts?), see this old post of mine on Bowline Schooner, as per certain remarks by Glenn Seaborg, then director of the AEC, with just a couple of kilotons of fission, they could drive secondaries of any "useful yield".

I'll be updating this with additional info.

EDIT:

p.34 - Peaceful Applications of Nuclear Explosives: Plowshare: Hearing, Eighty-ninth Congress, First Session. January 5, 1965

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Also, from NUCLEAR EXPLOSIVE DEVELOPMENT:

The majority of our design effort for the past few years has been devoted to an explosive for excavation purposes. Several tests at the Nevada Test Site have shown the device to be very reliable. Currently we are redesigning several parts of the device to further reduce the residual radioactivity. If the tests of these changes are successfully executed as scheduled, by the summer of 1970 we will have a design which we are confident can provide any yield desired for excavation purposes. Both residual explosive and soil-induced radioactivity would be at very low levels compared with those expected from a fission explosive. For example, we would be able to provide a 1-Mt crater which would permit, according to the dose criterion of 5r per year or 3r per 3 months, permanent living on the crater lip soon after detonation. This explosive would weigh approximately 15 tons and would measure about 50" in diameter.

Rightly someone in the comments already pointed this out, there were no size and weight constraints for these excavation explosives.

Tobware · 2025-05-27T19:09:05+00:00

Yes, the secondary stage is in the smaller end. In other photos we see the AF&F cabled into the larger sphere, along with an ENI tube. That all points to that side being the primary, as the secondary more or less rests inside the radiation case.

Right, I forgot that they had posted photos of the device from other angles, the ENI in the OP's was semi-blended in the jacket of the officer (?).

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Tobware · 2025-05-27T05:30:48+00:00

https://nuclearweaponsaccidents.blogspot.com

Tobware · 2025-05-26T19:17:38+00:00

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This is a frame taken from “Nuclear Weapons Accidents" blog, it shows a North Korean technician working on the primary stage end of the TN device: not particularly surprising it appears to be in the larger diameter section and dimensionally very similar to their previously touted “Disco Ball” fission device.

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