Jeffrey LewisB61 Replacement and Vacuum Tubes

You may recall the little spring dust-up that Kingston Reif and I had with STRATCOM Commander General Kevin P. Chilton over whether he should be running around with a vacuum tube in his pocket to make the case for warhead replacement.

We pointed out in the Bulletin of Atomic Scientists that vacuum tubes are used only in some older mods of one design (the B61) in the radar-fuse. Arming, Fuzing and Firing (AF&F) systems can be, and are routinely, replaced without replacing the Nuclear Explosive Package (aka “physics package”). In other other words, vacuum tubes had nothing to do with the WR1, which would have replaced the NEP in an entirely different warhead. We had some constructive suggestions about what Chilton might do with his little prop.

Chilton, however, wouldn’t let it go. Chilton told GSN’s Elaine Grossman that we were “confused,” but declined to clarify. Dick Garwin told Grossman that General Chilton was “really obfuscating and making things more difficult.”

That was were the story ended in May 2009.

Now, the Administration is gearing up to replace the B61 with something between Life Extension and the RRW — what I like to call the FrankenLEP. Bill Gertz reported — and I use the term lightly — that General Chilton is going to be heading to Hill to lobby for B61 FrankenLEP.

So, the big question is, will Chilton take his little vacuum tube to Capitol Hill? At least this time he has the right class of warheads.

It is always hard to predict what Chilton will say, though someone gave Gertz some draft STRATCOM slides, which he implies but does not state, are the basis for Chilton’s briefings to the Hill. The presentation contains the slide featured atop this post, which revisits the issue of the vacuum tubes, if obliquely.

As you can see above, the slide notes that the “Stockpile [was] built between 1979-1992 — some with 1960s components.” “Some with 1960s components” refers to vacuum tubes — as in “My father used to take these out of the television set in the 1950s and ’60s down to the local supermarket to test them and replace them.” The arrow points to — not surprisingly — the Arming, Fuzing & Firing system.

So, turns out, K-Reif and I were right. The United States can replace the vacuum tubes without replacing the physics package. Guess Kingston and I will be getting handwritten apologies from General Chilton. I won’t hold my breath.

Of course, we knew we were correct because we got the information from the horse’s mouth — Sandia National Laboratories, which makes the AF&F system. As for which end of the horse is General Chilton, well, I will leave that for you to ponder.

Comments

  1. yousaf

    And, of course, in many instances you do not want to replace vacuum tubes w/ ICs as vacuum tubes are more resistant to EMP. You may want to replace old vacuum tubes with new vacuum tubes, but we don’t need RRW for that.

    If the design of the physics package will be changed under FrankenLEP (I don’t know that that is being suggested), then the “new” (untested) weapon will be a less credible deterrent than the existing tested weapons.

  2. johnbragg (History)

    If the bombs in question were built before 1992, then they are not the B-61 Mod 11, first produced 1997. We have 20 active and 21 inactive of that type.

    Questions for Chilton: WTF do we think we’re going to drop more than 20 gravity bombs on? Or does Mod 11 suck too? And if Mod 11 sucks, is a Chilton protege going to be back up here in a dozen years arguing for RRW Mark 2 because RRW Mark 1 is flawed?

  3. George William Herbert (History)

    Just FYI, that diagram (the image on the page here) isn’t a B61, it’s a B57.

    Not only is the outline wrong for a B61, the primary and secondary are oriented wrong (B61 has secondary forwards, not aft). The B61 development film which was declassified shows the radiation case (opening aft), and indicates that the secondary is stuffed in place before the case was shipped to Pantex for final assembly with the primary and rest of the weapon.

    The clearly labeled B61 images later in the deck do show the primary and secondary in the correct orientation.

  4. Jeffrey Lewis (History)

    You all are awesome, that’s all I have to say.

  5. Allen Thomson (History)

    “B61 Tailkit Modification Program”

    I wonder what that’s about.

    Could be a variety of things, but JDAMification of some B61s is an idea that’s been floated for at least a decade and makes sense from a weaponeering point of view.

  6. Matt Hoey (History)

    George, when you have a moment could you please direct me to a website where I can view the B61 development film. I am very interested in checking that out. Thank you.

  7. Alex W. (History)

    Question: Page 9 of the slideshow says that “Small percent of stockpile has internal disablement features to prevent unauthorized use.” Is this true? I thought that PAL and etc. were very old news. Or do they mean something else? Similarly: “All weapons lack modern surety features to further reduce the possibility of a nuclear yield in an accident or terrorist attack.” Surely all of the weapons in the stockpile are one-point safe at the very least? Is the hedge there in terms of what they are defining as “modern”?

    Also, in terms of the depictions of primaries and secondaries, it’s interesting how the “three spheres in an rounded rectangular case” is clearly all that is allowed in terms of graphically showing the Teller-Ulam design. The same little drawing shows up all over the place.

  8. Andy (History)

    George,

    The image on this page (and others in the briefing) is clearly labeled as a “Notional Gravity Weapon” so I don’t think it’s meant to directly portray the B-61’s configuration (or any other weapon, for that matter).

  9. George William Herbert (History)

    Also, for the technical trivia buffs, the B61-1 (at least) used a cylindrical secondary. There are photos of that (and the spherical primary pit hemispheres and surrounding beryllium reflector hemispheres) in the open declassified literature as well.

    At some point, the B61 family probably grew a spherical secondary – the radiation case off the W80 shows signs of that. So the models in service could all have spherical secondaries for all we know. But alas, that is yet classified. Sort of silly – one can pretty trivially work out the secondary dimensions and component weights of both the clean and dirty versions based on known yields. But formally classified.

  10. Yale Simkin (History)

    I dunno…

    That is a pretty generic diagram, but I would bet that it is not a Mk-57, but is, in fact, a B61.

    Yale Simkin

  11. George William Herbert (History)

    Yale –

    Hmm. I may have to sit corrected, I forgot to check the B61-1 and other early mod fin configurations, which that profile does match. But the internals are wrong for B61 (or just fuzzed for generic purposes…)

    Matt Hoey –

    The film is available from the DOE nuclear history website, but it’s already been uploaded to YouTube by someone as well:

    http://www.youtube.com/watch?v=RlH7OuWiPb4

  12. Carey Sublette

    Alex W. said:
    …Small percent of stockpile has internal disablement features to prevent unauthorized use.” Is this true? I thought that PAL and etc. were very old news. Or do they mean something else?

    I believe the answer is yes, they are referring to an active protection system that destroys/damages essential components if tampering occurs. PALs are passive, they control activation of AF&F system.

    Similarly: “All weapons lack modern surety features to further reduce the possibility of a nuclear yield in an accident or terrorist attack.” Surely all of the weapons in the stockpile are one-point safe at the very least?

    This is apparently a reference, in part at least, to multi-point safety, an additional requirement. Though I’m all for greater safety, I wonder if we are approaching the point of “gilding the lily” in some respects.

  13. Yale Simkin (History)

    GWH,
    In addition to very different fin configurations, the B57 has a length to width ratio of about 8.5:1 and is continuously tapered (like the V-2) while the B61 is a cylinder and has a ratio of 10.5:1.

    Much more significant, the b57 was a Nagasaki-yield boosted fission bomb, while the b61 is a thermonuclear (in most yield choices) device (like the diagram) maxxing out about 1/3 megaton.

    AT-
    As to the tailkit, beyond active guidance possibility, simply the removal of the chute (as the penetrator version does now) frees up much space. “frees design space”

  14. Matt Hoey (History)

    Thank you very much George : )

    I hope you have a pleasant evening.

    Matt

  15. Yale Simkin (History)

    One possible place that vacuum tubes may still be in use in very old stockpiled weapons is in the neutron pulse units. I don’t mean the the linear accelerator (which is a form of vacuum tube) but in its supporting electronics.

    This is a fairly intimate subsystem of the primary.

    I don’t know if this is the current configuration, but it is worth considering. If so, it would be a non-trivial upgrade. Just something to look into.

  16. George William Herbert (History)

    I don’t know how intimate the pulse tube has to be; if you know the timing characteristics and pulse intensity / count characteristics of the original units, you can use any alternate pulse tube with similar timing and intensity / counts.

    The pulse is coming from outside the physically evolving implosion environment, which is the part most worried about in primary similarity. It’s not exactly the arming fuzing and firing system, but it’s pretty external.

  17. Stephen Young (History)

    Yousaf, the B-61 LEP in question will NOT have a new physics package. After considering options – including using an existing pit from another warhead, the decision was made to stick w/ the current physics package. The LEP in question will be a “non-nuclear” update. So – probably – this won’t be the ugliest FrankenLEP of reused, re-combined and screwed together components, but only a Steve Austin, 65 million-dollar-man update.

  18. Carey Sublette

    Stephen Young said:
    … the B-61 LEP in question will NOT have a new physics package. After considering options – including using an existing pit from another warhead, the decision was made to stick w/ the current physics package. The LEP in question will be a “non-nuclear” update.

    If that is indeed the case, it renders a substantial part of the slide package moot. Many of the implied issues/improvements are clearly shown to be related to the physics package.

    If ‘no new physics package’ includes re-manufacture of the physics package to original specs then some of the mooted slide points are regained (e.g. the value of a new pit production facility), but not claimed package safety and security improvements.

  19. Yale Simkin (History)

    GWH,
    I agree that the neutron generator is physically outside the implosion assembly. The “intimacy” I refer to is the absolute requirements in timing and output in order to make the primary light, versus the the SAFF, which is essentially an on/off switch – whether triggered by a radar signal or a burning fuze.

  20. Maggie Darwin (History)

    You’re dubbing it the “FrankenLEP”?

    Why, do you think Al will vote for it?

  21. Jeffrey Lewis (History)

    Maggie:”

    Because it comprises mixed-and-match parts (primaries and canned subassemblies) like Frankenstein’s Monster.

    Hence, FrankenLEP.

  22. Yale Simkin (History)

    jeffery,
    When I first saw the term FrankenLEP I knew what you meant, but I also knew it would lead to mass confusion with Al. Maybe instead some kind of reference to Transformers….

  23. Rwendland (History)

    Something that caught my eye in the STRATCOM slides was a suggestion that the F35 may be positioned to be the future NATO nuclear sharing aircraft. Would this be new information?

    Page 10 has a B61 interface improvement box “Future Aircraft (F35) Compatibility – Meets NATO requirements and enables increased security”. I wonder if “enables increased security” might mean in-flight PAL authorisation?

  24. Azr@el (History)

    I think there is some confusion regarding the RRW and thermonuclear weapons in general here. The RRW is by definition a new implosion assembly; i.e. boosted thermonuclear trigger. The ulam-teller component may or may not be an existing design, most modern weapons have modular triggers and ulam-tellers. Lastly the neutron pulse generator is outside of the implosion assembly but may be integrated into ulam-teller holhraum casing for certain compact thermonuclear weapons.

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