Jeffrey LewisW78 Pit Corrosion

I believe NNSA Deputy Administrator for Defense Programs Don Cook has provided the first open-source confirmation of rumors that the W78 warhead has a pit corrosion problem.

For some time, I have wondered why the Obama Administration wants to replace both the W88 and the W78 with a common warhead, utilizing newly manufactured W88 pits.  The statement of work for the W78 LEP isn’t all that helpful.

Stephen Young has previously noted rumors of pit corrosion problems with the W78.  The Jasons themselves noted that the 100 year estimate was only for “most” or “predominant” pit types.  There were other pit types for which NNSA was undertaking or considering “mitigation paths.”

Cook, in answer to a question by Senator Feinstein about why the Administration wants to produce between 50-80 pits per year appeared to confirm those rumors by describing how the decay of plastics and other materials may corrode the pit and then confirming “we’re seeing those kinds of problems” in some pit types.

MR. COOK: Again, I think this is a very good question. Let me try to give a quick technical answer.

JASON determined that the lifetime of the plutonium parts in pits are good for 100 years or 80 was their conclusion. Due to plutonium decay which is by alpha — that’s helium that interstitially causes a potential problem. The actual problems that we have go well beyond that.

We have the plutonium pits in the midst of the chemistry of high explosives with binders that decompose just like plastics in cars exposed to the sun. The plutonium is radioactive. The decay goes on. That degrades all of the plastics, all of the cushions, all of the things that are around the pit. And it also causes corrosion in the pit.

So on the one hand, JASON is absolutely correct about what they said. But the difficulty is that, as weapons get older, much of the chemistry in a radiolytic environment starts to take over. And that has been the problem, and we’ve invested many of the people and time in surveillance to actually pin down in which weapons systems we’re seeing those kinds of problems. And we can predict how long they’re good for.

Those are not good for 100 years.

That would seem to confirm the rumors about the W78, which is set to receive a W88 pit in the lifetime extension program.  Indeed, NNSA Administrator Tom D’Agostino jumped in to make clear that “what we are planning on doing is manufacturing a pit design that we currently have in the stockpile [the W88] that will allow us to potentially consolidate the number of different types of warheads” —  a reference to replacing the pits in the W78.

Of course, there may be other, less adventurous, mitigation strategies than a FrankenLEP.  But it does appear, reading between the lines, that Cook and D’Agostino confirmed that concerns about pit corrosion in the W78 are driving the common lifetime extension program.


  1. Kingston (History)

    My two favorite Di-Fi quotes from the hearing:

    1. “And it’s fair to say that you guys wanted to develop new nuclear weapons. That’s what RRW essentially did. It was killed because of it. And I don’t want to see, you know, RRW in Mufti right now.”

    2. (to D’Agostino) “I don’t want you to do it off the top of your head. As much as I think you’re terrific, I really — this is a big thing for me.”

    • Jeffrey (History)

      Thanks for sending along the transcript. Are you going to do a bigger piece at Nukes of Hazard?

    • Kingston (History)

      Only highlighted a few of her quotes to this point. Seems that she’d like a little more clarity from NNSA about what exactly it is they plan to do re: pit production, to put it mildly.

      Also, re: the pit that would be used for the W78/W88 common LEP, I’ve heard that the W87 would be the likely candidate, because, among other things, it already has IHE and a fire resistant pit.

  2. Stephen Young (History)

    Kingston is correct. In our post on the W78, to which you kindly link, we note that the planned pit for the common W78/W88 warhead is the W87, not the W88. I have this from numerous sources. This is, in my mind, confirmed when you look at public statements from NNSA that the production run for W88 pits will finish this year, and that certainly doesn’t give them enough pits to replace those in the W78.


  3. bobbymike (History)

    We need to research, develop, test (yes test) and deploy new modern nuclear warheads. If we are going to 1550 deployed and a couple more thousand in reserve we should have no doubt we have the ability to produce NEW warheads.

    Plus these warheads should be developed from a new ultra modern nuclear enterprise to be placed on a new Triad including MMII, D5 and bomber replacements. I would also produce a new line of tactical weapons for a new stealth cruise missile. Restart RNEP, RRW and the ACI programs immediately. The US should be world leading in all things nuclear.

    The nuclear enterprise should have a “ramping up” potential to double or triple warhead production to avoid strategic surprise or strategic deception.

    I would leave ZERO doubt in anyone’s mind that the US intends to preserve a strong nuclear deterrent.

    • Anon (History)

      Really glad no one elected you President. The guy who was elected wants to get rid of nuclear weapons. He encapsulates what the people want. You lose. So sorry.

      But have a nice day on Alpha Centauri or Somalia, or wherever you are writing in from.

    • bobbymike (History)

      Anon – At 6’3″ 220lbs blond hair/blue eyes I would stand out a little in Somalia.

      I stand firmly and proudly as a pro nuclear deterrent hawk. Your ad hominem attack bothers me not.

  4. anon (History)

    “The guy who was elected wants to get rid of nuclear weapons. He encapsulates what the people want. You lose. So sorry.”

    Yes, but “…the impermanence of power and the impermanence of place.”