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Sorry I am not an Engineering professional or student. But I had a question regarding US Nuclear weapons. Specifically, is it possible that Nuclear weapons we created in the 50s still work?

The major doubts I have (and pleases add "In the 75 years since these weapons were developed" to each doubt:

  1. Radioactive warheads and decay: would all this time affect the electronics in a bomb and or the ability for the core to go nuclear?
  2. Starter explosive: As I understand it, a nuclear bomb's reaction is activated by a conventional explosive. If so, do we believe that even with decay to the conventional explosive, that it's still enough to ignite the nuclear reaction?
  3. Delivery systems & ICBMs: Do the ICs on these weapon systems still function? Does anyone know how to repair or perform maintainance on them? Have they been replaced? Ditto with control systems.
  4. Control Systems: I can't imagine these systems have been replaced - it seems way too risky, or? So how have they been maintained, and does anyone know how to use them anymore?

In short, it seems to me like the bombs we built 75 years ago were built using technology... from 75 years ago. How in the world have they been able to maintain this (assuming that they have maintained it)?

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  • $\begingroup$ nuclear weapon warheads have a finite life and are replaced. Delivery systems that worked 40 years ago still work today if they need to. $\endgroup$
    – Tiger Guy
    Sep 10, 2023 at 0:41
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    $\begingroup$ They are maintained/upgraded via a quite enormous budget. Quite whether the Russian nukes have been maintained /upgraded/not sold off is an interesting point. $\endgroup$ Sep 10, 2023 at 3:49
  • $\begingroup$ This might be of interest: The delicate art of maintaining the United States' ageing nuclear weapons. $\endgroup$
    – Fred
    Sep 28, 2023 at 8:26
  • $\begingroup$ @Fred Thank you for the article! It directly addresses several of the doubts that I listed in this question, and reading about the modernization project is right in line with my expectation that many of the old weapon systems (if they are anything like America's other weapon systems) need to be updated/replaced. $\endgroup$ Sep 28, 2023 at 13:51

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  1. Electronics in today's sense didn't exist. The implosion explosives used a special sort of squib designed at Los Alamos. https://en.wikipedia.org/wiki/Exploding-bridgewire_detonator. There was a battery and a few switches and that was about it.

  2. The high explosives used in the lenses were a bit more carefully prepared than what was seen in a typical shell-filling process. They were individually bullet proof and quite well sealed and storage was decent. They can be considered viable for a good, long time. There are examples Comp B with far less care existing for 70 years. But the point that they need a very high degree of uniformity as a set in order to work is a bit of issue.

  3. Yes - they still work, and I know how to repair them. I was the chief of engineering for Minuteman at Minot From '89 to '93. That was long enough ago that some of the old hands that designed the things in the early '50s were still around - the Paperclip guys and the old Boeing Autonetics guys that designed the flight and ground computers. As far as IC's, The early Minuteman system didn't have any. By Minuteman III, they had a four-bit register, of which there was about a dozen in the ground computer. Minuteman's computer systems represented about 50% of the planet's total floating point operation capability during the several years of buildout. You can buy a computer that works a million times faster today, but you can't buy one that does what these old rack systems did. You would need about a million times more lines of machine code to duplicate the 2k program, and the telemetry wouldn't be as good. I was one of the last people to get detailed training on the system computers at the field level. Depot obviously had people. The command and control systems have been upgraded to deal with changings threats. The ground control hardware proved to be pretty robust. There has been some concern about encryption over the years.

  4. Within the missile fields, site to site comms is done via HICKS cable. It's the same as deep-sea phone cable. It has a pressurized armored jacket around the wires. The site terminations have lighting protection (via an ESA vault) and then it's just ordinary amplifiers and receivers. They all have real-time fault monitoring via message error counts and replacing them is routine maintenance work. So this is a matter of choosing to do adequate maintenance, which hasn't always been the case.

Odds and ends - these systems were designed to be maintained by 18-year-old kids out of high school that had a knack for mechanicing. They are very modular and seldom require more than simple remove-and-replace maintenance (Okay, some of it isn't exactly simple, but you can train for it). Everything went back to depot for repair work.

As to reliability, when I was at Minot, we had all the missiles on Strategic Alert all the time (unlike today). There are 150 silos. On any given day, one would be getting pulled apart for depot rework, one would be in the middle of depot rework, and one would be getting put back together. These sites belonged to depot and weren't my problem. So we had a baseline of about 147 silos on strategic alert. Our launch-ready rate was about 99.4% when I left in '93. That is computed on a minute-by-minute basis. The 0.6% was inop due to failures or a maintenance team being on site. We could expect 146 ready out of 147 given 20 minutes notice, and probably 148 given 24 hours notice.

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  • $\begingroup$ Early flight computer. en.wikipedia.org/wiki/D-17B $\endgroup$
    – Phil Sweet
    Sep 10, 2023 at 17:40
  • $\begingroup$ Phil;, this is all extremely coool. Did you ever work at the nevada underground test sites? $\endgroup$ Sep 11, 2023 at 3:18
  • $\begingroup$ Nope, I was a one trick pony. I was the top toolbox at Minot for missile maintenance. I ran the tech engr shop. I didn't work on any other systems. I got out after SAC went away. $\endgroup$
    – Phil Sweet
    Sep 12, 2023 at 0:00
  • $\begingroup$ I am imagining how entertaining it would be to sit across the table from you, with a good bottle of something-or-other between us, and just listen to you tell stories all night! $\endgroup$ Sep 12, 2023 at 2:20
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None of those old designs still exist. All of them are long obsolete and have been decommissioned: removed from service and disassembled so the plutonium components could be salvaged and reprocessed for use in more modern designs.

That said, the general issue of stockpile stewardship- answering the question of how old a weapon can be before it no longer can be counted on to work- has been a big deal for decades, for a variety of reasons. In brief:

It is known of course that the fissile components of a bomb lose their level of enrichment with time as those components undergo decay. How much decay will yield a bomb that doesn't go off?

It is also known that uranium and plutonium and other exotic metals used in bombs are susceptible to corrosion and oxidation over time, which can cause them to swell or crack or get glued to parts intended to move when the bomb is used. How much corrosion can a bomb sustain before it doesn't work?

Finally, tritium is used in hydrogen bombs, and since it decays fairly rapidly it has been known that the tritium capsules have to be removed and replentished at certain intervals- so this capability is included in the bomb design. However, that tritium has to come from somewhere, and there's no guarantee that the reactor that made the tritium used in the first capsule will still be on-line and actively manufacturing tritium 10 or 20 years down the road.

In years past, aging weapons were routinely pulled from the stockpile and tested by detonating them underground, and measuring their yield. For some time, the stockpile stewards have been working on simulating aging effects with computers instead.

I do not know what the current state of the art is in this field.

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  • $\begingroup$ The USA does still manufacture tritium $\endgroup$
    – Tiger Guy
    Sep 10, 2023 at 22:07

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