How do we know that our nukes still work?

In My Humble Opinion
1

We have moved past the cold war and have stopped testing our nuclear weapons. Say that a situation arises, be it with North Korea, Iran, or whomever, where we need to turn some place into glass.

Do we know that these missiles will respond and hit their targets? How are we sure?

Further, I’m not interested in any arguments about the necessity of doing this. Let’s assume that something happened that a substantial majority agrees requires this type of action.

Are these missiles gathering dust? Do soldiers go and “polish them off” at regular intervals? Have we updated the computers that launch them from 1960s? 1980s? technology?

2

Both the Air Force Global Strike Command and the Navy Fleet Ballistic Misisle program conduct operational test and evaluation (OT&E) flights several times a year out of the Eastern (Cape Canaveral Air Force Station) and Western (Vandenberg Air Force Base) ranges. These consist of the launch of an operational ICBM or SLBM with the active reentry vehicles replaced by inert mass simulators, additional instrumentation and telemetry systems, and a range destruct system in case the missile goes off track. Here is the latest Minuteman III OT&E flight. The Navy Trident D-5 undergoes a similar launch, albeit typically from a submarine. This provides verification of continued operational status of the delivery system or alerts to potential aging or operational problems.

The services also perform aging and serveillance testing on the solid propellant rocket motors, booster components, and various parts of the nuclear weapons, including ordnance and destructive safety system testing, static firing of motors, igniters, gas generators, and other propulsive components, testing of flight controllers and other avionics, and materials compatibility and dissection to evaluate aging trends. No full up (functional) testing is performed on the physics package itself for obvious reasons (Partial Nuclear Test Ban Treaty, Threshold Test Ban Treaty, and volunary compliance to the Comprehensive Test Ban Treaty despite not being formally ratified); however, both the United States and the Russian Federation (as well as probably other nuclear states such as the UK, France, and India) maintain facilities for evaluating the aging effects on nuclear weapon pits, fusion booster injectant (i.e. tritium), and various materials which contribute to the function or yield of nuclear weapons.

There is also system level testing and training which occurs with other parts of the weapon system such as communications, threat tracking and early warning systems, and personnel training. The operational systems undergo periodic upgrades and rebuilds to the booster systems, avionics, and countermeasures, but much of the support infrastructure, especially with the Minuteman Weapon System, is seriously out of date, as in 1960s and 1970s era computer and communication technology, and physical infrastructure that is leaky, unsafe, or just plain nonfunction in some cases. Infamously, the AFGSC had a scandal last year resulting in the dismissal of a significant number of missileers for cheating on evaluation tests including nine commanders, which is just the latest in a string of scandals involving the security and reliability of nuclear weapon systems. Although we know less about what has happened in the Soviet Union and the successor Russian Federation, there are credible stories about missileers holding weapon launch system keys in ransom for their promised but not delivered salaries, and rumors (none verified) of officers selling nuclear weapon components or plans to various third parties. In general, as with most systems, the human element is the most prone to failure to function, or in the case of safety, to provide assurance, which highlights the need for a robust fail-safe design in these massively destructive weapons.

There are no credible stories of full weapons and activiation sytems having been sold (despite Hollywood movies to the contrary) but a number of instances of weapons in inventory being at least temporarily unaccounted for. Fortunately, weapon activation systems are deliberately designed to age out and be serviced, so the fact that we haven’t had terrorists with Russian ‘suitcase bombs’ sneaking over the Canadian border tends to give us some degree in confidence that these measures to prevent proliferation have had some effect. However, the acknowledgement of Project Sapphire (the removal of over half a ton of very highly enriched uranium intended for use in a Soviet submarine program) should serve as a warning against complacency when it comes to nuclear proliferation. See this article in The Diplomat about the program and the threat that remains today, especially with the lack of consistent international cooperation in nuclear non-proliferation (and other weapon proliferation and counteraggression) efforts.

Stranger

3

The previous regime of testing has provided a statistical baseline for prediction of weapons success.

But…no, we can never be wholly sure. And the Department of Energy sure as hell isn’t telling us how many tests have failed, so “we” – we interested citizens who don’t have top secret clearance – are even less sure. But that’s okay, because our potential enemies aren’t sure either.

(I don’t know how many tests other countries perform, but their tests can be extrapolated to apply to our weapons. If Russia performed a series of tests that were hugely disappointing to them, this would lead us to consider our own weapons slightly less dependable.)

Yes, the military is constantly improving and maintaining the infrastructure: the computers, the silos, the rockets, the strategic plan, and so on. Although recent controversies indicate that the “human element” is not as dependable as we would like.

4

Take for example, the Cuban missile crisis. We were prepared to go to war. Are those same ICBM’s, with nuclear material, still sitting in their silos ready to launch over 50 years later? Can we be sure that they will work at all?

Have we scrapped the 1962 technology that we would have used to launch them and replaced it with something resembling modern technology? I’m not sure how simulations would ensure that such an ancient device could launch on demand today.

5

When we had an active nuclear test program, a lot of effort went into reconciling theoretical models and computer simulations with the actual test results.

It is no coincidence that many of the early supercomputers went to DOE labs. Nowadays it is not even very expensive to come up with MIPS that required a Cray a few decades back.

6

The only ICBMs operationally deployed during the Cuban Missile Crisis in October 1962 were the HGM-25A ‘Titan I’ and SM-65 ‘Atlas-D/E/F’ missiles, in addition to the PGM-17 ‘Thor’ and PGM-19 ‘Jupiter’ IRBMs emplaced in Southern Europe, all of these systems used cryogenic liquid oxidizer and took hours to fuel. Both of those systems were retired by 1965 in favor of storable liquid systems (LGM-25C ‘Titan II’) and solid propellant missiles (LGM-30A/B ‘Minuteman I’, LGM-30F ‘Minuteman II’, LGM-30G ‘Minuteman III’, LGM-118A ‘Peacekeeper’, and all of the Fleet Ballistic Missile program SLBMs i.e. Polaris/Poseiden/Trident).

All of these systems have been retired except for the Minuteman III ICBM and D-5 Trident II SLBM, both with progressive modernization in guidance and navigation systems and periodic remanufacture of motors and other age-sensitive elements. The nuclear weapons themselves deployed on these systems have been upgraded to modern fail-safe designs (W87 and W88 warheads). The oldest delivery vehicle components in service have been remanufactured no longer than twenty years ago at most, and there are ongoing modernization programs to improve the capability and reliablity of these systems to meet future strategic requirements, albeit subject to budget and planning limitations. There are no fifty year old launchers or warheads in service.

Stranger

7

I would imagine some of the nuclear components deteriorate over time and are swapped out.

8

Tritium, for one.

9

As **Stranger **points out above every aspect of our nuclear deterrent is still constantly tested, maintained, and upgraded where necessary. Everything except actual, live ‘physics packages’ inside nuclear warheads (the explosive core surrounding fissionable material then surrounded by fusion-able and/or more fissionable material). Nuclear physics is a very well understood and developed science, and without having to make bombs more powerful or smaller in size anymore there isn’t a whole lot of research that needs to be done. In fact, a lot of this type of nanosecond-level nuclear warhead design is done on supercomputers today.

That leaves the question of a warhead’s physics package’s shelf life. A nuclear warhead contains quite a bit of very precise and complexly engineered components, but again everything short of the nuclear material itself can be (and is) tested independently. And with the nuclear elements themselves their ‘integrity’ (purity, radioactive potency, physical consistency etc.) can also be monitored and tested independently (IOW without having to actually detonate it).

For better or worse we tested a shitload of nukes back in the day, thousands of them, and we accumulated mountains of hard data as to how they do (and sometimes don’t) work. More than to enough keep our ‘enduring stockpile’ reliable.

10

Just want to compliment Stranger on a Train for his answer. It’s responses like these that keep me coming back here everyday (more or less).

11

Helpful buzzwords to search if you want to learn more about this topic include “stockpile stewardship” and “life extension program.” Throw in “criticality experiment facility” for more fun. Damned smartphone touchscreen won’t let me hotlink properly, apologies for the below:

http://nnsa.energy.gov/ourmission/managingthestockpile/sspquarterly

12

An addendum to Stranger’s post.

Back in the day, there was a constant balance between safety and functionality in nuclear weapons. You both want that the weapon will not go off if you drop it on the tarmac, if the plane catches fire or crashes, or if the weapon takes a lightning strike, etc, but you also want to be sure it will go off when you want it to. I have read that there was a safety device added to some weapons in the 60s that was too safe - the bomb would likely have not gone off if used. (What if they gave a nuclear war and no one came?). That would have been…embarrassing. Also, batteries were a weak link - they had to be replaced all the time.

After watching an old Mission Impossible episode where they were tasked with recovering the physics package from a 2MT weapon, it got me thinking. I wonder if, in all these years since the cold war ended, if anyone has actually gotten to the point of being close to detonating a stolen weapon. What if some terrorist group had successfully stolen a weapon, put it in a shipping container, sent it to NYC, and pushed the button, only to have the bomb fail to explode? Would we ever know?

13

As far as we are aware, no one has ever successfully stolen a weapon, although individual components, designs, and materials have been stolen or copied. All modern US, Soviet/Russian, British, and French weapons (and likely Chinese also) have some variation of permissive action links which use public key encryption built into the initiator design; these PALs, along with insensitive high explosives (IHE), single point safe design, and environmental safety interlocks such as those on warheads delivered by ballistic missile which won’t release the inhibits until the vehicle passes through certain stages of flight as measured by sensed acceleration, prevent unauthorized use or inadvertent initiation of the devices. However, we know far less about the nuclear weapon surety programs of Pakistan, India, Israel, and other up-and-coming states, so both the weapons and enabling technologies may contribute to proliferation of nuclear weapons.

Shipping a nuclear weapon via CONEX container used to be a viable threat, but there are measures in place now to track and scan container inventories. A manifested container won’t remain in a container storage yard for very long, and one that is apparently abandoned will be inspected pretty quickly (within days). An ‘abandoned’, non-functioning weapon in a container would probably be found quickly.

Stranger

14

We just look the enemy in the eye, snarl and say “Yeah, it’s been in storage for 25 years. Might work, might not. Do you feel lucky, punk?”

15

I’ll never know for sure… and if I ever did, I’d be longing for the good old days pretty damn quick. :frowning:

16

As someone once said, “Instead of constantly working to develop bigger and better weapons, maybe we should be focusing on getting more use out of the weapons we already have.”

17

Stranger, I like your info, but I think you are thinking too much like a weapons designer (or a nuclear policy wonk) and less like a terrorist.

Even for the US and the USSR, not all nukes were ICBM. There were plenty of falling-bomb versions with fewer PAL devices attached. Also, there are a lot of ex-military out there who were bomb technicians back in the day, some of whom might be in a money crunch, or disillusioned by time, or whatever, who might be willing to dismantle the physics package from a stolen bomb, and rig up their own detonator. No matter how well it was theoretically designed to be protected, it was designed to be serviced as well. If it was put together, it can be taken apart. Ultimately, the weapon was designed to be used - it can’t be impossibly difficult to detonate, or it would be useless.

A lot of nuclear control is keeping them out of the wrong people’s hands. If you can get past that part (and as we see, that’s the hard part!), the rest is much easier.

And although I used a shipping container as an example, the bomb could be brought into the country via a yacht. Or the bomb could be set off in the middle of the Hudson river before the container ship even hits the port and the containers get inspected. Ground bursts are not ideal from a destruction POV, but I still wouldn’t want to be near one.

And my last comment - I meant, when the non-function nuke got found, would it make the news? Or would it become Top Secret?

18

Another description I’ve read regarding how nuclear warheads are secured is they use a complimentary system of ‘hard links’ and ‘soft links’. The hard links are strong but simple physical barriers, containers, locking mechanisms etc. that have to be breached with strong, physical impacts and/or temperatures. The soft links are more sophisticated sensors and encryption systems that require highly technical expertise to bypass.

And because the soft links are completely sealed within the hard links they fail-safe each other. IOW in order to get to the soft links you have to first break thru the hard links, but you can’t break thru the hard links without destroying or ‘irrevocably tripping safe’ the soft links.

Interestingly (and scarily) the original 'PAL’s for the Mark I series of bombs (Fat Man design) were simply combination locks*!* Well, that and I’m sure a constant, armed escort.

19

You know, the reason the nukes exist is not so they can blow up. It’s to create the impression in the minds of enemies of the USA who are armed with nukes that they might get vaporized.

Suppose you are an enemy leader and you have intelligence reports saying the American nuclear weapons are old and might not blow up. Are you going to gamble your whole nation on a dice throw and risk armageddon and the death of basically your entire civilization?

No, you won’t. Moreover, the American nuclear forces, if they act like the weapons are still live and are seen doing maintenance on them and they still look shiney go to further this impression that the things are ready to kill everyone.

If they ever lift the test ban, they might discover that half the inventory is duds. While Stranger is correct that every piece of an ICBM has been tested, the whole system hasn’t been tested, and there is the possibility that a missed faulty switch or something about exposing the physics package to spaceflight + reentry G-forces breaks every nuke in the inventory. We don’t know, no one has been ballsy enough to risk a test with a live ICBM.

You can do all the paper studies you want - it’s like looking at software you have never actually executed. People still make mistakes, even hundreds of people all crosschecking each other. (the “mistake” would be reality disagreeing with an untested part of the design)

Say on Doomsday, 2021 or something, the Russians snap and unload everything they have. Most Americans die. Does it actually matter to the defunct U.S. government whether or not every major metroplex in Russia got vaporized by the counterstrike?

20

There’s a report in “Command in Control” of a soldier stealing a nuclear weapon simulator from the base to show it to his girlfriend. He was not caught and returned it, supposedly. The simulator was stored right next to the live warheads in the same bunker. (the simulator was basically a warhead with inert explosives and something to substitute for the fissionable materials. It’s for training EOD techs how to disarm a nuke)