Nuclear silo explosion?

I have vague memories from the late 70-early 80s of some mushroom cloud on videotape from Nevada or New Mexico (it was someplace in the desert).

Did a nuke go off in a silo…or was it just an underground nuke shot that punched through the surface?

There were quite a lot of open-air nuclear tests (“shots”) in Nevada. Here’s some pix:

Nevada Test Site open-air blast images.

Here’s a quick overview on Wiki.

Here’s the Nevada Test Site…site itself.

But…you’re possibly confusing the NTS mushroom cloud images with this 1980 news story: Titan II Missile Explosion in Silo. But that was not a criticality event (one in which fissle material begins to undergo chain-reaction), just a rocket-fuel explosion and scattering of radioactive* and chemically-contaminated debris.

Unfortunately there was one death.

*that article says there was no rad contamination; I’ve read differently elsewhere…might be some controversy on this issue.


Could it have been a non-nuclear mushroom cloud? The 1970s and 80s were post-atmospheric Test Ban Treaty?

Or are you sure it was nuclear?

This won’t help much, but nukes are built failsafe to such a high degree that I would assume the chance of one accidentally going critical in a silo is practically impossible.

Are you sure it wasn’t just a normal Launch?

You would be wrong about that, at least for many of the older (but still retained in the Hedge Stockpile and Inactive Reserve). Nuclear weapons that are considered unlikely to achieve criticality from an accidental, partial explosion are called One Point Safe (OPS). Only the most modern weapons, like the W-87 that rode on the Peacekeeper (and now on the downrated Minuteman III) ICBMs is OPS. Other considerations are the sensitivity of the high explosive to detonation, the isolation or insensitivity of the explosive to electrical shock, and the resistance of the uranium or plutonium pit to combustion, dealt with respectively by the use of insensitive high explosive (IHE), enhanced electrical isolation (EEI), and fire resistant pits (FRP). Many older weapons, including those in service at the time of the aforementioned Titan II explosion, did not have these safeties and potentially could have detonated. This includes the W-68 warheads carried on the Class 1.1c propellant Trident C4 SLBM, which is why the warheads were installed only after the booster was loaded into the submarine vertical launch tube. See Appendix C of Assessment of the Safety of U.S. Nuclear Weapons and Related Nuclear Test Requirements (warning: PDF).

We haven’t had any accidental detonations or fizzles outside of early nuclear tests, but there is some suspicion that this may have occurred in the Soviet arsenal on a couple of occasions. It is not beyond conception even with a modern failsafe design that some accidental confluence of events could result in unintended detonation–in a couple of crash situations it has been found that standard safety systems were bypassed resulting in a near detonation–although the likelihood is low.

If you play with fire, you have to accept that your hands might get scorched.


No, Noooo, Stranger. They told us all of them were one point safe. You could only get an equivalent 4 lb high explosive yield from fission/fusion if say a bullet or fragment impacted a detonator, HE surround or other component.

Well, except for that one time we got a message about these old warheads we were retiring and they might not be as one point safe as originally thought (these warheads were kissing cousins to the original Trinity design). Oh yeah, and that test set we were checking them with every time they were moved, looked at, or thought about might do a little more than confirm continuity due to age and component variation. And, and the point we were checking just happened to be the “not quite one point safe” area. And we’d BETTER DAMN WELL ACCOUNT FOR ALL THOSE TEST SETS.

Okay people, move along now, next post, nothing to see here.

(And what Stranger on a Train said)

Well, not to get off topic but my point was that the OP would be better off not looking for an accidental nuclear explosion, as that seemed unlikely, and he seems to indicate a true explosion instead of a fizzle or the Titan fire. I assumed the earlier designs wouldn’t have been in operation in silos in the late 70s-early 80s, especially after OPS testing in the late 50s, but that may not be the case.

Wow. Cool footage. Why wouldn’t the missile be damaged during those few seconds it was surrounded by fire and smoke, before it rose clear?

Could someone kindly reconcile the “not as safe as you think” with “it’s damn hard to build a bomb”? I thought the safety factor was inherent in the need for a whole sequence of things to go just right just to get an explosion.

There is a video short that seems to have become widely used as stock footage of an underground nuclear test explosion, shot by a camera above ground (and I assume a couple miles away, at least).

I went to google > video > “underground nuclear tests”, and there are several videos there. Perhaps the image your looking for is there.

For the Minuteman family there is substantial amount of room in the silo to allow the plume to expand. The Minuteman is also a very robust vehicle, designed specifically with withstand silo launch overpressure and thermal loads and covered with thermal protection systems (TPS, or as the layman knows it, cork sheeting) which creates a protective char layer around the booster as it burns. Experienece in silo “hot launch” comes from Titan I days, which was stored in underground vertical silos but elevated to ground level before launch; it was discovered that the Titan body could withstand silo launch environments and the Titan II was designed from the beginning to hot launch from within a hardened underground silo.

However, this isn’t a dumb question; the Peacekeeper missile (which was loaded in retrofitted Minuteman silos) and the Polaris/Poseidon/Trident Fleet Ballistic Missiles are “cold-launched” by what is called a Launch Eject Gas Generator (LEGG), which is actually a small solid motor and a reservoir of water which is turned into high pressure steam that then ejects the missile before the first stage motor is ignited. (In the case of the FBMs, it also helps to provide a protective sheath of gas around the submerged missile until it broaches the surface.) The abortive ‘Midgetman’ Small ICBM and many Soviet designs are also cold launched boosters.


It’s really hard to get an implosive containment nuclear weapon to detonate reliably, especially one light and compact enough to fit into a bomb casing or missile reentry vehicle. Making a large and heavy weapon that will offer some significant yield, even at great inefficiency, is not hard, and in fact a bunch of guys in the middle of a desert managed to design one sixty years ago with little more than slide rulers and mechanical integrators that were scarcely more complicated than a mechanical cash register. A gun-type bomb is actually pretty trivial (albeit highly inefficient) and a large implosion weapon really just requires symmetry in the construction and actuation of the explosive shell.

The concern with more complex weapons is not that they’ll fully detonate, but that even a minor detonation (called a fizzle) may still yield several kilotons of blast energy, radiation, et cetera. Even if the weapon does not provide significant fissile yield, the release of harmful radioactivity from the burning of a plutonium pit may present a substantial and persistant environmental hazard. Nuclear weapons are inherently unsafe, insofar as that the only thing preventing detonation is the subcritical flux of neutrons; if you get enough flux in one way or another, even briefly, Bad Things[sup]TM[/sup] start to occur.


I read that to mean that an implosion weapon (albeit very inefficient) is not beyond the means of a terrorist organization. I always thought that they would be limited to gun-type weapons or dirty bombs.


I’m pretty confident that a small team of talented engineers, or perhaps even a single engineer gifted in multiple disciplines (mechanical design, electrical design, nuclear engineering, ordnance or optics) could design a usable nuclear weapons design, albeit not as efficient as modern weapons developed from test data.

Building one is another issue; the machining can be done by someone experienced with five axis CNC milling machines, but special precautions have to be taken to prevent releasing toxic and flammable dust. The ordnance also requires some particular knowledge. The kytrons and exploding bridgewire detonators have to be set up very carefully to ensure symmetric detonation. Then the obtaining of suitable fissile material (and especially tritium for thermonuclear or boosted fission weapons) is very difficult, essentially requiring a nuclear fission breeder reactor and gas centrifuge equipment (or obtaining material from someone else).