Alleged Nuclear "Near Miss" In Texas

[Syrinx]

This story is a few days old, but I just ran across it. Scary stuff.

WASHINGTON — An accident that occurred last year as a decades-old nuclear warhead was being dismantled at the government's Pantex facility near Amarillo could have caused the device to detonate, a nonprofit organization charged Thursday.

The Project on Government Oversight watchdog group said the "near miss," which led the Energy Department to fine the plant's operator $110,000, was caused in part by technicians at the plant being required to work up to 72 hours per week.

The organization said it was told by unidentified experts "knowledgeable about this event" that the accident, in which an unsafe amount of pressure was applied to the warhead, could have caused it to explode.

Project on Government Oversight investigator Peter Stockton, a former Energy Department official, said the weapon was a W-56 warhead, with a yield of 1,200 kilotons, 100 times the destructive power of the atomic bomb dropped on Hiroshima.

http://www.statesman.com/news/content/news/stories/nation/12/15/15pantex.html

[Kagemusha]

1. Well "near miss" is according to the watchdog group...

Who really knows? I'd rather never find out.

[Syrinx]

4. edited subject line to include "alleged"

Good point. But I would like to find out if the report is true.

[originalpckelly]

9. See post #8 to see the actual letter...

which specifically says:

"On November 29, 2006, Pantex was only fined $110,000 – 18 months after the near-miss incident. What was not made public at the time the fine was levied, however, is that according to safety experts knowledgeable about this event, it could actually have resulted in the detonation of the warhead. This incident was particularly dangerous because the W56 warhead was deployed in 1965, pre-dating the three basic enhanced safety features which reduce the possibility of an accidental detonation that are now required on more modern weapons. There are still several older warheads slated for dismantlement that do not include these enhanced features."

[Kagemusha]

16. Clearly some manner of pyrotechnics might have resulted but

a full nuclear detonation seems highly unlikely, no thanks to the shoddy management practices.

[Beelzebud]

2. It's not easy to detonate a nuke. I doubt this story is accurate.

To implode the plutonium core you have to have a very precise detonation that implodes the core from all angles at once. Nuclear weapons have gone down in aircraft before, and you can shoot down nuclear warheads without detonation. It's not something that is easy to do.

I could easily see them causing a criticality incident, where they would be exposed to dangerous levels of radiation, but I don't see how they could detonate one based on how the article describes the accident.

[Selatius]

3. If "pressure" is meant to mean the bomb was almost crushed, then it probably won't go nuclear.

All modern thermonuclear devices in the US arsenal are implosion-type devices. They are much more efficient at using up the plutonium fuel during nuclear detonation, thus yielding far more destructive power per gram of nuclear fuel, but they are far more difficult to build than simple gun-type devices, which are weapons that shoot a ball of weapons grade plutonium or uranium into a plug of the same material using high explosives.

An implosion-type device only works if the detonators are sparked at the very same time to ignite the high explosives encapsulating the nuclear fuel. The explosives compress the fuel and cause it to go critical. If the timing is off, you get an asymetric application of pressure on the nuclear fuel when the explosives detonate, and you may end up with either a partial fission reaction or no reaction at all. Crushing a bomb won't cause all the detonators to spark simultaneously.

In either case, there would've been a toxic cloud of radioactive dust and smoke spewing out of the facility when that bomb goes off. In the event of an explosion, the best case scenario is just a dirty bomb that poisons and kills a lot of people with fallout several miles downwind. In the worst case scenario, the bomb partially goes nuclear and creates a much bigger explosion with the same effects in terms of radiation and fallout.

[benEzra]

5. Detonating the chemical explosives will NOT detonate the warhead...

the result would be like detonating several pounds of explosives (big boom, building wrecked, worker killed if close by) and then you have plutonium/uranium/beryllium bits to clean up (big mess). But it takes a carefully sequenced chain of events to set off a thermonuclear warhead, from the sequencing of the detonators to the neutron pulse at the right time, and so on.

Sounds like somebody got careless and could have gotten themselves killed and/or made a big mess, but the idea of a 1200-kT explosion resulting from overpressure is sheer hyperbole. It looks like somebody confused "could have caused an explosion" (a chemical one) with "could have caused a full yield detonation," which is bogus.

[Kagemusha]

6. Thanks to you and the other people who replied

Not taking safety seriously is bad but, I'm glad to know that the warheads are not more fragile than I'd been led to believe with my rather civilian level of knowledge about nuclear detonations. It's still stupid to play with fire like this, though.

[benEzra]

15. See the links in post #13 - lots of details there. (n/t)

[originalpckelly]

8. This is an old nuclear weapon design, which doesn't have the modern...

safeties on it, hence the reason there was a near miss.

Here is the letter from the Project On Government Oversight:
http://pogo.org/p/homeland/hl-061201-bodman.html

Here is the specific excerpt about this:
"On November 29, 2006, Pantex was only fined $110,000 – 18 months after the near-miss incident. What was not made public at the time the fine was levied, however, is that according to safety experts knowledgeable about this event, it could actually have resulted in the detonation of the warhead. This incident was particularly dangerous because the W56 warhead was deployed in 1965, pre-dating the three basic enhanced safety features which reduce the possibility of an accidental detonation that are now required on more modern weapons. There are still several older warheads slated for dismantlement that do not include these enhanced features."

That's why this is such a big deal. Amarillo, Texas would not be here.

[benEzra]

13. Doesn't matter how old, b/c it is a plutonium based implosion system

and plutonium is much, much harder to set off than HEU. For that reason, accidentally setting off the chemical explosives in a disassembly accident wouldn't have detonated the first plutonium bomb ever built (Gadget/Trinity/"Fat Man"), although the Hiroshima bomb and other gun-type HEU systems would definitely be susceptible to that. For a plutonium implosion system, the explosive lenses have to be detonated within microseconds of each other in order to get a perfectly symmetrical implosion, and nothing but a synchronized electronic firing impulse will do that. You also need a neutron pulse at just the right time, and I'm thinking the W56 would have used pulse neutron tubes for that purpose, which again have to be electrically fired (it's a little particle accelerator, so it doesn't just "go off").

No, the W56 doesn't have the anti-tampering systems and such that modern warheads have--so an unauthorized commanded detonation would probably be more feasible (don't let anybody steal it!)--and an accidental core disassembly might be messier with the W56 than with newer designs--but it is a multistage thermonuclear weapon using a plutonium-based primary, and as such I think sigificant yield from anything other than a commanded detonation is extremely farfetched on physics grounds.

Cary Sublette's Nuclear Weapons FAQ is a FANTASTIC resource for those wishing to understand the technology on a qualitative level. Of course, he leaves out classified details about primary configuration and engineering bits, but it's an excellent overview of the physics. Here are some sections related to the incident described in the OP:

http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html#Nfaq4.1
http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html#Nfaq4.1.6
http://nuclearweaponarchive.org/Nwfaq/Nfaq3.html (background on the physics)

Also keep in mind that "core assembly resulting in nuclear yield" is not the same as a full yield explosion, though a reporter could easily get them confused. I'm not saying that accidentally setting off the chemical explosives might not result in a few pounds of nuclear yield in addition to the chemical explosion, just that I don't see any possible way to set off a large-order nuclear detonation in that manner.

[roamer65]

7. A 1.2 megaton bomb??? Holy f@#%.

[benEzra]

14. The Soviets built a 100-megaton bomb in 1960-ish

http://en.wikipedia.org/wiki/Tsar_Bomba



They actually tested this thing (at half yield) in 1961, at Novaya Zemla. It broke windows in Finland. :wow:

It was more a political statement than a practical weapon, though.

[originalpckelly]

10. Here is the W56 article in Wikipedia:

http://en.wikipedia.org/wiki/W56

Here is an article about the warheads being dismantled, it says they are particularly dangerous because they were not made to be taken apart:
http://www.washingtonpost.com/wp-dyn/content/article/2006/06/28/AR2006062802006.html

[Cessna Invesco Palin]

12. It does not say they are particularly dangerous.

In fact, the word "dangerous" is used nowhere in that article, nor is it implied.

The word "difficult" is used to describe the process of disassembling the bombs. Nowhere does it state that disassembly incurs any increased risk due to this particular design.

[bmbmd]

11. How about

a nice game of chess?