Atom bomb nearly exploded over North Carolina in 1961

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What's one state when you got 50?

A U.S. atom bomb nearly exploded in 1961 over North Carolina that would have been 260 times more powerful than the device that devastated Hiroshima, according to a declassified document published in a British newspaper on Friday.
http://news.yahoo.com/atom-bomb-nearly-exploded-over-north-carolina-1961-230654850.html
 
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  • #2
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Maybe there was some kind of von Neuman-esque logic at play.
 

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  • #3
nsaspook
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Makes me glad of the upgraded safety devices they had in the cruise missiles I worked on. I guess 20+ years of experience between designs works wonders.
The wiki article says it had six failsafes.
 
  • #8
Office_Shredder
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The wiki article says it had six failsafes.
From my reading, it had three fails, and one failsafe actually
 
  • #9
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Wiki said:
Former military analyst Daniel Ellsberg has claimed to have seen highly classified documents indicating that its safe/arm switch was the only one of the six arming devices on the bomb that prevented detonation.[1][10] Confirmation of this suspicion came in 2013 with the release of new information under the Freedom of Information Act.[11]
:confused:
 
  • #10
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From my reading, it had three fails, and one failsafe actually
Ironically what we referred to as failsafe devices were the same devices that armed the weapons.

Edit.

The only thing standing between us and an explosion so catastrophic that it would have radically altered the course of history was a simple electronic toggle switch in the cockpit, a part that probably cost a couple of bucks to manufacture and easily could have been undermined by a short circuit—hardly a far-fetched scenario in an electronics-laden airplane that's breaking apart.
http://www.motherjones.com/politics/2013/08/eric-schlosser-command-control-excerpt-nuclear-weapons
 
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  • #11
Drakkith
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From this wiki article: http://en.wikipedia.org/wiki/W39

Two Mark 39 nuclear bombs were carried by a B-52 Stratofortress that broke up in the air and crashed near Goldsboro, North Carolina on January 24, 1961. According to Parker F. Jones, a supervisor of nuclear safety at Sandia National Laboratories, in a 1969 report that was declassified in 2013, the Mark 39 bomb had four safety mechanisms, one of which was not effective in the air. On one of the bombs involved, two more safety mechanisms were "rendered ineffective by aircraft breakup." As a result, that bomb nearly detonated, and a catastrophic nuclear burst was prevented only by the fourth mechanism, a simple "ready-safe" electric switch.[1]
I'd guess that one of the safety devices is something that only works on the ground. Perhaps a physical pin, separating the connections of an arming device, which is pulled before flight. I don't know about the other two which were "rendered ineffective by the aircraft breakup".

Just found the following info as I was typing this post. From this site:http://nuclearweaponsaccidents.blogspot.com/
(Bolding mine)

The B-52G accident on 24 January 1961 near Goldsboro, North Carolina is another example of unfounded hysteria over a nuclear weapons accident. For decades, claims abounded that one bomb, a Mark 39 Mod 2, "went through five of it's six interlocking safety devices" and was only "one step" away from a nuclear detonation. This is not true.

First and foremost, B-52G aircraft power must be applied to the weapon via two crew members using the Aircraft Monitoring and Control System and a specific voltage and amperage (and for a specific amount of time) before the Ready/Safe Switch could be rotated to the "Arm" position.

The pilot of the bomber aircraft controlled power via his T-380 Readiness Switch, which was safety wired and sealed near his seat in the aircraft. The Radar Navigator could monitor the bomb's circuits via the DCU-9, but he could not arm it without electrical input via AMAC nor consent from the pilot. The aircrew, in two physically separate positions in the aircraft, had to perform at least 19 steps from their checklist before nuclear weapons could be pre-armed and dropped.

Bomb 2, the object of the Goldsboro controversy, was not "one step" away from detonation (nor was Bomb 1). The Mark 39 Mod 2 had two additional safety switches, the Trajectory Arm Switch and Rotary Safing Switch. It should be noted that aircraft power to monitor and pre-arm the bomb is separate from power supplied by the bomb's short life thermal batteries.

In Bomb 2, the High Voltage Thermal Battery was not activated, so no electrical power could reach any components necessary to fire the weapon and produce a nuclear explosion. In any regard, the R/S Switch, Trajectory Arm, and Rotary Safing Switch prevented any current from reaching the X-Unit.

While the Ready/Safe Switch in Bomb 2 showed "armed" after recovery, it was actually safe, and post mortem examination by the AEC proved it to be electronically open (the housing having been destroyed during impact). Most importantly, the high voltage necessary to fire bomb components was not present for bomb 2.

In Bomb 1, the HVTB did activate, however the three safety switches, the MC-772 Ready/Safe Switch, the MC-732 Trajectory Arm, and the MC-788 Rotary Safing Switch prevented any voltage to reach components necessary to arm and fire the bomb. The arming and firing sequence is quite complex, and much more was required to produce a nuclear explosion.

It should be noted that in several other accidents, thermal batteries were activated due to severe ground impacts. In all cases, from lightning strikes to accidental jettisonings to crashes, the safety features, although not as advanced as today's nuclear safety concepts, were well designed, tested, and robust.

Documentaton obtained through the Freedom of Information Act, including copies of the original AEC and EOD reports, are available in "Broken Arrow, The Declassified History of Nuclear Weapons Accidents" by Michael H. Maggelet and James C. Oskins. It should also be noted that Bomb 2's secondary, containing uranium and lithium, was not recovered and poses no detonation hazard.
Also this from the same site:

Goldsboro_fusingtable.jpg


I agree with the final words of the article.

How close was the Goldsboro bomb to producing a nuclear explosion? Not at all.
 
  • #13
OmCheeto
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Even if all the safeties had failed the "X UNIT" PAL still prevents the final sequence until it was programmed with the correct code that (in theory) the crew does not have until the NCA sends to them via a coded EAM.
https://www.cs.columbia.edu/~smb/nsam-160/pal.html
http://en.wikipedia.org/wiki/Emergency_Action_Message
Wiki's external link for the "Emergency Action Message" is food for some serious jokes.

Cover Sheet
EMERGENCY ACTION PROCEDURES
OF THE
JOINT CHIEFS OF STAFF

20 MARCH 1985​
Followed by 29 effectively blank pages.
Even the index is mostly whited out.

Hey! Has anyone read the declassified document, that supposedly started this conversation?

Its only two pages long, and pretty funny when you study it in detail. Someone wrote a book about the incident back in 1962. Page one of the declassified document contains a critique of page 127 of the book. (Right hand side notes)

Didn't this latest thing in the Guardian get aired because someone is once again writing a book?

Ugh..... :rolleyes:
 
  • #14
marcusl
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I attended a science policy and arms control conference (Student Pugwash) in grad school. Edward Teller, father of the H bomb, made an impassioned plea for students to work on the next generation of nuclear weapons. H claimed that a lot of thought went into the design of safety measures. "The US has never had a weapon detonate accidentally," he said. "We need the best and the brightest to continue this work to ensure that our nuclear arsenal is absolutely reliable and safe." I don't know if any students in attendance worked on weapons as a result (I did not), but I was somewhat reassured to hear about the emphasis on safety.
 
  • #15
SteamKing
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You know, the second nuclear core from the Goldsboro crash is still in the ground in NC. The point of impact of the bomb was found after the crash and excavated, but the nuclear core had so deeply penetrated into the earth that it was left there after digging stopped.

http://en.wikipedia.org/wiki/1961_Goldsboro_B-52_crash

UNC estimated that the core penetrated to a depth of about 180 feet, but because the ground was so swampy, the excavation filled with water before the core could be reached. Thus it was left in place and 'monitored' afterwards.

Investigators found that this second bomb left the aircraft partially armed, although it did not detonate when it struck the ground.
 
  • #16
FlexGunship
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Goldsboro_fusingtable.jpg
This raises a very significant question for me:

What are "nose crystals"?​
 
  • #17
AlephZero
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Just found the following info as I was typing this post. From this site:http://nuclearweaponsaccidents.blogspot.com/
(Bolding mine)
That quote all looks very nice and reassuring, but it makes one big assumption which does not apply to the situation: namely, that the aircraft systems and the aircrew were all functioning as per their design intent. That was clearly not the case, since the weapons were "accidentally" released from the plane.

IMO, the final words you quoted
How close was the Goldsboro bomb to producing a nuclear explosion? Not at all.
are simply a statement of historical fact (i.e. there was no explosion). The connection between that fact and the previous quote is not at all obvious to me.

But whether the author of the article actually believed his own (ill)logical argument, or was simply writing a PR piece, is probably an unanswerable question.
 
  • #18
Drakkith
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That quote all looks very nice and reassuring, but it makes one big assumption which does not apply to the situation: namely, that the aircraft systems and the aircrew were all functioning as per their design intent. That was clearly not the case, since the weapons were "accidentally" released from the plane.
Nonsense. They looked at the actual weapons after impact and determined the status of their safing devices. They didn't assume anything.

IMO, the final words you quoted

are simply a statement of historical fact (i.e. there was no explosion). The connection between that fact and the previous quote is not at all obvious to me.
Looks pretty obvious to me.
 
  • #19
SteamKing
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That quote all looks very nice and reassuring, but it makes one big assumption which does not apply to the situation: namely, that the aircraft systems and the aircrew were all functioning as per their design intent. That was clearly not the case, since the weapons were "accidentally" released from the plane.
You mean "accidentally" released from an unstable aircraft breaking up in mid-air? I don't know how you could keep two large bombs (approx. 6000 lbs apiece) from falling out of the wreckage in that case.
 
  • #20
SteamKing
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This raises a very significant question for me:

What are "nose crystals"?​

See this link: http://www.ibiblio.org/bomb/hansen.html

If a bomb fails to detonate in the air, 'nose crystals' are a back-up fuzing system which will detonate the bomb when it hits the ground, probably using piezo-electricity.
 
  • #21
FlexGunship
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See this link: http://www.ibiblio.org/bomb/hansen.html

If a bomb fails to detonate in the air, 'nose crystals' are a back-up fuzing system which will detonate the bomb when it hits the ground, probably using piezo-electricity.
Ahhhh... for the record, this is not what Google image search turned up.
 

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