Uranium-Filled 'Lost Nuke' Missing Since 1950 May Have Been Found (bbc.com)

Although the U.S. government "does not believe the bomb contains active nuclear material," schwit1 shares this report from the BBC: A commercial diver may have discovered a lost decommissioned U.S. nuclear bomb off the coast of Canada. Sean Smyrichinsky was diving for sea cucumbers near British Columbia when he discovered a large metal device that looked a bit like a flying saucer. The Canadian Department of National Defence believes it could be a "lost nuke" from a US B-36 bomber that crashed in the area in 1950.... The plane was on a secret mission to simulate a nuclear strike and had a real Mark IV nuclear bomb on board to see if it could carry the payload required...

The American military says the bomb was filled with lead, uranium and TNT but no plutonium, so it wasn't capable of a nuclear explosion... Several hours into its flight, its engines caught fire and the crew had to parachute to safety... The crew put the plane on autopilot and set it to crash in the middle of the ocean, but three years later, its wreckage was found hundreds of kilometers inland.
The crew says they dumped their bomb-like cargo into the ocean first to avoid a detonation on land.

Comments

WTF?

[YuppieScum]

You fly a test mission, and do it using a "dummy" bomb that contains TNT and uranium???

Is it just me, or does this sound like complete bollocks?

Of course, actually telling everyone, "Oopsy, we *lost* a live nuke" would be quite embarrassing...

Re:WTF?

[wonkey_monkey]

Uranium is nearly twice as dense as lead. The test run was apparently to "see if it could carry the payload required" which means you'd want the right weight/size/shape. They took the most dangerous bit out, at least.

Re:WTF?

[Richard_at_work]

When you get to the point of heavy metals (such as the uranium in this instance), you start running into problems with simulating stuff made from them - you cant have a precise physical replica because the weight will be off, and quite often you cant add more mass because then you have something that is physically larger than the original.

In aircraft, weight and balance issues can affect performance considerably - so when you need to run simulation flights to test performance you couldnt really get a truly accurate result if you used a replica as it would either be too light or it would put weight in the wrong place on the aircraft due to the increase in size. You cant add ballast outside the weapon for the same reasons.

So the only way to run these tests back then was to use a proper weapon. Of course the core was removed, but on these aircraft they were always removed for take off, landing and cruise - a crew member literally had to insert the core into the weapon en route because the safety systems were still not trusted at that point, so keeping the core on board but separate would still result in an accurate test flight.

Re:WTF?

[hey!]

The uranium in this case was unenriched, and incapable of going critical. It was part of the device's "tamper" -- a kind of shield that delayed the expansion of the material in the pit during explosion, thus boosting efficiency. It was used mainly for its phsyical density, not its nuclear properties.

The mark IV bomb was designed to be transported and loaded on the aircraft without the "physics package", which contained the actual fissile material. As such this particular bomb is no more dangerous than a small conventional bomb. There is no particular reason not to use one in a training exercise.

Which is not to say there weren't some hair-raising incidents over the years. The closest we came to a real disaster was the Goldsboro incident, in which two thermonuclear weapons were ejected from a disintegrating airplane with nearly all of their safety mechanisms too damaged to operate.

Re:WTF?

[SEE]

Read the summary again. It wasn't a "dummy" bomb, it was a real Mark IV nuclear bomb.

What it didn't have was the fissile core loaded. Which is exactly what would be expected; the Mark IV was designed to have the core loaded into the bomb by the aircrew during the flight.

So, it certainly wasn't a dummy bomb; it was a real Mark IV, with the normal uranium and TNT in the casing. But it almost certainly wasn't a live nuclear bomb, because there would have been no reason at all for the plutonium core to have been loaded on the plane, and even if the plutonium was on the plane, no reason at all for the aircrew to load the plutonium into the bomb.

Real bomb and no plutonium core.

Re:WTF?

[chill]

Boy, are you going to be surprised when you figure out how the Soviet Union used to dispose of nuclear reactors from ships and submarines. At least with the U.S. one it was an accident.

https://en.wikipedia.org/wiki/Decommissioning_of_Russian_nuclear-powered_vessels

A Russian government report acknowledged in March 1993, that "during the period of 1965 to 1988 the Northern Fleet had dumped four reactor compartments with eight reactors (three containing damaged fuel) in the Abrosimov Gulf in 20 to 40 meters of water." Six other compartments, containing nine reactors in all, had also been dumped into the water in the 1960s and 1970s.

Re:WTF?

[blindseer]

Ever think WHY the engines caught fire?

This was a B-36, those things would sometimes catch on fire because the radio operator farted. These aircraft were notorious for engine fires. A lot of this was because of it being a first of its kind, no one built an airframe that large before. It was put in service in spite of its problems because there were people that feared the Russians more than this aircraft.

In 1950 the B-36 was still new and not all of its problems were discovered yet. No doubt they learned a few things from this crash. This aircraft was designed to carry a much heavier load than this, but whether the design, or perhaps this specific airframe, met those design specs can certainly be disputed.

https://en.wikipedia.org/wiki/...

Poor summary and incomplete story

[mykepredko]

I don't know why the poster/editor put in the last line "The crew says they dumped their bomb-like cargo into the ocean first to avoid a detonation on land" as it adds confusion to the story. If you read TFA, it seems like the bomb was dropped into the water to avoid the problems of the TNT exploding and not the BOMB detonating (which doesn't seem possible).

I'd be interested in finding out why the USAF didn't try to recover the bomb if they thought they knew where it was.

Broken Arrow

[xororand]

Lost nuclear bombs are also called "Broken Arrow".

>the US Department of Defense has officially recognized 32 "Broken Arrow" incidents, including but not limited to
        1950 British Columbia B-36 crash
        1956 B-47 disappearance
        1958 Mars Bluff B-47 nuclear weapon loss incident
        1958 Tybee Island mid-air collision
        1961 Yuba City B-52 crash
        1961 Goldsboro B-52 crash
        1964 Savage Mountain B-52 crash
        1965 Philippine Sea A-4 incident
        1966 Palomares B-52 crash[6]
        1968 Thule Air Base B-52 crash
        1980 Damascus, Arkansas incident

https://en.wikipedia.org/wiki/...

Trusted source?

[ebonum]

Do you actually trust the U.S. government to be honest? It may have been a complete weapon - plutonium and all. They simply made something up to make sure people wouldn't panic (or the real motivation to lie: people would criticize the government for f'ing up. Again.). No one outside a select few has the ability to find out if it had been loaded with plutonium. If they were actually worried about safety, there would not be any TNT or uranium in it. They would have filled the bomb with something inert to give it the same mass, center of mass and maybe even moment of inertia. Nuclear bombs don't go off unless properly triggered, so the risk of a full explosion is about zero. There is a very real risk of it potentially becoming a dirty bomb.

Lying and deception are completely legit when keeping Americans safe. Doubly so for anything classified.

https://en.wikipedia.org/wiki/...

Re:Trusted source?

[hey!]

While you can't trust the military to report honestly to the public on an accident, in this case there is every reason to believe this bomb is quite safe. The Mark IV bomb had a hinge on it so you can open it up and load the fissile pit into it in flight, during an actual bombing run.

During a training mission there would be no reason to have the fissile pit on the aircraft.

Re:No plutonium is not an issue here

[Strider-]

No, the lead was a simulator for the plutonium pit. The Depleted Uranium tamper surrounding the weapon isn't particularly radioactive. The tamper is there for two reasons, one the density and high inertia of it confines the chemical explosion long enough for the nuclear reaction to occur. Secondly, fast neutrons from the plutonium chain reaction then cause the tamper to fission, generating another portion of the weapon's energy.

As to why you're flying the aircraft with a weapon such as this, it's because it is supposed to be a live training mission, testing all the electrical interfaces, mission profiles, etc... and without the plutonium pit, the weapon is inert from a nuclear perspective. At that point, they also didn't have really viable simulators that could be used as a proxy.

So, That's a "No", Then?

[Greyfox]

So I'm guessing the outcome of the study was that the plane can't carry the payload?

Re:So, That's a "No", Then?

[_merlin]

No, just because it was a B36 - it would've been more surprising if at least one engine didn't catch fire. The B36 had propellers in pusher configuration on the trailing edges of the wings to reduce turbulence in the leading edges and improve lift. This required the radial engines be flipped front-to-back relative to how they were designed to be installed. This meant that the carburettors had cold air passing over them rather than air that had been warmed by passing over the engine, leading to ice build-up. This caused fuel to somehow come out of the carburettors the wrong way, make its way onto hot parts of the engines, and catch fire. The B36 was infamous for engine fires thanks to this highly questionable piece of engineering.