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?

[pushing-robot]

The bomb would contain a layer of depleted uranium surrounding the plutonium core. Depleted uranium is not particularly radioactive and can't go critical on it's own, but assists the plutonium reaction.

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?

[Baloroth]

It makes no sense to use a simulated nuke shape that actually has a radioactive, dangerous, and expensive restricted component when it can easily be simulated by replacing it with a safe, inert, and cheap substance.

They removed the plutonium core (which is radioactive and expensive), and only had natural uranium, which on its own is none of those things (well, technically it's radioactive, but only barely. You could eat it without getting radiation poisoning. It'd kill you from heavy metal poisoning, but not radiation). Hell, you can buy it off Amazon. It's also almost twice as dense as lead, so you can't simulate it with lead (and anything close in density is fantastically rare and expensive, like platinum and gold). Not sure why they'd have TNT inside, though maybe they wanted to make sure it wouldn't explode during the transit process.

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?

[hey!]

Technically, a uranium tamper is still fissioned with fast neutron flux, so it is partly there for its nuclear properties, isn't it?

Yes, the tamper does fission a little and adds somewhat to the bomb's yield, which is why I said "mainly". I didn't want to obscure the important point, which is that that the uranium in this bomb cannot be made to explode by any means without installing the pit.

"Natural uranium" (meaning unenriched) is reasonably safe to handle; if you look up the MSDS for natural uranium metal the main hazards are ingestion and inhalation. You can handle it with disposable gloves.

Re:WTF?

[blindseer]

Depleted uranium is still toxic, though.

And lead isn't?

My question isn't why it would be packed with uranium, since uranium is rather unique in it's density and there is little else that would be of equivalent density and be as cheap. My question is, why would a dummy bomb be packed with TNT?

If it's packed with TNT then it is most certainly a live bomb. It might not be a nuclear weapon at this point but it can still "go boom" with considerable force if given a cross look.

As I understand nuclear weapon design the use of DU as a casing is beneficial for two reasons. First, it can provide enough mass to contain the force of the TNT explosive long enough to detonate the "pit" (nuclear primary) and not be too large to carry in a bomber. Second, even DU will fission if exposed to a "fast" neutron flux (where "fast" is defined by nuclear physics and in abundance during fission). This makes a nuclear weapon small, powerful, and "light" by 1950s weapons standards.

The presence of DU in a "dummy" nuclear weapon makes sense to me since it is a near requisite to make a proper stand-in for a real weapon without needing exceedingly exotic (for the military anyway) materials. TNT on the other hand is not terribly unique in the same way. I don't know how dense TNT is but I would imagine there are a lot of off the shelf stuff that would be close in density, chemical composition, etc. and still not "go boom" if in an aircraft crash or something.

Re:WTF?

[blindseer]

So this highly radioactive core is still at the bottom of the ocean somewhere?

If this was in fact a training mission then the radioactive core would not likely be on board. That is a very expensive and militarily sensitive part of the weapon. The rest of the weapon, the nearly 5 ton case, while still an expensive and sensitive piece of equipment is not nearly as easily lost, stolen, or capable of being simulated for a training mission.

Also, the plutonium used in the core has a half life of over 24000 years, not something many would consider "highly radioactive". Such material is regularly handled with only gloved hands, which is what the crew would have to do to arm the weapon while in flight.

Re:WTF?

[blindseer]

It makes no sense to use a simulated nuke shape that actually has a radioactive, dangerous, and expensive restricted component when it can easily be simulated by replacing it with a safe, inert, and cheap substance.

It makes sense if you have an inventory of hundreds of these weapons and you want to keep their specifications a secret.

A few questions for you. Who would build this "dummy" bomb? What would it be made of to keep the same size, weight, and shape? How far would someone want to deviate from the real thing in training or testing when considering that the success or failure could mean lives lost?

I'll answer the last question first, when doing testing like this they'd want to have something as real as possible since this is a matter of survival for future flight crews. To make this they'd want to use as much of the real deal material to keep the mission as close to a real deal mission as possible. The people that make the dummy would have to be the same people that make the real weapons for matters of security, and they will have access to the real stuff to make it.

My guess is that this "dummy" was one of two kinds of devices. It may have been a real deal bomb with all the important parts removed for the mission. The core was not likely on board, and if there was a core it would likely be a dummy device since the weight difference of that is not near as critical as the 5 ton case. It may also have been a "dummy" bomb in the sense it was a real bomb that failed during the inspection to certify it as a weapon fit for the inventory. It'd be stripped down of anything critical and be inert in many but not all respects. It'd still have to be guarded as a real weapon since in the hands of an enemy it could be used for all kinds of mayhem. Since it still matched the fit/form/function in many respects compared to a functional weapon it would be kept for missions like this one.

If you want to see something "expensive" then consider the expense of designing, producing, and testing, a handful of "dummy" weapons when there is an ample inventory of the real thing. When it comes to being radioactive consider that depleted uranium has a half life of billions of years, emits an alpha particle upon decay (which is easily blocked with a piece of paper), and is covered by the heavy steel casing. And then calling this "dangerous"? Of course it's dangerous. It's 5 tons and covered with steel armor, this is not something to be handled, ahem... "lightly". A simulation device would have to also weigh 5 tons and be covered with steel armor or the training mission is pointless.

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/...

Re:WTF?

[Cramer]

You do realize there's a difference between weapons grade, enriched uranium and depleted uranium, right? To accurately gauge the weapon carrying capabilities, it would be loaded with a "dummy load" which means no actual nuclear fuel. It gets loaded with depleted uranium to match the mass and weight distribution. In other words, the small ball of plutonium that actually makes the giant kaboom, isn't on the plane. (i.e. everything but the core. "In tonights test, the part of plutonium will be played by a ball of depleted uranium -- because we have a lot of that shit laying around.")

Re:WTF?

[quenda]

My question is, why would a dummy bomb be packed with TNT?

Its not actually a "dummy", but a real bomb with the core removed.

Re:WTF?

[stoatwblr]

The interesting thing is that those dumped reactors (and a couple of downed nuke subs) are monitored closely and NO radioactivity can be detected in their vicinity. It's only when you get closer than about 2 metres that anything can be detected at all.

For that reason it's been deemed safer to leave them where they are than to try and pull them out of the water.

The BBC ran a documentary on these reactors and the monitoring processes about a decade ago. It's worth looking at if you can find it.

Re:WTF?

[stoatwblr]

The U238 casing is used as a fission booster in "H-bombs" (and is where most of the explosion actually comes from - the fusion bomb boosts the fission bomb, etc.

But this isn't an H-bomb. It's one of the early crude fatman designs and you're right.

For those wondering about why a bomb complete with explosives was used for test flights:

This was early 1950s US Military. Safety and commonsense weren't high on the list of requirements back then, which is why there were a number of nuclear incidents including several prompt-critical induced reactor vessel steam explosions at various sites and the godawful messes at Hanford & Snake river that need cleaning up.

Re: WTF?

[blindseer]

A "gun type" weapon has the core in two halves. An "implosion type" weapon has the core as a single sub-critical piece. This was an implosion device, with a single piece core.

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/...

Re: Broken Arrow

[serviscope_minor]

Well this post proves that if you write a post attacking Hillary here, it does not matter how stupid it is, it'll still get modded up.

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.

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

[Bartles]

The icing carburetors were an entirely different problem. The engines overheated and caught fire just because air cooled engines do not work well in a pusher configuration. It's difficult to get airflow here it's needed.