According to those in the know, the US and USSR during the Cold War maintained secret inventories of suitcase nukes, nuclear backpacks, nuclear artillery shells, atomic demolition charges, and more. Since portability was paramount, it appears these small devices (e.g., W48, Mk54 SADM, RA-115s, etc) also had low explosive yields, well under 1 kiloton. Officially, both governments denied existence of these weapons.
Designing a small, lightweight, portable “atomic” nuke is challenging. Miniaturizing a thermonuclear unit would seem much more complicated. Generally speaking, would H-Bomb Samsonite luggage (with convenient “spinner” wheels) weigh that much more than a 60 lb. low-yield nuclear backpack? Is this even theoretically possible? Which would be harder to achieve: small weight or small size?
Historical unknowns aside, it seems to me the limiting factor is not size but portability. If I remember right, uranium is more than half again the density of lead, so a suitcase-size device would not be a casual end-of-the-arm carry, unlike a backpack with its better distribution. It’d definitely violate the airline maximum check-in weight, for example.
Why should we? The cold war lasted much longer, and the possibilities today should be even more interesting, if that is the word. The OP reminds me of the plot of The Fourth Protocol, by Frederick Forsyth, a thriller first published in 1984. Forsyth claimed in it that the nuclear device was small and light enough to be carried by one strong operative. He used to be realistic-ish in his plots, so I suspended my disbelief while reading the novel. Not his best book, but very readable. And the question seemed fair: why bother with ICBMs, tactical bombers, horribly expensive submarines and aircraft carriers and all that if you could theoretically plant a bomb in every city?
The W88 warhead, the thermonuclear device fitted to Trident missiles aboard ballistic missile submarines, is a tactical warhead with a half megaton yield. It’s about the size of a person and weighs somewhere between 300 and 700 pounds. Granted, there’s not much impetus at the moment to develop smaller warheads than this, it does an admirable job of destroying a target and everything else within a few square miles and it’s small enough to be delivered by a wide variety of platforms.
What’s the benefit of something smaller than that? If you can drive a white windowless van to your target you can deliver a W88 for the price of a tank of gas.
On the other hand, a suitcase-sized device checked into a flight would allow the perpetrator to do a nasty amount of damage while still having time to drive away.
I don’t think this will be possible. The device will have to be large enough to house the necessary components to shape the explosive shock wave and to effectively direct the x-ray radiation to compress the fusion fuel. And that doesn’t include the size of the fission primary itself.
With a remote triggering system, you’d have all the time you need to drive away. Rent an apartment with parking, and you’d have months of your truck bomb being undisturbed to work with.
This little beauty has been in the US arsenal from the late 1960s and its later variants are still in use today. The whole thing weighs ~700 lbs.
In the section of the wiki labeled “Deployment” there’s an “exploded” (heh) picture of a disassembled bomb. The caption calls out the actual warhead as one unexploded component we can readily identify. Take a look.
All the rest of the gizmos in that picture are the arming, safing, programming, and parachute stuff. So not relevant to a suitcase bomb. If you’re willing to dispense with all that security jazz and just install a pushbutton labeled “press to detonate”, or a couple of bare wires to connect to a cellphone’s speaker or LED to become a remote detonator. Works for me.
The warhead is about the size of a commercial percolator / coffee urn like this:
Which Amazon tells us has an 8L capacity. For all practical purposes almost all the coffeemaker’s volume is tank, not heater/percolator, so we can ignore that factor.
From basic public knowledge of nuke innards, inside the warhead is a hunk of plutonium, a hunk of uranium, a bunch of fancy explosives, and a wee bit of wiring. As we know, plutonium & uranium are dense whereas explosives are not. By volume it’s probably mostly explosives, but by weight it’s mostly Pu & U. Let’s average that out at the density of aluminum.
These nice folks tell me an 8L slug of typical aluminum alloy weighs ~63kg = ~140 lbs.
Even if we managed to make something half as big and therefore half as heavy, it’s still gonna be a bit overweight for a checked bag, so you’ll have to pay an extras ~$20 to check it. It’ll be seriously difficult to wrestle into an overhead bin, so don’t try the carry-on route.
Still, with a yield somewhere between ~1/2KT (in what’s probably a single-stage near-fizzle) to ~350KT at full blast, it’ll make an impressive mess when somebody pushes that button or makes that phone call.
The world’s strongest men can yoke walk weights up around 1,000 lbs. But that’s a device that’s already raised to near shoulder height and is only picked up a few inches as most. Nor is there going to be much clandestine about a 6’8" giant struggling to move some giant backpack in 50 yard stretches.
I see conflicting records for the Farmers Walk:
But somewhere between 300kg and 400kg seems to be the upper limit for two heavy suitcases, balanced on both sides of the body. With an uneven load on just one side, I might guess that you’d be looking at 140kg to 180kg (300-400lbs).
To get a relatively normal sized person able to move around functionally for some time, I’d probably guess that you want to be in the 200-300lbs range and do it as a backpack. You can get some people to help load the carrying person up and he should be able to squat and drop it without too much fuss so it’s mostly just the walking portion that needs to be accomplished and the human body is fairly strong in that position.
Caskets and lots of boxed cargo up to 1000 or so lbs get carried on narrowbody aircraft all the time. Much heavier stuff can be loaded into the widebodies. The limiting factor not being the aircraft size, but the more manual way the smaller planes are loaded.
Transporting the weight or bulk of a nuke has never been the long pole in a terrorist or rogue nation’s plot. It’s the buying or making a bomb, and smuggling the bomb that are hard. Also being confident enough you’ll get away without being blamed, or being fanatical enough you don’t care if you get blamed.
Those obstacles are the reason(s) nuke attacks are not already commonplace around the world
Why would you want to put it on an airplane? Park your van in the airport parking lot, and you’ll take out a whole bunch of planes. And the rest of the airport. And the rest of the city. Even these “small” thermonuclear bombs are about 20-30 times the energy of the devices that destroyed Hiroshima and Nagasaki.
Thermonuclear bombs still contain high explosives as part of the fission first stage, not to mention they give off a fairly significant amount of radiation (don’t ask me how I know). I know explosives detection equipment is used at most airports, and I’m reasonably sure any radiation monitoring equipment would detect a nuclear device moving through an airport. If your goal is to deliver a nuclear warhead to a major city I don’t think commercial airlines are the way to go regardless of how small you can make it.
I wouldn’t have it put on an airplane-I would check it in a couple of hours before the flight, leave the building and drive away, then have it detonate about 15 minutes before flight. Once it is checked in, it officially belongs there and no one will be suspicious.
