How big is a nuclear device?

I was reading about a possible terrorist “scenario” in Maxim the other day and I was left wondering, “Why would a terrorist group with the resources to purchase a nuclear weapon ship that nuke to a target in a container?” When I was in high school I worked at a marina on the intercoastal waterway and I saw some impressive yachts. I think that if I had the resources to buy a nuclear device, I could buy or hijack a luxury yacht to carry it where ever I wanted without suspicion. It wouldn’ take a good carpenter long to take out a few decks and rebuild it to appear different from any other yacht after the weapon is put in place. So here is my question: How big is a, say, 5 kiloton nuke in terms of size and weight? Is this something that could happen?

The smallest nuke I have encountered is a ‘suitcase’ type which is designed to be manpacked into two rucksacks each wieghing about 35 or so Kg. I was led to understand that it was a two-ruck design to provide additional security against theft.

I will not comment on the yeild of such a device. Let’s say ‘sufficient’ for hitting an offset target.

IIRC, the military has a 155 mm nuclear artillery shell. Call it about 6" at the base of the cartridge - the casing will be somewhat wider, and something on the order of maybe 2-4 foot long - it’s been a long time since I’ve seen one (a 155 mm shell, not a nuke shell - I’ve never seen one of those).

Take the projectile out of the casing and you’ve probably got about 6" across and a foot or two long, at most. For comparison, I’ve got a dummy 105mm howitzer shell around here - it’s a bit over 4 inches across and about a foot long.

ISTR that nuke artillery shells won’t arm unless they spin at a certain rate for a certain amount of time. There may be a G-sensor involved as well. Of course, if you can buy or steal a nuke shell, I’m sure you can figure out a way to arm it.

Upon further reflection, the old ADM (Atomic Demolition Munition) was carried on the back of a five-ton truck and had several basketloads of yield.

In the size v. yield marathon I would go with that. OTOH, I have never shook hands with an air-dropped nuke.

Here’s a photo of the bomb that was dropped on Nagasaki. The men in the picture give you an dea of the scale.

Here’s a link with info on the Japan bomb’s yields, as well as a photo of the Hiroshima bomb which was a lot smaller in size.

So that’s what’s acheivable using highly experimental WWII-era technology.

Today, a professional weapons engineering organization like the US or Russia or China can do a lot more. For example, the B61 bomb described here The active warhead part is just the silver cylinder in the foreground that looks like a Starbucks vacuum coffee urn on its side. This site tells us the overall physical dimensions of the bomb are about 13" in dimaeter, 12 feet long & 750 lbs.

By examing the disassembled (dare I say exploded?) photo, I crudely measure the active warhead as 10" in diameter & 4 feet long. And per the first site, it has a yield of up to 300KT.

Here’s some photos of so-called suitcase nukes made by the US.
The question you have to ask yourself is whether the bad guys are home-brewing these things, or just buying them already built by legitimate arsenals. That’ll tell you what to be watching out for if you’re the security forces.

But if your question is whether one of these will fit in a ocean container, the answer is Abolutely. The good ones will fit in the trunk of a Toyota.

Yikes. I had no idea the actual go-boom part of a ADM was so small.

Here is yet another graphic depicting the size/yield ratio of some common weapons. As LSLGuy notes, this is the optimum possible with highly professional engineers using today’s best technology and computer-assisted optimization. There’s a lot of money spent on the last 10%, and a lot more money spent on the last 1% of miniaturization. Also notice that the warheads in the design are two-stage fission/fusion weapons, and a fission weapon is probably “good enough” for a terrorist.

If you were to ask a physicist about the minimum size possible, these are probably large by comparison – but if you were to ask an Iranian engineer working from Korean or Pakistani blueprints how big it had to be you’d get a different answer.

What about the other end of the spectrum (just to add perspective to the discussion)?

The largest nuclear weapon[Sup]*[/SUP] ever constructed was the “Tsar Bomba” produced by the Soviet Union in 1961 (cite).

It was 8 meters long, 2 meters in diamater and weighed approximately 27 tonnes. The design yield was a whopping 100 megatons but when tested “the uranium fusion stage tamper of the tertiary (and possibly the secondary) stage(s) was replaced by one(s) made of lead” and the test yield was only 50 megatons.

That bad boy would fit pretty nicely in a standard 40ft shipping container which has a payload of 28.75 tonnes and internal dimensions of 12.0x2.35x2.39 meters.
*It’s debatable whether the Tsar Bomba can really be called a “weapon.” There’s a discussion of this point in the cite given above.

I’ve just finished reading Project Orion, about the nuclear pulse-powered rocket concept of the early Sixties (Freeman Dyson et al). The book is generally kind of meh (not enough technical discussion or in-depth understanding of the politics, and too much of author George Dyson fawning all over his father) but it does have some interesting bits, in particular, Ted Taylor, who was responsible for much of the fission and boosted fission designs of the Fifties, claims that the smallest “full implosion bomb” he concieved was under six inches in diameter. (It was never built, though.) This was a very advanced design by an expert with the advantage of test programs and calibrated computer simulation.

You could probably make a smaller bomb out of other exotic artificials–I recall at some distant time a discussion of a rifle bullet-size critical mass weapon of californium–but I doubt it would be very efficient even if you could get it to work.

I doubt a terrorist group itself would have the wherewithal to obtain the raw materials and equipment and build a weapon, even with the unlikely aid of experienced East Bloc weapon designers. However, there are plenty of small nation-states who could do so (Argentina is suspected of having a development program, and of course we know South Africa had a program that they gave up, neither having any strategic purpose for glow-in-the-dark toys) and while it would be damn-foolish of them to sell a weapon for cash, a transfer could occur during a regime change or under loose security.

If they did, yes, I think the easiest delivery method would be a yacht. It would be pretty simple to conceal it, especially coming into a busy port where the Coast Guard and harbor patrol are busy dealing with commericial traffic and won’t notice a yacht coming back from a day sail that didn’t actually leave from there. You wouldn’t want to use a superyacht–too likely to be boarded, and over a certain length/displacement they are required to register in advance–but it wouldn’t be hard to stash such a thing in a medium sized bluewater cruiser. 'Course, you’re going to have to convince the crew not to hand it over to the authorities and enjoy the life of Riley as defectors, and that depends on what is motivating them. Still, not undoable.

And I live within glowing distance of Port of Long Beach; yikes!


For maximum yield a nuclear device has to be above the target. Detonating one at ground level will certainly be a deadly blast but less effective.

If I Googled correctly a sub launched w-88 rentry warhead is 70" x 22" with a weight of approx 800 lbs. Yield is 475 kt compared to the Nagasaki explosion of 21 kt. There are 8 potential warheads to each D5 missle and there are 24 possible D5 missiles in a Trident-II sub. The range of a D5 missile is 4,000 miles. Not sure how many W-88’s are actually allowed under Salt-II treaties.

Feel free to correct me because I used a number of sights to get the info.

Don’t ground level blasts produce more fallout than aerial explosions?

From a terrorist’s point of view, that might make a surface burst more effective than an air burst (although I guess it’s pure speculation as to what constitutes “effective” in a nuclear terrorist’s mind).

This Wikipedia article points out that “fallout from seawater is unusually dangerous because it is difficult to remove by washing.” I guess that means there’s little incentive for the terrorists to wait until the container ship carrying their bomb is unloaded. Why not just let 'er rip while it’s sitting in the bay and let the fallout do the job?

Admittedly speculative - but I would guess that the standard for “effective” is very, very low for a terrorist nuclear detonation. Probably, anything that involved any sort of actual, honest-to-Ford nuclear reaction would qualify, almost regardless of body count. The idea of terrorism is to terrify, and nothing terrifies like the absolute certainty that the bad guys have nukes.

Doing you one better, you could pack the hold around the bomb with chemicals containing elements that have short and medium half-lives to create more dirty fallout, in addition to seawater. Plus, detonating it in a commerical harbor affects both strategic logistical and economic abilities. Far more effective than blowing up, say, Invesco Field.