Determining source of nuclear material

[Adam Reynolds]

Would it be possible to determine the source of nuclear material at an atomic bomb site after a century or so? What if the bomb fizzled? This is assuming a WW2 era fission device, I was thinking implosion style.

In addition what is the largest nuclear exchange that could take place without totally destroying a nation roughly the size of the US assuming WW2 era nukes?

[Mr Bean]

Hmm okay, interesting questions

Would it be possible to determine the source of nuclear material at an atomic bomb site after a century or so? What if the bomb fizzled? This is assuming a WW2 era fission device, I was thinking implosion style.

Tracking down where the fissionable material comes from is dependent on all sorts of tests at the site in question to test the fallout... somehow not really familiar with the exact process but I do recall tracking down the cleanest samples and running them through a spectroscopic analysis. I'm guessing that simple decay and contamination would render such tests impossible after a few months let alone a hundred years.

In addition what is the largest nuclear exchange that could take place without totally destroying a nation roughly the size of the US assuming WW2 era nukes?

Fatman was a 21 KT nuke which means a two mile circle of lethality to unprotected humans and a just over three fourths of a mile circle to destroy all armored units and most thrown together bunkers. So unless your going for sterilization you could easily throw around several thousand in battlefield usage. Your average city would require twenty to thirty to flatten.

[Magis]

Would it be possible to determine the source of nuclear material at an atomic bomb site after a century or so?

That type of investigation is part of a scientific field called nuclear forensics. There's a good deal of published material on the subject, but in one paper*, analysis was done on the site of the Trinity test about 65 years after the detonation and they were able to determine a good deal of useful information about the structure and design of the bomb.

* "Postdetonation Nuclear Debris for Attribution", Proceedings of the National Academy of Sciences of the United States of America [0027-8424] Fahey yr. 2010 vol.107 iss.47 pg.20207

[The Duchess of Zeon]

See Magis' response. We can find out almost anything about a bomb, including where the ore was mined, by immediate analysis. Location of the ore mining however relies on radioactive emissions (and contaminants basically) and is not so useful in the very long term, since we've never had a need to develop the technology. But we can find evidence of nuclear fission reactions even thousands or millions of years after they took place, see the natural nuclear reaction in west Africa.

As for the second question, it would require around 20 1 Mt bombs just to wipe out NY City, let alone 21kT devices for an entire country. A country with the population density of Germany probably would take ~200 nuclear devices like that to "totally destroy" in the sense of putting the country back to a level of development roughly comparable to the 18th century and killing 80 - 90% of the population. The United States is much harder to destroy because everything is much more spread out. A similar effort in the US would, tentatively, require on the order of 5,000 21kT fission devices. Remember that even modern relatively lightweight MIRVed warheads are at least ten times as powerful and more usually about twenty-five times as powerful. This is simply due to the huge number of towns of 5,000 - 10,000 people you'd have to waste a nuke on to take out some metal fabrication industry shop and an administrative concentration and rail marshalling yard.

[Simon_Jester]

Plus, those figures don't begin to factor in the huge numbers of nukes that would be destroyed on the ground when a nuclear bomber came overhead. Or shot down in the air by fighters attacking the (roughly) WWII-era bombers carrying them- if US Army Air Corps with Silverplate B-29s sent a nuclear attack against Clone!US Army Air Corps, they'd have to worry very hard about being intercepted by the clone guys' fighters.

Or the overkill used to hit key targets repeatedly just in case a bomber gets shot down, or a single bomb doesn't go off properly, or... yeah.

That's the reason the Cold War arsenals ran up into the tens of thousands- a few thousand is enough to totally neutralize a country for all practical purposes, no matter how big it is (probably including a one-world state if your definition of 'neutralize' is loose enough). But the redundancy requirements for being sure you get a killing shot in even if the enemy gets the first shot are enormous.

[khursed]

Would it be possible to determine the source of nuclear material at an atomic bomb site after a century or so? What if the bomb fizzled? This is assuming a WW2 era fission device, I was thinking implosion style.

In addition what is the largest nuclear exchange that could take place without totally destroying a nation roughly the size of the US assuming WW2 era nukes?

Just being a dick, if 1 person survives, then the nation wasn't totally destroyed. So you could argue that if you use a billion bombs to sterilize the continent, Alaska, Hawaii, and leave a couple dude on an island somewhere, you failed.

If you mean the nation is still able to function as an industrial powerhouse, then destroy more then 50% of the nation's industrial cities and I think it will be hard to recover. It's not so much killing the people I would think, but to cripple their ability to function. So some target would be of way more value then others. Such as big port cities, local for distributing food would be major targets, since hungry people aren't that productive. Then hit the major shipyards, and the biggest train hubs, and you've managed to cause a lot of problem without necessarily killing that many people.

They do say an army travel on its stomach, so if you kill the supply chain, you can defeat a nation, that's basically what hastened the end of world war 2 for Germany when they had a lot of material, yet no fuel to use it.

Heck, if you're smart about it, just destroy all the oil refinery of the USA, and you've just stopped in it's track the whole nation. Bomb the major oil field, and their recovery will be crippled.

[Sea Skimmer]

Well realistically you just wouldn't use vast numbers of bombs, if the goal is just to kill people in between the mushroom clouds you just start using bioweapons, this was the point the US biowarfare program. Since the Soviet and Chinese populations were so rural, bombers spreading bioagents (cluster bombs used, except the cluster bomb drops bomblets one by one rather then all at once) could wipe out everyone away from the cities. The collapse of normal channels of food and sanitation would enhance the effectiveness of the germs, also even 'low' levels of exposure to fallout radiation greatly depress the immune system which would make people a lot more vulnerable. Once relations thawed with China everything was destroyed as insanely unnecessary. Also it was realized at some point that a pretty huge chunk of the Chinese population could be killed just by heavily nuking a handful of the big rivers, thus contaminating the water supplies for most Chinese food production for a long time.

[Simon_Jester]

Heck, if you're smart about it, just destroy all the oil refinery of the USA, and you've just stopped in it's track the whole nation. Bomb the major oil field, and their recovery will be crippled.

Destroying all the oil refining capability would involve hitting targets spread widely over the country, some of which are colocated with population centers. You'd still be nuking a lot of places. And you'd still be beating down all the defenses that would be shooting back at your attackers. Plus you'd get hit with retaliation just the same as if you'd done a lot more damage. Blowing up oil refineries won't stop ICBMs from falling on your head or bombers from taking off once to blast you to bits.

The only kind of 'surgical' strike that really works in nuclear warfare is a devastating "counterforce" strike that wrecks the enemy's ability to shoot back, because then you can say "OK, now give us everything we want or we'll blow up one of your remaining cities in descending order of population every six hours." Or something of that nature.

Even then you're going to get hit back pretty hard, probably; it's just that your nation will be economically depressed and weakened for 'only' fifty years while the other guy's home continent will never be the same.

There's a reason nobody ever tried this...

[khursed]

Heck, if you're smart about it, just destroy all the oil refinery of the USA, and you've just stopped in it's track the whole nation. Bomb the major oil field, and their recovery will be crippled.

Destroying all the oil refining capability would involve hitting targets spread widely over the country, some of which are colocated with population centers. You'd still be nuking a lot of places. And you'd still be beating down all the defenses that would be shooting back at your attackers. Plus you'd get hit with retaliation just the same as if you'd done a lot more damage. Blowing up oil refineries won't stop ICBMs from falling on your head or bombers from taking off once to blast you to bits.

The only kind of 'surgical' strike that really works in nuclear warfare is a devastating "counterforce" strike that wrecks the enemy's ability to shoot back, because then you can say "OK, now give us everything we want or we'll blow up one of your remaining cities in descending order of population every six hours." Or something of that nature.

Even then you're going to get hit back pretty hard, probably; it's just that your nation will be economically depressed and weakened for 'only' fifty years while the other guy's home continent will never be the same.

There's a reason nobody ever tried this...

ICBMs?

I was looking at the original scenario, and he asked a question to which I answered, I gave absolutely zero thought to the counter attack, or the remaining forces dispositions.

I was also simply giving scenarios that would be considered valid in the frame of his question.

Because you can consider a single American alive as failing to destroy the USA, and you can also consider sending 80% of their population to 19th century technology a victory, it simply depends on your objective.

It's all hyperbole anyway, we don't even know who's the actual enemy in question, and their actual goals.

[Straha]

Would it be possible to determine the source of nuclear material at an atomic bomb site after a century or so?

Probably not.

Outside of very specific circumstances Nuclear Forensics is often little more than reading tea leaves. The techniques used to trace bombs rely on pre-existing databases of nuclear samples from around the world. If the detonation is occurring after a nuclear war it's probable that those samples/information about those samples has been destroyed. Secondly, even if the detonation is 'fresh' it still requires a sample of the source mine/lab, however the two nuclear libraries that exist (Oak Ridge and the IAEA maintain separate libraries) are both opt-in, and are missing some significant nuclear powers (India being the most notable one). This means that if the source hasn't been put into the library the scientists have to play a guessing game via process of elimination, which has lead to some hilariously awful mistakes already, e.g. when Libya turned over its nuclear material to the United States the U.S. declared with "90% certainty" that North Korea had been supplying them with nuclear material, the IAEA however declared with equal certainty that the material had come from Pakistan. Third, it's remarkably easy to spoof a source country, or obscure your own bombs. The technology has existed since the 60s (the CIA was worried in the 70s that China or Russia might plant a bomb in the US and try to misdirect retaliation to the other country), and all it requires is a few grams of nuclear material to do. Fourth, there isn't enough expertise in the field anymore. Larry Arbuckle puts the number of people who might still be qualified to do Nuclear Forensics at 35-50, but most of them are aging with no replacements coming up the academic ranks because of a lack of post-cold war funding. Finally, the best time to do source attribution is post-detonation from the airborne plume (for technical reasons I admit I have no understanding of), the US is the only country that maintains the ability to do airborne attribution by maintaining a plane especially built for the role, a WC-135, based in Offut Airbase in Nebraska. The crew responsible for operating the plane's attribution equipment, however, are stationed in Florida. I quote Larry Arbuckle on this again: "With the separation of the flight crew and the technical operators it is doubtful the aircraft could be ready to obtain the desired information from a nuclear detonation before the Xe-135 gas decays to levels indistinguishable from other isotopes."

Tl;dr. No. It's not likely you'd be able to determine the source of a nuclear detonation from the bomb alone.

Which is depressing because the U.S. uses this 'capability' as a corner stone for deterring nuclear terrorism, in what is probably its most stupid and dangerous post-cold war strategic nuclear decision.

[The Duchess of Zeon]

Other capabilities exist for the analysis, but I and anyone else in the civilian world without a security clearance don't have access to them, so this is one of those irritating situations where I can say, "people like writing scare articles about nuclear detonations from terrorists, so this is wrong, but I can't explain how it's wrong; I just know that it's wrong, and someone who could explain how it's wrong, couldn't explain how it's wrong."

[Straha]

Other capabilities exist for the analysis, but I and anyone else in the civilian world without a security clearance don't have access to them, so this is one of those irritating situations where I can say, "people like writing scare articles about nuclear detonations from terrorists, so this is wrong, but I can't explain how it's wrong; I just know that it's wrong, and someone who could explain how it's wrong, couldn't explain how it's wrong."

Larry Arbuckle is a Commander in the U.S. Navy, the quotes above come from selections I have of his Master's Thesis at the Naval Post-Graduate school. I trust him to be not just aware of the classified capabilities but to be writing for an audience who would also be aware of said capabilities.

For those curious, the thesis was entitled “The Deterrence of Nuclear Terrorism Through an attribution Capability”, and was published in June 2008, unfortunately I don't have my copy of the thesis anymore. However, a number of people who would also have had access to said capabilities, or who operate in a world where that knowledge seems to be widely known, back up Arbuckle independently. Michael Levi at the Council of Foreign Relations, Marko Beljac out of the University of Melbourne, Colonel Michael Meese who founded the "Combating Terrorism Center" at West Point, and Dr. Scott Helfstein who works at West Point now have all published articles articles saying much the same thing at various points over the past five years among others.

EDIT: I'll also say I find the argument that "The information that might prove this wrong would be classified, so we have to discount what X text has to say." to be specious at best.

[Straha]

Ghetto Edit: Larry Arbuckle was a Lieutenant when he wrote the thesis, not a commander. I confused him for another author. My bad. His thesis can be found here.

[The Duchess of Zeon]

At least in my experience, Naval school Masters' theses can range from genuinely useful to the most horridly ridiculous dreck imaginable, though I limit that to the area of naval architecture that I'm vaguely qualified to pass some judgement on these days. A Lieutenant writing a piece like that could simply lack the necessary information and/or be acting as a mouthpiece of a political agenda and still be published, unfortunately, as long as a certain level of academic rigour, regardless of fact, is used.

[Sea Skimmer]

The lack of/aging nature of skilled personal was a real problem, but given the creation by the Department of Homeland Security of its own nuclear forensics team specifically to cope with the problem, well, its being addressed. Also as noted in the thesis, ground sampling capabilities exist, and Xe-135 is hardly the only thing you have to work with.

WC-135 is definitely operational; it flew sorties after both North Korean nuclear tests and has been dispatched to Japan for extended periods several other times, out of fear of additional tests and following the Fukushima disaster. The U-2 also still operates with its own airborne sampling kit, been doing the job since the 1950s. Its not like you must use an aircraft, an aircraft is just very useful for mapping the entire extent of the fallout plume. Some of these aircraft also get used to spy on nuclear reprocessing activities, which blow some radioactive gas in the air that can be used for fingerprinting non cooperative sources. A sampling kit is planned for Global Hawk, but that whole ‘replace all U-2/ special reconnaissance capabilities’ effort is mired in delay to say the least. I wouldn't be surprised if someone came up with a kit for RQ-170, but who knows.

[Straha]

At least in my experience, Naval school Masters' theses can range from genuinely useful to the most horridly ridiculous dreck imaginable, though I limit that to the area of naval architecture that I'm vaguely qualified to pass some judgement on these days. A Lieutenant writing a piece like that could simply lack the necessary information and/or be acting as a mouthpiece of a political agenda and still be published, unfortunately, as long as a certain level of academic rigour, regardless of fact, is used.

I feel you on a number of parts of that assessment, I disagree with a number of his recomendations for future action, and feelings on deterrence. However, considering both his qualifications and the qualifications of those who agree with him I'm very willing to find his assessment of the state of both Nuclear Forensics and attribution capabilities to be credible.

The lack of/aging nature of skilled personal was a real problem, but given the creation by the Department of Homeland Security of its own nuclear forensics team specifically to cope with the problem, well, its being addressed. Also as noted in the thesis, ground sampling capabilities exist, and Xe-135 is hardly the only thing you have to work with.

These are both fair points, but it doesn't change the underlying problems with attribution or the art of nuclear forensics that would probably bedevil anything like the OP's scenario.

WC-135 is definitely operational; it flew sorties after both North Korean nuclear tests and has been dispatched to Japan for extended periods several other times, out of fear of additional tests and following the Fukushima disaster. The U-2 also still operates with its own airborne sampling kit, been doing the job since the 1950s. Its not like you must use an aircraft, an aircraft is just very useful for mapping the entire extent of the fallout plume. Some of these aircraft also get used to spy on nuclear reprocessing activities, which blow some radioactive gas in the air that can be used for fingerprinting non cooperative sources. A sampling kit is planned for Global Hawk, but that whole ‘replace all U-2/ special reconnaissance capabilities’ effort is mired in delay to say the least. I wouldn't be surprised if someone came up with a kit for RQ-170, but who knows.

The claim isn't that WC-135 isn't operational. It definitely is, it's that keeping it operable has never been a priority, and that were a nuclear strike to occur it'd would likely not be of any use to help determine the source of the nuclear material.

The WC-135 is admittedly off track from the OP, but the point is still clear: attribution capability as it stands now is lackluster at best. It's not something that can be relied on outside of certain very limited situations which are probably unlikely to arise in the first place.

[Adam Reynolds]

I appreciate all the interest. Regarding attribution, would it be possible that there was a fundamental difference in design of the two sides' nuclear weapons such that one side primarily used plutonium while the other used uranium? This is probably not entirely realistic but would work for my purposes. In terms of building the devices, is one or the other more suited towards implosion vs gun type detonations?

[Adam Reynolds]

I meant to put this in the earlier post but I must have missed the edit window. With regard to the earlier question how hard would it be to cause a bomb to deliberately fail without looking like it was designed to upon later analysis?

[The Duchess of Zeon]

Plutonium -- highly unsuited for gun-type device, ideal for implosion.

Uranium -- Only suitable type for a gun-type device. Less preferred for implosion.

Third: Not enough data.

[Simon_Jester]

Even a 'fizzle' (a deliberate failure that explodes) would totally ruin the physical structure of the bomb- vaporize it, if you get even something tiny like a tenth of the kiloton about it. It would be pretty hard to tell from looking at the bomb crater that there was, say, some defect in the placement of the explosive charges that triggered it. Even if there was, how could you guess it was deliberate?

I bet the real trick would be making it fizzle reliably, in a way that creates enough of a fission explosion to destroy the bomb totally without blowing up everything within five miles in every direction.

[Magis]

With regard to the earlier question how hard would it be to cause a bomb to deliberately fail without looking like it was designed to upon later analysis?

It would be trivially easy.