North Korea’s Nuclear Test: a Q & A


I just read your article in “Counterpunch“, October 17, 2006 .

As you know the US claims that it has detected radiation that “confirms” that North Korea actually did explode a nuclear device. I presume that detecting Pu239 wouldn’t prove that a Plutonium fission reaction was achieved. Instead, you’d need to detect fission products that aren’t present normally at the measured levels. What are these fission products, and what do you think the possibility is that these products could be detected in the air (probably a number of miles from the test site) after an underground test? Does a small underground nuclear explosion cause an EMP that could be detected by nearby aircraft at the time of the explosion?


Tony Heatwole
Damascus, MD

The US has claimed that airborne waste products from DPRK’s recently detonated nuclear device has been detected. The only radioactive gas I know of is Radon. Would there be any others such as rare isotopes of naturally occurring non radioactive elements? — J. Johnson

Dear Tony Heatwole and John Johnson,

Thank you for your letters.

Air sampling for nuclear explosion traces focuses on the collection of xenon and helium. There are short-lived (radioactive) isotopes of these gases that occur as trace products from fission (e.g., alpha emission, a helium nucleus), and as activated species from the air around the explosion, which was irradiated.

Also, if the bomb was “boosted,” which is to say if there was a small quantity of tritium, or a mixture of tritium with helium or xenon gas, within the initially hollow plutonium shell, then there would be radioactive byproducts. Boosting is a method of increasing yield by putting a small fusion core within a much larger fissile mass. The U.S. spy planes would certainly be on the lookout for any evidence of boosting. This would say a great deal about the DPRK program’s level of development.

Trace quantities of noble gases are difficult to eliminate because they are so resistant to reaction (e.g., oxidation) and because they are so light, hence buoyant and quite penetrating through porous media. A buried nuclear explosion will create a hot high-pressure cavity, and of any of the species within it, the noble gases are the most likely to leak. Other species will “stick” to the earth because of their mass (slower, less energetic, less able to migrate through pores) and reactivity (chemically combine with static material). The pressure of a nuclear explosion cavity can strain the earth and open cracks, allowing gases to migrate from the explosion; the pressure dies down as the cavity cools, so after a few days the pressure to expel gas has gone.

It should be noted that the emission of these noble trace gases is a normal effect of every underground nuclear test; these emissions are not considered a breaching of the containment. Sniffing for these gases was done on many U.S. tests, as a planned part of the measurements.

Electro-magnetic pulse (EMP) would be “small” (above ground) for the NK test, and probably contained within the cavity and emplacement shaft.

You may find other answers at the FAS (Federation of American Scientists web site. They are an excellent source for information on all aspects of nuclear energy and weapons.


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[threaded response follows]

Dear MB:

MB writes


I refer to your article today… Is it possible that N.Korea acquired a nuclear bomb from the Black Market, and having done a routine time-overhaul on it, then detonated it last week?

MG, Jr. replies

I think this very unlikely. A working nuclear bomb is a very complicated thing, it requires controlled storage conditions, and any professionally made unit would have a very sophisticated electronic locking/disable harness, requiring a code to access to enable activating the unit. Any government in possession of such a unit would find it far more profitable to keep under its control than to sell on the black market; too much liability in that kind of sale in any case.

How about everybody’s favorite black market supplier, Khan (?) of Pakistan? As I recall, he sold equipment and know-how, but no “turn key” units.

The industrial nations possessing nuclear weapons also have means to track them, not foolproof, but always being improved. Aside from tagging the units electronically (an assumption on my part), they are difficult to hide from radiation sensors, since they have kilograms of highly radioactive metal. Also, they heat up, requiring cooling, but visible to infrared detectors, which are now so common. Ah ha!, thick cases to shield it, but then it become a bulky thing to haul about.

How about a “homebuilt” unit? The tough part is getting hold of the plutonium. The more amateur the design, the more plutonium you need to ensure some part of it forms a critical assembly. Can an amateur get hold of 12 kg of plutonium? And, could an amateur with so much plutonium put together his unit without being noticed?

If you wanted to imagine a rogue organization putting together its own bomb, something with the flavor of a James Bond plot, then you would have to imagine a corporation with technical means, closed facilities, and a reliable group of committed people — SPECTRE — and you arrive at a remote physical possibility, though still (to me) a psychological impossibility.

So, no, I don’t see a black market bomb. I think North Korea did it all on its own. That is their message to everyone else nervous about having the U.S. come down on them: “we did it, you can too.”

It is known the North Koreans were harvesting plutonium from their reactors. This was confirmed by the IAEA, and precipitated the Clinton administration to make extraordinary conciliatory offers, leading to a breakthrough in relations with NK, including a cessation of their fuel enrichment activities. The Clintonians accomplished this in the 90’s. Sadly, the U.S. did not follow through on the promises made, the deal was abandoned, and NK resumed its plutonium production. A week ago, we saw the result.

Why should the North Koreans be unable to make their own bomb? Look at the South Koreans, they are very capable as regards modern technology. The same type of people, a few hundred kilometers north, and under a different political regime, should seem equally capable. We can assume that the technical experts involved, perhaps as little as a few thousand people, would be the intellectual cream of the crop in NK, and so regardless of how bizarre the public face of their ideology, they would have been afforded the necessary training and tools to be able to accomplish this, their life’s work. I suppose in a “Manchurian Candidate” type of plot, the NK scientists and engineers would have been identified in 2nd grade as sharp minds, and carefully groomed up a very special educational ladder leading to their roles today. For those so privileged in an otherwise poor land, there would be little temptation to do otherwise.

Pretty much everything you need to know to make a sophisticated nuclear weapon is out in the public domain, somewhere. The really hard part is in the actual doing. This takes time and money, which buys energy and equipment, which is used to produce material and a wide array of parts and sub-systems, all leading to integration in a unit. This is the DPRK’s moonshot, they’re very proud of themselves, they didn’t fake it.

I would guess they would be loathe to sell it because that would water down their investment of money and time (why give away exclusivity?). Missiles they might sell, but I’ll bet they hold tight to their bombs and bomb designs.

MB writes

The Korea Times reported last week that N.Korea has an H-Bomb to detonate shortly. Surely such a high-tech device as this would be way beyond North Korea’s manufacturing capability??

MG, Jr. replies

Not after you’ve produced a fission bomb. One could “boost” a hollow-shell fission bomb, that is fill the interior with tritium gas, which gets compressed by the implosion, ignites fusion reaction in the gas, which emit a flood of high energy neutrons and as these stream through the fission shell, multiply the number of fission reactions by orders of magnitude — vavoom, big yield.

Also, a “hydrogen bomb” is simply a supply of tritium gas (a radioactive isotope of hydrogen) in close proximity to a fission bomb, which is compressed and ignited by the energy of the fission bomb. This is accomplished in a heavy case, which reflects the energy radiated by the fission back in, so the hydrogen volume is compressed and heated to thermonuclear temperatures. A “hydrogen bomb” is like “turbo-charging,” in a manner of speaking; the fission bomb is the essential engine.

Tritium is produced from water circulating through nuclear reactors. If NK set off a plutonium fission bomb, then they have produced an implosion system, and reactor-based production of nuclear fuel. They have everything needed for tritium production — so we must assume they have tritium — and they have everything needed to produce a “hydrogen” bomb — a fusion bomb. Just as with the U.S.S.R. in 1951 (2?), we can expect another test soon, and probably that of a fusion device.


MB writes

In 1991 others found, and therefore the USAF certainly had lost some type W-69M H-Bomb warheads as attached to SRAMS, and carried on a B-52g plane……I am told that the Initiators on them have a half-life of only 12-years?

MG, Jr. replies

I have no idea about this. Are there published accounts? I would have thought this would be a big news story.

I have no idea about component lifetimes. As I recall, most everything in professionally made bombs have quite long lifetimes, though the metal does oxidize. Also, tritium decays fairly quickly, in fact this is never sealed in the units, but injected just before use from an external supply. Maintenance includes replacing tritium supplies periodically, as they go flat (I guess like club soda)

MB writes

We will have to wait and see what happens in North Korea. Maybe they bluff??

MG, Jr. replies

I think not.

MB writes

The logical time for N.Korea to detonate such a devices would be before the US mid-term elections.

MG, Jr. replies

They may, or may punctuate one of their own anniversaries. They first have to do their data analysis from the first test, make any corrections to units being planned now, and then initiate an actual test schedule once they feel confident of their state of knowledge again. At that point, they’ll look at the calendar, and pick out a desirable coincidence.


MB writes

This is the only record that we can find of a B-52 type G that fits everything else with regard to the nukes found in May 1991 off the coast of Somalia.

B-52G (59-2593). No B-52Gs were lost as a result of enemy action. However, several were damaged. One B-52G (59-2593) was lost on February 3 (1991) when it experienced a catastrophic electrical system failure while returning to its base at Diego Garcia. While responding to the failure, improper fuel management on the part of the crew caused five engines to flame out, and the aircraft began to descend. Three of the crew members ejected safely before the aircraft crashed into the Indian Ocean, but three others ejected too late and were killed.

These planes carried Short Range Attack Missiles (SRAMS) that have a range of about 115 miles. A forensic expert who did investigations on a consultancy basis for the FBI and CIA told me last year that the nuclear warheads on the SRAMS would have been type W-69M?

MG, Jr. replies

On your questions about “W-69,” I do not know. Certified U.S. warheads carry shorthand labels “W-2-digit-year.” Since no warhead has been certified since the 20th century, there is as yet no confusion with this system. There are web-sites of nuclear weapons watchers with a great deal of information as to the labeling and deployment of warheads and bombs (labeled “B-yy”). Also, one can look into congressional records and information about the NNSA part of the DOE, and probably find out what warhead goes to what missile. There are a few authors who specialize in these matters, and they have large books and web-sites. A little time with “Google” will easily yield many leads in this regard.

U.S. warheads dropped into the sea (especially deep water) would probably be unusable. At best one could salvage the fissile material (if not overly oxidized/corroded by sea water). The state of the HE (high explosive) and electricals might not be reliable again. Also, it is possible the PAL (enable/disable locking system) could have automatically ruptured key components as a “safing” procedure during the unplanned departure from storage and/or a planned sortie.

My knowledge is more about the physics, and much less so about the military application, and the many systems external to the actual nuclear core.

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Andy Pyle wrote:

Could they have deliberately moderated the force of the bomb with Lithium or something to create ambiguity?

MG, Jr. replies:

Speculation # 2, “spoof.” Covered in the article. What’s the point of spoofing?

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Ian Kaplan wrote:

I hope that the article is not a “career limiting move”. Not only is it a comment in the press or North Korea, but it’s in Alexander Cockburn’s Counterpunch. Someone commented once that you don’t get into as much trouble for publishing in, say, a fascist publication as you do in a leftist one. Sort of an interesting commentary on values. Finally, I’ll note that, for reasons that escape me, the United States has never been terribly committed to nuclear non-proliferation.


[Ian is a colleague of MG, Jr. at work, Lawrence Livermore National Laboratory; we are both members of SPSE/UPTE, the union group]

MG, Jr. replies:

It depends on what kind of career you wish to have. On looking back, I see that “career” was the limit.

[Note to the reader: if we don’t practice our 1st Amendment rights to free speech, then we don’t have them, regardless of what it says on a piece of paper under glass in a mausoleum of history — “use it or lose it.” Also, stop being afraid, that is how you are enslaved. MG, Jr.]

MANUEL GARCIA, Jr. is a physicist and can be reached at



Manuel Garcia Jr, once a physicist, is now a lazy househusband who writes out his analyses of physical or societal problems or interactions. He can be reached at