The word du jour is “denuclearization.”
This is the stated goal of our forthcoming talks with North Korea. Just yesterday President Trump announced that the rogue regime had “agreed to denuclearization.”
But what precisely does the word mean?
The simplest answer is the insistence that North Korea turn over its stock of manufactured nuclear devices to a third party. This is certainly desirable but we do not even know how many devices the North Koreans possess.
We know that there are a minimum of six, because there have been six tests—the latest and most concerning on September 3, 2017. (I will come back to this later.) But we do not know the actual number of devices which have been built. I have seen estimates based on the availability of fissile material (such as enriched uranium or plutonium) of as many as eighteen. A single nuclear bomb could be stored almost anywhere. You would have to inspect the entire country to find them.
The only other country to have turned over nuclear devices it had produced was South Africa (which had six of them). Some of the former Soviet Republics gave up nuclear weapons that they had been storing; but they hadn’t build these devices. And despite the popular misconception, Libya’s Colonel Qaddafi never turned over nuclear weapons. He didn’t even have a serious program underway to construct them.
So think about how difficult it would be to find a nuclear bomb hidden in a country the size of North Korea: The critical mass of a solid sphere of plutonium 239 is about 24 pounds—this is the mass needed to produce a self-generating fission chain reaction. And this mass resides in a sphere about four inches in diameter.
A clever bomb designer can reduce this required mass by about half. once again you could store this plutonium just about anywhere inside the 46,541 square miles which comprise North Korea’s land mass.
As far as I know all the North Korean tests have used plutonium-based devices. Plutonium is created in reactors. Uranium 238 absorbs a neutron becoming Uranium 239, which decays into Neptunium 239, which decays into Plutonium 239. North Korea has a nuclear reactor at its site in Yongbyon which is certainly plutonium producing and seems to be operating. It also has the facilities to extract the plutonium from the reactor fuel elements and to process it. What would happen to this reactor under a program of “denuclearization”?
Iran was in the midst of constructing a potentially plutonium-producing reactor at Arak, which has been modified under the supervision of the International Atomic Energy Agency. Is that what would happen at Yongbyon?
The last test the North Koreans performed raises questions on its own. First there is the matter of “yield.” This is the energy produced in the explosion. To visualize this it is normally stated in tons of equivalent TNT, with the practical unit being the “kiloton” (1,000 tons).
For comparison’s sake, the Ryder truck Timothy McVeigh used in 1995 to destroy the Murrah building in Oklahoma City contained about 2.5 tons of high explosive. The nuclear bomb dropped on Hiroshima was about 15 kilotons. And a conventional hydrogen bomb is measured in millions of tons.
What sort of yield would the North Korean weapons pack? The North Koreans took great pains to seal the actual seat of the explosion so its yield is not precisely known, but estimates range from 70 to 150 kilotons. Kim Jong-un referred to this last test as a “hydrogen bomb” but it is not clear exactly what he meant. True hydrogen bombs have been manufactured only by the Chinese, the British, the Russians, the French, and, of course, America. Most experts believe that Kim was referring to a fission device that was fusion-“boosted” If fission was involved this would require the manufacture of deuterium and tritium, the two heavy isotopes of hydrogen. Deuterium can be extracted from ordinary water, but tritium is made in reactors. But it can also be made in the exploding bomb by seeding it with Lithium 6. It is known that North Korea has facilities for making both. Indeed they were trying to sell Lithium 6 on the open market.
Would the disposition of these products be part of denuclearization?
Finally there is the matter of knowledge. I once heard an Israeli intelligence officer state with seriousness that the Iranians had to be deprived of their knowledge of nuclear weapons. He did not say how he proposed to go about this. The South Africans had hundreds of people in their program—all Afrikaners incidentally. The North Koreans must have several thousand, as well as an active university system that can supply more. Would denuclearization involve them? And if so, how?
None of this is to say we should not try to denuclearize North Korea. But before we go about the task, we ought to know precisely what we mean by that goal.