Uranium or plutonium?

It seems likely that the third North Korean nuclear test will take place soon ― perhaps, in a matter of days or weeks. There are signs of preparation at the test site, and it would fit into a well-established pattern: a test of a long-range rocket is usually followed by a nuclear test.

By Andrei Lankov

It seems likely that the third North Korean nuclear test will take place soon ― perhaps, in a matter of days or weeks. There are signs of preparation at the test site, and it would fit into a well-established pattern: a test of a long-range rocket is usually followed by a nuclear test.

In July 2006, North Korea launched Taepodong-2, the largest of its long-range missiles (it exploded shortly after liftoff), and then tested a nuclear device that October. In 2009, the pattern was repeated. In April, a Taepodong-2 was launched and in May the second nuclear test took place.

Perhaps the most interesting question that analysts, spies and scientists will try to answer is what the exact type of device used in the test would be. It makes a big difference whether they test a plutonium device, as they have done twice before, or if this time we will see the first test of a uranium one. There is a major difference between the two.

Plutonium occurs naturally only in tiny quantities and hence has to be produced artificially in a nuclear reactor where it is a normal byproduct of nuclear fission. However, a nuclear reactor is a large machine which cannot possibly be hidden by the prying eyes of satellites.

If the outside world knows the technical details of the reactor, it is possible to guess its total plutonium output, from when the reactor became operational. Analysts believe that North Korea’s nuclear reactors have produced between 30 and 50 kilograms of weapons-grade plutonium (enough for five to 10 nuclear bombs).

Uranium is different. Highly-enriched uranium (HEU), which is used in nuclear weapons, is produced by enriching uranium ore. There are different technologies but most of the time a cascade of centrifuges is used, with each centrifuge in the cascade producing a more concentrated product.

Unlike unwieldy reactors, such cascades are relatively easy to hide from satellites and reconnaissance planes. There is no way to be sure that all the centrifuge cascades have been located. Therefore it is difficult to estimate the size of stockpiles of HEU in a given country, and this means that HEU is remarkably more dangerous when it comes to proliferation.

In North Korea, the plutonium program began in the 1960s. However, North Korea’s nuclear reactors were shut down in the 1990s. North Korea does not currently produce plutonium.

It seems that North Korea began to advance its HEU production program in the late 1990s, if not earlier. The existence of the program became known to the United States and was the major factor which triggered the 2002 diplomatic crisis.

For a while, North Koreans denied the existence of the program, but in November 2010, they showed large HEU production facilities to a visiting US delegation. Siegfried Hecker, former director of the Los Alamos Laboratories, was proudly shown around North Korea’s new state-of-the-art facilities, seemingly with as many as 2,000 centrifuges.

He was not allowed to stay long enough to ascertain whether the facilities were fully functional, therefore the actual scale may be significantly smaller than Dr. Hecker’s hosts implied. But it might just be larger, too: an HEU program is very easy to decentralize and there is no reason why the North might not have more facilities elsewhere.

Experts agree that it is sometimes possible to distinguish between a uranium and plutonium test. At this stage, we cannot be certain which materials the North might use. If they test another plutonium device, it could be seen merely as a provocative waste of valuable resources. The test would amount to a waste of 5 kilograms of precious plutonium, which is not in abundant supply and no longer produced locally.

The political effect of a uranium test would be rather different. The implications of such a test are that the North is able to produce uranium in sufficient quantities to make nuclear devices. Uranium being so much easier to make secretly, this will produce a far more negative international reaction.

This is exactly what the North Korean leadership wants. Like the nuclear and missile program in general, the test is designed to achieve two strategic objectives. First, it should demonstrate North Korea’s nuclear capability, in order to deter hostile powers. Second, it should provide a serious incentive to foreign powers to negotiate with the North about dismantling and/or freezing the program in exchange for a large fee.

Indeed it is possible that from before its inception, the HEU program was made to be sold. The North is likely to freeze and even dismantle it, on the condition of a big pay off and if they are allowed to maintain their existing stock piles of weapons-grade plutonium (thus ensuring that they will have enough leverage for diplomatic blackmail as well as sufficient power of deterrence).

So, will it be uranium or plutonium? We may well know the answer soon.

Professor Andrei Lankov was born in St. Petersburg, Russia, and now teaches at Kookmin University in Seoul. Reach him at anlankov@yahoo.com.