th Korea’s procurement activities in the late 1990s to the early 2000s showed its objective to achieve industrial or semi-industrial scale enrichment capacity, based on a more efficient Pakistani P-2 centrifuge design. In 1997, an attempt was made to acquire large amounts of maraging steel suitable for manufacturing centrifuges. In 2002/2003, North Korea successfully procured large quantities of high strength aluminum from Russia and the United Kingdom, another requirement in making centrifuges. A simple tally of the amounts and types of equipment and material sought by North Korea suggests plans to develop a 5000-centrifuge strong enrichment capacity. This appears consistent with a separate earlier enrichment offer A. Q. Khan had made to Libya.
For North Korea to have embarked on procuring equipment and materials meant for a (semi)industrial scale enrichment facility, it is highly likely that the known Uranium Enrichment Workshop (UEW) at Yongbyon, which in reality approximates a full sized facility, is not the only one that exists. More workshops would have been needed to serve as test beds for pilot cascades of P-1 and P-2 centrifuges prior to (semi)industrial scale enrichment operations. While we have signs of North Korea’s enrichment goals, the final picture remains unclear given that the actual amount of items procured remains unknown. This problem is compounded by the fact that the North Koreans have and are continuing to source nuclear material and equipment from several parties. Moreover, there remains a high degree of uncertainty concerning the level of North Korea’s enrichment technology development.
In April 2009, after expelling IAEA inspectors, North Korea publicly announced for the first time that it was proceeding with its own enrichment program. To reinforce its intentions, North Korea followed up with a letter to the UN Security Council on September 3 to confirm that it was embarking on an enrichment phase. In November 2010, the North Koreans unveiled to Siegfried Hecker, a pre-eminent nuclear expert and former director of the Los Alamos Nuclear Laboratory, an enrichment facility in Yongbyon with 2000 centrifuge machines similar to the P-2 version, built with maraging steel rotors. The scale, level of sophistication, and brazenness for the North Koreans to have built a (until then) secret enrichment facility at the same site of a previously IAEA-monitored building, caught international attention. The plant is proof of North Korea’s steady pursuit to include uranium enrichment as part of its domestic nuclear fuel cycle.
What does this mean in terms of North Korea’s enrichment production capacity?
2000 centrifuges when operating at full capacity are sufficient to annually produce 1.8 tons of low enriched uranium (LEU) or at 3.5% U-235. This projected output is consistent with the needs of a small LWR currently under construction that was also shown to Dr. Hecker. North Korea may however face some material and quality limitations that would restrict enrichment output. On the other hand, such an enrichment plant can also easily be used for military purposes. There are two options to proceed with to make high enriched uranium (HEU): reconfigure the current 2000 centrifuge installation or add 800 new centrifuges for that purpose. An additional 800 centrifuges would be able to convert annually 1.8 tons of LEU to 40 kgs of HEU, an amount sufficient for the country to generate the necessary fissile material needed for one or two new nuclear bombs. Currently, North Korea is estimated to have between 25-40 kg of plutonium stocks, an earlier ingredient it had used to build and test its first bomb in 2006. Should North Korea use its current 2000-strong centrifuge capacity on an uninterrupted basis to produce 1.8 tons LEU annually, and have additional 800 centrifuges to enriched LEU further to HEU, we can expect its HEU stocks to exceed its current plutonium stockpile after three years.
Feed material in the form of uranium hexafluoride (UF6) is needed in sufficient quantities to power 2000 centrifuges. While no UF6 f