When will it ever end, NK?

It is highly likely that the UEW at Yongbyon is not the only uranium enrichment installation in North Korea. At least one other workshop would have been needed to serve as a test bed for pilot cascades of P-1 and P-2 centrifuges prior to the beginning of semi-industrial scale enrichment operations. Such an installation should have a few hundred centrifuges. While no uranium hexafluoride (UF6) fabrication plant has been located in the North, its existence has been traced as far back as 2000, when subsequent investigations revealed that North Korea had shipped UF6 to the Libyan enrichment program. Concerns over high enrichment were also prompted by the detection of HEU particles from aluminum samples handed over by the North Koreans to a US monitoring team in 2007 as part of the Six Party Talk agreement. As contamination could have resulted from either tainted imported centrifuge equipment or from indigenous enrichment, its source remains unknown.


In any event, work at the UEW site has never been monitored. A glimpse of the facility was revealed when North Korea invited a group of visitors from Stanford University (including Professor Siegfried Hecker, the former Director of the Los Alamos National Laboratory) to a brief visit in 2010. If commissioning of the UEW has been successful, North Korea would have at present at least 3.5 tons of UF6, enriched to 3.5% U-235. This output is consistent with the annual needs of the 100 MWth LWR currently under construction. By 2013, there should be enough material, about four tons of uranium dioxide (UO2), for the first core of the 100 MWth LWR.


Such an enrichment plant could also be easily modified to produce HEU for nuclear explosives. If we look at possible future HEU production in North Korea, there are several permutations to consider from a technical standpoint depending on the availability of vital raw materials such maraging steel. The following are three possibilities with regard to operations at the UEW:


Utilize the current LEU cascades and install additional cascades to enrich LEU to weapons-grade HEU;
Modify the existing cascades to produce HEU;
Utilize the current LEU configuration at the workshop and construct additional cascades for LEU and HEU production.
The first, most straightforward option would be to install an additional 1000 centrifuges to convert the annual production of 1.8 tons of LEU at Yongbyon to 40 kilograms of HEU. This is an amount sufficient to generate the necessary fissile material for one to two additional nuclear bombs per year. Such a step-wise scheme was foreseen in Libya by enriching 3.5% enriched uranium first to 20%, then from 20% to 60%, and finally from 60% to 90% U-235. The actual conversion of 3.5% to 90% would take only a couple of months. This scenario would require the availability of additional raw materials and key equipment. Here we are faced with a few unknowns. For instance, we do not know the source and amount of maraging steel—a key raw material for manufacturing additional centrifuges—available to North Korea.


Second, the existing UEW could be reconfigured to produce HEU by recycling LEU. This would be a viable option if North Korea lacks the key materials to manufacture new centrifuges. However, this scenario would not be able to take full advantage of the installed centrifuges since the cascades for HEU production have a different layout, which forces the operator to leave a number of centrifuges unused. Consequently, the time needed to produce HEU would increase under this scenario.


Third, for the DPRK to fully optimize its HEU production following the A.Q. Khan scheme, it would install an additional 2000 centrifuges that could produce 3.5% enriched uranium with an extra 1900 centrifuges for HEU production. This option, using 5900 centrifuges, would turn all natural UF6 into HEU and produce up to 80 kilograms of HEU annually or an amount sufficient for four nuclear bombs.  However, there are no indications that the DPRK has required key raw materials to be able to manufacture thousands of additional centrifuges. Such a scenario would require, for instance, an additional 60 tons of maraging steel.


Next Steps by North Korea


The DPRK has invited the International Atomic Energy Agency (IAEA) to monitor its moratorium on uranium enrichment, but it appears that arrangement will not go forward with the collapse of the February 29 agreement. If it does, IAEA inspectors will likely be limited by the DPRK to prior arrangements implemented in 2007, which would mean that the IAEA would verify that the UEW is shutdown, but it will neither be permitted to verify the inventory of LEU nor establish the historical production of enriched uranium. Under such circumstances, the IAEA would only have access to the UEW. Any other installations, including conversion and (potential undisclosed) enrichment facilities, would not be included. Access to those facilities would have to be negotiated within the Six Party Talks.


With the April 13 satellite launch, North Korea has stepped determinedly towards a confrontational course with its Six Party Talk partners, and the United Nations Security Council has issued a Presidential Statement condemning its actions. Under such circumstances, what are the nuclear-related options North Korea can exercise if it chooses to raise the stakes even further? Conduct another nuclear test? This is certainly possible, but one that would further deplete Pyongyang’s precious plutonium stocks. What about the alternative of a uranium bomb test? This assumes that the North Koreans have succeeded in producing HEU (in sufficient quantities as well) and have a bomb design. Yet another step is for North Korea to forge ahead with the production of HEU and demonstrate that capability to the international community short of a bomb test.


As governments, diplomats and experts assess how to deal with North Korea’s new leadership under Kim Jong Un, the message that everyone should remain mindful of is that the DPRK’s nuclear program has transitioned from solely relying on the production of plutonium to adding a new feature, the growing production of enriched uranium. Transitioning away from this ominous onward march through a slowdown, suspension and gradual turnaround will be the ultimate test of a true transition that will eventually integrate North Korea back to the international community.