Mark Hibbs Nuclear Fuel November 25, 2002
“CIA Assessment On Dprk Presumes Massive Outside Help On Centrifuges”

An estimate by the U.S. Central Intelligence Agency (CIA) predicting North Korea, if it isn’t stopped, will be able to make significant quantities of weapons-grade high-enriched uranium (HEU) by around 2005 presupposes that Pyongyang has obtained unprecedented assistance from foreign sources in building gas centrifuges, plus a complete design package for a proven subcritical centrifuge using aluminum, Western government officials and enrichment experts told NuclearFuel.

U.S. officials have said assistance has been provided, and that they have identified its sources. For diplomatic reasons, the U.S. has not publicly revealed the sources.

Last week the CIA provided the U.S. Congress with a ‘‘consensus estimate’‘ on efforts by the Democratic People’s Republic of Korea (DPRK) to make a nuclear weapon using U-235. According to that analysis, the DPRK ‘‘last year…began seeking centrifuge-related materials in large quantities.’‘ The CIA concluded that the DPRK could be making two or more bombs’ worth of HEU per year ‘‘as soon as mid-decade.’‘

The description of the DPRK program as going from raw centrifuge-building materials to HEU production in just six years would represent a dramatic telescoping of the timeline for less-developed countries to obtain nuclear weapons material using gas centrifuges. Iraq hadn’t gotten that far by 1991 after taking twice as much time and expending far more financial resources.

Western officials told NuclearFuel last week that the CIA assessment presumed that North Korea obtained a vast amount of outside help and, said one, with a very high probability the aid included the complete design package for a proven machine. The assessment has the DPRK beginning large-scale centrifuge production in 2001 and producing an HEU significant quantity by 2005.

Western officials would not confirm a Japanese media report last week, based on unidentified sources, that Pakistan had exported between 2,000 to 3,000 centrifuge rotor assemblies to the DPRK.

Sources said that information coming to light suggested instead that individuals with years of experience inside Pakistan’s uranium enrichment program had given the DPRK the design package for an aluminum centrifuge, prototype components, and manufacturing and some diagnostic assistance, which might dramatically reduce the timeline for the DPRK to enrich uranium.

Officials said that the procurement evidence suggested that the DPRK has tried to obtain materials for the program from variety of sources including China, Japan, Pakistan, Russia, and western and eastern Europe, but that most of the assistance related to the rotor assembly itself came from Pakistan, including some 6000-grade aluminum used in the components.

Sources said they believed that the DPRK obtained from Pakistan the design of an aluminum centrifuge with at least some characteristics of the CNOR/SNOR design which Pakistan stole from the Urenco program during the 1970s (Nucleonics Week, 1 Nov., 1).

Western officials and experts said it would certainly be technically feasible for Pakistan to have manufactured a few thousand complete rotor assemblies and to have brought machines to the DPRK for assembly. However, for reasons of efficiency it is preferable to assemble machines on site. The DPRK might have brought to the erection site centrifuges pre-assembled save for the positioning of the bottom bearing, experts said, but pre-assembly would imply that scoops inside the rotor tubes would be out of place, that many machines would fail initially, and that many more would crash prematurely during operation.

Sources said that because the DPRK wants to enrich uranium to weapons-grade as fast as possible, it probably would make such sacrifices.

Sources said that, in part based on procurement information, the design of the DPRK machine is believed to represent a composite design not identical to the CNOR/SNOR machine Pakistan obtained 30 years ago. Officials said analysts have had difficulty in identifying the design for the end caps of the rotor and some information suggests the design did not match known Western centrifuge designs.

One official said that some information suggests the DPRK may have ‘‘slavishly followed a recipe’‘ calling for some more advanced components or materials, as called for in the design package provided by its helpers. That would explain, other sources said, why North Korea tried to purchase more advanced materials for the machine than were in fact necessary, including 6000-grade aluminum and pure cobalt for top bearing assemblies. In some cases, intelligence said, the DPRK encountered financial difficulties in obtaining such materials.

Some of Pakistan’s aluminum-design rotor assemblies relied on 2000-grade aluminum and used earlier-generation magnetic bearings, made of aluminum and nickel, not samarium and cobalt.

The DPRK sought to obtain dozens of kilograms of cobalt powder with a purity in excess of 99.99%. Pure cobalt is not on nuclear commodity control lists, but Western officials said the attempted export drew the attention of customs intelligence agencies since North Korea is subject to blanket trade embargoes.

The DPRK did not need samarium-cobalt bearings for an aluminum centrifuge, nor did it require 6000-grade aluminum. One expert suggested that the North Koreans assumed that their path to HEU would be shortened if they procured the most advanced materials available. Iraq also ‘‘made that mistake,’‘ this expert said.

If in fact the basis of the DPRK machine is a subcritical aluminum centrifuge with a throughput of around one SWU/machine/year, one expert said, with 2,000 machines in place the DPRK could enrich ‘‘at least enough HEU for a bomb a year.’‘

Without massive assistance from the outside, Iraq and Pakistan worked on centrifuge development for a decade or more without getting to the point of setting up an initial cascade to produce weapons-grade uranium. With assistance in manufacturing centrifuges of proven design, one official said, ‘‘if we assume the DPRK started building machines in earnest a year ago, it might just be able to start’‘ enriching a bomb’s-worth of HEU a year in 2005, assuming there were no unanticipated bottlenecks.

But that, he cautioned, also assumed that the DPRK was willing to take decisions and shortcuts which would mean that the initial failure rate of the machines might be as high as 10% and that ‘‘after two or three years of operation, a very large number of machines would crash.’‘

This, another Western official said, was ‘‘exactly the route’‘ followed by Pakistan during the early years of its centrifuge program in the 1970s and 1980s when it set up its first SWU plant at Kahuta. ‘‘They built a lot of simple machines, there were lots of holes in the diagnostics, so they could make HEU in a hurry,’‘ one official recalled.

Lack of optimization meant that ‘‘their first cascades were getting devastated within about five years’‘ after they began operating, he said, requiring most of Pakistan’s resources to be expended on replacing capacity for another five to 10 years, he said, adding, ‘‘But they had made enough HEU for a one or two weapons by then.’‘ Given that the DPRK’s priority would be to acquire nuclear weapons capability as fast as possible using U-235, Pyongyang would be expected to also go down that path, experts said.

On the political side of things, does this lay to rest the accusation that the administration created/influenced the assessment to kill the agreed framework?