First Look at North Korea’s Uranium Enrichment Capabilities

On Friday, North Korean state media reported that Kim Jong Un visited uranium enrichment facilities to learn more about the country’s fissile material production process and capabilities. During the visit, Kim was accompanied by Hong Sung Mu, one of the country’s leading nuclear scientists, and the head of the country’s Nuclear Weapons Institute, whose name is unclear.

The North Korean media coverage of this site visit is the first time images of the country’s centrifuge program have been shown. While only five photos were provided, it is clear that the uranium enrichment program has advanced significantly since it was first revealed.

The centrifuges shown are not the P-2 equivalents observed by Dr. Siegfried Hecker during his delegation’s visit to the main Uranium Enrichment Plant (UEP) facility in Yongbyon in 2010, but a more advanced design. The size of the cascades and hall shown also signify substantial capacity, perhaps not to the level of “exponential growth” as Kim has mandated, but significant growth, nonetheless. And finally, it is probable that these centrifuges are North Korean designed and manufactured; however, they likely use at least some imported materials despite decades of increasingly harsh sanctions imposed to hinder the country’s nuclear development.

These images send a strong message that the country has ample capacity and continued will to expand its nuclear program.

The Centrifuges

The centrifuges in the image are not the P-2 centrifuge equivalents seen in 2010 when Sig Hecker visited North Korea but appear to be a more advanced design.

Based on the images, the cooling coils appear to be around the centrifuge motors inside a centrifuge housing. Centrifuges spin at incredibly high speeds and are subject to enormous stress that can lead to a mechanical failure. In such a case, the centrifuge housing serves as a barrier for blocking damage to nearby centrifuges caused by shrapnel.

Another important protection measure is the fast-acting valves on the feed, product and tailpipes of each individual centrifuge, together with vibration sensors. The valves isolate the ailing centrifuge, blocking pressure impulses or dust that damages other centrifuges. Such valves are subject to export controls and are both hard to obtain and difficult to manufacture.

The centrifuges are also secured by heavy footings to limit collateral damage in case of failures.

The size of the cascade hall shows that North Korea’s enrichment program has taken substantial steps forward.

What is shown in the images is probably of North Korean design, but likely required at least some imported materials to produce.

Configuration

In the first image, Kim Jong Un is seen standing alongside many centrifuges. There are approximately 70 visible in each row. There are two rows positioned close to each other and two more rows on the other side of the central piping. Added together, that makes approximately 280 centrifuges per section.

The image appears to show three sections, and additional centrifuges are visible past some support columns. These seem to be the same columns in the second image, which is taken from the same platform but on the other side of the room.

From this angle, we can see an additional three sections of centrifuges, so together, the hall could hold an estimated 1,680 centrifuges.

A third image shows hundreds more centrifuges in a different room, which is determined from the different floor covering, lower ceiling and different walls.

In this image, some of the centrifuges are not connected, providing visual proof of Kim’s intention to keep building up the country’s enrichment capability.

Taken together, the two rooms likely account for over 2,000 centrifuges, although it should be noted that it is impossible to determine if they are all functioning.

The Location

This is one of the biggest questions and difficult to answer from the images alone, particularly because the visual clues available are few. What is clear is that at least two different rooms are depicted.

The first is potentially at the UEP at the Yongbyon Nuclear Scientific Research Center.

The two halls at the UEP measure approximately 120 meters by 15 meters each, but based on commercial satellite imagery, interior walls subdivide this space, so the actual length of the open floor space is approximately 93 meters.

It is unclear where the second room is located. It is possible it is within the annex that was added in 2021 or 2022 to the centrifuge hall at Yongbyon, or it may be offsite at one of the suspected uranium enrichment facilities North Korea is yet to disclose.