Yongbyon Nuclear Scientific Research Center: A Suspected New Enrichment Facility and Dismantlement of 50 MWe Reactor

A series of commercial satellite images of a new facility at North Korea’s Yongbyon Nuclear Scientific Research Center appear to support the International Atomic Energy Agency’s assessment that the DPRK is expanding its uranium enrichment capabilities at the center.

A recent report by Rafael Grossi, Director General of the United Nation’s International Atomic Energy Agency (IAEA), suggested a recently built facility at Yongbyon has features similar to the suspected uranium enrichment facility at Kangson and is likely intended for that purpose. Additional open source assessments have come to similar conclusions given the likeness to the suspected Kangson uranium enrichment facility and compared to enrichment facilities in other countries. Additionally, a new probable radioactive waste storage facility appears to be nearing completion and major efforts to dismantle the decrepit 50 MWe Reactor are underway.

Kim Jong Un has called for the exponential expansion of its nuclear weapons arsenals, and highlighted its centrifuge facilities in recent months, revealing advanced centrifuge designs. Should this new facility prove to be for uranium enrichment, this would be a another step toward increasing the country’s overall fissile material production capacity towards achieving Kim’s directives.

Timeline of New Suspected Enrichment Complex

Commercial satellite imagery from December 9, 2024 provided the first indication that a new facility was being constructed at a support complex northeast of the Radiochemical Laboratory complex. At that time, a series of holes arranged in a grid-like pattern had been dug into the ground, separated by an old, single-story support building.

By late January, the support building that had separated the two groupings of holes had been razed, making clearer that the holes were the foundations for pillars to support a single structure. In addition, a security wall was being erected around this new complex.

Construction progressed rapidly, and by March 30, the framework for the new building including the supporting pillars and roof trusses were in place. Scores of pipes were arranged outside of the security wall on the west side of the complex, waiting to be installed.

The floor plan revealed a large central hall with support offices arranged along each side of the building and its ends. This layout is similar to the suspected uranium enrichment facility at Kangson, located south of Pyongyang. By April 10, a roof had been added over the central, open-bay portion of the building, and by May 26, the building was externally complete.

The use of pillars likely indicates the installation of a suspended floor, as high spin-rate centrifuges require vibration free floor support. The dimensions of this new building, measuring approximately 120 meters by 47 meters, are similar to the facility at Kangson, which measures approximately 116 meters by 47 meters.

Together, the footprint, construction design, and level of security for the new building are comparable to what is observed at Kangson, although differ from the known uranium enrichment facility at Yongbyon.

Other Developments

Two additional developments are notable.

First, imagery shows what is likely to be a second underground radioactive waste storge facility. The building, measuring approximately 20 by 12 meters, appears to have walls made of solid concrete and is fitted with nine probable access hatches on its roof. It is nestled into a hillside where its sides are likely to be backfilled with earth. Excavating in preparation for the new vault began sometime in early April. A similar burial vault is located 100 meters southwest. That site was visited by inspectors in the mid-1990s. It had been covered over with dirt and became part of agricultural field until May 2023 when it was exhumed, apparently for re-access to the vaults. Given the planned increase in nuclear materials production, an additional storage facility would be warranted.

Second, efforts to raze the abandoned 50 MWe reactor appear to have resumed in recent weeks. Previous dismantlement activities were detected in May 2021 when the roof to the reactor’s cooling pool was removed.  Dismantlement continued for number of months but was short-lived. The effort appeared to be more about cannibalizing construction materials than actual disassembly. This new activity appears to be a more serious effort and could indicate the site may soon be repurposed.