North Korea’s Yongbyon Nuclear Center: Signs of Activity at the Radiochemical Laboratory Facilities

On March 1, 2021, the IAEA Director General Rafael Mariano Grossi stated in his introductory statement to the Board of Governors that, since his last report to the Board on September 3, 2020, “some nuclear facilities in the DPRK continued to operate while others remained shut down.” Regarding North Korea’s Yongbyon Nuclear Center, he went on to state there were “recent indications of operation of the steam plant” that serves the Radiochemical Laboratory. Recent commercial satellite imagery indicates the coal-fired steam plant (thermal plant) is, indeed, in operation again after a nearly two-year hiatus. Smoke was observed emanating from the plant’s smokestack at various times from late-February and early March, suggesting that preparations for spent fuel reprocessing could be underway to extract plutonium needed for North Korea’s nuclear weapons. However, this could also mean simply the facility is being prepped to handle radioactive waste.

Yongbyon Radiochemical Laboratory

Satellite imagery from February 25 and March 2, 2021, reveals that operations at the steam plant, which provides heat to the Radiochemical Laboratory, have resumed. While there were hints of a plume from the stack observed in May 2018, rarely has such clear evidence of the steam plant’s operation been observed.

The steam plant is located 550 meters south of the laboratories. Steam pipes connect the plant exclusively to the laboratory facilities, and thus it is at least one indicator of some level of operations within the Radiochemical Laboratory complex. Although, it is worth noting there were no unusual movements at the 5 MWe reactor or its adjacent spent fuel storage building, which would be another indicator of reprocessing activities.

Imagery signatures of operations at the Radiochemical Laboratory are subtle, and thus monitoring the level of activity at the facilities is difficult. One to three vehicles seen in the motor pool area are a normal occurrence. An occasional mobile crane or truck has been seen near the Fuel Reception building, where spent fuel is delivered from the 5 MWe Reactor. In September 2019, a number of unidentified cylindrical containers were staged along the access road to the building, but were removed by that October. There is a large ventilation stack located within the Radiochemical Laboratory complex, used in the purification of exhaust gases from the reprocessing plant, but it is rare to capture its emissions on imagery. Additionally, while it is noteworthy when there are such obvious signatures of plant operations, such as the smoke emission at the steam plant, without other evidence of reprocessing activity, this signature cannot be viewed as definitive.

Adjacent to the steam plant is a large covered coal storage building, served by a single-track rail spur. A covered conveyor transfers the coal to the furnaces, and the steam generated is moved to the Radiochemical Laboratory through a pair of parallel steam pipes. Coal cars, which bring coal to the covered coal building, are rarely seen, so measuring the amount of fuel consumed is not possible.

There are several sludge ponds located to the south side of the heating plant. On imagery taken as far back as April 2002, nine sludge ponds (five small and four large) were present. By 2010, only the four large ponds, arranged side-by-side, appeared to remain active. And by 2014, only two seemed to be used on a regular basis.  This apparent reduction of sludge suggests the steam plant is now operated less frequently and is likely timed more closely with earlier reprocessing campaigns.

Figure 1. Overview of Radiochemical Laboratory and steam plant, March 2, 2021.

Satellite image © 2021 Maxar Technologies. All rights reserved. For media licensing options, please contact [email protected].

Figure 2. Steam plant operations resumed, smoke emissions observed March 2, 2021.

Satellite image © 2021 Maxar Technologies. All rights reserved. For media licensing options, please contact [email protected].

Figure 3. Close-up of Radiochemical Laboratory complex, March 2, 2021. 

Satellite image © 2021 Maxar Technologies. All rights reserved. For media licensing options, please contact [email protected].
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