Yongbyon Nuclear Scientific Research Center: Ongoing Fissile Material Production and Fall Harvest Activity

Recent commercial satellite imagery of the Yongbyon Nuclear Scientific Research Center indicates ongoing fissile material production. Vehicles and personnel continue to move about the complex and evidence of activity is apparent. It is worth noting that older, outdated and derelict buildings are being razed, and new smaller buildings are being added in their place. This points to a systematic approach to upgrading and modernizing the key facilities around the complex.

Harvest season is also well underway in and around Yongbyon. Imagery from November 2 reveals bales of cut wheat in the fields surrounding the center, and as is usual practice, grain has been spread across roads, parking lots, and roof tops to dry it before the next rain.

The 5 MWe Reactor

Activity observed at the 5 MWe Reactor is at relatively normal levels, including light traffic and continued water discharge into the Kuryong River, suggesting the reactor has been operating since July 2021.

Around the reactor, there are several vehicles, including a red-cabbed, flatbed tractor-trailer, with unidentified materials on the bed. A similarly configured flatbed vehicle can be seen in the motor pool area of the Radiochemical Laboratory (RCL), which might signal the movement of these vehicles and their cargo between the two locations. In addition to the flatbed semi-truck, four other trucks are present—three are cargo and the third appears to be a tank truck.

Figure 1. Cooling water discharge and vehicle traffic observed at 5 MWe Reactor on November 2, 2022.

The Experimental Light Water Reactor (ELWR)

Activity is light at the ELWR area, and the reactor’s status remains unclear. Construction on the new support building, located immediately south of the engineering building, appears to be completed. However, earthmoving is noted to its south, suggesting that additional building(s) is planned.

The three new support buildings located just outside the security wall of the reactor area also now appear complete.

Figure 2. New construction and earthmoving observed at ELWR.

The Radiochemical Laboratory (RCL)

Aside from the several vehicles observed in the motor pool area, there is a small gathering of personnel in the front of the spent-fuel reception building. Otherwise, activity at the RCL is minimal. The new building under construction southwest of the RCL is getting its roof installed. It appears to be a two-story structure, but its purpose is yet unknown.

There are no signs reprocessing has started or is imminent. The Thermal (Steam) Plant is not operating and activities observed around the spent fuel building seen earlier this year have ceased. The last known plutonium reprocessing campaign occurred in the spring 2021.

Figure 3. Minimal activity seen at RCL.

The Former Fuel Rod Fabrication Plant

The Uranium Enrichment Plant (UEP) complex best captures the ongoing modernization process. The dismantlement or repurposing of the UO2 to UF4 Conversion Plant continues. Sunlight can be seen beaming through the walls and windows, suggesting the interior is being gutted. A detached smaller, tower building abutting it to the west is similarly in the processes of being razed.

In contrast, work on a new building located to the west of the conversion plant continues. Its interior walls have been erected and window openings can be seen.

Figure 4. Building construction and dismantlement/repurposing observed at UO2 to UF4 Conversion Plant.

While construction dominates the observed activity, operations continue within the complex.  This is evidenced with emissions being vented from the UO2 Plant and from the possible hydrogen fluoride (HF) plant.

Figure 5. Emissions visible from UO2 and possible HF plant.

Uranium Enrichment Plant (UEP)

Three trucks are observed at the west end of the UEP; one is parked at the transfer station with unknown cargo.

Fall harvest activity is also evident, as grain has been spread to dry within the courtyard of the UEP (Figure 4).

Other Activity

Construction continues on a building in the field immediately north of the pump house that was previously associated with the never-completed 50 MWe Reactor. Construction was first observed on imagery from October 18. A building has occupied this space prior to 2010, but was subsequently razed. This new building appears to have a roof in place, upon which two, possibly three, structures or objects appear. It also appears to be enclosed by a fence or wall.

Figure 6. Construction continues on building north of pump house.

At the city railroad yard in Dong-an, three specialized chemical railcars are observed, which have been associated with activities at the former Fuel Rod Fabrication Plant and UEP area. These are flatcars with four or five cylindrical canisters mounted on them. While their content is unknown, these railcars return to Yongbyon three to four times annually. At present, a locomotive is attached to the three-car train at its west end, suggesting the railcars will soon be departing the Yongbyon area.

Figure 7. Specialized chemical railcars seen at railroad yard in Dong-an.

Finally, the dam at the causeway, configured with four spillways, has been repaired after the late summer flooding and is operating. At this location, the river has been divided into three channels, which are connected by a causeway. The main river flow is through the center channel. The dam blocks the smaller east channel, and the west channel is active only during times of high river flow.

Figure 8. Dam dividing river into three channels operating.

The channeling of the river at this location has been an ongoing project for the past several years. Dredges have been active in the area, deepening the channels and building up the islands which separate the channels.