KH-4B Mission 1109, March 17, 1970

Collected 14 months after the image provided in Yongbyon Declassified Part V (November 21, 1968) this March 17, 1970 KH-4B image of the Yongbyon Nuclear Research Center shows continued expansion within the village of Sang-dong, minor improvements in the operations, administration/laboratory and support areas, slowly continuing construction of the bridge across the Kuryong-gang and minor infrastructure improvements in the Pungang-ni area. Taken as a whole, these developments continue to indicate an ongoing first-phase construction project for the facility and very early infrastructure development efforts within a longer-term plan for future expansion.

Within the town of Sang-dong the construction of new buildings continues. This is most notable in the center of the town where structures for government, security and housing use are being erected. Along the southern outskirts there continues to be minor changes among the town’s smaller structures.

The only significant changes noted within the operations area are that the internal road network appears to have been improved (likely paved) and that an adjacent trail, along the banks of the Kuryong-gang, has been improved and extends south to the new bridge construction site. No observable changes are noted to the IRT-2000 reactor building, associated support buildings or the electric sub-station to the west of the reactor. Within in the administration/laboratory area, in addition to the improved road along the Kuryong-gang that passes through it, the internal road network also appears to have been improved and extended.

Within the developing support area around the village of Pungang-ni, a trail along the Kuryong-gang has been improved into a road and now extends from north of the operations area south to the bridge construction site. Work slowly continues on the road bridge with ongoing work on the bridge’s piers, which now extend to the west bank, and development of the access roads on the east bank. There are still no indications in the imagery that work has begun on the future road tunnel on the east bank. Immediately west of the support area the primary irrigation ditch has been straightened and improved and the abandoned railroad right-of-way may have undergone some improvement as it is more clearly defined than previously observed.

No changes of significance are noted at the precast concrete plant southwest of the Pungang-ni, or in the area southeast of the bridge that will house the future Radiochemistry Laboratory, 50MWe reactor, fuel fabrication, centrifuge and other related facilities.