New commercial satellite imagery confirms that North Korea is making important progress in activating key nuclear facilities at Yongbyon, including the 5 MWe gas-graphite reactor and the 20-30 MW(th) Experimental Light Water Reactor (ELWR). In addition, imagery of a transshipment yard created in 2011 for handling equipment and cargo to support construction at the ELWR and now probably the 5 MWe reactor shows a high-level of recent activity at these sites.
Pyongyang is nearing completion of work necessary to restart the 5 MWe reactor used to produce North Korea’s supply of weapons-grade plutonium. A new system to provide secondary cooling for the reactor using a nearby pump house appears almost finished. Two tanks adjacent to the spent fuel handling building have also been buried to ensure adequate water is available for the safe storage of used rods from the reactor. External activity suggests that work is continuing inside the reactor building.
The 5 MWe reactor may be 1-2 months from start-up but the availability of fresh fuel rods to power the reactor remains uncertain. Once operational, the facility will be able to produce approximately 6 kilograms of plutonium per year that can be used for manufacturing nuclear weapons. Whether production can continue indefinitely depends on the availability of fresh fuel rods.
The North Koreans appear to be finishing interior work on the ELWR and are connecting the end of the existing power line with the electrical substation adjacent to the reactor building in order to provide power to the reactor and possibly carry it to the grid. They may still be months away from beginning a shakedown period that could last as little as 9-12 months before the reactor becomes fully operational. Once again, the availability of fuel is uncertain and remains the key hurdle.
Recent imagery also shows the construction of an extension to a “barracks-style” building east of the 5 MWe reactor that was built in 2009 at the same time ground was broken at the ELWR and its Uranium Enrichment Facility. The building’s function remains unknown although the addition was finished in four months, indicating that it was a high priority.
Restart of the 5 MWe Reactor Moving Forward
Recent commercial satellite imagery of the 5 MWe reactor indicates that the North Koreans have essentially finished repairing the cooling system necessary to restart and operate the reactor. Rather than rebuilding the cooling tower that was destroyed in 2007 as part of the Six Party Agreement, the new system connects the secondary cooling system to the pump house that was built for its new Experimental Light Water Reactor (ELWR), which is located adjacent to the old reactor. The “copy” of the Yongbyon reactor that North Korea was constructing in Syria before it was destroyed by Israeli warplanes in 2006, also used a pump house instead of a tower to provide secondary cooling.
Piles of construction material are on the road and a probable truck delivering this material is present. This material is probably related to continued work inside the reactor building. Also, a new ditch is being built leading to the river on the buildings east side, perhaps creating a drain for water that will come from the reactor building. In mid May, the pipes for the drain can be seen on the adjacent road (figure 1) but by May 22, they have been installed in the ditch (figure 2).
Figure 1. Construction around the 5 MWe reactor.
Figure 2. Piping being installed in the drainage ditch.
The 5 MWe reactor may be 1-2 months from start-up. However, the availability of fresh fuel rods to power the reactor—a key factor that will determine when the North will restart the facility—remains unclear. Once the reactor is operational, it will be able to produce 6 kilograms of plutonium per year. Whether it can continue that production indefinitely depends on the availability of fresh fuel rods.
Reactivation of the Spent Fuel Facility
Originally built to store spent fuel rods for the 5MWe gas-graphite reactor, this facility will probably perform that purpose once the reactor is restarted. Since the facility is adjacent to the new ELWR, it may also serve the same function for the new reactor.
Two tanks adjacent to the spent fuel receiving building have been recently buried, probably to ensure that adequate water is available for storage of the spent rods. The tanks were seen on the road to the east of the ELWR in November 2012 as holes for them were being dug at the building (figure 3). By January 2013 they had been placed in the holes (figure 4). By early April 2013 the tanks were being buried and that process was completed by the middle of the month (figure 5). In addition, construction continues to be visible inside the center of the three buildings.
Figure 3. Water tanks spotted on the road.
Figure 4. Water tanks placed by the spent fuel storage building.
Figure 5. Water tanks buried.
Construction at Unidentified Building
East of the 5 MWe reactor is a new “long barracks-style” building built in 2009 at the same time North Korea broke ground on the ELWR and its new Uranium Enrichment Facility. They recently completed an extension to this building, which may be related to activities at the 5 MWe reactor. Imagery from March (figure 6) showed that the inside of the extension consists of 9-12 small rooms (approximately 5.5m x 4m in size) lining a central corridor. By April, the extension was externally complete with a roof added and a conduit was visible leaving the new portion of the building at its center and making a right angle turn south at the road (figure 7). The conduit was buried by May 3 (figure 8) and may connect to the water line serving the reactor.
Figure 6. Building extension construction underway.
Figure 7. Conduit leaving the building extension.
Figure 8. Conduit buried.
The function of this building extension remains unknown although the rapid completion of the addition indicates that it was a high priority. The only entrance into the extension is through the original building that also contains small rooms, indicating the two perform similar functions. The extension does not appear to be designed for administrative offices. A number of other roles are possible including as an auxiliary building for pumps and equipment related to the reactor’s secondary cooling system.
Final Touches on the ELWR
Satellite imagery from May 3 shows that the North Koreans have excavated a ditch that when complete, will probably connect the end of the existing power line with the electrical substation adjacent to the reactor building (figure 9). By May 22, while the trench for the electrical connection is still open and not yet connected to the reactor substation, the pipe has been partially laid and work is in progress (figure 11). The electrical cables will provide power to the reactor building and possibly carry power generated by the ELWR to the grid. In addition, imagery from mid May showed materials positioned at the southern side of the ELWR and assembled on the hardstand west of the reactor building probably for installation inside (figure 10). By the 22nd, most of the materials seen had been removed.
Figure 9. New ditch excavated.
Figure 10. Materials assembled for installation.
Figure 11. Materials removed and pipe partially laid.
Activity at the Transshipment Yard
North Korea created a large transshipment and storage yard just west of the ELWR in the five months between October 2010 and April 2011. The purpose was to facilitate construction of the new facility and perhaps the more recent effort to restart the 5 MWe reactor. Since Yongbyon is not served by rail-lines, all cargo must be shipped to the site by truck or barge. The yard, which allows North Korea to store construction materials and other reactor related items until they are needed, contains a large movable overhead crane, a movable vertical crane and a paved rectangular pad under the overhead crane. Since Yongbyon has been imaged frequently over the last three years, examination of past activity in the transshipment yard could help analysts better understand work underway at the two reactors.
Figure 12. Activity at the transshipment yard.
Recent satellite imagery shows a high-level of activity at the transshipment yard further confirming the conclusion that the work at the ELWR, the 5 MWe reactor and associated facilities is moving forward at a steady pace. On April 19, there was a large amount of materials on the pad, probably awaiting installation in the facilities. By mid May, most of the materials had been moved off the pad.
Figure 13. Several materials on the pad.
Figure 14. Most materials on the pad have been cleared.
 Siegfried S. Hecker, “A Return Trip to North Korea’s Yongbyon Nuclear Complex,” Center for International Security and Cooperation, Stanford University, November 201, 2010, http://iis-db.stanford.edu/pubs/23035/HeckerYongbyon.pdf.