There has been uncertainty about the reasons for the 5 MWe Reactor’s shutdown, with speculation focusing on routine maintenance, more serious problems possibly with the cooling systems, a partial unloading of fuel rods (possibly defective) or the removal of the entire core. Evidence from the most recent imagery, while still insufficient to make a firm judgment, would seem to reinforce the hypothesis of a partial unloading of fuel rods. (Those rods would be transported underground from the reactor to the spent fuel cooling pond and then moved to the reprocessing facility by trucks or vehicles.)
The activity noted to support this hypothesis includes:
- Steam coming from a nearby large cooling tower is consistent with maintenance and testing (as well as possibly the making of chemicals related to reprocessing) and would be one of the first steps taken before commencing operations.
- Truck activity near the vehicle door to the receiving building is consistent with the transport of spent fuel rods from the cooling pond (where they are stored after removal from the reactor via an underground trolley system) and before they are moved to the reprocessing facility.
- Growing piles of a gray substance are visible on the east side of the old pilot fuel fabrication plant, now believed to manufacture fuel rods for the 5 MWe Reactor, as well as at a nearby settling pond. These piles are possibly the result of chemical processes related to new fuel rod production taking place inside the facilty.
New Pipeline under Construction: Masking Future Operations?
The October 28 imagery also indicates that the North Koreans may be building a new pipeline running from the pipe that carries hot water and steam from the 5MWe Reactor turbine building to the river. A new trench heads north under the bridge and seems to end across the road from the pilot fuel fabrication building. The final destination of the pipeline remains unclear. At the northern end of the trench, a crane or backhoe is visible just off the road. No further work on this pipeline appeared in imagery from November 4.
One objective of this activity may be to eliminate a key indicator of 5 MWe Reactor operations. Observing the white froth from the steam and water discharged into the river helped private analysts determine that the reactor restarted in August 2013 as well as the short period when it has been shutdown over the past year. Without this indicator, determining what is happening at the facility will become more difficult.
Masking operations at nuclear facilities may be an important priority for North Korea if past actions are any guide. Since the mid-2000s, if not earlier, Pyongyang appears to have taken steps intended to severely limit the ability of outsiders to monitor activity at the Radiochemical Laboratory. The same appears true at North Korea’s Punggye-ri nuclear test site where extensive steps have been taken to hide preparations at tunnel entrances and to prevent the leakage of particles from nuclear tests that could provide significant information of its capabilities to other countries.
Read more at North Korea’s Yongbyon Nuclear Facility: Reactor Shutdown Continues; Activity at Reprocessing Facility