Thermal imagery analysis of the Yongbyon Nuclear Scientific Research Center indicates that from September 2016 through June 2017:
- The Radiochemical Laboratory operated intermittently and there have apparently been at least two unreported reprocessing campaigns to produce an undetermined amount of plutonium that can further increase North Korea’s nuclear weapons stockpile. This suggests batch rather than continuous processing of spent fuel rods from the 5 MWe Reactor during the period of analysis.
- Increased thermal activity was noted at the Uranium Enrichment Facility. It is unclear if this was the result of centrifuge operations or maintenance operations. Centrifuge operations would increase the North’s enriched uranium inventory; however, based on imagery alone, it is not possible to conclude whether the plant is producing low or highly enriched uranium.
- The thermal patterns at the probable Isotope/Tritium Production Facility have remained consistent, suggesting that the facility is not operational, or is operating at a very low level. This means, the facility is likely not producing tritium, which is an essential isotope used in the production of boosted yield nuclear weapons and hydrogen bombs.
- From December 2016 through January 2017, the thermal pattern over the Experimental Light Water Reactor (ELWR) was elevated. While that might indicate that the reactor was operational, the likelihood is low since the pattern does not appear in subsequent imagery over the last six months. It is possible that there are alternative explanations for the elevated pattern, for example, short-term activity at the ELWR such as the heating of pipes to prevent freezing. Regardless, any activity at the ELWR is cause for concern and bears continued monitoring.
- The 5 MWe Reactor has either been intermittently operating at a low-level or not operating. The notable exception to this was during December 2016 and January 2017 when thermal patterns suggests a higher level of operations.