North Korea’s Yongbyon nuclear complex kept its key reactors and processing plants running through 2026, according to my analysis of satellite imagery. High-resolution photos and thermal infrared data show the site steadily expanding its capacity to produce fissile material for nuclear weapons. The complex lies about 100 kilometers north of Pyongyang and remains the country’s only known source of plutonium.
Cooling water continues to flow from pumping stations into the Kuryong River beside the complex. Thermal images also show steady heat emissions of around 26 to 28°C (79 to 82°F) in the reactor area. Both signs indicate that the 5-megawatt electric (5MWe) reactor and the 25MWe experimental light water reactor are still operating.
The strongest heat signatures, reaching 29 to 30°C (84 to 86°F), appeared around the Radiochemical Laboratory and the older uranium enrichment plant. That pattern suggests both plutonium reprocessing and highly enriched uranium (HEU) production are actively underway. The Radiochemical Laboratory is where North Korea extracts plutonium from spent reactor fuel. HEU is the other main fuel for nuclear warheads, giving Pyongyang two parallel routes to building bombs.
North Korea also appears to be modernizing the complex while trying to evade outside surveillance. A new uranium enrichment building has finished its roof and frame and is nearing completion. Demolition of the long-abandoned 50MWe reactor, meanwhile, continues at a steady pace. Workers have also repaired the outer walls and roof of the 5MWe reactor to reinforce the aging structure. The repairs also appear designed to keep the reactor’s heat from registering on foreign satellite sensors.
Taken together, these moves suggest Pyongyang is concentrating on maximizing its output of nuclear material. That fits with Kim Jong Un’s repeated calls for an exponential expansion of the country’s nuclear arsenal.
New enrichment hall rises as an old reactor comes down
Imagery from Planet Labs shows the Yongbyon nuclear complex shedding outdated facilities for newer, more efficient infrastructure. Planet Labs is a U.S. commercial satellite company that photographs nearly the entire globe every day.
On the north side of the complex’s center, crews have completed the exterior and roof of a new uranium enrichment building. North Korea appears to have built it to hold many more centrifuges alongside the existing enrichment plant to the east. The expansion would sharply raise the country’s capacity to produce HEU for nuclear weapons.
Dismantling work also continues at the site of the old 50MWe reactor. North Korea halted construction of that reactor under a 1994 nuclear agreement with the United States and never resumed it. Clearing away the obsolete structure appears to be part of a broader effort to modernize the complex as a whole.
The Radiochemical Laboratory and a thermal power plant that supplies the site with electricity also remain in place. By scrapping an outdated reactor while expanding enrichment, North Korea is overhauling the backbone of its nuclear material production.
Thermal images reveal hot spots across the Yongbyon nuclear complex
Landsat 9 captured thermal infrared imagery of the complex on Sept. 19, 2026. The Earth observation satellite, run jointly by NASA and the U.S. Geological Survey, measures heat given off by the ground. Its data show surface temperatures across the complex ranging from 18 to 30°C (64 to 86°F), with an average of 23°C (73°F).
The Radiochemical Laboratory at the center of the site and the thermal power plant to the east stand out in red. Both register readings of 29 to 30°C (84 to 86°F). This indicates that the laboratory is carrying out reprocessing work involving steam generation and heat treatment. The power plant, meanwhile, keeps supplying the complex with heat and electricity.
The two enrichment facilities show a sharp contrast in their heat signatures. The existing plant in the southeast forms a broad hot zone of 27 to 30°C (81 to 86°F). That reading is consistent with centrifuges spinning to enrich uranium. The area around the new enrichment building north of the center reads a cooler 21 to 26°C (70 to 79°F). The new facility may be at a different stage of the process or may not yet be fully operational.
Planet Labs imagery also shows cooling water flowing steadily into the Kuryong River from pumping stations near both reactors. This confirms that the 5MWe reactor and the light water reactor have been running continuously in recent months.
The 5MWe reactor building underwent a full overhaul of its outer walls and roof around June and July 2025. The work likely shored up an aging structure while also hiding the reactor’s heat from foreign thermal sensors. That may explain why the reactor gives off a relatively weak heat signature even though it is clearly operating. Cooling water has kept flowing through its nearby pumping station ever since the repairs ended.
Clear discharge traces also continue to appear on the river near the light water reactor’s pumping station. These show that the reactor’s cooling system is working hard to remove heat from the core. The light water reactor can produce more than five times as much plutonium as the 5MWe reactor. In my assessment, its continuous operation points to a push to stockpile weapons-grade plutonium and mass-produce nuclear warheads.
The International Atomic Energy Agency (IAEA), the United Nations nuclear watchdog, has reached similar conclusions from recent satellite imagery. The agency reports cooling water discharges and other signs of operation at the 5MWe reactor. It says the reactor has paused only briefly for maintenance rather than shutting down for long periods. The IAEA also notes ongoing activity at the light water reactor and new annex buildings at the enrichment plant. It reads these moves as an effort to boost North Korea’s enrichment capacity.
North Korea expelled IAEA inspectors in 2009, and the agency has had no on-site access to the country since. It relies mainly on satellite imagery and open-source information as a result. Its assessments therefore cannot pin down actual operating rates or output at individual facilities. Instead, they highlight reactor operations, enrichment work and facility upgrades all advancing at Yongbyon at once. This combined activity keeps expanding the foundation of North Korea’s nuclear weapons program as Pyongyang rejects calls for denuclearization.