Satellite images takn on April 18 and 20 show steam being emitted from the thermal power plant within the Yongbyon Radiochemical Laboratory / Capture from RFA

Recent satellite imagery has revealed steam emissions from a building at North Korea's Yongbyon nuclear complex, likely indicating ongoing plutonium production activities. This observation lends credence to the assessment that North Korea continues to produce nuclear materials.

On Thursday, Radio Free Asia (RFA), a U.S.-based media outlet focusing on North Korea, reported that commercial satellite images captured by Planet Labs on April 20 showed steam rising from the radiochemical laboratory within the Yongbyon facility.

This laboratory is known to be the site where plutonium, a critical component for nuclear weapons, is extracted. Similar steam emissions were also observed on April 18. RFA interprets these occurrences as evidence of North Korea's intermittent nuclear fuel processing and reprocessing activities for plutonium production.

RFA's analysis of high-resolution satellite imagery of the Yongbyon area since January has consistently shown signs of cooling water discharge. Satellite images from March 12 and April 25 confirmed that cooling water was being released from a 5-megawatt reactor into the nearby Kuryong River.

The presence of cooling water discharge, according to RFA, indicates that the reactor is operational for plutonium production. Satellite imagery suggests that North Korea appears to be running the reactor almost daily.

However, Olli Heinonen, a former International Atomic Energy Agency (IAEA) deputy director general and current senior researcher at the Stimson Center, cautioned that if steam emissions persist for several weeks or longer, it would suggest ongoing plutonium extraction through nuclear fuel reprocessing. But if steam is observed only briefly, it might simply indicate waste transfer operations.

North Korea&#39;s nuclear material production facilities and nuclear weapons research institute / Rodong Sinmun

Significant Changes Observed at Fuel Rod Production Complex South of Yongbyon

Satellite imagery has repeatedly confirmed various construction projects throughout the Yongbyon nuclear facility, reinforcing its status as North Korea's primary nuclear site. A building with a blue roof, suspected to be a new uranium enrichment facility, completed its external construction between November and December last year.

From late December to early February, this building consistently showed no snow accumulation, unlike surrounding structures. Experts suggest this indicates active power supply to the building and ongoing internal construction work.

In March, two buildings within the radiochemical laboratory underwent roof replacements. These structures are believed to be connected to a facility for cooling and storing spent nuclear fuel and the plutonium laboratory.

Heinonen emphasized the importance of monitoring changes at the fuel rod production facility south of the Yongbyon complex. At least four new buildings have been erected in this area, with one notably fenced off from others, suggesting its high strategic importance.

While the exact nature of activities remains unclear, Heinonen argues they likely align with Kim Jong Un's plans to ramp up production of nuclear materials and weapons components.

Furthermore, numerous new high-rise buildings and houses have been constructed in residential areas near Yongbyon. Heinonen suggests these may serve as temporary accommodations for technicians and workers involved in the nuclear facility's construction projects, further indicating robust activity at the site.

Recent satellite imagery has revealed steam emissions from a building at North Korea's Yon …

North Korea's Yongbyon Nuclear Facility Shows Signs of Plutonium Production