I recently carried out thermal infrared analysis of the area around the Yongbyon nuclear complex, which is located in North Pyongan Province. The analysis detected signs of suspected activities related to the production of nuclear materials, with high heat emanating from the surface, suggesting the complex’s major nuclear facilities have been in operation even in the middle of winter.

The thermal infrared satellite photos were taken using NASA’s Landsat 8 satellite on Feb. 7. The Landsat 8’s thermal infrared images detect temperatures and heat emanating from the surface in 100 meter resolution. The Landsat series takes thermal infrared photos every eight days; the images are open to the public and can be downloaded from the Internet for free. Such photos are widely used in researching surface temperature changes, for example in the study of global warming and urban heat islands. They are also used to detect whether facilities are in operation by detecting heat produced by factories or other industrial facilities.

Using thermal infrared imagery, I carried out an analysis of the Yongbyon area (Image 1). For the names and positions of the major nuclear facilities, I referenced detailed analysis of the Yongbyon region from 38 North and Beyond Parallel.

(Image 1) Thermal IR analysis of Yongbyon’s nuclear facilities

Yongbyon nuclear facility analyzed using thermal infrared imagery. The reprocessing facility and uranium enrichment facility are bright pink because they are producing heat, which suggests they are in operation. (SkySat, Landsat 8)

The image above is a compilation of low-resolution Landsat thermal infrared imagery and high-resolution SkySat imagery (resolution: 50 centimeters). Changes in the temperatures detected in the thermal infrared images are shown in red of varying shades, while SkySat images taken on Feb. 4 form the background to help viewers get a better picture of the facilities on the ground.

In Image 1, the thermal infrared imagery used a gradation palette, with high temperatures shown in light red and lower temperatures in dark reddish brown. Looking at the reprocessing facility in the center and uranium enrichment facility on the right, one will see places in bright pink. Places in light pink are producing high heat because they are warmer than the areas around them. The area near the 5MWe reactor on the left side of the image is also producing high heat, albeit less so.

All the major facilities at the Yongbyon nuclear complex are producing high heat, suggesting that the three facilities have been in operation even in the middle of winter.

Next, I looked at the temperature distribution inside the complex by turning the brightness values in the thermal infrared imagery into Celsius numbers.

(Image 2) Analysis of temperature distribution at the Yongbyon complex

Thermal infrared imagery converted and analyzed to produce a temperature distribution map, with colors representing a 1 degree centigrade gradation. (Landsat 8)

Thermal infrared imagery indicates the intensity of heat or temperatures, so to perform meaningful analysis, one must transform the imagery into surface temperatures in Celsius using formulas and procedures. Using the geographic information system (GIS) software ArcGIS, I transformed the thermal infrared data with formulas and procedures in 2013 research produced by the US Geological Survey (USGS). The temperature distribution was rendered as colors and produced in Image 2.

In Image 2, the heat distribution at the Yongbyon nuclear complex was displayed as a color scale at one degree intervals. On Feb. 7 (around 10:30 AM), in cold, sub-zero temperatures, Yongbyon’s temperature distribution ranged from -1 degree to -7 degrees.

The temperatures determined from the thermal infrared imagery are indirectly measured using formulas, so there is a margin of error. According to 2013 research by the USGS, the margin of error is plus or minus 3 degrees celsius. For a more accurate measurement, one needs to directly measure the temperature on the ground using a thermometer.

(Image 3) Detecting high heat at major nuclear facilities at Yongbyon

Warmer areas of the temperature distribution map extracted and overlaid on SkySat’s high resolution imagery. (SkySat, Landsat 8)

From Image 2’s temperature distribution data, I extracted areas of high heat of -1 to -3 degrees celsius and superimposed them on SkySat’s high-resolution imagery to produce Image 3.

The reprocessing facility and uranium enrichment facility were generating heat, posting temperatures of -1 and -2 degrees (Image 3), relatively warm compared to surrounding areas that were at -3 and -4 degrees. In particular, the area around the incineration building at the reprocessing facility was lit up bright (-1 degree), suggesting brisk activities related to incineration. The 5MWe reactor was at -3 degrees — considering that the area around it was -4 or -5 degrees, this suggests the reactor was in operation and producing heat, too.

The website 38 North produced an analysis last October that suggested Yongbyon’s 5MWe reactor had been in operation for over a year, and that North Korea was expanding auxiliary facilities nearby.

Conclusion

Through my analysis, I detected circumstantial evidence that the major nuclear facilities of the Yongbyon complex in North Pyongan Province were in operation amid freezing cold and sub-zero temperatures the region has been experiencing. The reprocessing facility and uranium enrichment facility were producing high heat, suggesting they have been in operation. This suggests that North Korea is engaged in activities to produce nuclear materials like extracting plutonium or enriching uranium. The area around the 5MWe reactor is also producing heat, meaning the facility is likely in operation.

Over the past year, North Korea has conducted a great number of provocations, including a record 69 missile launches last year and the firing of an ICBM on Feb. 18. The detection of activity at the Yongbyon nuclear site through thermal infrared satellite imagery should be of concern to everyone worried about security issues on the Korean Peninsula and in Northeast Asia.

Bruce Songhak Chung is a former researcher at South Korea’s National Institute of Forest Science and now serves as the deputy director of the Geo Satellite Information Research Institute at Kyungpook National University in South Korea.

Corrections: This translation of the original Korean article was revised to correct several typos, including Lansat -> Landsat. 

Translated by David Black. Edited by Robert Lauler. 

Views expressed in this guest column do not necessarily reflect those of Daily NK.

Read in Korean

Dr. Bruce S. Chung previously worked for South Korea’s National Institute of Forest Science and is now the head of the Satellite Analysis Center at the Korea Institute for Security Strategy. Bruce received his Ph.D. in Remote Sensing and GIS from the University of Idaho in 1992, an M.S. from Seoul National University in 1986, and a B.A. from Chungbuk National University in 1982. He can be reached at chungsh1024@naver.com.