Manpo Unha Factory Part 1: A Missing Piece in North Korea’s Nuclear Puzzle

Key Findings

• The Manpo Unha Factory is an important but little-known component of North Korea’s nuclear infrastructure as the prime supplier of various bulk chemicals to the Yongbyon Nuclear Research Center.
• Among the chemicals reportedly supplied to Yongbyon is nitric acid, a crucial component to the chemical reprocessing campaigns conducted at Yongbyon’s Radiochemistry Laboratory for producing Plutonium-239 from spent fuel rods. Nitric acid also plays an essential role in the initial stages of the production of uranium hexafluoride (UF6) from yellowcake, which is used to produce highly enriched uranium (HEU) at Yongbyon.
• Aside from supporting the nuclear program, the Manpo Unha Factory has reportedly occupied a significant position in the research and production of liquid rocket fuel and chemical weapons at various times.
• The importance of the Manpo Unha Factory to North Korea’s nuclear, chemical, and ballistic missile programs is indicated by its ongoing development and several visits by the leadership.
• As the prime provider of chemicals to the Yongbyon Nuclear Research Center, the Manpo Unha Factory would presumably have to be subject to declaration, verification, and dismantlement in any future final and fully verifiable denuclearization deal with North Korea.

This two-part report identifies the Manpo Unha Factory as the source of the specialized rail tank cars first observed at the Yongbyon Nuclear Research Center during the early 2000s.¹ The first part introduces the Manpo Unha Factory and its connection to the Yongbyon Nuclear Research Center, and the second part will discuss the development the Manpo Unha Factory and its surrounding area over time.

Research Overview

The identification of the Manpo Unha Factory was made possible through the extensive analysis of commercial satellite imagery, interview data, and prolonged open source and declassified document research.² A synthesis of this research has also provided a basic understanding of the development of the Manpo Unha Factory for 20+ years as the prime supplier of various bulk chemicals to the Yongbyon Nuclear Research Center.³ Notable among the chemicals reportedly supplied is nitric acid,⁴ which is crucial to the chemical reprocessing campaigns conducted at the Radiochemistry Laboratory to produce plutonium from spent fuel rods and the initial stages for the processing of yellowcake (U3O8) into uranium hexafluoride (UF6) used to produce highly enriched uranium (HEU) at Yongbyon.

For this report, 514 high-resolution commercial satellite images were processed and analyzed. Of these images, 296 covered the Manpo Unha Factory and Yongbyon Nuclear Research Center, and 216 images covered seven additional chemical complexes in North Korea: February 8 Vinalon Complex (2.8 Vinalon Complex), July 21 Chemical Factory (Aoji Chemical Factory), Namhung Youth Chemical Complex, No. 13 Explosives Plant, Ponghwa Chemical Plant, Pyongsan Uranium Concentrate Plant, and the Sunchon Chemical Complex. While the specialized rail tank cars were observed on 97 occasions at either the Manpo Unha Factory or Yongbyon Nuclear Research, there were no sightings at any of these additional chemical complexes. This imagery analysis combined with interview data strongly supports the assessment that the Manpo Unha Factory is the source of the specialized rail tank cars observed at the Yongbyon Nuclear Research Center and that the factory is linked to North Korea’s nuclear program.⁵

This imagery analysis, while extensive, is not exhaustive. It is hoped that with additional funding, an even more comprehensive examination of the Yongbyon Nuclear Research Center, Manpo Unha Factory, and the broader North Korean chemical infrastructure will yield greater insight and potentially reveal new components of the nation’s nuclear infrastructure.

The publication of this report may result in a North Korean response that has the potential to make identification of the specialized rail tank cars more challenging in the future. Such response could include the sudden disappearance of these railcars or their appearance at other locations across the nation to camouflage, conceal, or deceive observers regarding their use and other infrastructure elements supporting the nuclear program.

Finally, it is important to note that accuracy in any unclassified discussion of North Korea’s nuclear, biological, chemical, or ballistic missile programs is always a challenge. Some of the information used in the preparation of this first public attempt to describe the factory will undoubtedly prove to be incomplete or incorrect. However, the report aims to provide a new and unique look into the subject and encourages future discussion.

The Connection to Yongbyon: Overview

The Manpo Unha Factory (만포은하공장) is located 5 kilometers southwest of Manpo-si (만포시, Manpo City), Chagang-do (자강도, Chagang Province), approximately 155 kilometers northeast of the Yongbyon Nuclear Research Center, along the Amnok-gang (압록강, Amnok River, Yalu River), and on the North Korea-China border.⁶

Construction of the Manpo Unha Factory began in late 1973, and the factory appears to have been operational by 1975. Since it became operational, various declassified intelligence documents and author interviews collectively suggest that the factory has produced and supplied chemicals to four different sectors including:

• Liquid rocket propellant production
• Chemical agent/weapons research and production
• Nuclear research, development, and production
• Industrial production

Liquid Rocket Propellants: According to a March 1980 report by the U.S. Central Intelligence Agency (CIA), the Manpo Unha Factory likely began operations in the mid-1970s when it likely began the production of liquid rocket propellants.⁷ According to the document, the factory was producing “highly concentrated hydrogen peroxide.”

Although it appears that the Manpo Unha Factory, along with the No. 13 Explosives Plant and Aoji Chemical Factory, was also producing nitric acid-based oxidizers (IRFNA – inhibited red fuming nitric acid) for the S-75 Dvina (SA-2 Guideline) surface-to-air missile and P-15 Termit (SS-N-2 Styx) anti-ship missiles, both acquired from the Soviet Union during the 1960s. During the early 1980s, North Korea acquired its first R-17E Elbrus (SS-1C Scud-B) surface-to-surface missiles from Egypt. The Scud also used a form of IRFNA, as have some of North Korea’s subsequent liquid-fueled missiles and space launch vehicles.

Chemical Weapons: During the late 1980s, private interviews and open source reporting began associated the Manpo Unha Factory with North Korean chemical weapons research and production.⁸ Reports of the factory’s involvement in chemical weapons production have continued until present, for example,⁹

“[The] Manpo Chemical Complex is a chemical weapons production plant.  One or more of sarin, tabun, phosgene, adamite, prussic acid, or mustard gas family of blood products or tear gas products are known to be manufactured here.”¹⁰

Although almost all such reports indicate actual chemical weapons production, there is a reasonable chance that the factory may only be producing chemical weapons precursors.

Nuclear Program: While details are lacking, the chronology of North Korea’s nuclear program suggests that the Manpo Unha Factory began supporting the Yongbyon Nuclear Research Center and North Korea’s broader nuclear program shortly after it became operational in the mid-1970s. This support likely centered around research originating with the operation of the IRT-2000 research reactor that first went critical in the mid-1960s—ten years before the Manpo Unha Factory became operational.¹¹

If confirmed, the Manpo Unha Factory’s support of the nuclear program likely increased in the years following the loading of the 5MW(e) Experimental Nuclear Power Plant in 1985 and its operation.¹² Subsequently, following the construction of the Radiochemistry Laboratory during the 1980s and the hot test of the facility during 1990s¹³, the quantity of the chemicals supplied to Yongbyon is highly likely to have increased.¹⁴ Given the Manpo Unha Factory’s experience with nitric acid-based oxidizers, nitric acid from the factory likely occupied a growing percentage of these deliveries as it was crucial in the early chemical reprocessing tests undertaken at small experimental laboratories and by the campaigns at the Radiochemistry Laboratory to produce plutonium from spent fuel rods.

Despite the bulk shipment of chemicals using the specialized rail tanks cars likely began in the late 1980s, this cannot be confirmed through satellite imagery as high-resolution declassified satellite imagery of both the Manpo Unha Factory and Yongbyon Nuclear Research Center is not yet available for the years from 1985 through 2000.¹⁵ However, high-resolution commercial satellite imagery of these facilities first became available in the early 2000s and has revealed the presence of these specialized rail tanks cars on 95 occasions at either location. The most recent observation of the specialized rail tank cars was in an image captured on March 17, 2023, demonstrating the continued relationship between these facilities.

The quantity and composition of the chemicals supplied by the Manpo Unha Factory to the Yongbyon Nuclear Research Center have undoubtedly ebbed and flowed over the years with the level and nature of activities at Yongbyon, international negotiations, and national economic and domestic conditions (e.g., Arduous March, COVID pandemic, etc.).

Industrial Production: Little is known concerning the Manpo Unha Factory’s reported contributions to wider military (e.g., arms production factories in Kanggye, Huichon, and others in Chagang-do and Pyongan-bukdo) and nominally civilian production.¹⁶ However, at least two reports suggest a contribution to the civilian sector, including a June 1960 KCNA report that stated the “Manpo Unha Factory topped its first half-year quota 26.5 percent at the end of April.”¹⁷ In addition, during September 2010, Kim Jong-il revisited the factory and viewed “…a variety of consumer goods made by the factory… He appreciated the devoted service rendered by the workers of the factory for improving the standard of people’s living.”¹⁸

Specialized Rail Tank Cars

To date, the specialized rail tank cars observed at the Manpo Unha Factory, along the Manpo Unha Factory’s spur line, and at the Yongbyon Nuclear Research Center have been seen in at least six different configurations. Although the reason for these different configurations is unclear, it is suggestive of different chemicals being transported, the date and location of rail car manufacture, or a combination of these and other factors.¹⁹ It should be noted that the dimensions presented below are provisional as the relatively small size of the railcars make it very challenging to precisely measure them considering the different resolutions, look-angles, and shadows present in the available satellite imagery.²⁰

1. An approximately 11-meter-long flatcar carrying four tanks mounted across the width of the railcar.

2. An approximately 13-meter-long flatcar carrying four larger tanks mounted across the width of the railcar.

3. An approximately 13-meter-long flatcar carrying five smaller tanks mounted across the width of the railcar.

4. An approximately 13-meter-long flatcar carrying five tanks, four of which are mounted across the width of the railcar, two at each end, and the fifth tank mounted in the center, in line with the length of the railcar.

5. An approximately 14-meter-long flatcar carrying four tanks. Two of which are mounted in the center across the width of the railcar, and the other two tanks mounted one at either end in line with the length of the railcar.

6. An approximately 14-meter-long flatcar carrying five tanks, four of which are mounted across the width of the railcar, two at each end, and the fifth tank mounted in the center, in line with the length of the railcar.

These specialized rail tank cars are almost always observed connected to, or in the company of, an approximately 12-meter-long railcar. This railcar is similar in design to what are called “transfer cabooses” in American railroading terms—this term will be provisionally used.²¹ If correct, it is probable that the personnel riding in this railcar are responsible for both physically protecting the tank cars and monitoring them for any breakdown or damage suffered during the rail trip between locations.²²

A review of 216 high-resolution commercial satellite images, taken between 2004 and 2023, of seven additional chemical complexes was conducted to further understand whether the Manpo Unha Factory is the source of the specialized rail tank cars seen at Yongbyon. The complexes reviewed included the February 8 Vinalon Complex (2.8 Vinalon Complex), July 21 Chemical Factory (Aoji Chemical Factory), Namhung Youth Chemical Complex, No. 13 Explosives Plant, Ponghwa Chemical Plant, Pyongsan Uranium Concentrate Plant, and the Sunchon Chemical Complex.

This review failed to identify the specialized rail tank cars at any of the studied locations. Instead, these factories contain numerous standard rail tank cars and sometimes lesser numbers of Horton Sphere railcars.²³ The lack of the specialized rail tank cars at the seven additional chemical complexes further indicated a relationship of significance between the Manpo Unha Factory and the Yongbyon Nuclear Research Center.

The Rail Route from Manpo to Yongbyon

Once loaded at the Manpo Unha Factory, the specialized rail tank cars are grouped by a diesel yard locomotive into what is called a consist in American railroading terms. This refers to a group of railcars with the same destination or grouped together for safety reasons. These have generally been observed composed of three specialized rail tank cars and a transfer caboose. However, on a few occasions, when they have consisted of only two or as many as four rail tank cars and a transfer caboose. These are then set out for pickup at the Unha Rail Station (Unha-yok, 운하역) inside the factory or further north along the Manpo Unha Factory’s industrial spur line.

Once picked up from the Manpo Unha Factory, the consist travels through the Manpo rail station and then along a section of the 288-kilometer-long Manpo-Sunchon Rail line passing through Kanggye and Huichon to the Kujang Rail Station (Kujangchongnyonyok, 구장청년역).²⁴ Here, they are switched to a branch line that takes them to the rail station at Namyang (Namyang-yok, 남양역) west of Yongbyon. At Namyang, they are switched to the industrial spur line leading to the Yongbyon Rail Station (Yongbyon-yok, 영변역, sometimes identified as the Pungang-ni Rail Station) and then into the Yongbyon Nuclear Research Center itself. Here, satellite imagery shows that it is not unusual for the consist to be uncoupled and moved around the facility individually. At Yongbyon, these railcars have been observed at four locations:

1. Yongbyon Rail Station
2. On the industrial spur line leading to the southern half of the center
3. At the Radiochemistry Laboratory
4. At the stub terminal immediately east of the Centrifuge Plant

What’s in a Name?

Regarding its nuclear, chemical, and biological weapons and missile programs, North Korea frequently assigns facilities several names: the de facto designation of the facility, a cover designation (often numerical),²⁵ and a public name and/or honorific. Many common public names used are derived from using a nearby city or town name and function type (e.g., coal mine, explosives plant, chemical plant, etc.).

We do not know the factory’s de facto designation, although one South Korean Government source uses “No. 14 Factory.” To ease readability and for consistency, this report uses the most common form of “Manpo Unha Factory.”

The transliteration of Korean place names into English is frequently challenging and often results in confusion, and the Manpo Unha Factory is no exception to this phenomenon. Some non-Korean names for the facility sometimes add additional confusion. Among the alternative transliterations and names commonly encountered are Jagang Province Manpo Chemical Factory, Manpo Chemical Plant, Liquid Propellant Plant in Manpo, Manpho Unhwa Factory, Manpo Chemical Complex, Manpo No. 14 Factory, Manpo Unha Plant, Manpo Unhwa Plant, Manpo-si Unhwa Factory, Manpo-up Explosives Plant, Manpo-up Liquid Propellant Plant, Manpo-up Propellant Plant, North Korean Liquid Propellant Facility, Unha Factory, and Unha Liquid Chemical Fuel Producing Factory.

To further add to the confusion, the Manpo Unha Factory is sometimes confused with the No. 13 Explosives Plant (a.k.a., “Manpo-up Explosives Plant,” “Manpo Up Propellant Ammunition Loading Plant 13,” and “Explosives Factory, Plant 13”) that is also located Manpo-si.²⁶

Author’s Note

This report has had a long and somewhat convoluted genesis. I first became aware of the Manpo Unha Factory during conversations with reliable sources in the late 1980s when it was identified as a facility associated with chemical weapons production. This subsequently led to an ongoing research effort to identify and describe the chemical weapons research, production, and storage infrastructure. Subsequently, during the very early 2000s, I was shown a commercial high-resolution satellite image of the Yongbyon Nuclear Research Center. Aside from an obvious interest in the nuclear facilities themselves, I was drawn to the presence of several specialized railroad tank cars both by their design and by the composition of their “consist” (railroad term for how the railcars are arranged). A few years later, while preparing a report on the Yongbyon Nuclear Research Center, these specialized railcars were again observed on numerous occasions. This precipitated an ongoing search over the years for similar railcars both in imagery of the Yongbyon Nuclear Research Center and North Korean chemical factories. A breakthrough was achieved sometime around 2018-2019 when a declassified U.S. Central Intelligence Agency (CIA) document was obtained that identified the Manpo Unha Factory as likely being involved in the production of liquid rocket fuel.²⁷ This added to my understanding of the factory and precipitated a detailed review of satellite imagery of the facility that revealed the presence of the same specialized rail tank cars that I had observed at the Yongbyon Nuclear Research Center. Subsequently, knowledgeable individuals confirmed the relationship between the two facilities.²⁸ Low-level research on the subject continued until early 2022 when it was decided to compile all this research into a single report to validate or negate assumptions and information concerning any relationships between the Yongbyon Nuclear Research Center, Manpo Unha Factory, and the specialized railroad tanks cars. The result of this effort is this report.

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