Grace LiuHot Dam(n): A Mistaken North Korean Enrichment Facility

by Grace Liu and Ben McIntosh

The possibility of undeclared North Korean nuclear facilities will be a major challenge to any effort to verifiably eliminate North Korea’s nuclear program.

In the past, diplomatic efforts have collapsed over allegations that North Korea was operating undeclared facilities. In some cases, claims of undeclared facilities have turned out to be mistaken. In other cases, however, such claims appear to have been true.

This issue reared its ugly head in Hanoi. According to US officials, North Korea offered to close a portion of the Yongbyon nuclear facility, but US officials chose to walk away from the agreement because North Korea had not offered to close the full “complex of sites that extends beyond Yongbyon.”

How far does this complex extend? What other facilities does North Korea operate? Answering these questions requires identifying facilities, but it also includes the far less glamorous work of excluding facilities that are alleged to be nuclear in nature but which can be ruled out on the basis of open-source information.

One facility that can be eliminated is the alleged uranium enrichment facility on the Taeryong river in Tongchang-gun (county).

In 2011 Park Sun-young, a South Korean parliamentarian, summarized defector testimony alleging that North Korea constructed a uranium enrichment facility in Tongchang-gun between 2006 and 2009. Ms. Park showed an image of the site (40.176667, 125.52111) which she asserted resembled the Yongbyon Nuclear Facility.

Alleged similarities between Tongchang (left) and Yongbyon (right). Source: Chosun Ilbo.

There are some aspects of the site that might catch the eye of an analyst. The most prominent is a large water outflow emerging from underneath the adjacent mountain. There are tunnel entrances providing access into the mountain, as well as large spoil piles from excavation within it. There also appears to be a transformer substation onsite.

Features around the area of interest in Tongchang-gun. Source: Digital Globe, annotations by author.

Open source information, however, allows us to identify the purpose of the location as something different altogether– an underground aqueduct that redirects water for hydroelectric power. The aqueduct is part of a large project to divert northward flowing water, originally headed to the Yalu River shared with China. The underground aqueduct carries the water 40 km underground southwest into the Taeryong River, to help fill a reservoir that was built to power five hydroelectric power stations near Taechon. This redirection also provides freshwater to irrigate crops in reclaimed tidelands west of Pyongyang.

The project began in the 1980s and is detailed in Hy-Sang Lee’s book, entitled North Korea: A Strange Socialist Fortress.  Beginning in 1981, Kim Jong Il authorized a number of ambitious nation-wide projects to reroute water for hydropower and crop irrigation. Excerpts taken from speeches given by Kim detail the national effort involved including building a 105 meter-high dam near Songwon, filling the reservoir, and draining the collected water through the underground aqueduct exiting at Tongchang.

Layout of the water redirection project, beginning at the Songwon reservoir. Source: Google Earth, annotations by author.

Satellite images from 1987 and 1988 show both the water outflow and spoil piles in place by the late 1980s, consistent with public descriptions of the construction of the hydroelectric facility.  This facility was not constructed in the 2006-2009 timeframe of the suspected enrichment plant.

Annotated images of Tongchang outlet and spoils piles in the late 1980s. Source:

This area was not immediately identifiable because North Korean officials usually refer either to Songwon, the source of the water for the aqueduct, or Taechon, the water’s destination.

For example, in 2000, premier of the DPRK cabinet Hong Seong-nam described work done on several hydropower projects, including expansion of Songwon and beginning the next phase of the Taechon hydropower project.

The Songwon-Taechon aqueduct is one of several underground aqueducts in North Korea. Similar aqueducts carry water to Chongjin (41.875058° 129.728037°), Wonsan and Anbyon (these as a series of interconnecting underground aqueducts from multiple reservoirs).

The underground aqueduct that supplies water to the Wonsan Youth Power Plant is the best of these projects and provides some insight into their structure and purpose.  This aqueduct carries water over thirty kilometers from the Kuryong reservoir to a series of hydroelectric plants in northeast Kangwon province.

A screenshot from a North Korean state news broadcast in the 2000s shows the layout for the water redirection to the Wonsan hydro-electric plants.

Drawing of concept for water redirection from Kuryong Reservoir to planned Wonsan power stations 1-4. Source: Youtube video (no longer exists)


Satellite image of possible aqueduct path. Source: Google Earth, annotations by author.

As with any analysis of North Korea, the convoluted actions taken by the regime in the name of Juche can fool even the sharpest eyed observer. In this case however, a combination of open-source information– first hand speeches by Kim Il-Sung, official videos, communications, and press releases from the government, and what can be physically seen from satellites– corroborates the true purpose of the Tongchang-gun site as a hydropower project, not an enrichment facility.

This case highlights the importance of establishing a deep understanding of what is “normal” and therefore what can be considered out of the ordinary in imagery analysis. While a large water outflow appearing from underneath a mountain may seem significant and potentially alarming, this is not especially unique in North Korea, given the country’s frequent and widespread practice of underground tunneling and water redirection projects. 

Art Lundahl once said to President Kennedy, when asked if he was sure about the missiles in the aerial surveillance photos that would spark the Cuban Missile Crisis, “I’m as sure of this, Mr. President, as we can be sure of anything in the photo interpretation field. And you must admit that we have not led you astray on anything that we have reported to you previously.”


  1. Lee Minjae (History)

    I do believe North Korea have done great job by not disclosing all nuclear facility or share the information of the location. The agreement should go both ways. US doesn’t want to give up anything but want they want North Korea to give up everything. This is not a good negotiation.