In the January/February issue of the Bulletin of the Atomic Scientists, Siegfried S. Hecker and Robert Carlin assessed North Korea‘s nuclear developments in 2011. That assessment preceded the death of Kim Jong-il on December 17. This article supplements the Hecker/Carlin piece with detailed overhead imagery, additional analysis of Pyongyang’s march toward a more threatening nuclear weapons capability, and brief commentary on how the accession of Kim Jong-un to leadership may influence North Korea’s nuclear trajectory.
The first publicly available overhead imagery that suggested North Korea was constructing a new nuclear reactor at its Yongbyon complex appeared on November 4, 2010. Charles L. Pritchard, a former special envoy for negotiations with North Korea and the president of the Korea Economic Institute, along with a delegation from the institute provided the first confirmation of this construction after a visit to Yongbyon that week. The following week, Yongbyon officials told PDF Stanford University’s John W. Lewis and two authors of this article (Hecker and Carlin) that the reactor was designed to be an experimental pressurized light water reactor (100 megawatts thermal, or 25-30 megawatts electric) to be fueled with low-enriched uranium fuel produced in a newly constructed centrifuge plant at the nearby Yongbyon fuel fabrication plant. The new reactor is being constructed on the former site of a cooling tower for a now-disabled, 5-megawatt electric, gas-cooled, graphite-moderated reactor that had been used to produce plutonium; the tower was demolished in 2008 as a step toward an eventual denuclearization agreement.
The Yongbyon construction site that Pritchard, Hecker, Carlin, and Lewis saw was essentially at the stage of development captured in the overhead image in Figure 1. The foundation slab had been poured, and the steel-reinforced concrete containment structure was about one meter high, on its way to a final height of 40 meters. Additional excavation was visible along with the construction of several new buildings that looked like storage sheds.
Overhead image that provided the first evidence of the construction
of a new reactor at the Yongbyon nuclear complex.
Overhead imagery tracks construction progress during the past year — from September 26, 2010, to November 3, 2011 — as shown in Figure 2. Early images indicated that the construction of this new light water reactor began in late September 2010, near the site of the destroyed cooling tower.
A time sequence of overhead images of the light water reactor
site tracking its development from September 2010 to November 2011.
The images show the rapid rate of construction of the reactor’s exterior, including the development of the reactor containment structure and the adjacent turbine generator hall. As the photos indicate, not much progress was made between December 2010 and April 2011, likely because of the harsh North Korean winter.
The September 23, 2011, annotated image shown in Figure 3 demonstrates that much has been done since May. The dashed lines represent underground cooling pipes running from a newly constructed pump house to the Kuryong River (as seen in a May 22 overhead not shown here). The reactor building containment dome is partially complete, and construction has begun on the turbine generator hall. Construction trucks can be seen in the right-hand corner of the image. On the north side of the reactor is the skeleton of a structure for transferring equipment into the reactor hall during annual maintenance outages.
Annotated diagram of the new reactor site, shown in a photo indicating
significant progress in construction.
The latest available close-up overhead image, taken on November 14, 2011 (Figure 4), shows that many of the reactor’s external components are almost complete. Much progress has been made on the turbine generator hall; a traveling crane rail is already visible. The structure of the turbine pedestal inside the turbine building is already apparent. This is significant; it indicates that North Korea has a turbine design and possibly the ability to manufacture a turbine generator set that will fit within the dimensions of the turbine pedestal now under construction. The reactor building containment dome on the east side of the reactor’s containment structure is complete and will be placed on top of the containment structure once the large internal components of the reactor’s core have been inserted. For the first time, we see the appearance of small cylindrical components near the dome; these are likely parts of the pressure vessel that will go inside the containment structure.
Close-up overhead image of the new reactor site. This is the most
up-to-date image publicly available.
Using overhead images from Figure 4, we constructed a 3-D model (Figure 5) of the light water reactor using the open-source program Google Sketchup. Based on the model, it is obvious that the reactor’s exterior is almost complete. The model also provides perspective on the size of the reactor, which will be 40 meters tall when completed and stretch 20 meters in diameter.
Three-dimensional model of the light water reactor based on the
latest satellite images.
Our analysis confirms Pyongyang’s plan to use this experimental reactor for electricity production. The rapid progress of construction also demonstrates that North Korea still has impressive manufacturing capabilities, in spite of the last two decades of economic downturn. However, we view this progress with alarm. Was the seismic analysis of the reactor site sufficiently rigorous? Did the regulatory authorities have the skills and independence required to license this reactor in such a short time period? And do Yongbyon specialists have sufficient experience with the very demanding materials requirements for the internal reactor components, including the pressure vessel, steam generator, piping, and fuel-cladding materials? Continue reading