Yongbyon (Nyongbyon)

Fuel Fabrication Plant
New Uranium Enrichment Facility

During a hearing before the Senate Committee on Foreign Relations on 21 January 2004, Siegfried S. Heckler reported that during a 8 January 2004 visit of the American delegation, the North Koreans stated that they had one more load of fuel for their reactor at Yongbyon fabricated at that time. The fuel fabrication facility was said to be partially operational and partially under maintenance. They said they were in no hurry to fabricate more fuel since the 2 bigger reactors under construction were not close to operation. The US delegation did not visit the fuel fabrication facility. The fuel fabrication complex was previously reported to have been making fuel elements containing about 100 tonnes per year of uranium. The complex was believed to have produced enough fuel for the initial loading of the core for the 50 MWe reactor then under construction, but the nominal capacity was assessed as being appreciably larger.

Heckler reported in November 2010 that during a return trip that month, his delegation was taken to a new facility at the fuel fabrication site. That facility was located in what had been previously a dilapidated building, but which had been refurbished, complete with a new roof, and now contained a modern, small industrial-scale uranium enrichment facility equipped with 2,000 centrifuges. The facility was reported to have been recently completed and to be actively producing low enriched uranium destined for fuel for a new experimental light water reactor. Unlike all previously visited Yongbyon nuclear facilities, Heckler reported that the uranium enrichment facility was ultra-modern and clean. His delegation was also told that this facility was constructed and operated strictly with indigenous resources and talent.

Heckler reported that when his delegation was at the fuel fabrication plant they entered an apparenty new building about 100 meters long, across from the tall uranium oxide production building. This was later identified as the former metal fuel rod fabrication building he had visited in February 2008 to verify the disablement actions of the North Koreans. The delegation then walked up polished granite steps to the second-floor control room and observation area. Looking through the windows of the observation deck into the two long high-bay areas, the Heckler reported that he and his delegation saw a modern, clean centrifuge plant of more than a thousand centrifuges all neatly aligned and plumbed. There were 2 high-bay areas on each side of the central island. The high-bay areas were 2 stories high and Heckler's group was told they were 50 meters long each. The group estimated the width of the bays to be 12 to 15 meters. There were 3 lines of centrifuge pairs, closely spaced, the entire length of each hall. The group was told that the North Koreans had begun construction in April 2009 and completed the operations a few days prior to Heckler's arrival. Overhead imagery showed the building to have a new blue roof about 120 meters long.

Heckler's group estimated the centrifuges to be about 8 inches (20 cm) in diameter and approximately 6 feet (1.82 meters) high. They appeared to be smooth aluminum casings (no cooling coils visible) with 3 small stainless steel tubes emanating from the top to the central plumbing that ran the length of the facility. The chief process engineer later confirmed that they were aluminum alloy. The highest horizontal line appeared to be an insulated pipe about 10 cm diameter. The chief process engineer told us that the facility contained 2,000 centrifuges in 6 cascades (one thousand centrifuges and 3 cascades on each side). He did not provide Heckler's party with the physical dimensions, stating that the United States would also not release such proprietary information. The process engineer denied they were P-1 centrifuges. After being questioned by Heckler's group, the process engineer said that the rotors were made of alloys containing iron and implied that the rotors had single bellows. He claimed all components were manufactured domestically, but modeled after the centrifuges at Almelo in the Netherlands and Rokkasho-mura in Japan.

Heckler reported that the control room was "astonishingly modern." Unlike the reprocessing facility and reactor control room, which looked like 1950s US or 1980s Soviet instrumentation, the control room resembled a modern American processing facility. There were 5 large panels in the back that had numerous LED displays of operating parameters. There were computers and 4 flat-screen monitors, which had flow diagrams and lots of numbers displayed.

In the recovery room, Heckler reported seeing 2 operators, 2 flat screen panels, and lots of tanks and plumbing. There was a set of steps leading down to the ground floor. There were many small, galvanized steel panels and small tanks, and one big tank in the back. Heckler estimated the tank at about one meter diameter and 2 meters long, horizontally positioned.

The chief process engineer at the facility stated to Heckler's group that enrichment capacity was 8,000 kg SWU/year. The stated average enrichment level was 3.5 percent and the tails were 0.27 percent. Reactor designers in North Korea had told the chief process engineer to target enrichment levels from 2.2 to 4 percent. He claimed that the North Koreans were producing uranium hexafluoride, the feed material for gas centrifuges, but which they had never admitted having produced in the past. They said they had sufficient throughput for the size of the centrifuge facility. He said the process for learning how to make UO2 had begun, that it was difficult and that there would be problems. With no outside help, the chief process engineer said that the work would have to be done indigenously. When posed with a question from Heckler's group about potential concern about the production of HEU at the facility, he stated that anyone could tell just by looking at the monitors in the control room that the cascades were configured for producing LEU.