Work at North Korea Reactor Site Unclear

Peter Crail

North Korea is engaged in new construction work near its dormant nuclear reactor, the South Korean Defense Ministry said Oct. 5, raising concerns that Pyongyang is preparing to reconstitute the plant used to produce plutonium for its nuclear weapons. Yet, experts said that the purpose of the construction work seen via satellite photos is not clear and does not appear consistent with efforts to rebuild critical reactor structures.

North Korea is restoring nuclear facilities and continuing maintenance activities at Yongbyon,” a ministry spokesman said, citing Defense Minister Kim Tae-young’s comments to parliament the day before. The Yongbyon nuclear complex houses several facilities involved in North Korea’s nuclear weapons program, including a nuclear reactor to produce plutonium for weapons and a reprocessing facility to separate that plutonium from the reactor’s spent fuel.

In 2007, North Korea disabled three critical nuclear facilities at the complex as part of a February 2007 six-party agreement that included China, Japan, Russia, South Korea, and the United States. (See ACT, March 2007.) Pyongyang withdrew from those talks in April 2009 and subsequently reconstituted its reprocessing facility to separate an estimated bomb’s worth of additional plutonium. (See ACT, May 2009.)

Seoul’s claim appears consistent with a Sept. 30 analysis by the Institute for Science and International Security (ISIS), which said that commercially available satellite imagery showed construction at the former site of the Yongbyon reactor’s cooling tower. The reactor’s cooling tower was destroyed in June 2008 as part of the six-party talks. It would have to be rebuilt before the reactor could operate again unless Pyongyang decided to construct an alternative cooling system or run the reactor at far lower levels.

The ISIS analysis said, however, that “there is no indication in the imagery that North Korea is rebuilding its cooling tower.” The report notes that North Korea has constructed two buildings of unknown purpose instead and identifies construction or excavation equipment visible in the satellite photos.

Former Los Alamos National Laboratory Director Siegfried Hecker, who has visited the Yongbyon complex on several occasions, said in an Oct. 20 e-mail to Arms Control Today that there is no need to construct buildings to replace the cooling tower. “They must be doing something else,” he said.

Before North Korea can operate its reactor once again, it also must restore its secondary cooling loop, which was severed as part of the 2007 agreement, and prepare additional reactor fuel. Hecker said that restoring the cooling loop only requires replacing or rejoining the piping system, which “could be done in days to a week.”

A more time-consuming step is the preparation of fresh fuel for the reactor. North Korea still has about 2,000 fuel rods for the Yongbyon reactor left over from 1994, when the fuel fabrication facility last operated. It also has about 12,000 bare fuel rods for a larger reactor whose construction was halted that same year under a nuclear freeze agreement with the United States. A large portion of those fuel rods would need to be modified and clad in magnesium alloy before they can be used in the Yongbyon reactor.

“This may take up to six months,” Hecker said, “in which time [North Korea] could easily reconstruct the cooling tower.”

The Yongbyon reactor is North Korea’s sole source of plutonium for weapons, leaving its plutonium stockpile effectively capped until it is restarted. Pyongyang is believed to possess enough plutonium for four to 12 weapons.

North Korea also is believed to be pursuing a uranium-enrichment program, which can provide highly enriched uranium for weapons. After years of denial, Pyongyang first admitted to carrying out work on uranium enrichment last year. An Oct. 8 ISIS report assesses that Pyongyang has escalated this work, moving beyond “laboratory-scale work” to a possible pilot plant.

Pyongyang has recently repeated claims that it would strengthen its nuclear deterrent. Deputy Foreign Minister Pak Gil Yon told the UN General Assembly Sept. 29, “As long as U.S. nuclear aircraft carriers sail in the seas around our country, our nuclear deterrent can never be abandoned, but should be strengthened further.”

In an annual meeting of U.S. and South Korean defense ministers Oct. 8, Secretary of Defense Robert Gates told reporters that, in response to nuclear and conventional-weapons threats from North Korea, Washington is “committed to providing extended deterrence using the full range of American military might, from our nuclear umbrella to conventional strike and ballistic-missile defense.” A joint communiqué issued by the two countries the same day said that they agreed to institutionalize the Extended Deterrence Policy Committee to enhance the effectiveness of the extended deterrence relationship.