The cylinder sections in this Nov. 3, 2011, satellite image of a North Korean nuclear reactor in Yongbyon suggest that the building is nearly complete. A reactor vessel and equipment will likely be installed through the open roof using overhead cranes. (DigitalGlobe)

North Korea has made rapid progress on the construction of a new nuclear reactor, with work nearly complete on the outside walls of the reactor building, according to an analysis of recent satellite images.

Because the reactor building hasn’t yet been loaded with sensitive nuclear equipment, the plant might not be operational for two or three more years, one analyst said. But the accelerated pace of construction, coming one year after North Korea disclosed the plant publicly, lends credence to Pyongyang’s claim that it has the materials and know-how to build nuclear plants on its own.

It is less clear, though, whether North Korea wants the plant as a power source or as a decoy for its weapons program. With a completed light-water reactor, North Korea would pose the same problem as Iran: Its officials can claim that their uranium-enrichment program is being used to fuel the reactor, not to produce weapons-grade uranium for nuclear bombs.

“It’s a nice cover story, potentially, for their highly-enriched-uranium program,” said Joel Wit, a former U.S. nuclear negotiator who obtained the satellite images for publication on his Web site from the DigitalGlobe Analysis Center.

Fear over accident threat

In the wake of Japan’s Fukushima Daiichi accident this year, the prospect of a North Korean plant poses security concerns for neighboring countries, who fear Pyongyang might struggle to contain an accident and limit the spread of radiation. The 25- or 30-megawatt light-water nuclear reactor has been constructed with no apparent outside help — and no international oversight. There’s also concern about how North Korea would reliably cool the reactor core; newly laid piping connects to a nearby river, Wit said, but the river freezes in the winter.

The reactor, and a related uranium-enrichment program, is part of a recent North Korean plan to revamp its nuclear capabilities.

When North Korea booted international inspectors from the country in 2009, its reactors from earlier decades were already shut down or abandoned. It had enough plutonium for six to 12 atomic bombs, according to the Washington-based Arms Control Association.

That’s when leader Kim Jong Il pledged to build up his country’s uranium program, giving the Stalinist dictatorship another pathway to make nuclear weapons.

Outside analysts weren’t sure whether isolated and impoverished North Korea had such a capability, even though it had received important Pakistani technology and manuals in the 1990s. That skepticism disappeared last November when a U.S. scientist was given a tour of the Yongbyon nuclear facility. The scientist, former Los Alamos National Laboratory director Siegfried Hecker, was shown a modern uranium-enrichment facility with 2,000 centrifuges — enough to produce fuel for a modest light-water reactor. If calibrated differently, those centrifuges each year could produce enough highly enriched uranium for one or two bombs, Hecker said.

Hecker also saw the beginnings of North Korea’s light-
water reactor. At the time, the reactor was just a 23-foot hole in the ground and a concrete foundation. Hecker spotted 50 workers in blue coveralls and a sign that read, “Safety first — not one accident can occur!”

Satellite images track work

Satellite images from Nov. 3 show a reactor building that is nearly complete, along with the turbine room and other supporting facilities, Wit said. The reactor building’s domed roof sits off to the side. The reactor vessel itself, Wit said, will likely be lowered by crane into the building before the roof is placed atop the facility.

The reactor building, Wit said, could be completed within six to 12 months. But it could take two or three years to install the wiring and fine components, including the control rods and fuel cladding.

North Korea also would have to produce uranium dioxide fuel pellets to power the reactor. When Hecker toured the facility last year, he was told that the uranium-enrichment facility was operational, but he didn’t see it in use.

Despite diplomatic pressure from its neighbors and from Washington, Pyongyang has shown little interest in denuclearization. Its officials contend that former Libyan leader Moammar Gaddafi fell from power only because he surrendered his nuclear arsenal years earlier. “Peace can be preserved only when one builds up one’s own strength,” an unnamed North Korean Foreign Ministry official told the state media this year.

North Korea is trying to build up its infrastructure — improving its factories, its electrical grid and its supply of hard currency — in advance of 2012, the 100th anniversary of the birth of founder Kim Il Sung. North Korea has touted 2012 as a showpiece year for its achievements, and officials told Hecker that the light-water reactor would be
finished in time for the anniversary.

An account in the state-run news last week again mentioned the reactor but gave no exact timetable for its completion.

“The day is near at hand,” the article said, “when a light-water reactor entirely based on domestic resources and technology will come into operation” in North Korea.