North Korea, which in December re-opened a frozen nuclear reactor in violation of international non-proliferation agreements, says it will have its Yongbyon complex producing electricity in a few weeks. Some nuclear experts, however, warn it should take at least three months to reactivate the idle plant and much longer to ensure safe operation.
Nuclear safety experts estimate it could be months, even years, before North Korea's Yongbyon nuclear plant can safely operate.
David Lochbaum, with the U.S.-based Union of Concerned Scientists, says the time needed to restart a reactor depends on whether any of the plant's systems, such as piping and wiring, need major repairs. "The experience in the United States is that it takes easily two years of focused effort to go through the process of preparing a plant for restart, to make sure the equipment is ready and capable of functioning the way its supposed to," he says.
But that is not the timetable North Korea has in mind as it digs in during a growing nuclear confrontation with the United States and its allies over the North's non-proliferation pledges.
After several months of U.S. accusations that it has a secret illegal nuclear weapons program, the North has ignored calls to freeze its activities. Instead it escalated the dispute by moving to reactivate its main Yongbyon nuclear complex in December.
The international community is concerned because the facility, idled in 1994 under a deal with the United States, is capable of producing plutonium for nuclear weapons.
But Pyongyang says it only plans to generate power, which it needs since the international community cut fuel shipments in the confrontation over the North's resurgent nuclear ambitions.
No matter what its use, starting up Yongbyon will not be easy - despite an announcement by North Korea that it will be ready to generate electricity in just a few weeks. Reactivating a modern nuclear reactor after a shutdown of one or two years takes 18 months or more. Yongbyon, built more than 20 years ago using old technology, has been shuttered for eight years.
William Horak heads the energy sciences department at the Brookhaven National Laboratory in the United States, and has studied the Yongbyon facility. He says in theory the North Koreans could restart Yongbyon in 90 days - but not necessarily safely. "It looks like restart is possible," he says. "But does that mean it could be operated in the United States? I would go on the record saying no way, hell no, absolutely not. We would not consider it safe."
He says it would take at least a month just to make sure that all 8,000 fuel rods are safe and usable.
Scientist David Lochbaum adds that a major concern after a long shutdown is whether workers are properly re-trained on all systems and procedures. "That eight-year time frame, people have forgotten, or have to relearn, what needs to be done when a certain problem develops so they don't take a misstep and make that relatively minor problem a bigger problem," he says.
Mr. Horak, of the Brookhaven laboratory, says technological capability is one thing, but he questions whether economically crippled North Korea has the means to begin the actual start-up.
It takes a lot of electricity to start or stop a nuclear reactor - and that power has to be generated from an outside source, usually oil or coal. Given that fuel aid has been cut off, it is not clear if North Korea can bring Yongbyon on line, and more importantly take it back off line again if there is a problem.
In assessing safety risks, Mr. Horak says the worst scenario would be if air got into the graphite used in the reactor - which would ignite a fire and could lead to massive amounts of radioactivity being released into the air. He says, however, that smaller problems are more likely. "Low end of the scale is they start operating the reactor, and one or two elements are busted, they didn't inspect them properly," he says. "So then you have what we call leakers, and they start to leak out small amounts of radio [radioactive] nuclei, which probably just affect people that are within the boundaries of the plant."
Mr. Lochbaum at the Union for Concerned Scientists notes safety problems often show up fairly quickly. "If you look at the serious accidents we've had in the industry across the world, … they've all occurred within a year or so after a plant started up," he says.
He warns, too, that even if Yongbyon's pipes, wires, alarms and turbines all work perfectly, ultimately, all depends on the people working at the plant. The world's worst nuclear accidents, including Chernobyl in Ukraine and Three Mile Island in the United States, were the result of human errors.
North Korea's neighbors and the United States, however, hope to avoid all safety problems by keeping Yongbyon shuttered. Diplomats around the world are conferring to find ways to pressure Pyongyang into fulfilling its treaty obligations, and keep all its unapproved nuclear programs frozen.