It is hardly surprising, yet it is utterly scary to hear that experts are concerned about the possibility of a massive nuclear disaster stemming from North Korea’s mishandling of its outdated reactor. What gives cause for greater concern is that the North has restarted its 28-year-old nuclear reactor in Yongbyon after an eight-year hiatus.

The experts, quoted by the IHS Jane’s Defence Weekly, noted that just a single fire in the Yongbyon nuclear site could cause a disaster potentially worse than the catastrophe that hit Chernobyl in 1986. More to the point, the radioactive plume from Yongbyon could hit Pyongyang, which is only 85 km away, and as far as Siberia and northern Japan. It could also threaten Seoul, which is only 300 km south.

One of the experts quoted in the report pointed out that as the Yongbyon site has a concentration of nuclear facilities, if there was a fire in one building it could lead to a disaster worse than Chernobyl. Seo Kyun-reul, a professor at the nucleonic department of Seoul National University, noted that the 5 megawatt reactor in Yongbyon uses “obsolete magnox” technology that, combined with the reuse of old graphite moderators, greatly increases the risk of a fire.

Another expert, Peter Hayes of the Royal Melbourne Institute of Technology, added, “The safety issue in Yongbyon is straightforward ― the graphite moderator catches fire, and you have a perfect storm: a fire with powerful thermal plume carrying contents high into the sky.”

Seo said that in a fire engineers were likely to lose control of the reactor, triggering a disastrous chain reaction. Rising temperature and pressure would lead to an explosion, projecting radioactive particles high into the atmosphere, like what happened in Chernobyl.

That is truly a horrible scenario. The problem is, however, is that there is no ground whatsoever to dismiss the experts’ grim assessment of the reality in Yongbyon.

The reactor started operation in 1986. It stopped operation in 1994, under a denuclearization accord with the U.S., but the North reactivated it in 2003. Pyongyang disabled it again in 2007, only to restart it last year.

Clearly, even a country with an advanced level of nuclear technology would have difficulty ensuring safety with such a worn-out reactor that has been in and out of operation. And we know where North Korea stands in terms of industrial technology and safety standards.

Another key point is that North Korea is one of the most isolated countries in the world. It is almost certain that the world will never know of any nuclear accident in North Korea any time before it is too late.

Mainly because of the North Korean regime’s bellicosity, the world has been closely following its nuclear weapons program, which resulted in three underground tests, but not as closely as the possibility of an accident involving its nuclear facility. We don’t feel like imagining so, but the experts’ warning tells us that even without bad intent, North Korea could spell nuclear disaster on the peninsula and beyond.

The Seoul government must work out contingency plans on an emergency in Yongbyon. It would be better to secure cooperation from the International Atomic Energy Agency and neighboring countries like China, Japan and Russia.

All considered, it is vital that South Korea, the United States and the international community hasten efforts to stop the North’s nuclear program, including resumption of the six-nation talks that were suspended five yeas ago.