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Satellite photos taken on Sept. 17 of Gilju in North Hamgyeong Province, where North Korea may have conducted a nuclear test. The photos pinpointing several possible test sites were released on Tuesday by the Institute for Science and International Security (ISIS), a nuclear watchdog in Washington DC./Yonhap
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North Korea may have detonated conventional bombs underground and pretended they were a nuclear weapon, experts here suspect. What the North claims was a nuclear test on Monday is estimated to have yielded a 0.8 kT or the equivalent of detonating 800 tons of TNT. Experts say to achieve the result with conventional explosives, a huge amount of TNT and a large detonating site are required, but powerful bombs can produce such yields. The international press has also suggested North Korea blew up conventional explosives to make it look as if it carried out a nuclear test.
¡°It is hard to conclude whether it was really a nuclear test or just a test conducted with conventional bombs,¡± said Lee Choon-geun with the Science and Technology Policy Institute. ¡°Technically, it is possible to carry out a test with a yield of 0.8 kt if sophisticated explosives more powerful than TNT are used.¡± Detonating powerful bombs in several places simultaneously could produce yields equivalent to a small nuclear bomb even without a single large detonating site.
Between the tremor on Monday and Wednesday, no xenon and Krypton85 radioactivity was observed in the atmosphere. The Japanese government said Wednesday it collected and analyzed airborne particulates above the East Sea but did not observe any radioactive material. The detection of radioactivity would be critical evidence that the North really tested a nuclear weapon. Even a nuclear test very deep underground and under highly sealed conditions cannot prevent vaporized Krypton and iodine from being released into the air. Both Japan and the U.S. are flying climate planes above the East Sea to detect radioactive material. The South Korean government also started operating radioactivity detection devices from Sweden on Wednesday, sources said.
Experts say if it was really a nuclear bomb, radioactivity should be detected at some point in time in whatever form. It could take one or two weeks, however, to detect such material depending on the amount of radioactivity released and wind directions.
¡°Even if we fail to detect any radioactivity till the end, we can¡¯t say for sure that it wasn¡¯t a nuclear test,¡± said Dr. Kim Tae-woo of the Korean Institute for Defense Analysis. ¡°It¡¯s too early for any conclusion, and we have to wait and see for several more days.¡± It could remain an unsolved mystery, but experts say radioactivity has always been detected after all previous nuclear tests, so time will provide fairly conclusive evidence.
(englishnews@chosun.com )
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