January 07, 2016 10:53
Pundits have widely dismissed North Korea's claim that it tested a hydrogen bomb on Wednesday, but some more adventurous speculation points in the direction of a kind of intermediate-stage weapon.
A few experts said North Korea may have attempted to test a "boosted fission weapon," a step on the way to making a nuclear bomb easier to miniaturize.
The main reason behind the skepticism is that the magnitude of the quake that followed the nuclear test was much smaller than what is normally detected after a hydrogen bomb blast.
The Korea Meteorological Administration said it detected a 4.3-magnitude quake but revised that to 4.8 later on. The quake that followed North Korea's third nuclear test in February 2013 was 4.9 in magnitude.
Lee Cheol-woo of the National Assembly Intelligence Committee said the blast generated by the third nuclear test produce an estimated yield of 7.9 kilotons -- 1 kiloton equals 1,000 tons of dynamite -- but the blast this time was equivalent to just six kilotons. A hydrogen bomb should produce a yield of up to 1 megaton, and even a small device would produce a yield of at least 150 kilotons.
In the announcement, North Korea referred to a "newly-developed experimental hydrogen bomb," a veiled admission perhaps that it was not a full-blown H-bomb.
But the magnitude of the blast could appear smaller due to the geological make-up of the underground test site, which would require further analysis of seismic data. It is also possible that the North achieved a partial success in testing a boosted fission weapon, a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate and yield of a fission reaction.
It would normally produce a yield of around 40 to 150 kilotons and is easier to miniaturize and mount on a warhead. "If North Korea succeeded in detonating a proper boosted fission weapon, the earthquake generated by the blast should have been at least 5.5 on the Richter scale," said Lee Choon-geun at the Science and Technology Policy Institute.
"Judging by the earthquake, the North appears to have succeeded in detonating a boosted fission weapon, but the magnitude was less than it had hoped for."
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