SEOUL (AP) -- Abnormally high radiation levels were detected nearthe border between the two Koreas days after North Korea claimed tohave mastered a complex technology key to manufacturing a hydrogenbomb, Seoul said Monday.
The Science Ministry said itsinvestigation ruled out a nuclear test by North Korea but failed todetermine the source of the radiation. It said there was no evidence ofa strong earthquake, which follows an atomic explosion.
On May12, North Korea claimed its scientists succeeded in creating a nuclearfusion reaction, a technology necessary to manufacture a hydrogen bomb.In its announcement, the North did not say how it would use thetechnology, only calling it a "breakthrough toward the development ofnew energy."
South Korean experts doubted the North actually madesuch a breakthrough. Scientists around the world have beenexperimenting with fusion for decades, but it has yet to be developedinto a viable energy alternative.
On May 15, however, theatmospheric concentration of xenon -- an inert gas released after anuclear explosion or and radioactive leakage from a nuclear power plant-- on the South Korean side their shared border was found to be eighttimes higher than normal, according to South Korea's Science Ministry.
SouthKorea subsequently looked for signs of a powerful, artificially inducedearthquake. Experts, however, found no signs of a such a quake in NorthKorea, a ministry statement said.
"We determined that there was no possibility of an underground nuclear test," it said. The ministry said the gas is not harmful.
Whileany fusion test would have registered seismic activity, according tonuclear expert Whang Joo-ho of South Korea's Kyung Hee University, thepresence of xenon could also have come from a leak.
Since thewind was blowing from north to south when the xenon was detected, aScience Ministry official said the gas could not have originated fromany nuclear power plants in South Korea.
But the official --speaking on condition of anonymity, citing department policy -- saidthe xenon could have come from Russia or China. Mr. Whang agreed,saying a nuclear test or radioactive leakage would be the only reasonsthat could explain the atmospheric concentration of xenon reported bythe ministry.