Abnormal radiation detected near intra-Korean border

SEOUL (AP) -- Abnormally high radiation levels were detected near the border between the two Koreas days after North Korea claimed to have mastered a complex technology key to manufacturing a hydrogen bomb, Seoul said Monday.
The Science Ministry said its investigation ruled out a nuclear test by North Korea but failed to determine the source of the radiation. It said there was no evidence of a strong earthquake, which follows an atomic explosion.
On May 12, North Korea claimed its scientists succeeded in creating a nuclear fusion reaction, a technology necessary to manufacture a hydrogen bomb. In its announcement, the North did not say how it would use the technology, only calling it a "breakthrough toward the development of new energy."

South Korean experts doubted the North actually made such a breakthrough. Scientists around the world have been experimenting with fusion for decades, but it has yet to be developed into a viable energy alternative.
On May 15, however, the atmospheric concentration of xenon -- an inert gas released after a nuclear explosion or and radioactive leakage from a nuclear power plant -- on the South Korean side their shared border was found to be eight times higher than normal, according to South Korea's Science Ministry.
South Korea subsequently looked for signs of a powerful, artificially induced earthquake. Experts, however, found no signs of a such a quake in North Korea, 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.
While any fusion test would have registered seismic activity, according to nuclear expert Whang Joo-ho of South Korea's Kyung Hee University, the presence of xenon could also have come from a leak.
Since the wind was blowing from north to south when the xenon was detected, a Science Ministry official said the gas could not have originated from any nuclear power plants in South Korea.
But the official -- speaking on condition of anonymity, citing department policy -- said the xenon could have come from Russia or China. Mr. Whang agreed, saying a nuclear test or radioactive leakage would be the only reasons that could explain the atmospheric concentration of xenon reported by the ministry.