First radiation detected in Japan from N. Korea February nuke test


Possible radioactive traces from a North Korean nuclear test in February have been detected for the first time, although it remains unclear what fissile material Pyongyang used, a monitoring organization said Tuesday.

“The ratio of the detected xenon isotopes (xenon-131m and xenon-133) is consistent with a nuclear fission event occurring more than 50 days before the detection,” the Comprehensive Test Ban Treaty Organization (CTBTO) said. “This coincides very well” with the North Korea’s announced nuclear test on Feb. 12.

The detection at a monitoring station in Japan came 55 days after the explosion.

The group said, however, that the discovery couldn’t help it answer the key question of whether Pyongyang used plutonium or uranium in the blast.

North Korea used plutonium in its 2006 and 2009 tests and any discovery that it used highly enriched uranium for its third test would mark a significant technological step for the impoverished and unpredictable regime.

It would also raise international concerns that North Korea might pass on weapons-grade uranium, or the necessary technology and knowhow to make it, to rogue states or terrorists seeking to make crude nuclear explosive devices.

It is also possible that the so-called radionuclides were from a nuclear reactor or other atomic activity, and the CTBTO said it is currently examining the traces to see whether this is the case.

It ruled out however that the source was the crippled Fukushima No.1 nuclear plant.

The detection was made in Takasaki, Gunma Prefecture, 1,000 km from the North Korean test site. Lower levels were also picked up at Ussuriysk, Russia, one of several hundred sites worldwide reporting to the CTBTO.