Lack of data shrouds nature of N Korea nuclear test

SEOUL (AFP) – Urgent efforts to find out the type of device detonated in North Korea’s latest nuclear test appeared to be getting nowhere Thursday, with South Korean experts unable to detect any radioactive fallout.

The North’s test on Tuesday triggered an immediate scramble to collect and analyse any fallout data that might provide crucial clues about the nature of the test and the progress Pyongyang’s nuclear weapons programme has made.

While seismic data was able to shed light on the likely yield of the underground test – estimated at six to seven kilotonnes – the main hunt was for elusive radioisotopes that might confirm the type of fissile material that was used.

Experts are particularly keen to establish whether the North switched from plutonium – used in the 2006 and 2009 tests – to a new and self-sustaining nuclear weaponisation programme using highly enriched uranium.

The South’s state-run Nuclear Safety and Security Commission said Thursday it had analysed eight atmospheric samples apparently collected by warships and air force planes equipped with highly sensitive detection devices.

“No radioactive isotope has been found yet,” the commission said in a statement.

Their priority target was traces of xenon gases released in the detonation that would point to the weapon type. “We are analysing samples and xenon has not been found,” the commission statement said.

If the underground test was well contained, it is quite possible there would be little or no radioactive seepage into the atmosphere.