38 North: 'Suspicious activity' noted at North Korean nuclear site

The North Korea monitoring project 38 North says that satellite imagery shows "suspicious activity" at a nuclear enrichment site in North Korea.

Plumes of exhaust steam, a byproduct of heating the main plant at the Yongbyon Radiochemical Laboratory complex, have been seen in commercial satellite images taken March 12 and over the preceding five weeks, the group says.

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This activity is unusual, the report by the Washington, D.C.-based project, says.

"Exhaust plumes have rarely been seen there and none have been observed on any examined imagery this past winter," the report says. "The plumes suggest that the operators of the reprocessing facility are heating their buildings, perhaps indicating that some significant activity is being undertaken, or will be in the near future."

It does, however, note that U.S. Director of National Intelligence James Clapper recently testified that Pyongyang had "announced its intention to 'refurbish and restart' its nuclear facilities," including the uranium enrichment facility at Yongbyon and that it could be able to recover plutonium from the reactor's spent fuel "within a matter of weeks to months."

Separate images appear to show further work on the site's Experimental Light Water Reactor (ELWR), a key facility for the enrichment of nuclear fuel, is ongoing, with a new transformer yard and road built, and the installation of electrical cables completed.

The report states that "slow, steady progress" is being made on this component of Pyongyang's nuclear project.

Construction of new buildings near the Uranium Enrichment Complex is also ongoing, with some buildings nearing completion and new projects started. While there is speculation as to the purpose of these new buildings, the report says evidence is insufficient to reach any firm conclusions.