Detecting Radioactive Gas over the North Korean Sky

The Japanese Asahi Shimbun reported on March 3, citing some news sources of the United States, that after analyzing atmospheric samples collected around North Korea last year, the U.S. government found “Krypton 85,” an element generated by extracting plutonium from the practice of reprocessing spent fuels. The newspaper reported that the fact that the Krypton 85 was found again after a year and a half hints at the possibility that the North either has “a second nuclear facility,” which has been unknown so far, or that nuclear reprocessing may be secretly ongoing.

Some interpret the detection of the gas as proof that North Korea intends to go nuclear in earnest, instead of using its nuclear weapons program as a bargaining chip.

With a WC-135W reconnaissance plane that is usually used to monitor signs of nuclear activity in the East Sea, the U.S. has been watching the nuclear activities of the North by extracting a sample of the air over North Korea. The fact that Krypton 85 was detected was reported to a few U.S. government officials, and a thorough analysis is reportedly continuing on when and where the gas appeared.

When an explosion occurred in September last year near Yanggang Province on the border with China, the Korean and U.S. governments were closely watching over the North on the possibility of nuclear experiments. However, they made a tentative conclusion that it was a simple explosion as no material evidence such as Krypton 85 was detected.

Won-Jae Park parkwj@donga.com