Low-Yield Nuclear Testing by North Korea in May 2010: Assessing the Evidence with Atmospheric Transport Models and Xenon Activity Calculations

Seismological Evidence for a Low-Yield Nuclear Test on 12 May 2010 in North Korea

“…The fissile material of the possible mid-May 2010 nuclear test is indicated as uranium-235 rather than the plutonium-239 inferred from the radioxenon signal detected at Geojin in South Korea (De Geer, 2012, althoughWright (2013) suggested they cannot be clearly discriminated from atmospheric transport modeling of the observed radionuclides. Other studies also obtained similar findings based on the detected types and ratios of isotopes (De Geer, 2013;Ihantola et al, 2013;Wotawa, 2013;Wright, 2013). Based on 2 hr time slices, a more accurate time-zero is estimated to be 16:00 UTC on 12 May 2010 by Ihantola et al (2013), which is limited between 9:00 UTC on 11 May 2010 and 13:00 UTC on 13 May 2010 based on its 95% uncertainty.…”

“…The existence of a mid-April event was proposed to explain the disagreements of the xenon ratio between the data and De Geer's model. In later studies, the xenon signatures are also explained by an underground nuclear explosion in mid-May 2010 without postulating an early event (De Geer, 2013;Wright, 2013). The origin time we have determined is within the time window based on the analysis of radionuclide isotope ratios (Ihantola et al, 2013).…”

“…The origin time we have determined is within the time window based on the analysis of radionuclide isotope ratios (Ihantola et al, 2013). However, the yield of the 2010 test es-timate based on the seismic data (2:9 0:8 t) is much smaller than the 50-200 t suggested by De Geer (2012) or a few hundred tons inferred based on radionuclide activity calculations (Wright, 2013). If the inferred yield based on radioisotopes holds true, the large difference in yield estimates may suggest that the 2010 test is at least partially decoupled, consistent with the indication from the noble gases as suggested by De Geer (2013).…”

“…Based on 2 hr time slices, a more accurate time-zero is estimated to be 16:00 UTC on 12 May 2010 by Ihantola et al (2013), which is limited between 9:00 UTC on 11 May 2010 and 13:00 UTC on 13 May 2010 based on its 95% uncertainty. Wright (2013) concluded that the most likely origin of the radionuclides is close to North Korea's nuclear test site (NKTS). Coincidentally, on 12 May 2010, the North Korean official daily morning newspaper Rodong Sinmun reported that North Korea succeeded in nuclear fusion on the Day of the Sun (http://www.kcna.co.jp/item/2010/201005/ news12/20100512-05ee.html; last accessed July 2014), although the report was ridiculed by the South Korean and Western media (Brumfiel, 2012).…”

Evaluation of a Seismic Event, 12 May 2010, in North Korea

“…Five days in April and May 2010 were at first proposed as the candidate dates on which a nuclear test may have been carried out. Subsequent papers based on the radionuclide observations, and discussion of candidate locations from which atmospheric transport of radionuclides would fit those observations, focused on 11 May 2010 as the likely date of a claimed low-yield nuclear test in North Korea (De Geer, 2013;Wotawa, 2013;Wright, 2013). Schaff et al (2012) attempted to detect seismic signals from small explosions in North Korea on the specific days in 2010 proposed by De Geer.…”