Lake Karachay The lake accumulated some 4.44 exabecquerels (EBq) of radioactivity over less than one square mile of water, including 3.6 EBq of caesium-137 and 0.74 EBq of strontium-90. For comparison, the Chernobyl disaster released 0.085 EBq of caesium-137, a much smaller amount and over thousands of square miles. (The total Chernobyl release is estimated between 5 to 12 EBq of radioactivity, however essentially only caesium-134/137 [and to a lesser extent, strontium-90] contribute to land contamination because the rest is too short-lived). The sediment of the lake bed is estimated to be composed almost entirely of high level radioactive waste deposits to
Radiation effects from the Fukushima Daiichi nuclear disaster Iwate), in Saku, Karuizawa and Sakuho (prefecture Nagano, in Tabayama (prefecture Yamanashi) and elsewhere. Based on radiation measurements made all over Japan between 20 March and 20 April 2011, and the atmospheric patterns in that period, computer simulations were performed by an international team of researchers, in cooperation with the University of Nagoya, in order to estimate the spread of radioactive materials like caesium-137. Their results, published in two studies on 14 November 2011, suggested that caesium-137 reached up to the northernmost island of Hokkaido, and the regions of Chugoku and Shikoku in western Japan at more than 500 kilometers