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
Timeline of the Fukushima Daiichi nuclear disaster of a new leak of radioactive water into the sea. The Itabashi Ward Office announces that a concentration of caesium-134 at 2,700 becquerels per kilogram – in excess of the government's provisional limit – was detected in tea processed from leaves picked on 9 May in Tokyo. The water decontamination and water recycling systems are now both functional. 100% recycled water is now used for reactor cooling, and no additional volume of contaminated water is being generated. Radioactive caesium-137 is found in Tokyo's tap water for the first time since April. Radioactive caesium from Fukushima was expected to enter the