Fukushima Daiichi nuclear disaster (Unit 2 Reactor) the plant would be decommissioned once the crisis was over. The Japanese government estimates the total amount of radioactivity released into the atmosphere was approximately one-tenth as much as was released during the Chernobyl disaster. Significant amounts of radioactive material have also been released into ground and ocean waters. Measurements taken by the Japanese government 30–50 km from the plant showed caesium-137 levels high enough to cause concern, leading the government to ban the sale of food grown in the area. Tokyo officials temporarily recommended that tap water should not be used to prepare food for infants. In May 2012,
Caesium-137 samples of caesium-137, Am-241 and strontium-90. The samples were moved out of a secure location to be used for education. When the samples were supposed to be returned the university was unable to find them. the samples are still missing. On 3 and 4 March 2016, unusually high levels of caesium-137 were detected in the air in Helsinki, Finland. According to STUK, the country's nuclear regulator, measurements showed 4,000 μBq/m³ — about 1,000 times the usual level. An investigation by the agency traced the source to a building from which STUK and a radioactive waste treatment company operate. Caesium-137 Caesium-137