Timeline of the Fukushima Daiichi nuclear disaster of caesium-137 by the Atmospheric Chemistry and Physics journal—an estimate about 42 percent of that released into the atmosphere in the Chernobyl explosion in 1986. Caesium-137 has a half-life of 30 years. TEPCO reports the completion of a cover for the reactor unit 1, which is 54 metres high, 47 metres wide and 42 metres deep. The cover has a built-in ventilation system that is supposed to filter radioactive material. Boric acid is injected into reactor number 2 after the discovery of xenon in its containment vessel. The presence of xenon may be an indication that a self-sustained fission reaction
Effects of the Chernobyl disaster most soils because it binds to the clay minerals. Tests (c. 1997) showed that caesium-137 levels in trees of the area were continuing to rise. It is unknown if this is still the case. There is some evidence that contamination is migrating into underground aquifers and closed bodies of water such as lakes and ponds (2001, Germenchuk). The main source of elimination is predicted to be natural decay of caesium-137 to stable barium-137, since runoff by rain and groundwater has been demonstrated to be negligible. An increased incidence of thyroid cancer was observed for about 4 years after the accident