Alkali metal from the Chernobyl accident. Caesium-137 undergoes high-energy beta decay and eventually becomes stable barium-137. It is a strong emitter of gamma radiation. Caesium-137 has a very low rate of neutron capture and cannot be feasibly disposed of in this way, but must be allowed to decay. Caesium-137 has been used as a tracer in hydrologic studies, analogous to the use of tritium. Small amounts of caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Goiânia accident and the Chernobyl disaster. As of 2005, caesium-137 is the principal source
Radiation effects from the Fukushima Daiichi nuclear disaster tests. As the isotope signature of the plutonium is closer to that of power-reactor plutonium, TEPCO suggested that "two samples out of five may be the direct result of the recent incident." The more important thing to look at is the curium level in the soil; the soil does contain a short-lived isotope (curium-242) which shows that some alpha emitters have been released in small amounts by the accident. The release of the beta/gamma emitters such as caesium-137 has been far greater. In the short and medium term the effects of the iodine and the caesium release will dominate the