Video part ICesium has a half life of 30 years, but it will take over 300 years to disappear. Cesium in the form of gas will be and is most definitely released from any nuclear accident where any reactor's nuclear or spent fuel melts down.   Radioactive Xenon gas will also be released in large quantities, … Continue reading As Little As 10-30 Bq/kg of Cesium Radiation In Kids Causes Health Problems