Xe131

Xe-131 is a radioactive isotope of xenon, the noble gas with atomic number 54. It has mass number 131. It is produced as a fission fragment in nuclear reactors and during the detonation of nuclear devices, and is a component of the decay chains of heavier radioisotopes. The nucleus contains 54 protons and 77 neutrons. Xe-131 is unstable and decays primarily by beta minus emission to cesium-131, a decay process often accompanied by gamma radiation. The half-life of Xe-131 is relatively short compared with the stable xenon isotopes, typically on the order of days to hours, depending on the particular measurement. In environmental and reactor-monitoring contexts, Xe-131 can serve as a tracer for particle transport and for studying reactor integrity, but it has no large-scale medical or industrial application. Being a noble gas, Xe-131 is chemically similar to other xenon isotopes and shares xenon’s low chemical reactivity, so its behavior in the environment is governed mainly by its physical transport as a gas. The isotope is cataloged in nuclear data compilations with a decay scheme that includes beta decay to Cs-131 and associated gamma lines used for spectroscopic identification. See also xenon isotopes, iodine-131, and cesium-131.