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Caesium-137 (137 55 Cs), cesium-137 (US), [7] or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclear weapons.
The radioactive 135 Cs has a very long half-life of about 2.3 million years, the longest of all radioactive isotopes of caesium. 137 Cs and 134 Cs have half-lives of 30 and two years, respectively. 137 Cs decomposes to a short-lived 137m Ba by beta decay , and then to nonradioactive barium, while 134 Cs transforms into 134 Ba directly.
The low decay energy, lack of gamma radiation, and long half-life of 135 Cs make this isotope much less hazardous than 137 Cs or 134 Cs. Its precursor 135 Xe has a high fission product yield (e.g., 6.3333% for 235 U and thermal neutrons ) but also has the highest known thermal neutron capture cross section of any nuclide.
As a result, if the zircaloy tubes holding the pellet are broken then a greater release of radioactive caesium from the fuel will occur. The 134 Cs and 137 Cs are formed in different ways, and hence as a result the two caesium isotopes can be found at different parts of a fuel pin.
The 137 Cs level is higher in the sample that was further away from the ground zero point – this is thought to be because the precursors to the 137 Cs (137 I and 137 Xe) and, to a lesser degree, the caesium itself are volatile. The natural radioisotopes in the glass are about the same in both locations.
A mining company dropped a tiny capsule of caesium-137 somewhere along an 870-mile stretch of Western Australia’s Great Northern Highway. The plan is to find it before someone gets hurt, Liam ...
OSLO (Reuters) -Norway said on Wednesday that elevated levels of radioactive caesium (Cs-137) it had detected near the Arctic border with Russia were likely due to a forest fire near Chornobyl in ...
Caesium-137 is one such radionuclide. It has a half-life of 30 years, and decays by beta decay without gamma ray emission to a metastable state of barium-137 (137m Ba). Barium-137m has a half-life of a 2.6 minutes and is responsible for all of the gamma ray emission in this decay sequence. The ground state of barium-137 is stable.