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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. Trace quantities also originate from spontaneous fission of uranium-238. It is ...
Caesium (55 Cs) has 41 known isotopes, the atomic masses of these isotopes range from 112 to 152. Only one isotope, 133 Cs, is stable. The longest-lived radioisotopes are 135 Cs with a half-life of 1.33 million years, 137 Cs with a half-life of 30.1671 years and 134 Cs with a half-life of 2.0652 years. All other isotopes have half-lives less ...
caesium-137: 30.17 952 10 9 seconds (gigaseconds) isotope half-life years 10 9 seconds ... half-life 10 15 years 10 24 seconds hafnium-174: 70 2.2 vanadium-50: 140 4.4
Caesium-137, with a half-life of 30 years, is the main medium-lived fission product, along with Sr-90. Cs-137 is the primary source of penetrating gamma radiation from spent fuel from 10 years to about 300 years after discharge. It is the most significant radioisotope left in the area around Chernobyl. [12]
Decay of caesium-137. 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 ...
The longest-lived of these is 133 Ba, which has a half-life of 10.51 years. All other radioisotopes have half-lives shorter than two weeks. The longest-lived isomer is 133m Ba, which has a half-life of 38.9 hours. The shorter-lived 137m Ba (half-life 2.55 minutes) arises as the decay product of the common fission product caesium-137.
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.
The radiation source in the Goiânia accident was a small capsule containing about 93 grams (3.3 oz) of highly radioactive caesium chloride (a caesium salt made with a radioisotope, caesium-137) encased in a shielding canister made of lead and steel. The source was positioned in a container of the wheel type, where the wheel turns inside the ...