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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.
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 Kramatorsk radiological accident was a radiation accident that happened in Kramatorsk, Donetsk Oblast, in eastern Ukrainian SSR from 1980 to 1989. A small capsule containing highly radioactive caesium-137 was found inside the concrete wall of an apartment building, with a surface gamma radiation exposure dose rate of 1800 R/year. [1]
The lifecycle of fuel in the present US system. If put in one place the total inventory of spent nuclear fuel generated by the commercial fleet of power stations in the United States, would stand 7.6 metres (25 ft) tall and be 91 metres (300 ft) on a side, approximately the footprint of one American football field.
As caesium 133, 135, and 137 are formed by the beta particle decay of the corresponding xenon isotopes, this causes the caesium to become physically separated from the bulk of the uranium oxide fuel. Because 135 Xe is a potent nuclear poison with the largest cross section for thermal neutron absorption, the buildup of 135 Xe in the fuel inside ...
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 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.
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.