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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 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 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.
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 ...
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 external relative gamma dose for a person in the open near the Chernobyl disaster site. The intermediate-lived fission products like Cs-137 contribute nearly all of the gamma dose now after a number of decades have passed, see opposite. The relative contributions of the major nuclides to the radioactive contamination of the air after the ...
June 6, 1988 – Radiation Sterilizers, Inc. (now Sterigenics) in Decatur, Georgia reported a leak of 137 Cs at their facility. Seventy thousand medical supply containers and milk cartons were recalled. [28] 5 February 1989 – Three workers were exposed to gamma rays from the 60 Co source in a medical products irradiation plant in San Salvador ...
Figure 1: Sodium iodide gamma spectrum of caesium-137 (137 Cs) An example of a NaI spectrum is the gamma spectrum of the caesium isotope 137 Cs —see Figure 1. 137 Cs emits a single gamma line of 662 keV. The 662 keV line shown is actually produced by 137m Ba, the decay product of 137 Cs, which is in secular equilibrium with 137 Cs.