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This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
The high short-term radioactivity of spent nuclear fuel is primarily from fission products with short half-life.The radioactivity in the fission product mixture is mostly due to short-lived isotopes such as 131 I and 140 Ba, after about four months 141 Ce, 95 Zr/ 95 Nb and 89 Sr constitute the largest contributors, while after about two or three years the largest share is taken by 144 Ce/ 144 ...
The longest-lived radioisotope is 14 C, with a half-life of 5.70(3) × 10 3 years. This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reaction 14 N + n → 14 C + 1 H. The most stable artificial radioisotope is 11 C, which has a half-life of 20.3402(53) min. All other radioisotopes ...
Each group of radionuclides, starting with the longest-lived primordial radionuclides, is sorted by decreasing half-life, but the tables are sortable by other columns. no (number) column A running positive integer for reference. This number, i.e. position in this table, might be changed in the future, especially for nuclides with short half-lives.
used in radioisotope thermoelectric generators (RTGs) and radioisotope heater units as an energy source for spacecraft Plutonium-239: 94: 145: 24,110 y: α: 5245 Synthetic: used for most modern nuclear weapons Americium-241: 95: 146: 432 y: α: 5486 Synthetic: used in household smoke detectors as an ionising agent Californium-252: 98: 154: 2.64 ...
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. [6] All other isotopes have half-lives less than 2 weeks, most under an hour.
Technetium-99 (99 Tc) is an isotope of technetium that decays with a half-life of 211,000 years to stable ruthenium-99, emitting beta particles, but no gamma rays.It is the most significant long-lived fission product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste.
Had all of the plutonium given to Stevens been the long-lived Pu-239 as used in similar experiments of the time, Stevens's lifetime dose would have been significantly smaller. The short half-life of 87.7 years of Pu-238 means that a large amount of it decayed during its time inside his body, especially when compared to the 24,100 year half-life ...