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The long half-life of technetium-99 and its potential to form anionic species creates a major concern for long-term disposal of radioactive waste. Many of the processes designed to remove fission products in reprocessing plants aim at cationic species such as caesium (e.g., caesium-137) and strontium (e.g., strontium-90). Hence the ...
Technetium-99m's short half-life of 6 hours makes storage impossible and would make transport very expensive. Instead, its parent nuclide 99 Mo is supplied to hospitals after its extraction from the neutron-irradiated uranium targets and its purification in dedicated processing facilities.
The metastable technetium-99m (99m Tc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body.
97m Tc is the most stable, with a half-life of 91.0 days (0.097 MeV). [4] This is followed by 95m Tc (half-life: 61 days, 0.038 MeV) and 99m Tc (half-life: 6.04 hours, 0.143 MeV). 99m Tc only emits gamma rays, subsequently decaying to 99 Tc. [7] For isotopes lighter than 98 Tc, the primary decay mode is electron capture to isotopes of molybdenum.
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
With the longest-lived isotope of technetium, 97 Tc, having a 4.21-million-year half-life, [10] no technetium remains from the formation of the Earth. [ 11 ] [ 12 ] Only minute traces of technetium occur naturally in Earth's crust—as a product of spontaneous fission of 238 U, or from neutron capture in molybdenum —but technetium is present ...
Technetium-99m's short half-life of 6 hours makes long-term storage impossible. Transport of 99m Tc from the limited number of production sites to radio pharmacies (for manufacture of specific radiopharmaceuticals ) and other end users would be complicated by the need to significantly overproduce to have sufficient remaining activity after long ...
The longer-lived isotope, technetium-95m with a half-life of 61 days, is used as a radioactive tracer to study the movement of technetium in the environment and in plant and animal systems. [116] Technetium-99 decays almost entirely by beta decay, emitting beta particles with consistent low energies and no accompanying gamma rays.