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Half-life (symbol t ½) is the time required for a quantity (of substance) to reduce to half of its initial value.The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.
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 ...
Uranium-232 (232 U) is an isotope of uranium.It has a half-life of around 69 years and is a side product in the thorium cycle.It has been cited as an obstacle to nuclear proliferation using 233 U as the fissile material, because the intense gamma radiation emitted by 208 Tl (a daughter of 232 U, produced relatively quickly) makes the 233 U contaminated with it more difficult to handle.
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.
From this bottom, the average binding energy per nucleon slowly decreases with increasing atomic mass number. The heavy nuclide 238 U is not stable, but is slow to decay with a half-life of 4.5 billion years. [1] It has relatively small binding energy per nucleon. For β − decay, nuclear reactions have the generic form A Z X → A Z+1 X ...
Caesium-134 is found in spent nuclear fuel but is not produced by nuclear weapon explosions, as it is only formed by neutron capture on stable Cs-133, which is only produced by beta decay of Xe-133 with a half-life of 3 days. Cs-134 has a half-life of 2 years and may be a major source of gamma radiation in the first 20 years after discharge.
Not all molecules in the solution have a P-32 on the last (i.e., gamma) phosphate: the "specific activity" gives the radioactivity concentration and depends on the radionuclei's half-life. If every molecule were labelled, the maximum theoretical specific activity is obtained that for P-32 is 9131 Ci/mmol.
Technetium-99 (99 Tc) is an isotope of technetium which 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.