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With a half-life of 432 years, the americium-241 in an ionization smoke detector includes about 3% neptunium after 20 years, and about 15% after 100 years. Under oxidizing conditions, neptunium-237 is the most mobile actinide in the deep geological repository environment of the Yucca Mountain project in Nevada . [ 154 ]
Neptunium-239 has 146 neutrons and a half-life of 2.356 days. It is produced via β − decay of the short-lived uranium-239 , and undergoes another β − decay to plutonium-239 . This is the primary route for making plutonium, as 239 U can be made by neutron capture in uranium-238 .
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.
The back-end of the nuclear fuel cycle, mostly spent fuel rods, contains fission products that emit beta and gamma radiation, and actinides that emit alpha particles, such as uranium-234 (half-life 245 thousand years), neptunium-237 (2.144 million years), plutonium-238 (87.7 years) and americium-241 (432 years), and even sometimes some neutron ...
Thus they again take their places in the chain: plutonium-239, used in nuclear weapons, is the major example, decaying to uranium-235 via alpha emission with a half-life 24,500 years. There has also been large-scale production of neptunium-237, which has resurrected the hitherto extinct fourth chain. [7]
Actinium-225 has a half-life of 10 days and decays by alpha emission. It is part of the neptunium series, for it arises as a decay product of neptunium-237 and its daughters such as uranium-233 and thorium-229. It is the last nuclide in the chain with a half-life over a day until the penultimate product, bismuth-209 (half-life 2.01 × 10 19 ...
The second of five storms that will slam the eastern half of the United States with snow and ice over a two week period is on the way – and this one has more snow than the first. Not 1. Not 2.
No fission products have a half-life ... Neptunium-237 and some isotopes of americium might be usable, but it is not clear that this has ever been implemented.