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Uranium Transport in the Sub-Surface Environment Koongarra - A Case Study
Published in Herbert E. Allen, E. Michael Perdue, David S. Brown, Metals in Groundwater, 2020
Uranium-238, the chief constituent of natural uranium (99.27% abundance) decays via alpha particle emission with a half-life of 4.468 × 109 years to the relatively short-lived 234Th (t½ = 24.1 days). Thorium-234 then decays via (3 emission to 234Pa which in turn decays by β emission (with half-life of 6.7 hours) to the longer-lived 234U (t½ = 2.48 × 105 years). This beta stable, alpha-emitter then decays to 230Th. Thorium-230, with a half-life of 7.52 × 104 years, is relatively stable decaying to 226Ra (t½ = 1602 y) and finally to 206Pb via a number of other relatively short-lived intermediates (including 222Rn and 210Pb).
Relation Between Natural Radionuclide Activities and Chemical Constituents in Ground Water in the Newark Basin, New Jersey
Published in Barbara Graves, Radon, Radium, and Other Radioactivity in Ground Water, 2020
It is well known that iron and manganese hydroxides adsorb radium very strongly [18, 19, 25]. Radium-226 is produced by decay from its parent radionuclide, thorium-230. Thorium-2 3 0 decays to radium-226 by ejecting an alpha-particle. The momentum of the ejected alpha-particle causes the newly created radium-226 radionuclide to recoil in the direction opposite to the one in which the alpha-particle departed. This mechanism is known as alpha-recoil. Although the distance a radium-226 radionuclide travels due to alpha-recoil is very small [26], a small fraction of radium-226 at the edge of a host mineral grain may be ejected from the host into an adjoining pore space or into a microfracture within the mineral grain [26]. In this way, radium-226 is continuously released to ground water contained in the pore space. However, because radium is so strongly adsorbed by iron and manganese hydroxides, a radium-226 radionuclide ejected into a pore space (or microfracture) would quickly be adsorbed onto the iron or manganese hydroxides.
Elements, Isotopes, and Their Properties
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
And finally, there is Uranium-234. Uranium-234 is the least common form of naturally occurring uranium, and it has a half-life of about 245,000 years. So, it does not exist in significant quantities in nature relative to the other two isotopes of uranium that we have discussed. Uranium-234 has a smaller number of neutrons than U-238 does, and it is created primarily by the alpha decay of U-238. This process begins when a Uranium-238 nucleus emits an alpha particle to become Thorium-234 (Th-234). Thorium-234 immediately emits a beta particle to become Protactinium-234 (Pa-234) and Pa-234 then emits another beta particle to become U-234. The U-234 that is produced in this way has a half-life of about 245,000 years, and when it decays, it does so by emitting another alpha particle to become Thorium-230.
Applications for Thorium in Multistage Fuel Cycles with Heavy Water Reactors
Published in Nuclear Technology, 2018
Timothy Ault, Steven Krahn, Andrew Worrall, Allen Croff
The Thorium-Only option sought to completely eliminate reliance on uranium fuel cycle facilities such as conversion and enrichment for steady-state operations. It was calculated that a thorium/233U–fueled HWR could breed an excess amount of 233U that could be used to sustain a thorium/233U–fueled HTGR; both stages employed full recycle of thorium and uranium. While this option would represent a development and deployment challenge due to its relatively low level of technological maturity, this preliminary assessment suggests that breeding in the HWR stage is adequate to support a significant fraction of power production in HTGRs.