Uranium-238 decay chain

The temporal resolution of the multiple parent-daughter pairs within the uranium decay chain, 238U- Th (approaching secular equilibrium with a 75 ka half-life), °Th- Ra (1,500 a) and (—32 ka) is a powerful tool. It has been used to estimate the elapsed time between subduction modification of the mantle and lava emption to the surface, and to identify multiple... 

The temporal resolution of the multiple parent-daughter pairs within the uranium decay chain, 23 u 230rj (approaching secular equilibrium with a 75 ka half-life), (1,500 a) and... 

Unstable decay products of thorium may exceed their parent in their importance both in occupational and nonoccupational environments as contributors to the radiation dose. They produce only radiological effects. In view of the lesser importance of thorium decay products as compared to the uranium decay chains, this aspects are dealt with later (see Chapter 26.2, Section 26.2.6.3). 

Waste Products and Recycling The mining and milling of uranium produce large quantities of low-level radioactive waste containing most of the members of the uranium decay chain. °Th and "Ra with half-lives of 250000 and 1600 years, respectively, are most critical. Depleted ura-... 

Radioactive decay is probably not high on your list of household worries, unless you happen to live next door to a missile silo or Three Mile Island. However, private homes are the locations of greatest radon health concern simply because people spend so much time in them. Uranium decay-chain elements occur naturally in geologic formations and thus is continually formed underground. It migrates upward through the... 

Some special types of intermediate continuous daughter loss could cause either normal or reverse discordance but no studies were found dealing with this. Starik et al (1960) do report, however, that radium and radon in the uranium decay chains may be leached from the crystal... 

ThSiO "Th and Th are present in naturally occurring uranium Th and Th occur in uranium minerals as members of the decay chain. The remaining isotopes are formed upon neutron bombardment of those isotopes discussed, or by charged particle bombardment of various targets. 

Soon after this discovery the harnessing of the technique to the measurement of all the U isotopes and all the Th isotopes with great precision immediately opened up the entire field of uranium and thorium decay chain studies. This area of study was formerly the poaching ground for radioactive measurements alone but now became part of the wonderful world of mass spectrometric measurements. (The same transformation took place for radiocarbon from the various radioactive counting schemes to accelerator mass spectrometry.)... 

In this volume, for the first time, all the methods for determining the uranium and thorium decay chain nuclides in Earth materials are discussed. The range of problems solvable with this approach is remarkable—a fitting, tribute to the Curies and the early workers who discovered them for us to use. 

Strongly radioactive, short-lived element that can be found in tiny amounts in uranium ores. It arises fleetingly from 235U in its decay chain through actinium (227Ac). Is only of scientific value as it has a maximum half-life of about 22 minutes. Nevertheless, in its short existence it is the atom with the largest diameter (0.270 nm cesium 0.265 nm). 

McKee PM, Snodgrass WJ, Hart DR, et al. 1987. Sedimentation rates and sediment core profiles of uranium-238 and thorium-232 decay chain radionuclides in a lake affected by uranium mining and milling. Can J Fish Aquat Sci 44 390-398. 

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