Recoil and Transmutation Effects in the Migration Behaviour of Actinides

Accounting for long alpha-particle stopping distances in (U–Th–Sm)/He geochronology: Refinement of the baseline case

“…The ejection effect can be significant and its quantification is of primary importance not only for noble gas thermochronology for various mineral phases (Farley et al, 1996;Tagami et al, 2003;Gautheron et al, 2006), but also nuclear waste, U-Th disequilibrium, etc. (Adloff and Rö ssler, 1991;Bourdon et al, 2003). In the case of (U-Th-Sm)/He thermochronology, the fraction of 4 He retained after loss due to this mechanism is termed F T , and, to first order, the (U-Th-Sm)/He age can be corrected by dividing it by F T (Farley et al, 1996).…”

Fracture smectite as a long-term sink for natural radionuclides – indications from unusual U-series disequilibria

“…Possible oxidation of U-234 and its occurrence in the oxidised form is related to the radioactive decay process itself or oxidation potential difference between the displaced site and the original site of the recoiling U atom. (e.g., Ordonez Regil et al, 1989, Adloff andRoessler, 1991).…”

Understanding sulphuric acid leaching of uranium from ore by means of 234U/238U activity ratio as an indicator

“…Studies on developing the conceptual model of oxidative isotope fractionation of 234 U have shown that 234 Th, the daughter of 238 U, is due to alpha-recoil pushed into areas of rock matrix where oxygen atoms accumulate around it (Adloff and Roessler, 1991;Regil et al, 1989). Extra energy generated during decay may increase the oxidation potential at the end of the 234 Th recoil trajectory.…”