Uranium Isotope Materials
With new and improved instrumentation allowing for much smaller sample sizes, δ238/235U variations of the order of 1 ‰ have been observed in naturally occurring terrestrial materials. This variation could be a result of uranium oxidation–reduction reactions and/or due to a nuclear field shift which would cause preferential separation of some uranium isotopomers.
|NIST SRM 950-A||uranium oxide||0 ‰ *|
|NBL CRM C112-A||solution||+0.02(5) ‰|
|NBL CRM 129-A||uranium oxide||-1.2 ‰|
|IRMM 184||solution||-1.15 ‰|
* Exact value defining the δ238/235USRM950A scale.
Values in parenthesis are expanded (k = 2) uncertainties applicable to the last digits. The values listed in this table are compilation and are not necessarily CIAAW recommendations.