A new highly enriched U reference material for improved simultaneous determination of uranium amount and isotope amount ratios in trace level samples.

A highly-enriched U reference material (>0.99987 n(U)/n(U)) has been prepared and characterized for use as an isotope dilution mass spectrometry spike. An ion exchange separation was performed on 1 g of high purity U to further reduce trace amounts of contaminant Pu in the material.

A highly‑enriched Pu reference material for nuclear safeguards and nuclear forensics measurements.

A highly-enriched Pu isotope dilution reference material has been prepared and characterized for metrologically traceable measurements of very small quantities of plutonium. The amount of plutonium in samples associated with nuclear safeguards and nuclear forensic measurements can be significantly less than 1 ng. Accordingly, the ability to quantify the amount and isotopic composition of plutonium from a single mass-spectrometric analysis is particularly desirable.

Plutonium Desorption from Nuclear Melt Glass-Derived Colloids and Implications for Migration at the Nevada National Security Site, USA.

The migration of low levels of plutonium has been observed at the Nevada National Security Site (NNSS) and attributed to colloids. To better understand the mechanism(s) of colloid-facilitated transport at this site, we performed flow cell desorption experiments with mineral colloid suspensions produced by hydrothermal alteration of NNSS nuclear melt glass, residual material left behind from nuclear testing. Three different colloid suspensions were used: (1) colloidal material from hydrothermal alteration of nuclear melt glass at 140 °C; (2) at 200 °C; and (3) plutonium sorbed to SWy-1 montmorillonite at room temperature.

Preparation and calibration of a Pa reference material.

A Pa reference material has been characterized for amount of protactinium. This reference material is primarily intended for calibration of Pa tracers produced for U-Pa model age measurements associated with nuclear forensics and nuclear safeguards. Primary measurements for characterization were made by isotope dilution mass spectrometry of a purified Pa solution using a Pa isotopic spike.