Engineering topics

Stene, Riane E.

Publications and source records attributed to Stene, Riane E..

3 records

DOE OSTI2024

Chlorine Isotope Separations using Thermal Diffusion

As of the close of 2023 a thermal diffusion isotope separations (TDIS) apparatus was constructed, successful shakedown testing was achieved and enrichments of isotopic concentrations relative to natural abundance 35/37 Cl were collected. Further, the model for these enrichment experiments drove the timing for sampling and other critical, extrapolated functions that are discussed herein. Our decision to move forward in 2024 with the installation of a larger set of separation tubes and associated equipment was based on the successful development of the predictive model. The Chlorine Isotopes Project Team at PNNL is prepared to claim that the installation and hence its separative power is restricted only by the spatial limitations of the laboratory, and this at present appears to be the limiting feature to first pass high enriched 37 Cl.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2021

Single-Use Destructive Assay for Uranium Hexafluoride Sampling

Sampling uranium hexafluoride (UF6) for the determination of enrichments by destructive analysis (DA) is a critical component in the International Atomic Energy Agency’s layered safeguards approach for uranium processing facilities. Typically, gram-quantity UF6 samples are collected during inspections and stored under tag-and-seal until transportation to an off-site analytical laboratory. The shipping times can be long, and evolving restrictions on radioactive/corrosive materials shipments may increasingly limit the IAEA’s ability to transport UF6 samples easily. Pacific Northwest National Laboratory has developed a low-cost UF6 sampling technology called Single-Use Destructive Assay (SUDA) that addresses these challenges, as well as provides DA sample geometries that can be tailored for different analytical methods, including potential on-site analyses. The SUDA samplers, along with a unique holder, are designed for direct attachment to existing taps at uranium processing facilities, allowing gaseous UF6 to come into direct contact with a zeolite film. The SUDA technology features the ability to capture uranium in a more easily shipped and handled form as the solid, more stable, and relatively less hazardous hydrated uranyl fluoride (UO2F2•nH2O), which is formed through the controlled hydrolysis of UF6. We have recently simulated uranium collection under enrichment plant sampling conditions to further improve our understanding of SUDA sampling. Presented here is our recent work on measuring the relationship between sampling conditions and uranium collection, which includes control of the uranium-mass-to-zeolite ratio and assessing variable UF6 gas and sampling parameters that can affect collection using the SUDA sampler.

Pope, Timothy R.↗

DOE OSTI2021

Aspects of Crystal Growth and Atomic-Scale Characterization of U/Th Age-Dating Particles

Trace analysis of particulate material collected on environmental swipe samples continues to be one of the cornerstones of the IAEA’s process of verifying member state compliance as part of the Non-Proliferation Treaty (NPT). While complementary to traditional bulk analysis, the ability to measure individual particles can be far more impactful from a radiochronometry perspective. The 234U/230Th radiochronometer is being evaluated as a means of establishing model ages for discrete particles with sufficient confidence. To support the extension of current capabilities, reference materials with a suitable particle form factor and well-documented purification date are actively sought for development with large geometry secondary ion mass spectroscopy.

Nuclear Safeguards, IAEA, Particle Standards↗