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Hanson, Susan K.

Publications and source records attributed to Hanson, Susan K..

Trace Actinide Signatures of a Bulk Neptunium Sample

In nuclear forensic analyses, measurements of actinide elements in a sample can assist with identifying interdicted or unknown materials. While these radiochemical signatures have been extensively investigated in uranium materials, less is known about bulk neptunium samples. This paper describes the measurement of trace actinide concentrations and isotopic profiles in a 237 Np oxide sample. Uranium, plutonium, americium, and curium concentrations and isotopic profiles in the sample were determined and deemed potentially useful for distinguishing different sources of 237 Np. Furthermore, several different potential radiochronometry systems were also investigated; discordant results indicate that the Np sample was never completely purified of other actinide elements, or that subsequent contamination of the sample occurred. Few prior studies of neptunium materials have been reported, and these data suggest that trace actinide constituents could provide unique signatures to identify material out of regulatory control.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Demonstration of 151 Sm analysis using Trinity nuclear debris samples

Here, the long-lived fission product 151 Sm (T 1/2 ≈ 90 y) present in archived dissolved Trinity nuclear test debris samples was analyzed using liquid scintillation counting and the results were compared to the expected values based upon historical analysis results. The measured 151 Sm activities were found to agree with the expected values within experimental error. This demonstration validates the use of this technique in situations where the sample is too old for traditional shorter half-life radioactive fission product signatures such as 99 Mo (T 1/2 = 2.75 d), 97 Zr (T 1/2 = 16.7 h), 147 Nd (T 1/2 = 10.98 d), and 153 Sm (T 1/2 = 46.3 h), or too dilute for determining fissions through stable isotope ratio measurements.

151Sm↗

R-Value Measurements Performed on Actinide Targets Irradiated using the GODIVA IV Critical Assembly in FY22

The separation and characterization of two irradiated uranium targets, a depleted uranium (DU) and a highly enriched uranium (HEU) target as well as a plutonium (Pu) target, was conducted in April of 2022. The three targets were assembled at Los Alamos National Laboratory (LANL) and irradiated using the GODIVA critical assembly at the National Criticality Experiments Research Center (NCERC). Splits of the dissolved targets were received by Pacific Northwest National Laboratory (PNNL) after which the PNNL and LANL teams chemically separated the solutions using independent separation schemes and analyzed the separated fractions for short lived actinides and fission products. Chemical separations were traced with stable or radioactive tracers to allow for the determination of chemical yields, analyzing using either inductively coupled plasma optical emission spectroscopy (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS) or gamma emission analysis (GEA) depending on the nature of the tracer. The Pu target solution was traced with stable elements at LANL to follow elemental fractionation during a Pu removal step. Many analytical techniques were used by PNNL including kinetic phosphorescence analysis (KPA), ICP-OES, ICP-MS, GEA, and thermal ionization mass spectrometry (TIMS) depending on the analyte’s need.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Weapons Radiochemistry: Trinity and Beyond

On July 16, 1945, the Trinity nuclear test exploded in the desert near Alamogordo, New Mexico. A variety of new diagnostic experiments were fielded in an effort to understand the detailed performance of the nuclear device. This paper describes a series of radiochemical experiments that were designed to measure the efficiency and neutron fluence of the test. These experiments, and the scientists who led them, laid the foundation of weapons radiochemistry for decades to come.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗