Publications
Showing 126 results for Author: Laetitia H. Delmau
Jul, 2026
Journal
Pu(IV) quantification via visible–near-infrared absorption spectroscopy: tackling interferences using D-optimal design and partial least squares
This study presents a novel analytical approach for quantifying Pu(IV) in glove box environments using fiber-optic-based visible–near-infrared absorption spectroscopy in combination with partial least squares regression (PLSR) and design of experiments. The method addresses significant challenges posed by overlapping spectral features arising from Nd(III), which is a commo…
Apr, 2026
Journal
Evaluating Np(v) disproportionation: effect of Np concentration
The role of Np(V) concentration as a potential chemical driver of Np(V) disproportionation was investigated by probing Np redox chemistry in two different acid media using visible-near-infrared absorbance spectroscopy. In situ spectroscopy of chemically and electrochemically manipulated Np oxidation states at molar concentrations of Np underscores the difficulty in stabili…
Mar, 2026
Journal
UV–Vis–NIR Reflectance Spectroscopy and Chemometrics for Monitoring Pu Directly on an Ion Exchange Column
We present a fiber-optic UV–vis–NIR reflectance spectroscopy method for direct, noninvasive monitoring of Pu(IV) in a glass ion exchange column during dynamic loading and elution in a glovebox. A movable probe enables spatially resolved spectral acquisition along the column axis, capturing distinct features associated with Pu(IV) nitrate complexes during loading and free i…
Mar, 2026
Conference Paper
Initial Testing of Mediated Electrochemical Oxidation for Inclusion in the Plutonium-238 Production Program
Oak Ridge National Laboratory is currently restarting the United States’ capability to produce kilogram quantities of 238Pu annually for space power applications. This involves the purification of 238Pu from neutron-irradiated 237Np targets and conversion to heat-source plutonium oxide product for shipment to Los Alamos National Laboratory. Dissolution of the plutonium oxi…
Mar, 2026
Conference Paper
Process Development for Plutonium-238 Production at Oak Ridge National Laboratory
The third chemical processing campaign conducted at Oak Ridge National Laboratory (ORNL) with irradiated neptunium oxide–aluminum cermet targets produced plutonium-238 oxide product meeting purity specifications for space power applications. This is a major step for the Plutonium-238 Supply Program toward reestablishing production. This summary highlights results to date a…
Feb, 2026
Journal
Capture of Volatile RuO4 from Oxidized Simulated Used Nuclear Fuel Solutions
Ruthenium is a challenging fission product in used nuclear fuel (UNF) reprocessing due to its complex redox chemistry, variable speciation in nitric acid, partial extractability, and volatility. This work presents a strategy for Ru removal based on the volatilization of RuO4 using the strong oxidant sodium bismuthate, followed by RuO2 deposition onto various substrates. Am…
Jan, 2026
Journal
Recovering High-Purity Uranyl Nitrate from Simulated Used Nuclear Fuel Dissolver Solutions by Crystallization: Rejecting Technetium
The separation of U from Tc and other problematic fission product elements like Mo and Ru, along with Sr, Zr, Cs, and Nd, has been achieved via the crystallization of uranyl nitrate hexahydrate (UNH). Rejection of technetium as pertechnetate anion (99TcO4–) is an especially important feature of this system, as it otherwise tends to follow U(VI) in extractive separations. I…
Dec, 2025
Journal
Remote Sensing of Pu in Uranyl Nitrate Crystals Using Reflectance Spectroscopy and Chemometrics
Remote quantification of Pu(VI) (0–5 mol%) co-crystallized with U in uranyl nitrate hexahydrate (UNH) crystals was achieved in a glove box using reflectance spectroscopy coupled with chemometric modeling. Reflectance spectra were also acquired for Pu(IV) and Np(VI) (0–5 mol%) crystallized with UNH; revealing spectral features consistent with their solution-phase analogs. P…