Dennis Patrick Montoya

4,4′,6,6′-Tetra-Substituted Hydrazo- and Azo-1,3,5-Triazines

The syntheses of 4,4′,6,6′-tetra(amino)- (1), tetra(hydroxylamino)- (2), tetra(hydrazino)- (3), and tetra(azido)hydrazo-1,3,5-triazines (4) are described. Compound (4) was oxidized to 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (5). The thermal and sensitivity properties of (4) and (5) are reported in addition to all physical properties of new compounds

Elemental composition in sealed plutonium-beryllium neutron sources.

Five sealed plutonium-beryllium (PuBe) neutron sources from various manufacturers were disassembled. Destructive chemical analyses for recovered PuBe materials were conducted for disposition purposes. A dissolution method for PuBe alloys was developed for quantitative plutonium (Pu) and beryllium (Be) assay. Quantitation of Be and trace elements was performed using plasma based spectroscopic instruments, namely inductively coupled plasma mass spectrometry (ICP-MS) and atomic emission spectrometry (ICP-AES). Pu assay was accomplished by an electrochemical method. Variations in trace elemental contents among the five PuBe sources are discussed.

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of nine materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. The microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.

Novel sample introduction system to reduce ICP-OES sample size for plutonium metal trace impurity determination

A new methodology for trace elemental analysis in plutonium metal samples was developed by interfacing the novel micro-FAST sample introduction system with an ICP-OES instrument. This integrated system, especially when coupled with a low flow rate nebulization technique, reduced the sample volume requirement significantly. Improvements to instrument sensitivity and measurement precision, as well as long term stability, were also achieved by this modified ICP-OES system. The sample size reduction, together with other instrument performance merits, is of great significance, especially to nuclear material analysis.

Combining accuracy and precision of traceable standards to estimate uncertainties in trace element content measurements

AbstractThe accuracy and precision systematic of traceable certified reference material (CRM) standards can be combined to estimate the uncertainties that are achieved in analytical measurements. Standards (CRMs or other well characterized materials) in matrices similar to the unknown sample can be used for evaluation of the accuracy. The standards should be prepared following same preparation steps as the unknown samples and analyzed in the same analytical sequence as the samples using similar instrumental methods. The accuracy and precision of these quality control (QC) standards are combined to calculate uncertainty estimates for trace element contents. The uncertainties calculated from the QC standards are compared with those estimated following the guide to expression of uncertainty in measurements (GUM). For trace element content measurements using ICP-AES and ICP-MS instruments, the uncertainty estimates obtained by combining the accuracy and precision of the QC standards are found to be more conservative than those calculated by a model following GUM methodology. LA-UR-17-31180.

Assessment of the excitation temperatures and Mg II:I line ratios of the direct current (DC) arc source for the analysis of radioactive materials

The direct current (DC) arc plasma has been assessed with an emphasis on excitation temperature (Texe) and ionization/excitation efficiency by monitoring magnesium ionic:atomic ratios (Mg II:I). The primary goal is to improve the analytical performance of the DC arc instrumentation such that more sensitive and reproducible measurements can be achieved when analyzing trace impurities in nuclear materials. Due to the variety of sample types requiring DC arc analysis, an understanding of the plasma’s characteristics will significantly benefit the experimental design when moving forward with LANL’s capabilities for trace metal analysis of plutonium metals.

Analytical Chemistry and Materials Characterization Results for Debris Recovered from Nitrate Salt Waste Drum S855793

Solid debris was recovered from the previously-emptied nitrate salt waste drum S855793. The bulk sample was nondestructively assayed for radionuclides in its as-received condition. Three monoliths were selected for further characterization. Two of the monoliths, designated Specimen 1 and 3, consisted primarily of sodium nitrate and lead nitrate, with smaller amounts of lead nitrate oxalate and lead oxide by powder x-ray diffraction. The third monolith, Specimen 2, had a complex composition; lead carbonate was identified as the predominant component, and smaller amounts of nitrate, nitrite and carbonate salts of lead, magnesium and sodium were also identified. Microfocused x-ray fluorescence (MXRF) mapping showed that lead was ubiquitous throughout the cross-sections of Specimens 1 and 2, while heteroelements such as potassium, calcium, chromium, iron, and nickel were found in localized deposits. MXRF examination and destructive analysis of fragments of Specimen 3 showed elevated concentrations of iron, which were broadly distributed through the sample. With the exception of its high iron content and low carbon content, the chemical composition of Specimen 3 was within the ranges of values previously observed in four other nitrate salt samples recovered from emptied waste drums.