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Tandon, Lav

Publications and source records attributed to Tandon, Lav.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Morphological Comparison of U3O8 Ore Concentrates from Canada Key Lake and Namibia Sources

Uranium ore concentrates from two different sources were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The ore powders are referred to as Namibia (id. no. 90036, LIMS id. no. 18775) and Canada Key Lake (id. no. 90019, LIMS id. no. 18774). Earlier work identified the ores as the U₃O₈ phase of uranium oxide using x-ray diffraction. Both sets of powders were in the form of dark brown to black powder fines. However, the Canada Key Lake concentrates contained larger chunks of material on the millimeter scale that were easily visible to the unaided eye. The powders were mounted for SEM examination by hand dispersing a small amount onto conductive sticky tape. Two types of applicators were used and compared: a fine-tipped spatula and a foam-tipped applicator. The sticky tape was on a standard SEM “tee” mount, which was tapped to remove loose contamination before being inserted into the SEM.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Determination of initial fuel state and number of reactor shutdowns in archived low-burnup uranium targets

This article presents a method for destructive analysis of irradiated uranium (U) targets, with a focus on collection and measurement of long-lived (t 1/2 > ~10 years) and stable fission product isotopes of ruthenium and cesium. Long-lived and stable isotopes of these elements can provide information on reactor conditions (e.g. flux, irradiation time, cooling time) in old samples (> 5–10 years) whose short-lived fission products have decayed away. The separation and analytical procedures were tested on archived U reactor targets at Los Alamos National Laboratory as part of an effort to evaluate reactor models at low-burnup.

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DOE OSTI2015

Dissolution of aerosol particles collected from nuclear facility plutonium production process

Here, a simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO 3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 °C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

Plutonium oxalate precipitation for trace elemental determination in plutonium materials

In this study, an analytical chemistry method has been developed that removes the plutonium (Pu) matrix from the dissolved Pu metal or oxide solution prior to the determination of trace impurities that are present in the metal or oxide. In this study, a Pu oxalate approach was employed to separate Pu from trace impurities. After Pu(III) was precipitated with oxalic acid and separated by centrifugation, trace elemental constituents in the supernatant were analyzed by inductively coupled plasma-optical emission spectroscopy with minimized spectral interferences from the sample matrix.

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DOE OSTI2015

Analytical and Radiochemistry for Nuclear Forensics

Information about nonproliferation nuclear forensics, activities in forensics at Los Alamos National Laboratory, radio analytical work at LANL, radiochemical characterization capabilities, bulk chemical and materials analysis capabilities, and future interests in forensics interactions.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

Annual Report on the Activities and Publications of the DHS-DNDO-NTNFC Sponsored Post-doctoral Fellow at Los Alamos National Laboratory

This report is a summary of the projects Jung Rim is working on as a DHS postdoctoral fellow at Los Alamos National Laboratory. These research projects are designed to explore different radioanalytical methods to support nuclear forensics applications. The current projects discussed here include development of alpha spectroscopy method for 240/239 Pu Isotopic ratio measurement, non-destructive uranium assay method using gamma spectroscopy, and 236 U non-destructive uranium analysis using FRAM code. This report documents the work that has been performed since the start of the postdoctoral appointment.

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DOE OSTI2014

Report: Update of chemical analysis results for the Japan Atomic Energy Agency (JAEA) collaboration study sample (CRM 124-3)

Additional measurement data for collected by the Actinide Analytical Chemistry group at Los Alamos National Laboratory is provided in this report. Initial data was provided in April 2014 (LA-UR-14-22300) on the same sample material. That earlier document also contained procedure references for all the utilized techniques including those used to generate the data in this document. The Measurement Protocol table below summarizes the characterization that was planned for this sample material.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2013

Design and Application of TIMS-Based Thorium Measurement Methods in the Actinide Analytical Chemistry Group at Los Alamos National Laboratory

Quantitation of inter-related actinides in nuclear materials, whether they be intercepted (e.g. stolen fuel pellets) or purposefully collected (e.g. cotton swipe samples), is essential in modern nuclear forensics and safeguards. Well-designed procedures may provide insight into a material’s “age” (i.e. time since last purification), suggest processing/preparation routes, and point to involved parties. In the present work, we detail the design and preliminary application of a thermal ionization mass spectrometry (TIMS) based approach to the analysis of thorium-230 within uranium-bearing materials. These efforts are in-line with a chronometric-type analysis strategy and focused on identification of appropriate preparation procedures, development of required spiking materials (i.e. 229 Th), and evaluation of uranium certified reference materials (CRMs). The presence of thorium in these materials is expected to be largely due to a combination of the decay of parent uranium (e.g. 234 U) to daughter nuclides (e.g. 230 Th), and thorium persistence following last purification.

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DOE OSTI2012

Opening the Plutonium-Beryllium Neutron Sealed-Source RGMA1002-468/67

The Foreign Material Characterization Project requires that PuBe neutron sealed-sources be opened to determine the chemical and physical characteristics of the PuBe materials produced for source manufacture. In order to provide an accurate and thorough evaluation of PuBe materials, the sealed-sources must be opened with care so that all PuBe material is retained in the innermost sealed-source container and free from the transfer of nuclear material previously processed in the glovebox.

Isotope & Radiation Sources(07)↗
DOE OSTI2012

A Report on the Activities, Publications, and Pending Research of a DHS/DOD Sponsored Postdoctoral Research Associate at Los Alamos National Laboratory

Since beginning at Los Alamos National Laboratory in February of 2012, I have been working as a DHS/DNDO Postdoctoral Research Associate under the mentorship of Lav Tandon and Khalil Spencer (NA-22 and mass spectrometry). The focus of these efforts, in addition to pursuing training and qualifications, has principally been the application of Thermal Ionization Mass Spectrometry (TIMS) methods to the characterization of actinide systems of interest in nuclear forensics research. Recently pursued initiatives have included the adaptation of modified total evaporation (MTE) strategies to current group methods and the preliminary development of TIMS-based uranium age-dating approaches; each of these points is discussed below, along with future plans.

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DOE OSTI2012

Opening the Plutonium-Beryllium Neutron Sealed-Source RGMA1002-113

The radiograph of the PuBe neutron sealed-source was useful in determining dimensions and identifying construction details. This information gives the engineer and machinist a better idea of where to breach the outer container. It would be advantageous to use a higher energy radiography system to provide information about inner container dimensions, construction details, and nuclear material location to facilitate disassembly. Characterization of the inner and outer container materials would be useful for selecting proper cutting inserts to provide more efficient and cleaner cuts. A real-time, in-line method for qualitatively identifying metal compositions such as handheld x-ray fluorescent (XRF) may prove sufficient. The disassembly of PuBe sealed-sources generally involves numerous attempts to pry a lid or plug from the innermost container. The forces involved make it impractical to hold the source so this attempt must take place with the container held horizontally in the collet. The horizontal orientation risks the flow of PuBe materials out of the container when the plug is freed as occurred in this disassembly. To mitigate this risk, it was agreed that a small vise should be introduced into the glovebox to hold the container firmly in a vertical orientation for attempts to pry off lids or plugs. The vise should hold cylindrical containers firmly without inflicting scratches or gouges into sealed-source metal surfaces. Documentation of PuBe neutron sealed-source disassembly is effectively recorded with a series of professional photographs as presented in this report. Unfortunately, the prevalence of metal surfaces and materials combined with uneven, low light conditions reduce the contrast between disassembled parts and background. To improve the photographic record of disassembly, colored liner materials should be identified and introduced as a staged background for PuBe component pictures.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2012

Qualification of the Savannah River National Laboratories Coulometer, Model SRNL-Rev. 2 (Serial # SRNL-003 Coulometer) for use in Process 3401a, Plutonium Assay by Controlled Coulometer

This report discusses the process used to prove in the SRNL-Rev.2 coulometer for isotopic data analysis used in the special plutonium material project. In May of 2012, the PAR 173 coulometer system that had been the workhorse of the Plutonium Assay team since the early 1970s became inoperable. A new coulometer system had been purchased from Savannah River National Laboratory (SRNL) and installed in August of 2011.

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DOE OSTI2012

Nuclear Forensics at Los Alamos National Laboratory

The overview of this presentation is: (1) Introduction to nonproliferation efforts; (2) Scope of activities at Los Alamos National Laboratory; (3) Facilities for radioanalytical work at LANL; (4) Radiochemical characterization capabilities; and (5) Bulk chemical and materials analysis capabilities. Some conclusions are: (1) Analytical chemistry measurements on plutonium and uranium matrices are critical to numerous defense and non-defense programs including safeguards accountancy verification measurements; (2) Los Alamos National Laboratory operates capable actinide analytical chemistry and material science laboratories suitable for nuclear material forensic characterization; (3) Actinide analytical chemistry uses numerous means to validate and independently verify that measurement data quality objectives are met; and (4) Numerous LANL nuclear facilities support the nuclear material handling, preparation, and analysis capabilities necessary to evaluate samples containing nearly any mass of an actinide (attogram to kilogram levels).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Application of Micro-XRF for Nuclear Materials Characterization and Problem Solving

Micro-X-ray fluorescence (MXRF) used for >> 20 years To date MXRF has been underutilized for nuclear materials (NM) spatially-resolved elemental characterization. Scanning electron microscopy (SEM) with EDX much more common for NM characterization at a micro scale. But MXRF fills gap for larger 10's microns to cm{sup 2} scales. Will present four interesting NM applications using MXRF. Demonstrated unique value of MXRF for various plutonium applications. Although SEM has much higher resolution, MXRF clearly better for these larger scale samples (especially non-conducting samples). MXRF useful to quickly identify insoluble particles in Pu/Np oxide. MXRF vital to locating HEPA filter Pu particles over cm{sup 2} areas which were then extracted for SEM morphology and particle size distribution analysis. MXRF perfect for surface swipes which are far too large for practical SEM imaging, and loose residue would contaminate SEM vacuum chamber. MXRF imaging of ER Plutonium metal warrants further studies to explore metal elemental heterogeneity.

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