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Makarashvili, Vakhtang

Publications and source records attributed to Makarashvili, Vakhtang.

14 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Side-reaction products identified for photo-nuclear production of 99 Mo

Production of 99 Mo by the 100 Mo (γ, n) 99 Mo reaction through the bremsstrahlung process using an electron accelerator is one of the feasible options currently pursued by several countries. In this work, we report experimental results on identification of side-reaction products after the irradiation of natural and enriched 100 Mo targets. Side-reaction products identified include various Mo, Nb and Zr isotopes. Comparison of experimentally determined reaction production rates with those determined based on theoretical cross-sections will be presented. Moreover, activation products formed due to presence of impurities introduced during the manufacturing of the Mo targets will also be discussed.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Nek5000 Simulations on Turbulent Coolant Flow in a Fuel Assembly Experiment - AREVA/ANL collaboration for advancing CFD tools

The NEAMS program aims to develop an integrated multi physics simulation capability “pellet to plant” for the design and analysis of future generations of nuclear power plants. In particular, the Reactor Product Line code suite’s multi resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2017

A performance analysis of ensemble averaging for high fidelity turbulence simulations at the strong scaling limit

We analyze the potential performance benefits of estimating expected quantities in large eddy simulations of turbulent flows using true ensembles rather than ergodic time averaging. Multiple realizations of the same flow are simulated in parallel, using slightly perturbed initial conditions to create unique instantaneous evolutions of the flow field. Each realization is then used to calculate statistical quantities. Provided each instance is sufficiently de-correlated, this approach potentially allows considerable reduction in the time to solution beyond the strong scaling limit for a given accuracy. This study focuses on the theory and implementation of the methodology in Nek5000, a massively parallel open-source spectral element code.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Compendium of Phase-I Mini-SHINE Experiments

Argonne National Laboratory is assisting SHINE Medical Technologies in their efforts to develop the technology to become a domestic Mo-99 producer using low-enriched uranium (LEU). Mini-SHINE experiments are being performed with the high-current electron linear accelerator (linac) at Argonne. The target solution is a 90-150 g-U/L LEU uranyl sulfate at pH 1. In Phase 1, the convertor was tantalum with a maximum beam power on the convertor of 10 kW, and the target solution was limited to 5 L. This configuration generated a peak fission power density of 0.05 W/mL. Nine experiments were performed between February and October 2015. Results are reported and discussed for each experiment regarding the off-gas analysis system, the sampling and Mo-recovery operation, and the Mo-product concentration and purification system. In Phase 2, the convertor will be depleted uranium; beam power will increase to 20 kW; and the solution volume will be 18 L. This configuration will generate a fission power density of up to 1 W/mL.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Assessment of candidates for target window material in accelerator-driven molybdenum-99 production

NorthStar Medical Technologies is pursuing production of an important medical isotope, Mo-99, through a photo-nuclear reaction of a Mo-100 target using a high-power electron accelerator. The current target utilizes an Inconel 718 window. The purpose of this study was to evaluate other candidate materials for the target window, which separates the high-pressure helium gas inside the target from the vacuum inside the accelerator beamline and is subjected to significant stress. Our initial analysis assessed the properties (density, thermal conductivity, maximum stress, minimum window thickness, maximum temperature, and figure of merit) for a range of materials, from which the three most promising were chosen: Inconel 718, 250 maraging steel, and standard-grade beryllium. These materials were subjected to further analysis to determine the effects of thermal and mechanical strain versus beam power at varying thicknesses. Both beryllium and the maraging steel were calculated to withstand more than twice as high beam power than Inconel 718.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Optimization of the Processing of Mo Disks

The objective of this work is to decrease the processing time for irradiated disks of enriched Mo for the production of 99 Mo. Results are given for the dissolution of nonirradiated Mo disks, optimization of the process for large-scale dissolution of sintered disks, optimization of the removal of the main side products (Zr and Nb) from dissolved targets, and dissolution of irradiated Mo disks.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Micro-Bubble Experiments at the Van de Graaff Accelerator

In order to test and verify the experimental designs at the linear accelerator (LINAC), several micro-scale bubble ("micro-bubble") experiments were conducted with the 3-MeV Van de Graaff (VDG) electron accelerator. The experimental setups included a square quartz tube, sodium bisulfate solution with different concentrations, cooling coils, gas chromatography (GC) system, raster magnets, and two high-resolution cameras that were controlled by a LabVIEW program. Different beam currents were applied in the VDG irradiation. Bubble generation (radiolysis), thermal expansion, thermal convection, and radiation damage were observed in the experiments. Photographs, videos, and gas formation (O 2 + H 2 ) data were collected. The micro-bubble experiments at VDG indicate that the design of the full-scale bubble experiments at the LINAC is reasonable.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Experimental Results for Direct Electron Irradiation of a Uranyl Sulfate Solution: Bubble Formation and Thermal Hydraulics Studies

In support of the development of accelerator-driven production of fission product Mo-99 as proposed by SHINE Medical Technologies, a 35 MeV electron linac was used to irradiate depleted-uranium (DU) uranyl sulfate dissolved in pH 1 sulfuric acid at average power densities of 6 kW, 12 kW, and 15 kW. During these irradiations, gas bubbles were generated in the solution due to the radiolytic decomposition of water molecules in the solution. Multiple video cameras were used to record the behavior of bubble generation and transport in the solution. Seven six-channel thermocouples were used to record temperature gradients in the solution from self-heating. Measurements of hydrogen and oxygen concentrations in a helium sweep gas were recorded by a gas chromatograph to estimate production rates during irradiation. These data are being used to validate a computational fluid dynamics (CFD) model of the experiment that includes multiphase flow and a custom bubble injection model for the solution region.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

Design and Testing of Subsystems for Mo-99 Production Facility

So far, three beamline configurations have been proposed for the SHINE Medical Technologies facility for producing fission-product 99 Mousing a D/T-accelerator (Figure 1). One configuration, proposed by Los Alamos National Laboratory (LANL), includes a three-bend magnet system with a total 20 o bending angle. This configuration also includes a set of octuplet magnets to generate a non-Gaussian beam profile. Argonne has proposed two beamlines based on a (1)10° bending magnet (Appendix A and Ref. 1) and (2) alpha magnets (Appendix B) that use a pair of raster doublets to redistribute the beam over the face of the target. While those configurations are quite different, and each of the configurations has its advantages and disadvantages, they all have to incorporate the means to verify beam parameters before placing the beam on the target, monitor beam position and shape during a run, protect the target housing from the overheating due to beam displacement, and protect the beamlines from overheating due to beam misalignment.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

Design and Testing of Subsystems for Mo-99 Production Facility

Three beamline configurations have been proposed for the SHINE Medical Technologies facility for producing fission-product 99 Mo using a D/T-accelerator (Figure 1). One configuration, proposed by Los Alamos National Laboratory (LANL), includes a three-bend magnet system with a total 20° bending angle. This configuration also includes a set of octuplet magnets to generate a non-Gaussian beam profile. Argonne has proposed two beamlines based on a (1) 10° bending magnet (Appendix A and Ref. 1) and (2) alpha magnets (Appendix B) that use a pair of raster doublets to redistribute the beam over the face of the target. This report gives an overview of the various designs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Irradiation of HDPE Bottles

The short-term plan of NorthStar Medical Technologies for production of Mo-99 is to use the research reactor at the University of Missouri in Columbia (MURR). The Mo-99 will be produced by the activation reaction Mo-98(n, Υ) Mo-99 using enriched Mo-98 targets. There is a concern about the radiation stability of the high-density polyethylene (HDPE) bottles to be used to move the Mo product from the MURR recovery hot cell to the dispensing cell. Therefore, Argonne performed an experimental study to measure the radiation stability of the HDPE bottles, which can be used to transfer ~450 Ci of Mo-99. The first part of the study was to calculate that the dose the bottle will receive over two weeks with starting activity of 450 Ci of Mo-99. Then, irradiation experiments were performed with a Van de Graaff electron generator.

HDPE Bottle↗
DOE OSTI2014

Formulation and Analysis of Compliant Grouted Waste Forms for SHINE Waste Streams

Optional grouted waste forms were formulated for waste streams generated during the production of 99Mo to be compliant with low-level radioactive waste regulations. The amounts and dose rates of the various waste form materials that would be generated annually were estimated and used to determine the effects of various waste processing options, such as the of number irradiation cycles between uranium recovery operations, different combinations of waste streams, and removal of Pu, Cs, and Sr from waste streams for separate disposition (which is not evaluated in this report). These calculations indicate that Class C-compliant grouted waste forms can be produced for all waste streams. More frequent uranium recovery results in the generation of more chemical waste, but this is balanced by the fact that waste forms for those waste streams can accommodate higher waste loadings, such that similar amounts of grouted waste forms are required regardless of the recovery schedule. Similar amounts of grouted waste form are likewise needed for the individual and combined waste streams. Removing Pu, Cs, and Sr from waste streams lowers the waste form dose significantly at times beyond about 1 year after irradiation, which may benefit handling and transport. Although these calculations should be revised after experimentally optimizing the grout formulations and waste loadings, they provide initial guidance for process development.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗