Levi Gardner Email & Phone Number

Lemont, Il, Us

A high-temperature rotational viscosity measurement system was developed for the characterization of molten salts in support of advanced reactor commercialization efforts. Assistance with thermal diffusivity, melting behavior, and heat capacity measurements was also provided in connection with these efforts. ASME NQA-1-ready standard operating procedures for viscosity, vapor pressure and thermal diffusivity measurements were authored. Physical property data (melting behavior, thermal diffusivity, X-ray diffraction patterns, and viscosity) were measured for various molten salt systems relevant to advanced nuclear energy applications (assisted several projects as either PI or co-PI). Project updates and dissemination of engineering data were regularly provided to public and private sponsors in periodic meetings. Data packages and reports were authored detailing the syntheses, chemical analyses, and thermophysical property measurements of various molten salts. Daily operations of radiological/beryllium gloveboxes were overseen including material characterization tasks, radiological material inventory and accountancy, safety inspections, radioactive waste management, and maintenance.

Lemont, Il, Us

Salt Lake City, Ut, Us

Alternative processing paths were investigated for the minimization of radioactive waste salt volume via halide ion removal as HCl gas. Dehalogenation (using hydrogen-stabilized Y zeolite) and subsequent consolidation (via sintering) produced a multiphase ceramic waste form with a 35% reduction in end storage volume compared to the baseline disposal process. A set of optimal sintering parameters for ceramic waste form synthesis was developed according to X-ray diffraction (XRD), differential scanning calorimetry (DSC), and microscopy results. These synthesis parameters resulted in a 60% decrease in chemical release rate in solution compared to the baseline ceramic waste form (measured using ASTM C1308 accelerated leach test). A process for waste salt immobilization using a bismuth borate matrix was demonstrated, and the properties of the resulting intermediate borate glass-ceramic were characterized using microscopy, XRD, DSC, and accelerated leach testing. These results highlighted the need for additions of glass-forming compounds to strengthen the glass network. These findings resulted in the Outstanding Student Research Award from the Nuclear & Environmental Technology Division (NETD) of the American Ceramics Society (ACerS) at Materials Science & Technology (MS&T) 2018.Working temperature regions were identified for a novel series of bismuth aluminoborosilicate and bismuth borate glasses for use in radioactive waste immobilization. Glasses were synthesized using melt-quench-anneal methods. DSC and parallel plate viscosity measurements were used to characterize glass transition, crystallization behavior, viscosity, and fragility of glasses. Microstructural images were used to assess glass homogeneity. These data were used to construct compositional-property regression models for thermal property prediction within this novel glass space. These findings resulted in the Best Student Presentation award from ACerS NETD at MS&T 2017

Lemont, Il, Us

An Excel Visual Basic regression code was refined for use in predicting long-term chemical release behavior of monolithic waste forms in solution. These bug fixes and user instruction edits were incorporated into the latest revision of ASTM standard C1308 to improve clarity of the modeling portion of the standard. A series of accelerated leach tests (ASTM C1220, C1285, C1308) were carried out to investigate the effects of crystallization and solution feedback on the durability of iron phosphate glass waste forms.

Logan, Utah, Us

The thermal conductivity of chemically treated kenaf bio-fiber-epoxy composites was measured to evaluate their potential as a green construction material. Thermal transport in composites made from NaOH-treated and untreated fibers was characterized using laser flash analysis (LFA) and DSC to investigate the effect of fiber treatment on conduction at fiber-epoxy interfaces. The thermal conductivities of individual kenaf fibers were measured separately using the transient electro-thermal (TET) technique to estimate fiber contributions to overall thermal transport. Interface morphologies, fiber diameters, and the effects of chemical treatment of fibers were evaluated using scanning electron microscopy (SEM). A set of thermal resistance models were developed based on these property measurements to provide improved prediction of heat transfer in kenaf-epoxy composites.

Richland, Wa, Us

The corrosion rates and electrochemical behavior of uranium-10 wt% molybdenum alloy (U-Mo) fuel was investigated as functions of thermomechanical processing and temperature. 1000+ safe working hours were logged performing tasks in a radiological fume hood in support of these tasks. Experimental data provided baseline information supporting the future implementation of this fuel in research and test reactors. In support of U-Mo characterization, ImageJ software was used to correlate fission gas bubble evolution with burnup in irradiated fuel plates for use in mesoscale thermal property modeling. Also, a multi-layer heat model was used to extract fuel meat thermal diffusivity values from the bulk fuel plate diffusivity. These findings represent the best approach currently available in literature regarding thermal diffusivity determination of multi-layered systems and were reported in a PNNL internal report.

Richland, Wa, Us

Used ImageJ software to correlate fission gas bubble evolution with burnup in uranium-10 wt% molybdenum (U-Mo) alloysUsed a multi-layer heat model and solutions to the heat equation to extract the thermal diffusivity of U-Mo fuel meat from bulk fuel plate diffusivity valuesEvaluated temperature dependence of U-Mo specific heat and thermal diffusivity using differential scanning calorimetry (DSC) and laser flash analysis (LFA) dataEvaluated electrical resistivity measurement needs of U-Mo alloy foils for verification of microstructureAssisted in matlab code development correlating U-Mo optical micrograph grayscale with molybdenum content

Logan, Utah, Us

Employed comparative longitudinal heat flow methods to experimentally measure the thermal conductivity of surrogate nuclear fuel compactsPrepared numerous test assemblies by welding and setting thermocouples, insulating test pieces, and operating power-controlled heaters and furnace

Logan, Utah, Us

Completed full CRLA Tutoring Certification coursework for environments of higher education Tutored undergraduate students in all math disciplines 8 hours per week

London, England, Gb

Worked with engineers to create assembly bills of material and manufacturing bills of processes using Siemens Teamcenter and NX-UnigraphicsAuthored weekly organizational change management newsletters, detailing transformation program progress to the entire business siteUpdated transformation program webpage, highlighting engineering solution milestones and future plansCompleted Yellow Belt process excellence training and accompanying process analysis projectParticipated in multiple volunteer service opportunities at family assistance centers in Knox County, OH

Salt Lake City, Utah, Us

Completed HAZWOPER, Radiation Worker, and Safety & Health training including emergency response procedures, and stop work policyWorked with project manager to maintain open communication between engineers and machinery operatorsEvaluated disposal site ground compaction and density during construction using Troxler Nuclear Density gaugeMeasured clay liner thickness and elevation and groundwater testing points with Trimble GPS survey equipmentSurveyed personnel and vehicles exiting restricted area with radiation rate meter

Doctor Of Philosophy - Phd, Metallurgical Engineering

Master Of Science (M.S.) Mechanical Engineering, Emphasis: Corrosion And Materials Science

Bachelor Of Science (B.S.), Mechanical Engineering

Associate'S Degree, General Studies