Engineering topics

Ebert, W. L.

Publications and source records attributed to Ebert, W. L..

5 records

DOE OSTI2024

Simplifying Ceramic Waste Form Processing

The glass-bonded sodalite ceramic waste form (CWF) was developed in the 1990s to immobilize chloride salt-bearing waste streams generated during treatment of spent sodium-bonded nuclear fuel. This was necessary because chloride salts are essentially insoluble in borosilicate glasses (on the order of 1%). In the CWF, synthetic sodalite (Na 8 [Al 6 Si 6 O 24 ]Cl 2 ) is generated by the reaction of zeolite 4A and NaCl during processing to sequester the chlorine. The resulting sodalite crystals become microencapsulated in borosilicate glass. Based on the current understanding of the reactions involved and advancements in pyroprocessing operations in which the waste salt is generated, the processes developed for producing fullsize CWF materials with waste salt may be unnecessarily complicated. Aspects of processing that could be simplified and initial studies to justify further engineering development are recommended.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2024

Effects of open circuit immersion and vertex potential on potentiodynamic polarization scans of metallic biomaterials

Abstract Electrodes made of commercially pure titanium (CP-Ti) and a CoCrMo alloy are immersed at an open circuit in a phosphate buffer saline electrolyte at room temperature for different durations prior to electrochemical analyses. Open circuit potential measurements, electrochemical impedance spectroscopy measurements, and cyclic potentiodynamic polarization (CPP) scans are used to assess the impact of the immersion time on derived property values. Stable passivation layers formed on both materials during immersion. The corrosion potentials determined from the anodic legs of CPP scans become more cathodic, and the corrosion currents decrease to lower values after longer immersion times. Measured currents indicate the layers formed on CP-Ti stabilize during forward anodic scans and persist to the vertex potential, whereas passivation breakdown occurs during anodic scans with CoCrMo with active corrosion at voltages up to the vertex potential. The characteristics of the return cathodic legs of CPP scans represent the surface conditions at the vertex potential: characteristic corrosion property values derived from the test responses represent passive surfaces on CP-Ti and leached surfaces on CoCrMo rather than intrinsic properties of those materials.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Corrosion rates measured under potentiostatic conditions to represent performance of a cermet nuclear waste form

Electrochemical tests were conducted to assess the corrosion performance of a developmental multiphase cermet nuclear waste form in different conditions. Corrosion currents were monitored as the surface equilibrated in an acidic brine solution during potentiostatic tests at different imposed potentials. Electrochemical impedance spectroscopy was used to quantify differences in the electrical properties of surfaces stabilised at different potentials. The passivating oxides that will stabilise the surface under disposal conditions are formed and maintained during testing. The measured corrosion currents were two orders of magnitude lower for passivated surfaces than for polished surfaces over a wide range of redox conditions. The electrochemical results were correlated with microscopic analyses of the corroded surfaces and physical models of the surface passivation and degradation processes are proposed. The measured corrosion rates are suitable for the long-term performance modeling of cermet nuclear waste forms.

Gattu, V. K.↗

DOE OSTI2023

Technology Development Roadmap for Volatile Radionuclide Capture and Immobilization

An "Off-Gas and Waste Forms Strategy Workshop" was held in Washington, D.C. on January 31, and February 1, 2023, to review the current state of the art (baseline) technologies for capturing and immobilizing these volatile radionuclides in waste forms (WFs). The discussions in that workshop were used to develop a roadmap for future research and development to mature technologies that are presently not ready for use in a commercial reprocessing facility and develop and demonstrate technologies that provide more safety, more simplicity, or lower costs compared to the current baseline.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1978

A two satellite technique for measuring atmospheric surface pressure

A two-satellite system configuration is designed in which one satellite transmits a signal which is reflected from the sea surface and received by the other satellite. The time delay of the signal is measured. By selecting the geometry such that the signal path makes a small grazing angle with the sea surface, the amount of troposphere passed through and hence the magnitude of the tropospheric effect is maximized; requirements on timing accuracy are thus relaxed. The vacuum path length of the radar signals must be subtracted from the measured path length in order to compute the tropospheric effect, which is highly correlated to the atmospheric surface pressure. This is done by measuring the time delays along three additional paths. The use of an operational constellation of several satellites further decreases sensitivity to geoidal errors.

Goldfinger, A. D.↗