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Non-destructive Evaluation of LiAlO2 Pore Structure and Microstructure


EMSL Project ID
51794

Abstract

Tritium (3H) is a strategically important isotope of hydrogen. In the U.S. Tritium Sustainment Program (operated by DOE National Nuclear Security Administration (NNSA)), tritium is generated through a thermal neutron reaction in γ-LiAlO2 pellets contained within tritium-producing burnable absorber rods (TPBARs) placed within a nuclear reactor. During the irradiation, point defects are produced in the LiAlO2 pellet microstructure, leading to significant structural changes and concurrent modifications in thermomechanical properties as irradiation progresses. The lack of scientific understanding of the relationship between pellet microstructure and strength, particularly following irradiation, limits 6Li burnup to very conservative value to avoid the loss of mechanical and structural integrity of the target material. We will establish non-destructive evaluation (NDE) methods to evaluate LiAlO2 pellets so that strength data can be correlated directly to the microstructure of the samples being measured. We will use the EMSL capabilities of spectroscopic ellipsometry and Brunauer-Emmett-Teller (BET) gas adsorption to characterize the pore structure of unirradiated pellets, and correlate this data with resonant ultrasound spectroscopy measurements of whole pellets. Our non-destructive structural property measurements will enable correlations with mechanical testing of the same sample, and hold the potential for in-situ pellet evaluation.

Project Details

Start Date
2020-12-07
End Date
2021-09-30
Status
Closed

Team

Principal Investigator

Tiffany Kaspar
Institution
Pacific Northwest National Laboratory

Team Members

Joelle Reiser
Institution
Pacific Northwest National Laboratory