Design and Fabrication of a Thermodynamic Reference Electrode Using Chemical Vapor Deposition
Molten salt-cooled reactors have the potential to be significantly more efficient than other nuclear reactor designs, as they offer higher heat transfer capacity, higher operating temperature, and lower operating pressure. Thermodynamic reference electrodes (TRE) are necessary for control of the primary coolant chemistry, identifying air and/or moisture ingress into the coolant, and gauging structural material corrosion, all of which factor into the operational safety of the reactor. The stability and accuracy of TREs are currently limited by their materials of construction, which must be able to withstand hundreds of hours of thermal cycling in extremely corrosive conditions. Ultramet is developing a thermodynamic reference electrode for use in molten salt-cooled reactors that is fabricated from a porous open-cell foam graphite body. The body of the electrode is electrically insulated using a chemical vapor deposited (CVD) coating of boron nitride (BN). Lanthanum fluoride (LaF3), a selectively permeable membrane for fluoride ions, is deposited onto and wicked into the internal surfaces of the TRE cell. CVD allows for the precise control of grain size and orientation and coating morphology, which will improve the properties of the insulator and membrane structures. This in turn will result in improvements to the thermomechanical properties, thermal shock resistance, and life expectancy of the TRE. This project focused on initial development of the TRE design and initial establishment of CVD processes for the insulator and membrane coatings. Porous graphite coupons were coated with BN and tested by the SALT Research Group at the University of California, Berkeley for long-term salt compatibility. Electrochemical accuracy was tested using porous graphite electrodes that were coated with BN on the outside and infiltrated with the LaF3 membrane. The initial feasibility of the TRE was demonstrated, with ionic contact established and accurate measurements of electrochemical potential obtained. The development of production-scale TREs for use in monitoring and controlling the redox potential of molten salts is pivotal to the safety of the molten salt reactor. The technology will be marketed to developers and manufacturers of molten salt reactors. Additionally, Ultramet will expand its TRE development for use in other applications that use molten salts, such as extraction of energy-intensive metals, carbon dioxide capture, energy storage, and the commercial production of novel materials such as carbon nanoparticles, nanodiamonds, and graphene.
- Research Organization:
- Ultramet (Pacoima, CA)
- Sponsoring Organization:
- USDOE Office of Science (SC); USDOE Office of Nuclear Energy (NE)
- Contributing Organization:
- University of California, Berkeley (SALT Research Group)
- DOE Contract Number:
- SC0021952
- OSTI ID:
- 1988080
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-ULTRAMET-0021952; ULTRA-TR-22-17295
- Country of Publication:
- United States
- Language:
- English
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