Stable High-Temperature Molten Salt Reference Electrodes

Thermodynamic, high-temperature reference electrodes (HTRE) with lifetimes of up to 6 months are necessary for monitoring the redox potential of nuclear- relevant, molten salts at elevated temperatures for corrosion control. Unfortunately, robust thermodynamic HTRE for this challenging application are not commercially available which inhibits the development and deployment of next-generation, molten-salt-cooled, high-temperature nuclear reactors. The HiFunda/INL/UofU team is proposing to leverage HiFunda’s Phase I electrochemical sensor and materials development and INL’s and UofU’s high- temperature molten salt electrochemical testing, first principles and thermodynamic experiences to develop and demonstrate new robust HTRE designs that meet the thermal, chemical, mechanical, electrical, manufacturability, cost, and reliability requirements for this demanding high-temperature molten salt application. The HiFunda/INL/UofU team is proposing to build upon the Phase I results to further develop and demonstrate a HTRE specifically designed and engineered for the high-temperature molten fluoride salt application. Robust thermodynamic HTRE designs that utilize a Ni/Ni(II) or Ag/Ag (I) couple with controlled porosity frits and robust seals will be established. HTRE material compatibility, seal performance, and electrochemical performance will be evaluated in molten fluoride salts as a function of time and temperature. Cost models will be established to identify cost drivers and to evaluate trade-offs between HTRE design, performance, and cost. A detailed commercialization plan will be developed and potential commercialization partners will be identified for participation in Phase II. The proposed approach will help to enable next-generation nuclear power generation which will have a significant positive effect on power generation and CO2 emissions in the US and worldwide. Reducing the reliance on fossil fuels and increasing the supply of energy produced from nuclear fuels will have an enormous impact on US energy security and US energy demand with abundant emission-free electricity. In addition, the HTRE developed for this application can be used to corrosion monitoring and control in other molten salt systems such as concentrated solar power (CSP).