AVS 66th International Symposium & Exhibition
    Actinides and Rare Earths Focus Topic Tuesday Sessions
       Session AC+AS+LS-TuA

Paper AC+AS+LS-TuA11
Reactivity of Potential TRISO Fuel Barrier Layers (SiC and ZrN) with H2O Probed with Ambient Pressure Photoelectron Spectroscopy

Tuesday, October 22, 2019, 5:40 pm, Room A215

Session: Forensics, Science and Processing for Nuclear Energy
Presenter: Jeff Terry, Illinois Institute of Technology
Authors: J. Terry, Illinois Institute of Technology
M. Warren, Illinois Institute of Technology
R. Addou, Oregon State University
G.S. Herman, Oregon State University
Correspondent: Click to Email
While the use of TRISO fuels has been long postulated within High Temperature Gas Reactors, another potential use for the TRISO fuels is as an accident tolerant fuel in Light Water Reactors (LWRs). Before TRISO fuels can be used in LWRs, the corrosion properties of the different layers of TRISO fuels must be well understood. Photoelectron Spectroscopy (PES) has long been utilized to study the oxidation behavior of materials due to its sensitivity to both element and chemical state. The problem with PES has been that it has historically been a technique that required Ultrahigh Vacuum conditions for measurements. This made it difficult to study corrosion in situ. New instruments have expanded the capabilities of PES. It is now possible to measure photoemission spectra at ambient pressure. We have measured the in situ corrosion of a SiC layer grown as a TRISO simulant at a pressure of 1 mbar of H2O at temperatures up to 500 C using an ambient pressure photoemission system. We see no oxidation of the SiC layer by water at temperatures up to 350 C. Above 350 C, the SiC begins to oxidize with the formation of SiO2. In contrast, ZrN reacts at a pressure of 1 mbar of H2O at room temperature. As the temperature increases, the ZrN layer is completely converted to ZrO2. In the TRISO fuel, the barrier layer is surrounded by pyrolytic carbon. We model the protective ability of the outer carbon layer by making multilayers SiC/C and ZrN/C and measuring these under the same conditions. We find that a 2 nm carbon layer prevents the underlying barrier layers from reacting with water.