Standardization of Silicon Carbide Passive Temperature Monitors for In-Core Irradiation Experiments

Accurately measuring the temperature of in-core nuclear experiments is critical to understanding temperature-dependent irradiation effects in fuel, structural, and other nuclear materials. Silicon carbide has long been used as a passive temperature monitor in such experiments because it can be fabrication into compact geometries, does not require instrumentation leads, and can provide a continuous indication of temperature between approximately 200 - 1,000°C. Over the past 60 years, researchers have used several types of SiC and a range of analytical methods in determining the experiment irradiation temperature. The majority of these approaches rely on isochronal or continuous annealing of the monitor and repeated measurements of thermophysical properties - such as swelling, stored energy, coefficient of thermal expansion, electrical resistivity, or thermal diffusivity - to determine the temperature where property recovery begins, corresponding to the temperature of the monitor during irradiation. Despite the sizeable body of research which use SiC monitors, a guide to using, measuring, and interpreting SiC monitor data has not been established. This paper presents recent work towards developing a standardized approach to material selection, implementation, and analysis of silicon carbide temperature. A review of historical techniques, along with more recent and automated analytical methods is also included. Finally, a proposed approach to round-robin testing by independent laboratories using previously irradiated silicon carbide is discussed.