Interaction of Palladium, the Rare Earths, and Silver with Silicon Carbide in HTGR Fuel Particles.

摘要

The interactions of the simulated fission products palladium, rare earths, and silver with the silicon carbide (SIC) Triso-coated, high-temperature, gas-cooled reactor (HTGR) particles were investigated out-of-reactor in the temperature range 1500 to 1780 K. Both palladium and the rare earths interact in proportion to time (rather than the square root of time) up to 8600 h (0.98 year), the time limit of the study. Grain-boundary mechanisms are suggested. Effects of the SiC microstructure on the palladium reaction rate were minimal in comparison to the temperature effects. Silver interactions with SiC were observed, but could not be quantified. In a second set of experiments, the addition of silicon to carbide-containing kernels resulted in retention of U-Pd-Si-C compounds in the kernel. These prevented the reaction of palladium with SiC at temperatures of 1670 to 1920 K as long as rare-earth carbides were not present.