NANO-INDENTATION HARDNESS MEASUREMENTS AS A CHARACTERIZATION TECHNIQUE OF SiC- AND PYROLYTIC CARBON LAYERS OF EXPERIMENTAL PBMR COATED PARTICLES

摘要

The Pebble Bed Modular Reactor (PBMR) fuel consists of Tri-Isotropic (TRISO) coated particles in a graphite matrix. The containment of fission products inside the TRISO coated particles (CPs) is dependent on the integrity of the three layer system namely Inner Pyrolytic carbon (IPyC)-SiC-Outer Pyrolytic Carbon (OPyC). The dependency of the fission product transport mechanisms on the properties of SiC is considered in the design of the PBMR Fission Products Transport Mechanism Experimental Program, therefore experiments are developed to study the combined effect of temperature and irradiation properties on SiC properties. Nano-indentation hardness measurements were identified as a possible characterization technique to show changes due to SiC decomposition and PyC becoming anisotropic. The nano-indentation technique is briefly discussed in this article, followed by a discussion of recent nano-indentation results from five experimental PBMR coated particle batches annealed at a temperature range of 1000℃ to 2100℃, The effect of long-duration annealing on these nano-indentation hardness values will also be demonstrated by comparing results from 1 hour; 5 hours and 100 hours annealing of coated particles at a temperature of 1600℃.