Abstract
Six developmental sets of as-fabricated and heat-treated, near- and hyper-stoichiometric ZrC coated TRISO particles were subject to fast neutron (E > 0.1 MeV) fluences of 2 and 6 × 1025 neutrons/m2 at 800 and 1250°C to assess the effects of irradiation on the coating microstructure and mechanical properties. Pre-irradiation microstructural analysis showed that the all but one of the near-stoichiometric samples fabricated by CVD had a homogenous grain structure while others including the hyper-stoichiometric sample had a distinct tiered band pattern with alternating carbon rich interlayers. The band structure in the near-stoichiometric samples became prominent following the heat treatment and the homogenous grained sample underwent severe grain growth. Post-irradiation observations indicated that neutron irradiation did not have any significant effects on the bulk microstructure of any of the samples regardless of the stoichiometry. Post-irradiation softening and reduction in modulus at the highest dose (6 dpa) were observed in all samples regardless of the composition and structure but were less significant in specimens with a banded microstructure. It was concluded that the carbon interlayers which contributed to the formation of the band structure had played a role in preserving the microstructure and the mechanical properties following both heat treatment and irradiation.
| Original language | English |
|---|---|
| Pages (from-to) | 245-255 |
| Number of pages | 11 |
| Journal | Journal of Nuclear Materials |
| Volume | 464 |
| DOIs | |
| State | Published - May 6 2015 |
Funding
This work was supported by the International Nuclear Energy Research Initiative (Project Number: 2006-001-J) and the Advanced Gas Reactor projects under the aegis of the US Department of Energy. The work described above is a collaborative effort involving the Oak Ridge National Laboratory and the Japan Atomic Energy Agency. The authors wish to acknowledge the staff at ORNL-LAMDA, ORNL-IMET facilities for their assistance at various stages of the project. The authors also gratefully acknowledge the assistance rendered by the ORNL’s SHaRE user program by allowing the use of XL-30 and JEOL 6500F Scanning electron microscopes for the microstructural observations.