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Title: Microstructure and mechanical properties of heat-treated and neutron irradiated TRISO-ZrC coatings

Journal Article · · Journal of Nuclear Materials
 [1];  [2];  [3];  [3];  [2]
  1. Virginia Commonwealth Univ., Richmond, VA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Japan Atomic Energy Agency (JAEA), Ibaraki Ken (Japan)

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. 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.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1265781
Journal Information:
Journal of Nuclear Materials, Vol. 464, Issue 5; ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English