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Title: Neutron irradiation induced microstructural changes in NBG-18 and IG-110 nuclear graphites

This paper reports the neutron-irradiation-induced effects on the microstructure of NBG-18 and IG-110 nuclear graphites. The high-temperature neutron irradiation at two different irradiation conditions was carried out at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. NBG-18 samples were irradiated to 1.54 dpa and 6.78 dpa at 430 °C and 678 °C respectively. IG-110 samples were irradiated to 1.91 dpa and 6.70 dpa at 451 °C and 674 °C respectively. Bright-field transmission electron microscopy imaging was used to study the changes in different microstructural components such as filler particles, microcracks, binder and quinoline-insoluble (QI) particles. Significant changes have been observed in samples irradiated to about 6.7 dpa. The closing of pre-existing microcracks was observed in both the filler and the binder phases. The binder phase exhibited substantial densification with near complete elimination of the microcracks. The QI particles embedded in the binder phase exhibited a complete microstructural transformation from rosettes to highly crystalline solid spheres. The lattice images indicate the formation of edge dislocations as well as extended line defects bridging the adjacent basal planes. The positive climb of these dislocations has been identified as the main contributor to the irradiation-induced swelling of the graphite lattice.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. Boise State Univ., ID (United States). Dept. of Materials Science and Engineering; Idaho Falls, ID (United States) Center for Advanced Energy Studies
  2. Boise State Univ., ID (United States). Dept. of Materials Science and Engineering; Idaho Falls, ID (United States) Center for Advanced Energy Studies; Idaho National Lab. (INL), Idaho Falls, ID (United States)
  3. Idaho Falls, ID (United States) Center for Advanced Energy Studies; Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1177630
DOE Contract Number:
NE0000140; 00041394/00026
Resource Type:
Journal Article
Resource Relation:
Journal Name: Carbon; Journal Volume: 86; Journal Issue: C
Publisher:
Elsevier
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); Nuclear Regulatory Commission (NRC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; EDGE DISLOCATIONS; NEUTRONS; ATOMIC DISPLACEMENTS; GRAPHITE; Hexagonal Lattices; IRRADIATION; IDAHO NATIONAL LABORATORY; MICROSTRUCTURE; TRANSMISSION ELECTRON MICROSCOPY; BINDERS; TEST REACTORS; TEMPERATURE RANGE 0400-1000 K; CRACKS; FILLERS; PARTICLES; SWELLING NUCLEAR GRAPHITES