A study of the annealing behavior of neutron irradiated graphite
โ Scribed by T.D. Burchell; P.J. Pappano; J.P. Strizak
- Book ID
- 104009320
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 652 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0008-6223
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โฆ Synopsis
Recycle is being considered as a waste mitigation option for irradiated graphite from gas cooled reactors. Thermal annealing was performed on irradiated graphite samples to establish what fraction of in-crystal (displacement damage) and ex-crystal (pore generation) damage could be recovered. The sample dimensions and electrical resistivity were measured after isochronal annealing at 500, 1000, 1500, and 2000 ยฐC. Sample dimensions were unaffected by annealing. Some fraction of the resistivity was non-recoverable at 2000 ยฐC, this behavior which was attributed to (a) structural changes resulting from pore generation (also causing dimensions to be unaffected by annealing) or (b) defect structures in irradiated graphite that persist even at an annealing temperature of 2000 ยฐC. The resistivity annealing behavior was different in low irradiation temperature samples, T irr < $400 ยฐC and high irradiation temperature samples T irr > $400 ยฐC, which indicated defect structures established during irradiation were different in these two temperature regimes. Moreover, the extent of recovery was much greater in the specimens with higher irradiation temperatures, and was small for lower dose-low temperature specimens. Evidently, some in-crystal defects that scatter or trap electrons are still present in the crystal lattice after annealing and their tenacity depends upon the irradiation temperature and accumulated neutron dose.
๐ SIMILAR VOLUMES
A reactor grade graphite irradiated by fast neutrons at 30ยฐC to the total dose of 5% x 102\* nvt was stepwise annealed between 100" and 23OO"C, and was examined each time by measuring the internal friction and dynamic modulus at temperatures from 300" down to 80ยฐK. The recovery process has been foun