Capsule HRB-15B postirradiation examination report
Capsule HRB-15B design tested 184 thin graphite trays containing unbonded fuel particles to peak exposures of 6.6 x 10/sup 25/ n/m/sup 2/ (E > 29 fJ)/sub HTGR/ fast fluence, approx. 27% fissions per initial metal atom (FIMA) fissile burnup, and 6% FIMA fertile burnup at nominal time-averaged temperatures of 815 to 915/sup 0/C. The capsule tested a variety of low-enriched uranium (approx. 19.5% U-235) fissile particle types, including UC/sub 2/, UC/sub x/O/sub y/, UO/sub 2/, zirconium-buffered UO/sub 2/ (referred to in this report as UO/sub 2//sup *), and 1:1(Th,U)O/sub 2/ with both TRISO and silicon-BISO coatings. All fertile particles were ThO/sub 2/ with BISO, silicon-BISO, or TRISO coatings. The findings indicated that all TRISO particles retained virtually all of their fission product inventories, except small quantities of silver, at these irradiation temperatures, while some of the silicon-BISO particles released significant amounts of both silver and cesium. No kernel migration, pressure vessel, or outer pyrolytic carbon (OPyC) failures were observed in the fuel particles, which had total diameters of < 900 ..mu..m; however, the incidence of failed OPyC coatings was found to increase with particle size in the TRISO inert particles, which had diameters of 1000 to 1200 ..mu..m. UO/sub 2//sup */ particles exhibited no detrimental irradiation effects, but they contained pure carbon precipitates in the kernels after irradiation which were not observed in the undoped UO/sub 2/ particles. Postirradiation examination revealed no differences in the irradiation performance of three UC/sub x/O/sub y/ kernel types with varying oxygen/uranium ratios.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- DOE Contract Number:
- AT03-76ET35300
- OSTI ID:
- 6332616
- Report Number(s):
- GA-A-15940; ON: DE81028590; TRN: 81-013856
- Country of Publication:
- United States
- Language:
- English
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