Neutron Irradiation Effect on Isotopically Tailored ^<11>B_4C

概要

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The present investigation was carried out to elucidate the effects of neutron irradiation on the dimensional change and thermal conductivity of isotopically tailored 11B4C. The specimens used in the present investigation are 99% 11B-enriched 11B4C, 91% 10B-enriched 10B4C, and β-SiC. 10B4C was sampled from an irradiated material used as a neutron absorber in a “JOYO” MK-II control rod. The 11B4C and SiC specimens were irradiated in the experimental fast reactor “JOYO” to fluences of 1.94×1026 n/m2 (E>0.1 MeV) at 530°C and 3.12×1026 n/m2 (E>0.1 MeV) for 10B4C, with a 10B burnup of 47.3×1026 cap/m3. Measurements on changes in dimensions and thermal conductivity, as well as postirradiation annealing up to 1400°C, were carried out. The results of such measurements indicated that the changes in the dimensions and thermal conductivity of neutron-irradiated 11B4C were substantially smaller than those of 10B4C and SiC. Postirradiation annealing measurements for 11B4C showed that the thermal conductivity was almost completely recovered at 1400°C. The changes in thermal conductivity by annealing were analyzed in terms of phonon scattering theory. The onset of recovery of the thermal conductivity of 11B4C agreed well with irradiation temperature; however, the recovery of length did not coincide with irradiation temperature.
社団法人日本原子力学会の論文
2008-09-01