ELECTRICAL-CONDUCTIVITY CHANGE IN SINGLE-CRYSTAL AL2O3 AND MGO UNDER NEUTRON AND GAMMA-RAY IRRADIATION

In situ electrical conductivity measurements under reactor and gamma-r ay irradiation were carried out for Al2O3 and MgO specimens using JRR- 3 and a Co-60 gamma-ray irradiation facility at JAERI. The specimens w ere irradiated in the temperature range 573 to 723 K for two cycles (a bout 0.2 dpa) with an applied de electric field of 100 V/mm. The condu ctivity level evaluated after the shutdown of the reactor was substant ially smaller than those during the reactor operation. Thus, it was co nsidered that radiation induced electrical degradation (RIED) did not occur or was a negligibly small level, up to 0.2 dpa for Al2O3 and MgO specimens. The conductivity of the Al2O3 specimen evaluated at variou s reactor powers in JRR-3 was consistent with that measured under the Co-60 gamma-ray irradiation and was in fairly good agreement with the other radiation induced conductivity (RIC) data of high-purity Al2O3. (C) 1998 Elsevier Science B.V.