ELECTRICAL-RESISTIVITY OF CERAMIC INSULATORS UNDER IRRADIATION USING 14 MEV NEUTRONS

Ceramic insulator materials used for various components such as diagno stic systems, in-vessel components, RF windows, etc. in fusion reactor s are exposed to severe irradiation environments which are characteriz ed by high energy neutrons with energies up to 14 MeV. The electrical resistivity of ceramic materials decreases due to radiation-induced co nductivity (RIC) during irradiation. The RIC due to 14 MeV neutrons fo r Al2O3 in the temperature range 300-570 K was measured in the neutron dose rate range 10(-2) to 100 Gy s(-1) using the fusion neutronics so urce (FNS) at the Japan Atomic Energy Research Institute. The RIC of A l2O3 was estimated for the more severe irradiation environment in ITER and a prototype fusion reactor (SSTR) by extrapolating the data due t o 14 MeV neutrons in the present study and those due to gamma-ray in a nother study. The estimated electrical degradation due to the RIC is c onsidered to be accommodated with appropriate fusion reactor designs.