Evaluation of insulating property of ceramic materials for V/Li blanket system under fission reactor irradiation

To examine radiation effects on electrical insulating performance of candidate ceramic materials developed for the V/Li blanket system, in situ conductivity measurements for bulk specimens of Y2O3, CaZrO3 and Er2O3 were carried out during irradiation with fission neutrons in JMTR (Japan Material Testing Reactor). Evaluated radiation induced conductivities (RIC) of the specimens were 5.2 × 10−9 S/m for Y2O3 at ∼8 Gy/s (50 °C), 1.8 × 10−8 S/m for CaZrO3 at ∼40 Gy/s (35 °C) and 2.1 × 10−8 S/m for Er2O3 at ∼50 Gy/s (45 °C), respectively. The present results were consistent with the values extrapolated from the previous data obtained by DT neutron irradiations at low dose rate of up to ∼0.1 Gy/s. The flux dependence of the data indicates that RIC of the candidate ceramics with different radiation species could be well correlated using Gy/s as a parameter. The present results showed that the electrical degradation due to RIC will not prevent the achievement of required insulating performance for the blanket system.