Characterization of Y 2O 3 coating under neutron irradiation

Abstract

Ceramic coatings on the surface of structural materials such as 316SS have been considered for electrical insulators and tritium permeation barriers in fusion reactor designs. Y 2O 3 is one of the most promising materials as a coating from a point of high electrical resistivity, etc. In this report, the electrical conductivity of a Y 2O 3 coating was investigated under neutron irradiation with the Japan Materials Testing Reactor (JMTR). The specimen was 316SS with a Y 2O 3 coating, and was irradiated at 300°C in a He atmosphere. From the results of in situ measurements on the electrical conductivity of a Y 2O 3 coating, the Radiation Induced Conductivity (RIC) was observed at JMTR power-up. The electrical conductivity of the coating before neutron irradiation and under neutron irradiation were about 3 × 10 −13 and about 1 × 10 −9 1/Ω/cm, respectively. The electrical conductivity of the coating was constant under neutron irradiation but after neutron irradiation recovered up to that before neutron irradiation. The Radiation Induced Electrical Degradation (RIED) in the Y 2O 3 coating was not recognized up to a fluence of about 5 × 10 20 n/cm 2 (>1 MeV). It was clear that the coating had good electrical resistivity under neutron irradiation corresponding to about 4 × 10 10 Gy.