CHARACTERIZATION OF Y2O3 COATING UNDER NEUTRON-IRRADIATION

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. Y2O3 is one of the most promising materials as a coating from a point of high electrical resistivity, et c. In this report, the electrical conductivity of a Y2O3 coating was i nvestigated under neutron irradiation with the Japan Materials Testing Reactor (JMTR). The specimen was 316SS with a Y2O3 coating, and was i rradiated at 300 degrees C in a He atmosphere. From the results of in situ measurements on the electrical conductivity of a Y2O3 coating, th e 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 x 10(-13) and about 1 x 10( -9) 1/Omega/cm, respectively. The electrical conductivity of the coati ng was constant under neutron irradiation but after neutron irradiatio n recovered up to that before neutron irradiation. The Radiation Induc ed Electrical Degradation (RIED) in the Y2O3 coating was not recognize d up to a fluence of about 5 x 10(20) n/cm(2) (>1 MeV). It was clear t hat the coating had good electrical resistivity under neutron irradiat ion corresponding to about 4 x 10(10) Gy. (C) 1998 Elsevier Science B. V. All rights reserved.