INFLUENCE OF REACTOR IRRADIATION ON THE PHYSICOMECHANICAL PROPERTIES OF ELECTRO-CERAMICS OF SOME COMMERCIAL GRADES

The international thermonuclear experimental reactor (ITER) foresees t he use of electrical insulation ceramic materials in the chamber, cont rol elements and diagnostic apparatus. During their lifetime these ele ments will be exposed to a high fluence of neutrons. The electro-ceram ic materials of commercial grades of low cost can quite meet the prese nted requirements in the unirradiated state. Objective of this work is the investigation of the neutron irradiation influence on the physico -mechanical properties of such ceramics. The irradiation of specimens was carried out in the BOR-60 reactor at 340-370 degrees C up to maxim um neutron fluence of 2.2 x 10(26) m(-2) (E > 0.1 MeV). The specimens were made from commercial ceramics of the high-alumina (grades MK, GB- 7, 22 HS) end steatite (grade SPK-2) classes. It was observed that the high-alumina ceramics underwent significant irradiation induced swell ing, reduction in rupture strength, Young's and shear modulus, and Poi son's ratio. The ceramics of the steatite class was found to be more r esistant to the radiation swelling and strengthening.