Electrical behaviour of ceramic breeder blankets in pebble form after γ-radiation

Abstract Lithium orthosilicate (Li 4 SiO 4 ) ceramics in from of pebble bed is the European candidate for ITER testing HCPB (Helium Cooled Pebble Bed) breeding modules. The breeder function and the shielding role of this material, represent the areas upon which attention is focused. Electrical measurements are proposed for monitoring the modification created by ionizing radiation and at the same time provide information on lithium movement in this ceramic structure. The electrical tests are performed on pebbles fabricated by Spray-dryer method before and after gamma-irradiation through a 60 Co source to a fluence of 4.8 Gy/s till a total dose of 5 ∗ 10 5  Gy. The introduction of thermal annealing treatments during the electrical impedance spectroscopy (EIS) measurements points out the recombination effect of the temperature on the γ-induced defects.