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

• Ionizing radiation could change the physical properties of a ceramic pebble bed for breeder blanket applications.
• A low total dose of γ-radiation causes a slight decrease in the electrical conduction calculated along the entire volume.
• In general a good electrical stability for Li4SiO4 ceramic can be stated.

Lithium orthosilicate (Li4SiO4) 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 60Co source to a fluence of 4.8 Gy/s till a total dose of 5 ∗ 105 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.