Abstract
Beryllium is planned to be used as a neutron multiplier in the Helium Cooled Pebble Bed (HCPB) European concept of a breeding blanket of DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron irradiated at temperatures typical for fusion blanket. Beryllium pebbles with a diameter of 1mm produced by the Rotating Electrode Method were subjected to a TEM study after irradiation at the HFR, Petten, at temperatures of 686, 753, 861, and 968K. The helium production in the pebbles was calculated in the range from 2090 to 3090appm. Gas bubbles as disks of hexagonal shape were observed for all four irradiation temperatures. The disks were oriented in the (0001) basal plane with a height directed along the [0001] “c” axis. The average diameters of the bubbles increase from 7.5 to 80nm with increasing irradiation temperature, the bulk densities accordingly decrease from 4.4×1022 to 3.8×1020m−3. With increasing irradiation temperature, the swelling of the pebbles increases from 0.6% at 686K up to 6.5% at 968K.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call