Effect of Irradiation Temperature on the Growth of Helium Bubbles in Boron Carbide

Abstract

Boron carbide, in nuclear reactor neutron absorber applications, generates large quantities of helium, some of which is trapped in small bubbles within the grains. Transmission electron microscopy was used to examine the size distribution, shape, and density of these bubbles in boron carbide irradiated, at 540° to 1850°C, to burnups of 62 × 1020 captures/cm3. Bubble density was reduced but bubble diameter was increased at high temperatures. Bubbles were flat disks at low temperatures and more equiaxed at higher temperatures.