Blister test of B4C-Al composite materials with different density were
completed and the rate of water absorption was calculated. The results reveal that the
difference on the rate of water absorption is significant, and the bubble occurs only
when the rate of water absorption is in a specific range, which is different with the
result of EPRI. The reason of blister may be that the pressure of hydrogen produced
in the corrosion reaction exceeds the bonding of clads and core, subsequently plastic
deformation would take place and blister formed.