Technique for cladding of poison sheets for Cd-poisoned moderator

To make use of cadmium (Cd) as a poison structure in the liquid hydrogen moderator, various cladding methods such as explosion, heating up a solder of 70%Cd–30%Zn in Al case, cold spraying and cold rolling as well as HIP method were tested to seek the best fabrication method. Cd could be partially bonded to aluminum (Al) in all cases. The explosion method made a rather rigid bond between Al and Cd but generated a crack on Al plates behind Cd plate. Solder also bonded well with the Al case, although a part of the Al case was dissolved due to a mixture of Zn and Al. A porous Al layer on Cd plate was formed in the cold spray treatment. The applicability of the ultrasonic test is also discussed for the non-destructive defect inspection of the bonded materials.