Nondestructive Characterization of Void Swelling in Reactor Structural Materials

The Nuclear Regulatory Commission has recently required that a void swelling surveillance program be in place for austenitic core internals, prior to their unconditional authorization of lifetime extension of current light water reactors. Void swelling was the life-limiting damage mechanism in fast reactors, but sodium-cooled Generation IV and GNEP fast burner reactors will experience exposure to much higher levels. This project will use ultrasonic methods to develop nondestructive measurement techniques and sensors to characterize complex radiation-induced microstructures, especially voids giving rise to swelling. The efficiency of these methods will be tested to determine the distribution of swelling in three well-characterized, large hexagonal reflector blocks. Commercial Applications and other Benefits as described by the awardee: These techniques and tools would enable the surveillance of internal components of prototype fast burner reactors, giving early warning of any unanticipated problems associated with void swelling. Additionally, these tools would reduce the need for more expensive destructive examination in both the material development and selection phases of the GNEP fast burner program.