ACKNOWLEDGMENTS The authorsw ould like to acknowledget he assistance of P. Brashear of UCSB for his optical metallographym easurements;
P . McCon-nell and W. Daniels of Fracture Control Corporation (FCC) who conducted the Charpy testing and T. Lechtenbergo f GA Technologies for providingt he materiala nd helpful discussions on the metallurgy of HT-9. The authors also thank R. Ritchie of UC Berkeley and R. Wullaert of FCC for many helpfuld iscussions. This work was sponsoredb y the US DOE Office of Fusion Energy under contractA M03-76SF0034;