Damage analysis and fundamental studies for fusion reactor materials development for the period March 1, 1991--February 28, 1994. Final report

The philosophy of the program at the University of California Santa Barbara has been to develop a fundamental understanding of both the basic damage processes and microstructural evolution that take place in a material during neutron irradiation and the consequent dimensional and mechanical property changes. This fundamental understanding can be used in conjunction with empirical data obtained from a variety of irradiation facilities to develop physically-based models of neutron irradiation effects in structural materials. The models in turn can be used to guide alloy development and to help extrapolate the irradiation data base to the fusion reactor regime. This philosophy is consistent with that of the national and international programs for developing structural materials for fusion reactors. During this period work has encompassed: (1) analysis of the degradation of the mechanical properties of austenitic stainless steels for the purpose of assessing the feasibility of using these steels in ITER; (2) examining helium effects on radiation damage in austenitic and ferritic stainless steels; (3) development and application of electropotential drop techniques to monitor the growth of cracks in steel specimens for a variety of specimen geometries (4) development of advanced methods of measuring fracture properties; (5) combining micromechanical modeling of fracture with finite element calculations of crack and notch-tip stress and strain fields to predict failure; (6) developing a data base on flow and fracture properties of ferritic steels. Each of these activities is described in more detail below and in greater detail in the attached publications