“…In FIRD ferritic/martensitic steels developed in the European Union, Japan, and the United States, molybdenum was replaced by tungsten in the conventional Cr-Mo steels to produce Cr-W steels; niobium was replaced by tantalum. [4,5,6] Just as the work on conventional steels emphasized the high-chromium steels 9Cr-1MoVNb and 12Cr-1MoVW, [1,2,3] work on reduced-activation steels has concentrated on 7 to 10 pct Cr steels. [4,5,6] Initial studies at Oak Ridge National Laboratory (ORNL) were on steels with 2.25 to 12 pct Cr.…”