Nuclear reactor technologies being developed for Generation IV reactors promise significant improvements in economics, safety, reliability and sustainability over present technologies by proper choice of cladding and structural material for the nuclear reactor. Studies to develop optimum combination of properties for steels intended for use as wrappers indicated that 9-12Cr type ferritic steels presented superior high temperature strength at temperatures below 873 K and excellent dimensional stability at high irradiation doses. Increasing the operating temperature by Oxide Dispersion Strengthening (ODS) of these steels will make them a promising candidate materials for advanced fast reactor core and fusion reactor blanket applications. The monograph elaborates the synthesis of nano-sized yttria dispersed 9%Cr martensitic steel by Mechanical Alloying (MA) and consolidation employing various powder compaction methodologies. Alloy powder characterization allowed optimization of experimental synthesis and bulk production. Characterization of the consolidated specimens was carried out to study the micro structural evolution during compaction.