Abstract: This technical report covers the investigation of 17-4 PH steel components used in the SM-1, SM-1A and PM-2A nuclear power plants, which consist of control rod drive racks, pinions, seal shafts and associated parts. Evidence supporting the continued use of 17-4 PH steel in these applications is presented. Alco's current procurement and processing specifications for 17-4 PH steel are included. The evidence presented is in the form of stress calculations, test and environmental data and the results of non-destructive and destructive metallographic analyses.