The U.S. Nuclear Regulatory Commission (NRC) is amending its regulations to incorporate by reference the latest revisions of three NRC Regulatory Guides (RGs) approving new and revised Code Cases published by the American Society of Mechanical Engineers. This action allows nuclear power plant licensees, and applicants for construction permits, operating licenses, combined licenses, standard design certifications, standard design approvals, and manufacturing licenses, to use the Code Cases listed in these RGs, as alternatives to engineering standards for the construction, inservice inspection, and inservice testing of nuclear power plant components. This final rule changes NRC's regulations to address a petition for rulemaking (PRM), PRM-50-89, submitted by Mr. Raymond West. The final rule also restructures the NRC's requirements governing Codes and standards to align with the Office of the Federal Register's guidelines for incorporating documents by reference. This final rule announces the availability of the final versions of the three RGs that are being incorporated by reference, and a related RG, not incorporated by reference into the NRC's regulations, that lists Code Cases that the NRC has not approved for use. For additional information on these RGs, see Section XVII, Availability of Regulatory Guides, of this document.