The U.S. Nuclear Regulatory Commission (NRC) is amending its regulations to incorporate by reference revisions of three regulatory guides to approve new, revised, and reaffirmed 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 regulatory guides as voluntary alternatives to engineering standards for the construction, inservice inspection, and inservice testing of nuclear power plant components. These engineering standards are set forth in the American Society of Mechanical Engineers Boiler and Pressure Vessel Code and American Society of Mechanical Engineers Operation and Maintenance Code, which are currently incorporated by reference into the NRC's regulations. Further, this final rule announces the availability of a related regulatory guide, not incorporated by reference into the NRC's regulations, that lists code cases that the NRC has not approved for use. Finally, this rulemaking provides more flexibility to licensees by expanding the code of record interval from ten years to two consecutive inservice testing and inservice inspection intervals.