This standard specifies the required earthquake instrumentation at the site and on Seismic Category I structures of light-water-cooled@ land-based nuclear power plants. It may be used for guidance at other types of nuclear facilities. This standard does not address the following: (1) instrumentation to shut down a nuclear power plant automatically at a predetermined parameter of the ground motion or the in-structure response; (2) procedures for evaluating records obtained from seismic instrumentation and instructions for the treatment of data. These procedures and instructions are specified in ANSI/ANS-2.23-2016 [1]1); (3) instrumentation for nuclear power plant designs incorporating base isolation techniques Purpose This standard defines the minimum requirements for an earthquake instrumentation system to be installed at nuclear power plants. These instruments are intended to provide timely (within 4 hours) information on the earthquake ground motion at the site and the corresponding response vibratory motion of Seismic Category I structures@ when subjected to earthquake ground motion. By comparing this information with the vibratory motions used in the facility??s seismic design@2) an evaluation can be made as to whether or not the design basis vibratory motions have been exceeded. 1)Numbers in brackets refer to corresponding numbers in Sec. 10@ ??References.?? 2)Appendix A provides an overview of applicable licensing practices used in the issuance of early site permits and combined licenses.