ISO 4917-5:2024

This document specifies the utilization and characteristics of instrumentation used to detect seismic events at nuclear power plants with water cooled reactors. The document can also be applied to other nuclear facilities after verifying its applicability. The following types of electrical systems and equipment are not covered by this document: — seismic instrumentation involved in the implementation of nuclear safety functions as defined by IEC 61226, for example automatic shutdown systems; — seismic instrumentation not involved in the implementation of nuclear safety functions as defined by IEC 61226 but which due, for example, to close proximity to other safety classified systems, requires hardware qualification to be performed. Such systems are specified, designed, manufactured, qualified, operated and dismantled according to the relevant requirements of IEC standards, in particular IEC 61513 and the lower level IEC standards according to the safety class and technologies used. Seismic instrumentation used for the implementation of seismic reactor trip systems are developed according to the requirements of IEC 63186. An automatic shutdown system is not covered by this document. This document specifies the requirements to be fulfilled by the seismic instrumentation such that, firstly, it can be ascertained whether any of the design quantities on which the plant walk-down level and the inspection levels are based have been exceeded and that, secondly, the recording of the time history of the earthquake provides the necessary input values for a post-seismic analysis. The requirements are specified such that, independent of the detection and recording system, comparable results within tolerances are achieved in the time range as well as the frequency range.