ISO 4917-4:2024

Overview

ISO 4917-4:2024 - Design of nuclear power plants against seismic events - Part 4: Components specifies requirements for demonstrating earthquake safety of components in nuclear power plants with water-cooled reactors. It covers the seismic verification scope, modelling and analysis approaches, and testing/qualification principles for mechanical and electrical components (including their support structures). The document complements structural requirements in ISO 4917-3 and the principles in ISO 4917-1.

Key topics and technical requirements

• Scope and component types
  • Applies to mechanical components such as vessels, heat exchangers, pumps, valves, lifting gear, distribution systems, pipelines and supports (excluding civil structures per ISO 4917-3). Liners, crane runways, platforms and scaffoldings are excluded.
  • Defines electrical components as devices plus their electrical connections and support structures (cabinets, frames, brackets).
• Verification methods
  • Verification by analysis: response spectrum, time-history, quasi-static and non-linear time-history methods; modelling of fluids, system characteristics, decoupling and relative displacements.
  • Verification by testing: requirements for test objects and excitations (base excitation, single/multiple-frequency, centre-of-gravity and multi-axis considerations), and test-analysis correlation.
  • Verification by analogy and by plausibility considerations are also addressed.
• Seismic inputs and modelling
  • Use of design spectra, demand response spectra, and considerations for modal damping, center of gravity, and the behaviour coefficient q (reducing linear-analysis forces to account for dissipation).
• Limits of the document
  • Does not set operation-specific safety performance criteria (load-bearing capacity, integrity, functionality); component-specific standards must be consulted for those checks.
• Guidance and references
  • Annex A provides recommendations largely based on Eurocode design philosophy; equivalent standards are acceptable if they meet the general requirements.

Practical applications - who uses this standard

• Seismic and structural engineers designing or evaluating components for nuclear power plants (water-cooled reactors).
• Component manufacturers and suppliers performing seismic qualification and documentation.
• Test laboratories conducting seismic tests (shake-table, base excitation) and dynamic characterization.
• Nuclear safety assessors, plant operators and regulators verifying compliance with seismic design requirements.
• Consultants integrating component-level verification into plant-level seismic safety cases.

Related standards

• ISO 4917-1:2024 - Principles (series foundation)
• ISO 4917-3 - Structural components (civil structures)
• IEC/IEEE 60980-344 - Seismic qualification of electrical components (supplementary)

Keywords: ISO 4917-4:2024, seismic design, nuclear power plant components, seismic qualification, response spectrum, time history analysis, seismic testing, water-cooled reactors, component verification.