BS ISO 4917-1:2024
Design of nuclear power plants against seismic events - Principles

Standard No.

BS ISO 4917-1:2024

Release Date

2024

Published By

British Standards Institution (BSI)  GB  /  BSI

Latest

BS ISO 4917-1:2024

Introduction

Overview of the core content of the standard

BS ISO 4917-1:2024, as the first part of the series of standards for seismic design of nuclear power plants, establishes the seismic design principles for nuclear power plants with water-cooled reactors. The standard requires that by determining the design basis earthquake (DBE) parameters, nuclear power plant components and civil structures must meet four major safety goals: controlling reactivity, cooling fuel assemblies, limiting the leakage of radioactive materials, and reducing radiation exposure.

---

Earthquake Engineering Parameter Specifications

Chapter 5 of the standard specifies in detail the method for determining the design basis earthquake, which must be evaluated through probability method and/or deterministic analysis. The key parameters include:

• Minimum horizontal peak ground acceleration of 0.1g
• Acceleration response spectrum of 5% critical damping
• Duration of strong shaking
• Vertical to horizontal motion ratio (V/H)

Analysis method	Input requirements	Output parameters
Deterministic analysis	Historical earthquake data, active fault survey	Maximum credible earthquake scenario
Probabilistic analysis	Seismic hazard curve (10-2-10-7/year)	Uniform hazard response spectrum

---

Safety classification and verification requirements

Chapter 6 of the standard divides nuclear facility components into three seismic resistance categories:

1. Category 1: Systems that directly affect safety targets and require verification of bearing capacity, integrity and functionality
2. Category 2: Auxiliary equipment that may affect Category 1 systems
3. Category 3: Non-safety related facilities

Verification methods include time history analysis (at least 3 sets of independent acceleration time histories) and response spectrum method (CQC combination rule).

---

Technology Evolution and Implementation Recommendations

Compared with the earlier versions, the main updates of the 2024 version include:

• Introduction of IAEA SSG-67 requirements for beyond-design basis earthquakes
• Refinement of soil-structure interaction analysis specifications
• Clear compatibility standards for artificial seismic motion histories

Implementation Recommendations: For new nuclear power plants, it is recommended to cross-validate the probabilistic and deterministic methods; the assessment of existing facilities should focus on checking the seismic margin of Category 1 systems.

BS ISO 4917-1:2024 history

• 2024 BS ISO 4917-1:2024 Design of nuclear power plants against seismic events - Principles

Standard and Specification