IEC 63435-2025 PDF

Full title and description

IEC 63435:2025 — Nuclear facilities - Human machine interfaces - Operator support systems. This international standard specifies the characteristics, lifecycle principles and human factors engineering (HFE) requirements for operator support systems (OSS) used by control room staff, maintenance engineers and emergency response personnel in nuclear facilities. It defines OSS functions, design guidance and verification & validation (V&V) criteria to support safe operation and decision making.

Abstract

IEC 63435:2025 establishes a unified design framework and technical requirements for operator support systems (OSS) in nuclear installations. The standard sets out OSS characteristics, lifecycle and project-organization principles, human factors (HFE) guidelines for OSS design, and verification & validation (V&V) requirements. It is aimed primarily at OSS introduced in new nuclear facilities whose conceptual design is initiated after the standard's publication, while also serving as guidance for upgrades or retrofits in existing plants.

General information

• Status: Published (International Standard).
• Publication date: 6 October 2025.
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 27.120.20 (Nuclear power plants — Safety / HMI topics).
• Edition / version: Edition 1.0 (2025).
• Number of pages: 33 pages (base IEC publication).

Details above are based on the IEC publication record for IEC 63435:2025.

Scope

IEC 63435:2025 applies to operator support systems (OSS) that provide decision support, situation assessment and related functions for control room operators, maintenance engineers and emergency response staff in nuclear facilities. The standard is written principally for OSS introduced in facilities whose conceptual design begins after 6 October 2025, but it may also be applied when designing or upgrading OSS in existing plants. It covers OSS lifecycle principles, human factors engineering requirements for design, and verification & validation procedures to demonstrate safety and performance.

Key topics and requirements

• Definition of OSS concept, functional roles and interfaces with control-room HMI and plant systems.
• Lifecycle and project-organization principles specific to OSS procurement, development, commissioning and maintenance.
• Human factors engineering (HFE) requirements and guidelines for OSS design (usability, information presentation, decision support ergonomics).
• Verification and validation (V&V) requirements and recommended methods to demonstrate OSS safety, reliability and performance.
• Requirements for integration of OSS with existing control-room hardware/software and operations procedures.
• Guidance on use of OSS in operation, maintenance and emergency response contexts to reduce human error and improve situational awareness.

The list above summarises the technical scope and normatively framed requirements given in IEC 63435:2025.

Typical use and users

Primary users are nuclear utilities, nuclear control-room designers, HMI/HFE engineers, safety and licensing authorities, OSS vendors and system integrators, and plant modernization project teams. Typical uses include specifying OSS performance and HFE requirements for new builds, developing procurement specifications, guiding OSS integration and conducting V&V activities during commissioning and modernization.

Related standards

IEC 63435:2025 is part of the IEC body of nuclear HMI and HFE standards. Closely related standards include: IEC 63351:2024 — Nuclear facilities — Human factors engineering — Application to the design of human‑machine interfaces, and IEC 60964:2018 — Nuclear power plants — Control rooms — Design (and related MCR/HMI design guidance). National adoptions (for example BS IEC 63435:2025) reflect regional publication/adoption dates and pagination differences. These related documents should be used together when specifying HMI/HFE and OSS requirements.

Keywords

operator support system, OSS, human–machine interface, HMI, human factors engineering, HFE, verification and validation, V&V, nuclear facilities, control room, decision support.

FAQ

Q: What is this standard?

A: IEC 63435:2025 is an international standard that sets requirements for operator support systems (OSS) used in nuclear facilities, covering OSS characteristics, lifecycle, human factors guidance and V&V.

Q: What does it cover?

A: It covers OSS functional roles, design and integration with control-room HMI, HFE programme requirements for OSS design, lifecycle and project organization principles, and verification & validation methods to demonstrate OSS safety and performance.

Q: Who typically uses it?

A: Nuclear plant operators, control-room and HMI designers, human factors engineers, safety assessors and regulators, vendors/integrators of OSS, and project teams responsible for new-builds or modernization of plant control systems.

Q: Is it current or superseded?

A: IEC 63435:2025 is a current IEC publication (Edition 1.0, published 6 October 2025). The IEC webstore lists the document as the published international standard with a stability date indicated by the publisher. Users should check national adoption records for any local status differences.

Q: Is it part of a series?

A: It is part of the family of IEC documents addressing HMI and human factors for nuclear facilities (for example IEC 63351:2024 and IEC 60964:2018) and is intended to be used together with other nuclear HFE and control-room design standards.

Q: What are the key keywords?

A: operator support system, OSS, HMI, HFE, verification and validation (V&V), control room, nuclear facilities, decision support.