IEC 62138:2018

Overview

IEC 62138:2018 - “Nuclear power plants – Instrumentation and control systems important to safety – Software aspects for computer-based systems performing category B or C functions” - specifies requirements for the software of computer-based I&C (instrumentation & control) systems used in nuclear power plants when those systems perform safety category B or C functions (per IEC 61226). It complements IEC 60880 (software for category A systems) and aligns with system-level requirements in IEC 61513. The 2018 edition updates alignment with newer IEC documents, tightens traceability expectations, revises pre‑developed software selection criteria, merges repetitive clauses, and adds informative annexes.

Key Topics and Technical Requirements

• Software safety lifecycle: Defines lifecycle activities and software quality assurance that must support safety case development and maintenance.
• Gradation and class applicability: Requirements tailored by safety category (B or C) and safety class (class 2/class 3) with proportional rigor.
• Selection of pre‑developed software: Criteria and evidence of correctness for off‑the‑shelf or pre‑built components, including documentation and qualification processes.
• Software requirements specification (SRS) and design: Expectations for clear, traceable SRS, architectural design, and detailed software design inputs/outputs.
• Verification and validation: Systematic verification, testing, and validation practices to demonstrate conformance to safety requirements.
• Configuration management & traceability: Formal CM practices and traceability from requirements through code, tests and deployment in line with IEC 61513.
• Tools, languages and implementation: Guidance on tool selection, language considerations, and implementation controls for both application‑oriented and general‑purpose languages.
• Integration, installation & anomaly reporting: Requirements for system integration testing, site installation, operational anomaly reporting and controlled modification.
• Defence against common‑cause failures: Measures to reduce software common‑cause risks in redundant or diverse systems.
• Informative annexes: Typical documentation lists and mappings to IEC 61513 and IEC 61508 for cross‑reference.

Practical Applications and Users

IEC 62138:2018 is used by:

• Nuclear I&C engineers and software developers designing computer‑based safety systems (category B/C).
• System integrators and manufacturers qualifying pre‑developed software or embedded devices.
• Quality assurance, configuration management, and verification teams implementing software safety lifecycle controls.
• Regulators, safety assessors and plant owners evaluating conformity and supporting licensing evidence.
• Procurement and project managers specifying supplier deliverables and documentation for safety‑related software.

Related Standards

• IEC 61513 - Nuclear I&C system-level safety requirements (complementary).
• IEC 60880 - Software for category A (highest safety) systems.
• IEC 61226 - Classification of safety functions by category.
• IEC 62645, IEC 62671 - Related nuclear I&C standards aligned in the 2018 update.
• IEC 61508 - Functional safety framework (informative relation via Annex C).

Keywords: IEC 62138:2018, nuclear power plants, instrumentation and control, I&C systems, software safety lifecycle, category B C functions, pre‑developed software, traceability, verification, configuration management.